< Geanini 7 Lunar Measurements

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1 AF.CR L EPTcM8ER 1968!~CVIROI'IMENT AL RESEARCH PAPERS, NO. 291 (j') I.. ~, \:_.,.Ill AIR FORCE CAMBRIDGE RESEARCH LABORATORIES L. G, HI~()M FIELD, BII!Df'ORD, M...SSACHUSETTS Q < Geanini 7 Lunar Measurements T. P. CONDRON J. J. LOVETT W. H. BARNES L. MARCOTTE R. NADILE OFFICE OF AEROSPACE RESEARCH United States Air Frce I :. 1 ~ l t ' 1 I C l. l A '~ i r 1 ', I~ 0 U S E! I r, ~.., 1! ' ' ', ], f, ~ ' ' l. I : I '.. J " f I : ' ; I ' ~ ' I ' ' I. l. I.'.' I ~) :

2 AFCRL SE PT EMBER 1968 ENVIRONMENTAL RESEARCH PAPERS, NO. 291 OPTICAL PHYSICS LABORATORY PROJECT 8662 AIR FORCE CAMBRIDGE RESEARCH LABORATORIES L. C. HANSCOM FIELD, BEDFORD, MASSACHUSETTS Gemini 7 Lunar Measurements T. P. CONDRON J. J. LOVETT W. H. BARNES L. MARCOTTE R. NADILE Supprted by SSD 631A and ARPA Order 363 Disfributin f this dcument Is unlimited. It may be released t the Clearinghuse, Department f Cmmerce, (r sale t the general public. OFFICE OF AEROSPACE RESEARCH United States Air Frce

3 Abstract Radimetrie and interfermetric measurements were made f the lunar surface during a penumbral eclipse frm the Gemini 7 spacecraft. Data were btained in the regin frm 0.25 t 2.6 micrns. The bnd albed f the mn is cmputed fr the spectral regins measured. iii

4 Cntents 1. INTRODUCTION 2. DATA OBTAINED 3. SOLAR-LUNAR-EARTH GEOMETRY 4. ALBEDO EQUATIONS 5. GEOMETRICAL ALBEDO G. PHASE VARIATION 7. BOND ALBEDO 8. ALBEDO TABULAR SUMMARY 9. LUNAR TEMPERATURE AND EMISSION 10. CONCLUSIONS AND RECOMMENDATIONS ACKNOWLEDGMENTS REFERENCES APPENDIX A. APPENDIX B. APPENDIX C. MEASUREMENT SYSTEMS GEMINI 7 RADIOMETER CALIBRATIONS GEMINI 7 INTERFEROMETER CALIBRATIONS Al Bl Cl

5 Illustratins 1. Lcatins f Instruments 2 2. Lunar Spectral Irradiance vs. Wavelength t 3050 A 4 3. Lunar Spectral Irradiance vs. Wavelength 1. 0 t 2. 8 w 4 4. Eclipse Gemetry 6 5. Lcatin f Lunar Disk with Respect t Earth's Shadw 6 6. Lunar Phase Variatin Curve 9 7. Gemetrical Albed vs. Wavelength UV Gemetrical Albed vs. Wavelength Phase Variatins fr SS"^' Phase Angle vs. Wavelength Bnd Albed vs. Wavelength 14 A-l. Spectral Respnse f th«1-14 Interfermeter PbS Sectin A6 A-2. Saturatin and Nise Equivalent Irradiance Curves fr 1-14 Interfermeter PbS Sectin A6 A-3. Radimeter Field f View Phtmultiplier Sectin A6 A-4. Radimeter Field f View PbS Sectin A6 A-5. Interfermeter Field f View PbS Sectin A7 A-6. Instrument Alignment Pattern A7 A-7. MODE 3 Radimeter and Interfermeter Data Bresight Experiment A8 A-8. MODE 2 Phtmultiplier Data -Bresight Experiment A9 A-9. MODE 2 PbS Radimeter and Interfermeter Data Bresight Experiment A 10 A-10. Full Mn Phtmultiplier Data All A-11. Full Mn PbS Radimeter and Interfermeter Data A12 A-12. Full Mn Interfermeter Spectrum A13 A-13. Full Mn Data Cmpared With 4000 K Blackbdy A13 B-l Radimeter Schematic Diagram B28 B-2. V T vs. V E B28 B-3. V T vs. f(p) B29 B-4, thru B-13. V T G vs. Effective Irradiance B29-B34 B-14. thru B-23. V- vs. Effective Irradiance B34-B39 B-24. Radimeter Respnsivity vs. Temperature B39 B-25. Radimeter Field f View Phtmultiplier Sectin B39 B-26. Radimeter Field f View PbS Sectin B40 vi

6 lustratins B-27. thru B-36. System Respnse Curves Phtmultiplier Channels B40-B42 B-37. thru B-46. System Respnse Curves PbS Radimeter Channels B42-B45 C-l. Interfermeter Schematic Diagram C5 C-2. Interfermeter Output vs. Spectral Irradiance at 2.2 ß C5 C-3. Interfermeter Inverse Spectral Irradiance Respnsivity vs. Wavelength PbS Sectin C6 C-4. Interfermeter Respnsivity vs. Temperature PbS Sectin C6 C-5. Interfermeter Field f View -PbS Sectin C7 Tables 1. Lunar Irradiance Values 3 2. Albe- 3 Cmputatins Average Albed Cmputatin Lunar Emissin Irradiance 17 A-l. Gemini-7 Radimeter Characteristics A5 B-l. IBM Cmputatins fr Phtmultiplier Channels B8-B17 thru B-10. Bll. IBM Cmputatins fr PbS Channels B18-B27 thru B20. vn

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8 Gemini 7 Lunar Measurements 1. INTRODUCTION During the flight f Gemini-7, AP'CRL ptical instruments munted n the capsule were aimed at the mn n 5 and 8 December 1965 by Astrnauts Frank Brman and James Lvell. The bservatin n 5 December was designated the "bresight" experiment, since it was designed t check the alignment f the ptical instruments with the astrnaut's sighting scpe. The bservatin n 8 December was designated the "full mn" experiment. The primary bjective f the lunar bservatins was t satisfy a NASA- APOLLO requirement fr lunar ultravilet irradiance measurements in five brad spectral bands (200 A) lying between 2200 and 3000 A, but lunar data were als btained in additinal filtered regins that had been selected fr ther experiments. A secndary but very imprtant bjective f bth lunar bservatins was t btain in-flight mef: jurements f a target that is relatively well knwn in rder t check the validity f the data btained fr ther targets during the Gemini-7 flight. Tw interfermeters and ne radimeter manufactured by Blck Assciates were flwn n Gemini-7. The Mdel 1-14 interfermeter, which perates at ambient temperature, was equipped with a PbS detectr and a thermistr blmeter; n lunar data were btained with the blmeter sectin f this instrument. The Mdel 1-15 interfermeter was equipped with a mercury dped germanium detectr (Received fr publicatin 1, July 1968)

9 Figure 1. Lcatins f Instruments cled t liquid nen temperature; since the clant life was 15 hurs, n lunar data were btained with this instrument. The Mdel E3G radimeter flwn n Gemini-7 w^s equipped with a PbS detectr and an EMR slar blind phtmultiplier; it had a 20-psitin filter wheel that allwed fr btaining measurements in 10 filtereu spectral bands with each detectr. The lcatins f the three instruments n the spacecraft are shwn in Figure 1, a phtgraph f the Gemini-7 spacecraft taken frm the Gemini-6 craft in flight; all f the instruments were munted n the aft sectin which was jettisned befre re-entry. Detailed descriptins f the instruments used fr the lunar measure- ments are given in Appendixes B and C.

10 2. DATA OBTAINED The spectral irradiances measured with the radimeter n 5 and 8 December 1965 are given in clumns 4 and 6 f Table 1 where L is the wavelength abve and belw which 50 percent f the radimeter utput wuld be cntributed by a target having the relative spectral distributin f a 4000 K blackbdy and AL is the wavelength interval within which 7 0 percent f the utput wuld be cntributed by this blackbdy. (See Appendixes A and B.) The angles in parentheses in Table 1 are lunar phase angles and the dashes in clumns 4 and 6 indicate that the radiatin was abve the saturatin limit fr thse channels. Table 1. Lunar Irradiance Values H L (1 5 ) Signal H L (38'32' Signal! Chan N. L AL ^ t Nise ^ -2-1 t Nise micrns micrns wem t-i Rati w cm (i Rati j 1 G I ! j G I I j j The irradiances tabulated in Table 1 are pltted vs. wavelength in Figures 2 and 3. Included n Figure 3 are the irradiances btained with the PbS sectin f the 1-14 interfermeter. The scatter in the interfermeter data at the shrter wavelengths was caused by lw signal-t-nise ratis which in turn were caused by a dichric filter used in the instrument. (See Appendixes A and C.)

11 10" E 10" r < < a: FULL MOON BORESIGHT 10" WAVELENGTH (micrns) Figure 2. Lunar Spectral Irradiance vs. Wavelength 2200 t 3050 A O E I 10- z < < a. a. UJ a. FULL MOON (Rdimeler) B BORESIGHT (Radimeter) FULL MOON (Interfermeter) 10" WAVELENGTH (micrns) Figure 3. Lunar Spectral Irradiance vs. Wavelength 1,0 t 2.8 M

12 Nne f the fine spectral structure indicated by the interfex'metric data in Figure 3 is cnsidered significant; the dips near 1. 3 M were caused by the dichric filteri and the rise at 2,7 /u is a calibratin errr caused by water vapr in the ptical path during calibratin. The radimeter was flushed with nitrgen during calibratin and the respnsivities were nt affected by atmspheric cnstituents. N interfermeter data fr the bresight experiment are given in Figure 3 because the n-bard tape recrder was nt used during these measurements; the bresight interfermeter data were telemetered t the Madagascar telemetry receiving statin. A nisy dub f these data was scrutinized but, althugh the interfergrams are well abve the cntinuus telemetry nise, there are many large shrt-duratin transients which make it impssible t reduce the data with the cmputerized wave analysis system being used fr the n-bard tape recrd- ings. 3. SOLAR-LI \AR-EARTH GEOMETRY The 5 December data given in Figures 2 and 3 (Bresight Case) were btained frm apprximately 18:28 t 18:32 GMT when the lunar phase angle was 38 32'. The 8 December measurements were made in the interval frm 1^:45 t 16:50 GMT when the lunar phase angle was apprximately 1 5'. Gecentric ppsitin in right ascensin ccurred apprximately 45 min later at 17:33:37.,02 F. V, ; at that time, the mn was in a partial penumbral eclipse with a penumbral magnitude f An apprximate gemetrical representatin f the slar-lunar-earth gemetry at the time f the 8 December measurements is given in Figure 4 in which distances were greatly reduced fr purpses f illustratin. At 10:47 GMT apprximately eight-tenths f the lunar disk was in the penumbra; if it were nt fr the duble refractin f the earth's atmsphere, an bserver n the side f the mn facing the earth wuld have seen the slar disk in partial eclipse everywhere except in the vicinity f the mn's nrthern limb. Hwever, since the sun's limb is raised by refractin in the earth's atmsphere 27' beynd that f the earth (Kuiper and Middlehurst, 1961), the entire slar disk wuld be visible t an bserver anywhere n the mn's hemisphere facing the earth. The slar radiatin incident n mst f the mn's surface, hwever, wuld be attenuated by an amunt that is dependent upn the altitude at which the sun's rays traversed the earth's atmsphere. The altitudes invlved in the Gemini-7 measurements can be mre cnveniently discussed in terms f the prjected earth's shadw depicted in Figure 5. The large circle n Figure 5 is the prjectin f the earth's limb nt a plane in the vicinity

13 MOON Figure 4. Eclipse Gemetry Dtcambar S, GMT Figure 5. Lcatin f Lunar Disk with Respect t Earth's Shadw

14 f the mn. The mn is represented by the small circle in the nrthern prtin f the penumbra. At the time f the measurements, the pint n the mn's limb clsest.t the umbra was apprximately 5' away frm it. Thus, the rays which emanate frm the sun's suthern limb wuld pass 27' frm the earth's limb and traverse the earth's atmsphere at an altitude f 9 km befre irradiating that pint n the mn (Table 1, page 2 50, Vl. 3, ibid). Radiatin incident at that pint frm all ther prtins f the sun's disk wuld traverse the earth's atmsphere at altitudes greater than 9 km; radiatin frm the center f the sun's disk, fr example, wuld traverse the earth's atmsphere at an altitude f 15 km, and that frm the nrthern slar limb wuld pass at an altitude greater than 40 km. The net effect f the earth's atmsphere at the lunar lcatin clsest t the umbra during the Gemini-7 measurements wuld be t reduce the visible radiatin by 85 percent; this estimate is based n the curve given in Figure I, page 252 f Kuiper and Middlehurst. The increase in visible inslatin with distance frm the umbra based n the Kuiper and Middlehurst curve is depicted by the dashed cnturs drawn n Figure 5. A rugh integratin f these cnturs indicates that the ttal reductin in visible slar inslatin at the time f the Gemini-7 measurements wuld be apprximately 20 percent. 4. VLBKDO EQUATIONS Mst f the material presented in this sectin is discussed in mre detail in Kuiper and Middlehurst. The Bnd Albed, A, is defined as the rati f the ttal flux reflected in all directins t the ttal flux incident n an bject and is given fr spherical bjects illuminated by the sun and viewed frm the earth by: A = 5 / j(a)a* sin da = iffl J p x 2 / $ (a) sina da = pq (1) TrFa 1. 0 where A = Bnd Albed 2 fffa ttal incident slar flux a. = apparent diameter f the sphere if it were at unit distance frm bth the earth and the sun 2 j(a) a 1 = flux reflected by the sphere in the directin f earth

15 a phase angle defined as the angle subtended at the center f the sphere by the earth and the sun $(a) = J^i = phase variatin p = J m p =. gemetrical albed q = 2 I I $ (a) sinada = phase integral. The frmula fr cmputing the gemetrical albed f the mn is: lg p = 0. 4 [m(sun)-m{l,0)] - 2 lg cr (2) where H a, = sin R E R/R F = rati f mn's mean radius t the earth's mean radius = m(sun) = magnitude f the sun m(l, 0) = magnitude f the mn at unit distance frm the sun and earth u = slar parallax Thus, Eq. (2) becmes lg (p) = 0.4 [m(sun)-m(1.0)j (3) Fr the analysis f the Gemini data, it is mre cnvenient t express p in terms f spectral irradiance, FK, as fllws:. H.y(mn, 0) Pi A 4. 88x101 M ; H-. (sun)! W) h where the zer dentes a = 0.

16 5. GEOMETRICAL ALBEDO Althugh the definitin f the gemetrical albed given abve is cnvenient frm a mathematical standpint, it is smewhat cnfusing in that the mn is in ttal eclipse when a = 0 ; therefre, ne must imagine that the earth is replaced by a pint bserver in rder t btain the crrect value fr substitutin int Eq. (1). In practice the gemetric albed can be cmputed by extraplating the phase variatin curve. The phase curve mst cmmnly used appears t be that based n Rugier's data which is tabulated n page 214 f Kuiper and Middlehurst. A plt f Rugier's curve which applies t a wavelength f 4450 A (Figure 6) shws that althugh the variatin is mst rapid near full mn, an increase f less than 10 percent is expected in the interval frm a = 0 t a = 1.5, the minimum phase angle at which measurements can be made withut sme effect frm the earth's shadw PHASE ANGLE, degrees Figure 6. Lunar Phase Variatin Curve

17 10 X 0 X A 0X A 0X ft * ex N Z Q t- 01 ( X 111 _l O z z < Ui a. z en H 1 Q n: p (J UJ CE O 0 j 0 H X 0 A 0 A 0 0 -\ A -a A A A A _ p 43 S CD i i OJ > Wl ra c ^ 1 U) > X 0 2 0) UJ J3 -J UJ < s ü M g (U E Ü t> 0) fa r-l S 3 i i -1 1 _L 1 _L _ 1 x <) 'aaaiv iwimawa O 0O N I

18 11 - u^ _1 03 < _J 5 02 _ s K Ul 01 O i WAVELENGTH ( A ) Figure 8. UV Gemetrical Albed vs. Wavelength Since it is nt knwn whether the cnturs drawn n Figure 5 wuld apply at all wavelengths cvered by the Gemii.i-7 data, the gemetrical albed was cmputed withut adding any crrectin fr the penumbral eclipse effects. A plt f the results (Figure 7) shws that there is reasnably gd agreement between the Gemini-? data and the data presented in Table 22, page 310 f Kuiper and Middlehurst. It wuld appear, hwever, that the transitin frm the Kuiper and Middle- hurst data t the Gemini data beynd 1.0/u wuld be smther if a small crrectin factr were applied t accunt fr the decreased inslatin caused by the penumbral eclipse. The ultravilet data given in Figure 7 are presented n an expanded scale in Figure 8 where the albed levels ff t within 15 percent in the 2500 t 3050 % regin. Since there is a large spread in the slar spectral irradiance data used in cmputing the gemetric albed (Valley, 1966, page 16-11) it is nt knwn whether this trend is real. A value f fr p at 3050 Ä appears reasnable based n an extraplatin f the reflectance measurements reprted by Stair and Jhnstn (1953), and a decrease t at 2200 K als appears reasnable n the basis f their reflectance versus wavelength slpe. It wuld appear that the fractin f the slar inslatin which traversed the atmsphere at altitudes abve the zne layer was sufficient t reduce zne absrptin belw the level detectable within the precisin f the measurements since n large dip at 2500 A was bserved.

19 12 d. PHASE VARIATION The ratis f the irradiances measured n 5 December t thse measured n 8 December are pltted versus wavelength in Figure 9, which raises sme interesting questins. In the ultravilet regin, the value f the phase functin at $ = 38 32' is as much as fio percent greater than that indicated by Rugier's curve; in the infrared regin at 1, 0 n the value is less than 10 percent greater than Rugier's value, but at 2.4 ^ it is nearly twice Rugier's value. There are undubtedly many pssible ways t interpret these results, but we shall nt pursue the subject further until time is available fr cmputing the effect f the earth's atmsphere n the bservatins. :. BOND \i,iu:im The value f the phase integral, q, is required fr the cmputatin f the Bnd Albed. An empirically derived value fr q based n visible radiatin bservatins is available (Kuiper and Middlehurst, page 309) but the variatin f q with wavelength is nt knwn. Figure 9 indicates that $ increases with increasing wavelength in the 1.0 t 2. 8 ß regin; it is als quite pssible that this trend will be fund t cntinue dwn t 2200 A after crrectins fr atmspheric absrptin, scattering, and refractin have been applied t the full mn irradiances. If $ increases with wavelength, ne wuld expect q t increase with wavelength als. Since n detailed investigatin f atmspheric effects has been perfrmed fr this preliminary reprt, the value f q = given in Kuiper and Middlehurst was used fr all wavelengths in the cmputatin f the Bnd albed; the results are given in Figure 10, 8. ALBEDO TABULAR SUMMARY T allw ther investigatrs t check ur cmputatins withut reading the graphs n which the pints are pltted, a cmplete summary f the data used in the cmputatins is given in Table 2. The cmputatins are carried ut t three significant figures, but the measured irradiance data are prbably gd t n mre than 5 t 10 percent and the smth curves drawn in Figures 7 and 10 are subject t the whim f the analyst and draftsman. The use f a mean slar inslatin curve culd have intrduced a small additinal errr.

20 13 c v i i > A > C < m ra x; OH CO CO U O cn c.2 > 01 3 (.ZEBC) 'NOIiViaVA 3SVHd

21 14 - > a - ( 10 0» ( «z (0 </> Ul 2 UJ - 1- a: I t 3 I» -I» S IE a z * Ul u UJ K i t UJ 3 O 5 O Ü 0 Q X - _ z > < * I c S p i > a) (0 > 0 4 a CQ \ 0) u I III. "f^».,, x V'0Q38nV ONOB

22 15 Table 2, Albed Cmputatins 1 ^ micrns H«(38, '32 l H M 0 5') H, SUN V -2-1 wem n wem \X wem ij P f(38 < '32') A ] , , , , i LUNAR TEMPERATURK AND EMISSION The self emissin f the mn was neglected in the albed cmputatins reprted abve since it was nt cnsidered t be f sufficient magnitude t affect the results except at the lng wavelength extremity f the curve. It is aprps, hw- ever, t cmpute the average lunar surface temperature during he eclipse as a further check n the validity f the data btained. The lunar surface temperature based n an albed f 7 percent yields a temperature f 38C K if Stefan's equatin is used (Kuiper and Middlehurst, page 413). Thus, the temperature during the eclipse Tp can be cmputed as fllws:

23 16 Fable 3. Average Albed Cmputatin \ H AV H AK A X q q ^ , , , = E 385 (knk) \ 0. 93/ 1 T (1) The A in Eq. (1) was determined by taking the prduct f the smth curve in Figure 10."md the mean slar spectral irradiance curve in Valley (1965) t btain the sum given at the bttm f Table 3. Taking the rati f this integrated prduct

24 17 t the slar cnstant gives an average albed f int Eq. (1) yields: Substituting this value T E = 385 /l \ \ 0.93 / 1? 0.97 x K (2) If the albeds given in Figure 10 were increased t accunt fr the eclipse and a variatin f q with wavelength, the value f A in Eq. (2) wuld be increased and a lwer temperature wuld result fr an uneclipsed full mn. The lunar emissin based n the assumptin f a K blackbdy was cn ;-nted and the results are given in Table 4; these values were used fr the cmputatin f the pints pltted as crsses n Figures 7 and 10, Table 4. Lunar Emissin Irradiance \ Irradiance Due T Emissin -2 wem n HL (l 0 5') Crrected Fr Emissin -2 Wem (J P A , CONCLUSIONS \ND RECOMMENDATIONS The primary purpse f the Gemini-7 lunar measurements was accmplished. Measurements in the 2200 t 3000 A regin were made with sufficient accuracy t establish sensitivity and dynamic range criteria fr the UV spectrmeter t be flwn by NASA n Gemina-12. t btain measurements thrughut mst f the spectrum. It appears that the dynamic range f film is sufficient There are many Fraun- hfer lines in the slar spectrum in this regin, hwever, which culd be masked, particularly if radiatin utside the band is nt blcked sufficiently t reduce film

25 18 fgging. An estimate f the effect f scattered radiatin can be btained if spectra f a Bureau f Standards Lamp are taken with and withut Schtt glasses WG1 thrugh WG8; als, the spare Gemini-7 brad UV filters culd be useful in checking ut the spectrmeter. It is pssible that an analyst wuld interpret the strength f the lunar Fraunhfer lines n the basis f lunar flurescence; if scattered radiatin is a prblem his cnclusins culd be misleading. The reductin and analysis f the Gemini-7 data wuld have been simplified if cntinuus mtin picture cverage were available and if the spacecraft inertial system were erected during the measurements t btain accurate rientatin and angular rate infrmatin; if pssible, these tw types f infrmatin shuld be sught during the Gemini-12 lunar measurements. The secndary bjective f the lunar bservatins was als accmplished. Althugh the agreement with ther lunar bservatin is nt perfect in all respects, we can prceed t reduce data btained n Other Gemini-7 targets, cnfident that n large errrs will be intrduced by unpredictable changes in instrument respnsivity due t the envirnment in which the data were taken. Althugh neither the instrument nr the experiment was designed specifically fr the purpse, reasnably accurate lunar gemetrical albedes were determined in the 2000 t 3000 X regin (where the earth's atmsphere is practically paque) and in the 1. 0 t 2. 8 M regin (where the earth's atmsphere selectivity absrbs and r attenuates radiatin). It is recmmended that detailed cmputatins be perfrmed t arrive at an estimate f the reductin in slar inslatin caused by the penumbral eclipse, particularly in the UV regin. It is als recmmended that the 36 mtin picture frames taken with the spacecraft camera during the full mn measurements be densitmetered.

26 19 Acknwledgments We are particularly indebted t the fllwing rganizatins and persnnel: USAF Space Systems Divisin fr their financial supprt and fr the assignment f Majr B. Brentnall t the prject. NASA persnnel at Hustn, St. Luis, and Cape Kennedy whse excellent supprt and cperatin are sincerely appreciated. AR PA fr supprt in the reductin and analysis f the Gemini ptical data. We als acknwledge the fllwing persnnel wh cntributed a great deal f their time, effrt, and skill t make the prgram a success: Warren Hwell f Blck Engineering C. fr supervising the develpment and fabricatin f the ptical instruments; James Pwers, David Newell, and Vernn Turner f Cncrd Radiance Labratry fr their excellent field engineering. A special nte f thanks is als due Prf. G. Mumfrd f Tufts University fr his guidance in the cmputatin f cla r-lunar-earth gemetry. Last but nt least, t Gemini-5 Astrnauts Grdn Cper and Peter Cnrad and t Gemini-7 Astrnauts Frank Brman and James Lvell ges ur sincere appreciatin fr their cperatin befre, during, and after the flights and fr their accurate recrding f persnal bservatins which cntributed significantly t the interpretatin f the data.

27 21 References Kuiper, G. P. and Middlehurst, B. M. (1961) Planets and Satellites - The Slar System--Vl Stair, R., and Jhnstn, R. (1953) Ultravilet spectral radiant energy reflected frm the mn, Jurnal f the Natinal Bureau f Standards, 51 (N. 2):81. Valley, Shea L. (1965) Handbk f Gephysics and Space Envirnments, AFCRL, r. \n. USAF.

28 Al Appendix A Measurement Systems I. MEASURING EQUIPMENT CHARACTERISTICS A cmplete descriptin f the instruments used fr the lunar measurements is given in Appendixes B and C where the calibratin prcedures are discussed and cmplete calibratin data are presented. A summary f the mre imprtant equip- ment characteristics is given belw. The characteristics f the 20 Gemini-7 radimeter channels are given in Table A-l where X is the wavelength f peak system respnse; AX is the waves s length interval fr which the system respnse is greater than r equal t ne-half the peak respnse; H N f is the effective irradiance equivalent t the system nise; and H-,.. is the effective irradiance abve which saturatin ccurs. Meff The spectral respnse curve fr the PbS sectin f the 1-14 interfermeter is given in Figure A-l, while the nise equivalent irradiance curve and the saturatin irradiance curve btained fr the 2100 C blackbdy surce used during calibratin are given in Figure A-2. The peak t peak utput f the interfermeter is the vltage prduced by the target in the entire wavelength regin t which the instrument respnds; thus, narrw bands f much higher irradiance than thse given in Figure A-2 will nt saturate it. The field f view curves fr the tw radimeter sectins and the interfermeter PbS sectin are given in Figures A-3 thrugh A-5. These were measured by placing the instrument in cllimated radiatin and rtating it while the cllimatr remained fixed; the target subtended an angle f apprximately radian.

29 A 2 2. Kyi IPMENT OPER VTI\(; MODES The astrnauts had a chice f ne f three pssible perating mdes fr each experiment. In MODE 1 the radimeter filter wheel cycled repeatedly thrugh the las' fur psitins, cmpleting a cycle in 40 sec, while the utput f the cled 1-15 interfermeter was fed t a meter n the capsule instrument panel. In MODE 2 the radimeter cycled repeatedly thrugh all 10 filter psitins, cmpleting each cycle in 100 sec, while the utput f the 1-14 interfermeter was fed t the panel meter. In MODE 3 the filter wheel was lcked in psitin number 3 and the utput f radimeter channel 13 was fed t the panel meter. In all three mdes the utputs f all instruments that were turned n were fed t the capsule telemetry transmitting system and culd be transmitted in real time t a grund based receiving statin if the spacecraft were near ne. In all three mdes the radimeter utputs culd be recrded n an n-bard PCM tape recrder that culd be "dumped" when the capsule was near a receiving statin. The interfermeter utputs were recrded nly n an n-bard EM tape recrder that culd nt be "dumped". This EM recrder had a ttal recrding capacity f nly 1 hr and was, therefre, used sparingly during the flight. :i. THE BORESIGHT EXPERIMENT At the beginning f the bresight experiment the instruments were perated in MODE 3 t check the alignment f the radimeter with the sighting scpe. Astrnaut Brman maneuvered the spacecraft s that the mn wuld appear at varius lcatins in his scpe, while Astrnaut Lvell read the meter (mnitring radimeter channel 13) and reprted the values t him. When the psitin f peak signal had been determined the equipment was switched t MODE 2 and the PbS sectin f the 1-14 interfermeter was mnitred fr peak signal. The results are given in Eigure A-6, which was taken frm the flight lg bk and shws that the tw instruments peaked within 0. 5 deg f the reticle crss-hairs; the 1-15 interfermeter had been checked earlier n a different target. The lunar irradiances btained with the radimeter during MODE 3 are given in Figures A-7(a) and A-7(b). The peak t peak utput vltage f the 1-14 interfermeter PbS sectin is pltted versus time in Figure A-7(c). The UV irradiances measured during MODE 2 when the filter wheel was cycling are given in Figure A- 8(a). These data are repltted in Figure A-8(b), which was nrmalized t the peak that ccurred at 18:28:50 GMT. The Figure A-8(b) plt represents ur best estimate f the variatin that wuld have ccurred in the measuring interval if the filter wheel were lcked in ne psitin. Three versins f Eigure A-8(b) were

30 A3 made (by three independent analysts) and the three plts agreed t within 5 percent. The series f small tick marks at the tp f Figure A-8 indicate the times when the filter wheel psitin changed. The PbS irradiance values given in Figure A-9(a) were als measured when the filter wheel was cycling in MODE 2. The PbS data varied much mre in a 10-sec interval than did the UV data, and the three analysts' versins f Figure A-9(b) agreed t within nly 10 percent. The larger variatin is prbably due t the smaller and mre variable field f view f the PbS sectin f the radimeter. The behavir f the interfermeter utput with time during the MODE 2 measurements is shwn in Figure A-9(c). The filter psitin marks n the figure have n significance, since there was n filter wheel in the interfermeter; they are drawn as a visual aid in cmparing the variatin f the measurements with time fr the tw instruments. The variatin in signal during the 100-sec interval required fr a cmplete cycle presented a serius prblem in the data reductin. Fr example, nly tw measurements were btained fr filter psitin 19, and ur best estimate f the tempral (actually sighting) variatin with time indicates that the signals measured at thse times were lwer than wuld have been measured if psitin 13 ccurred at 18:28:50 GMT when the ptical axis was mre nearly aligned with the mn. The data tabulated in Table 1 f the main bdy f this reprt were btained by crrecting the irradiances fr all filter wheel psitins n the basis f the sighting variatin curves given in Figures A-8(b) and A-9(b) and, thus, cntain an uncertainty factr f ±2. 5 percent in the UV and ±5 percent in the 1R. I. THE 11 1,1. MOON MEASI REMENT The planned prgram fr the 8 December full mn measurement was t rient the capsule s that the mn wuld initially appear at the lcatin f peak radi- meter respnse and then t maneuver the craft until the mn appeared at the lca- tin f peak interfermeter respnse. was cycling during the entire measuring perid. MODE 2 was used and, thus, the filter wheel The radimetric data fr the full mn measurements (Figures A-10 and A-ll) varied as much with time as thse btained during the bre-sighting measurement, and the prcedure described fr the 5 December measurements was used fr remving sighting variatins frm the full mn data; the results are given in Figures A-10(b) and A-11(b). The interfermeter irradiance vs. time behavir is given fr a wavelength i 2,4 ß in Figure A-11(c), where the data have been nrmalized t an irradiance - R «2-1 f 3.83 x 10 watt cm JU ccurring at 16:46:08 GMT. An interfermetric spectrum taken frm a 2-sec magnetic tape lp cmmencing at 16:46:06 GMT is

31 A4 given in Figure A-12; the fluctuatins at the shrter wavelengths are due t lw signal-t-nise ratis which in turn were caused by a dichric interference filter used in the instrument. A tabulatin f the irradiances fr bth lunar measurements was presented in Table 1 in the main bdy f the reprt where it was mentined that L is the wavelength abve and belw which 50 percent f the radimeter utput wuld be cntributed by a target having a given nrmalized spectra.l distributin. * The nrmalized spectral distributin used fr cnverting the lunar effective irradiances t spectral irradiances was determined by first reducing the data using the nrmalized slar spectral distributin as a target and then cmparing the results with the spectral distributin f blackbdies at varius temperatures. It was fund that a 4000 K blackbdy prduced the spectrum that mst nearly matched the lunar data (Figure A-13). The spectral irradiances were then recmputed using a nrmalized 4000 K blackbdy curve t cmpute the respnsivities that were used in the final cnversin f effective irradiance t spectral irradiance. Incidentally, althugh it has n physical significance, the 4000 K surce wuld have an emis- sivity f percent if it were a disk having the diameter f the mn and pssessing Lambertian prperties. *See Appendix B fr a detailed discussin f the methd used t cnvert effective irradiance t spectral irradiance.

32 j A5 Table A-]. Gcmini-7 Radimeter Characteristics K s L\ s H "Neff, H Meff 2 Chan N. micrns micrns w cm w cm" i 1 i ' 1 G r ) «, ^ ^ l G i L Ill Z t 7? : J HI j 1 These values apply fr an instrument temperature f 85 F.

33 Ac 10 10" SATURATION IRRADIANCE en z a. en M 0" 6 ; E < > z 10" UJ O 10" < r B < a: 10" a NOISE EQUIVALENT IRRADIANCE WAVELENGTH (Micrns) " WAVELENGTH (Micrns) 34 Figure A-l. Spectral Respnse f tlu 1-14 Interfermeter PbS Sectin Figure A-2, Saturatin and Nise Equivalent Irradiance Curves fr I- 14 Interfermeter PbS Sectin I Oi I 0 in z a. in Q 10 Q Nl -J < IT O Z 10" ANGLE-DEGREES FROM OPTICAL AXIS ANGLE-DEGREES FROM OPTICAL AXIS Figure A-3. Radimeter Field f View Phtmultiplicr Sectin Figure A-4. Radimeter Field f View PbS Sectin

34 A I ANGLE-DEGREES FROM OPTICAL AXIS Figure A-5. Interfermeter Field f View PbS Sectin 1R SPECT - 1/2 X AXIS RAD - 1/2 Y AXIS I-l5 + 9/l6 0 YAXIS,+ 9/l6 0 X AXIS Figure A-6. Instrument Alignment Pattern

35 A8 FILTER POSITION 3 ID -8 I...i.-' v i 'E (a) 2940 A I lo" 9 J 1 I L < a < a: a. - -'-. \ -.*.;V- " ;. H,. V ;\-H..--.v-; v* 1 - J ' ", * *' _.v-. \ - (b) lo" l.8?bji i i i i i i i 1..: *'-'- >. ". UJ e> < _l > ' "-.' (C) a. \- 3 O INTERFEROMETER TIME, GMT Figure A-7. MODE 3 Radimeter and Interfermeter Data Bresight Experiment

36 A9 FILTER POSITION: I I T-i i i i i i i i i i i i i r~i rn i i rn i r~ 10".-'- 'E v 2 < a 10" < a: a. (l 3 K I- a. UJ _,*.'*.,-10 J L J L J L I I I I I I I I 1 I I I I I I I I Tn i i i UJ z 10 s «I 8 a: UJ. ^ ^. «.rs^rf*.. (b) < > a: z lo" 1 L ± 29: TIME, GMT Figure A-8. MODE 2 Phtmultiplier Data Bresight Experiment

37 AK) FILTER POSITION II I 1 I I T i i i i i i i i i i i i r.. V.V-* X ü '»./ "".. (0) * \ * RADIOMETER v. i _ 'b) ö z < Q < i i Q ÜJ M i l0 z - «' ': **. ; / S y. ^».. i,-* " * / -. / -.. /.....^- (c) INTERFEROMETER 1826:00 i TIME, ÜMT 1 1.1, 1_ :00 Figure A-9. MODE 2 PbS Radimeter and Interfermeter Data Bresight Experiment

38 All (a) TI rn i rn i i i "i r~f i n n -! r T~I rrn r 1.0 < a: a: a LU M < s tr z 1* >. 'v ^^*.'..'-', \ I.«' -w 10" TIME, GMT (b) Figure A-10. Full Mn Phtmultiplier Data

39 i i An FILTER POSITION; II II II III m i i i i i i i i i i i i i i i i i L ' '».....,_ 10-' i \ - '' * ' i u 5 Q d IE a. «... * v ' "._.-.! ' ' - '.. -.«/ ^ (a) S 0 -a V 1 ;. '-- 1 i FULL MOON PbS I I 1 1 i i i i i i i i i i i i i i i 1 i... "' *.w»,. 1. 'v -.-'-.. N,! % % l ; ' t.* (b) ui z 5 02 < a. - FULL MOON PbS u I I i i I r~i r I I I I I I I I I I I I I I I I I I I I 1.0 z (c) FULL MOON INTERFEROMETER 10" TIME,GMT Figure A-11. Full Mn PbS Radimeter and Interfermeter Data

40 A ' IO-* i WAVELENGTH (micrns) Figure A-]^!. Full Mn Intrfcrmeter Spectrum i-« WAVELENGTH (micrns) Figure A-13. Full Mn Data Cmpared With 4000 K Blackbdy

41 r BLANK PAGE

42 Bl Appendix B Gemini 7 Radimeter Calibratins DESCRIPTION 01 THE E3G RADIOMETER The E3G Radimeter flwn n Gemini-7 (Figure B-l) was a mdified versin f the E3G Radimeter flwn n Gemini-5. In the riginal cnfiguratin, ne-half f the pwer cllected by the 4-in. Cassegrain fre-ptics was diverted t a blmeter, and the ther half was divided between a PbS detectr and a IP28 phtmultiplier. Since it was impssible t btain filters fr wavelengths shrter than 2800 A having sufficient lng wave rejectin t be used reliably with the IP28 phtmultiplier, the IP28 was replaced by an EMR type slar blind phtmultiplier fr the Gemini-7 flight. Because f the mdificatin, the blmeter had t be remved; thus, ne-half f the incident radiatin was directed t a vid in the Gemini-7 radimeter. The ther half f the incident radiatin was chpped at a frequency f 150 Hz by vibrating chpper beamsplitter and transmitted t a frnt-surfaced, stripedaluminum mirrr. This mirrr transmitted ne-quarter f the riginally available pwer t a frnt-surfaced, aluminum mirrr that reflected it t the PbS detectr thrugh ne f ten pssible filter wheel apertures. The remaining 2 5 percent was reflected by the striped mirrr thrugh ne f the phtmultiplier filter wheel apertures t a frnt-surfaced, aluminum mirrr that reflected it t the slar blind phtmultiplier. The utputs f bth detectrs were amplified, cmmutated, and fed t a PCM recrder and t the telemetry transmitting system. The phtmultiplier sectin f the Gemini-7 radimeter was equipped with an autmatic fur-step attenuatr that allwed linear peratin ver mst f its

43 B2 dynamic range, the attenuatin factrs being 1,3, 10, and 30. The PbS sectin f the radimeter was equipped with a lgarithmic amplifier designed t cmpress fur decades f incident irradiance int a 4-vlt utput. An ff-set f 1 vlt was prvided t allw measurement f targets that were clder than the radimeter chpper and t raise the utput vltage fr small signals t a level well abve telemetry nise. 2. mwmk; RANGE CALIBRATION The first step in the calibratin f the tw radimeter sectins was t drive the utput slightly abve the 5-vlt telemetry limit, using a 2000 C blackbdy surce, and then t reduce the irradiance in knwn steps with neutral density filters until n drp in vltage was bserved with a further decrease in irradiance; this threshld vltage, V,,, was then subtracted frm the vltages btained with each neutral density filter, V T+N, t arrive at the target vltage, V Plts f V^, vs. neutral density filter transmissin were then made. These plts shwed that the phtmultiplier sectin had a linear respnse fr the three lwest attenuatr settings but was nn linear fr utputs abve 4. 6 vlts n the highest attenuatr setting; during this calibratin the attenuatr factrs were als determined. Thus fr all vltages n attenuatr settings 1, 2, and 3 the cnversin f target vltage t irradiance culd be accmplished by an equatin f the frm H eff " B eff V T G (1) where _2 H ff = effective irradiance (watt cm ) -2-1 B f, = inverse effective irradiance respnsivity (watt cm vlt ) G = attenuatr factr. This equatin culd als be used fr attenuatr setting 4 fr utput vltages less than 4. fi vlts; fr larger utput vltages a quantity Vp was substituted fr V _. A plt f V vs V-p is given in Figure B-2. The PbS sectin was nn linear by design, and the equatin which applied is H eff = B f(p) (2) eff where B.. is the effective irradiance crrespnding t an f(p) value f unity and is the effective irradiance required t prduce a V,- f 4. 5 vlts. A plt f V_ vs f(p) based n the neutral density filter run is given in Figure B-3.

44 B3 3. ABSOLUTE RESPONSlVm CALIBRATION The 20 radimeter channels were calibrated abslutely by placing the instrument in the cllimated beam f a 25-inch-fcal-length, fl-inch-diameter, ff-axis cllimatr manufactured by Infrared Industries, Inc.. The radiatin surce was a ne-quarter-inch circular aperture 2000 C blackbdy manufactured by Rcketdyne. The radimeter was riented t btain maximum utput and the system was then flushed with nitrgen. Calibratin pints were btained by rtating the precisin aperture plate prvided with the cllimatr and by varying the surce tempera- ture; a Leeds and Nrthrup ptical pyrmeter was used t set and mnitr the blackbdy temperature. Plts f V.pd vs. effective irradiance fr channels 1 t 10 are given in Figures B-4 t B-13, and plts f V p vs. effective irradiance fr PbS channels 11 t 20 are given in Figures B-14 t B-23. The effective irradiance values were cmputed using the equatin: c H eff = y*h( s where H(^) = spectral irradiance incident at the radimeter aperture (watt cm ß ) s(m = system spectral respnse X S = wavelength f peak system respnse. These integratins were perfrmed n an IBM cmputr ver the wavelength regin t which the detectr respnded significantly. I. VARIATION OK RESP0NSIVITY WITH TEMPERATURE A summary f the data presented in Figures B-4 thrugh B-2 3 is given in Table A-l f Appendix A. Past experience has shwn that the respnsivity f a PbS radimeter varies cnsiderably with temperature; thus, the values given in Table A-l apply nly fr calibratin ambient cnditins. The magnitude f the increase in sensitivity accmpanying a decrease in temperature is usually independent f wavelength, except at the lng wavelength cut ff. Thus the respnsivity as a functin f temperature was determined bth at n and at 2. 7 M by placing the instrument in an envirnmental chamber and varying the temperature while the instrument was irradiated with a cnstant surce.

45 B4 Plts f ri'.spnsivity vs. temperature as detertnined by reading the utput vltage frm n thermistr bead lcated in the radimeter near the detectr are given in Figure M-24. These plts were nrmalized t the respnse at 85 F, the temperature indicated by the radimeter thermistr during the abslute calibratin described earlier. It is interesting that the respnse in bth wavelength regins ges thrugh a maximum; the nly explanatin we can ffer fr this behavir is that changes in the characteristics f lg amplifier with temperature eventually cause an verall decrease in system gain which cunteracts the increased detectr sensitivity as the temperature is decreased. All three K3(i radimeters tested exhibited this type f behavir. The change in the phtmultiplier sectin respnsivity with temperalure is cnsidered insignificant and n crrectin was applied t the data btained with this sectin f the radimeter. 5. RADIOMETER I II ID III VIE«The field f view curves fr the tw radimeter seciins are given in Figures and B-2(i. These were measured by placing the instrument in clllmated radiatin and rtating it while the cllimatr remained fixed; the target used subtended an angle f apprximately radian, (.. RADIOMETER \)\\\ RED1 CTION METHODS Equatins (1) and (2) were used t reduce the telemetered vltages t effective irradiances. Since the effective irradiance by itself des nt describe the spectral distributin f the target, the spectral irradiance was als cmputed. The prcedure used fr cnverting effective irradiance t spectral irradiance was t assume a target having an unknwn abslute radiance but having the spectral distributin H(A). riius (X) f^iy dx (4) fr the assumed target, and r. if 7v*># / " r v ' 3(A1 da (5)

46 Rf) fr the measured target. Since bth targets have the same spectral distributin, "r (A) 11(A),,... (A)..,, TIT = 7T f 7 ur H T (X) "Hr H Teff ' (6) I ell elf eff H(A.)B ff Cmbining I'^qs. (1) and (6) and substituting H fr rj gives "eff II [.(A) = BG V T (7) and Kq. (2) becmes il T (A) = B f(p). (8) In rder t determine hw critically the cnversin f effective irradiance t spectral irradiance depended n the target spectral distributin fr the varius channel system spectral respnses, cmputatins were perfrmed fr blackbdies at temperatures f 1500 t fiooo K in 500 increments. In additin, cmputatins were perfrmed fr the 1700, 2000, 2100, and 2200 C blackbdies used during calibratin fr a spectrally flat surce and fr the mean slar spectrum. The results are given in the secnd clumn n the lwer half f Tables B- 1 t H-2(). By way f illustratin, the values f B fr channel 1 given in Table B-l vary nly slightly with target spectral distributin, except fr a temperature f 1500 C. At that temperature a significant cntributin t the channel utput vltage wuld be made by radiatin at wavelengths far remved frm the nminal pass band. In rder- t assign the cmputed spectral irradiance t a particular wavelength regin, a wavelength I, was cmputed such that / 0 S L b eff (9) Thus, ne-half f the radimeter utput wuld be cntributed by irradiance in the wavelength regin belw L and the ther half by irradiance at wavelengths lnger than L. A wavelength interval AL = L - I., was als cmputed such that Lj L 2 f "W-^X^j-dA = H ff and / H(A) ^^ da = H eff. (10) '0 s -^0 s

47 B6 Thus, 70 percent f the radimeter utput wuld be cntributed by irradiance in the wavelength interval AL. The values f L, L,. I,,., AL, ll(l ), and H,, 1' 2 0 eff are given in the tp prtin f Tables B-l t B-20. The T(L ) given in the tables is the transmittance f the channel filter at wavelength L. The quantity labeled "c" n the lwer tables is the factr used t cnvert II t spectral radiance fr eff r a target filling the field f view f the radimeter. The ther quantities given in the tables are: 1' LAMBDA () = peak filter transmittance LAMBDA () wavelength f peak filter transmittance, (n) LAMBDA (A) and LAMBDA (B) = wavelengths at which filter transmittance is ne-half the peak transmittance, iiu ) LAMBDA (C) = (LAMBDA (A) + LAMBDA (B)) + 2, (M ) IAMBDA (S) wavelength f peak system respnse, (M ) W = Field f View (ster) A, f = Inverse effective irradiance respnsivity fr an auxiliary filter used in calibratin. A. = B, if instrument is eff eff calibrated with flight filter installed, as was the case fr all Gemini-? channels. The system respnse curves used fr the IBM cmputatins are shwn n an expanded scale in Figures B-27 thrugh B-4G. All UV filters were measured n a C'ary 14 spectrphtmeter and had ff band rejectin f 5. 5 r mre rders f magnitude. All infrared filters were measured with a Beckman DK2A spectrphtmeter and exhibited ff band rejectin f 4 r mre rders f magnitude. a further check n ff band rejectin, all channels were tested against the blackbdy set at 2200 C after the filters were installed, using varius blcking filters t test fr "leaks"; all channels behaved well and exhibited n ff band leaks. As 7. PRECISION \M) ur.iiun OF CALIBRATION The spread in the calibratin data is shwn in Figures B-4 t B-23. The spread is caused by many factrs such as surce temperature setting, meter read- ing, aperture area, neutral density filter calibratin, etc.; in sme cases the prducts f errrs are invlved, e. g., when the target vltage is multiplied by the attenuatr factr. One culd cmpute the respnsivity based n each calibratin pint and cmpute standard deviatins but there are nt enugh pints t warrant this apprach. Hwever, using the equipment and methds emplyed fr the Gemini-7 instru- mentt., the smallest spread in a large number f calibratin pints we ever bserved n an abslute basis was ±5 percent. This was i very carefully cntrlled calibratin

48 B7 f an excellent radimeter equipped with a narrw interference filter and a PbS detectr. The radimeter was a Mdel R4K, built by Barnes Engineering C.; it perated linearly ver 4 decades, was prvided with a ttal radiatin chpper, was state-f-the-art when purchased 5 years ag, and is prbably still better than mst radimeters ne can buy tday. Apprximately 100 calibratin pints were btained during the calibratin, and apprximately ne-half f the data spread was traced t the vltage level recrder. The spread in the calibratin data fr the Gemini-7 instruments appears t be apprximately twice that btained during the Barnes radimeter calibratin n the average. Since ne-half f the filters used n Gemini-7 peaked in the ultravilet regin where accurate abslute respnsivities are nt easy t measure, an investigatin f UV calibratin methds was undertaken. The main cause fr cncern was the rapid decrease in blackbdy radiance with decreasing wavelengths and temperature in the 2000 C temperature range; anther cause fr cncern was whether the Rcketdyne surce was actually black in the ultravilet regin. A slar blind phtmultiplier system that culd be perated linearly ver a range f 4 rders f magnitude was used fr the tests t cmpare the blackbdy with a Bureau f Standards Spectral Irradiance Standard. The instrument was first calibrated abslutely at ne wavelength, using bth surces, and then relative spectral calibratins were perfrmed with the tw surces. A 2850 A filter 200 A wide was used fr the abslute respnsivity cm- parisn, and pints were taken at distances f 25, 50, and 100 inches frm each surce. It was fund that althugh the spread in the respnsivity values btained with each surce was 5 percent, the average respnsivity value btained with the blackbdy differed frm that btained with the standard by nly 1. 2 percent. The radiatin frm each surce was then fed t a Leiss mnchrmeter, using the Leed's and Nrthrup ptical pyrmeter t set the blackbdy temperature. The utput vltages btained with the Standard Lamp at 10 wavelengths in the interval 2500 and 3200 A were divided by the irradiance values prvided by the Bureau f Standards t determine the relative spectral respnse f the Leiss-phtmultiplier system. The relative spectral respnse was als determined, using the blackbdy set at 2100 C. Several runs were made with each surce and varius Schtt glasses were used t check fr scattered radiatin effects. The ratis f the relative spectral respnsivity values btained with the tw surces were then taken. The ratis were cnstant t within ±3. 5 percent; thus, it was cncluded that the blackbdy was in fact behaving accrding t Plank's law. Since there is n standard fr wavelengths shrter than 2500 A, it is necessary t assume that the blackbdy surce remains black dwn t 2200 A where the shrtest wavelength Gemini-7 filter peaked.

49 ns Table B-l. CHANNEL GT7-1, CUKVE NO. 1 -LAMÖL)A(C) I.AMdÜAl Ct LAMQUA(C) LMÜüAi SI, bcce-o 1 Ü.^löÜ 0.2^15 0.^160 LAMbüA(A) LAMdOA(ü) UbLTrt LAMbUA 0.21Uä O.OtLlM M ÜitH-i Clbl-F) 1.Ü^OE-03 <.ö f'ü t-13 3.S)90t-l J fcmp K. Ll LO LZ UtLlA L I (LO) h(loj ri{ ti-^ ) IbÜO 0.ZZH1 Q»2Hi1 t.3äo t-Ü3 7.73t-W b.23fc-ld b 0.^32ö.243ö 0.J bE-02 4.ÖÜL-12 l.llt-13 2J t ^ 0.240'» J E E bt-li 2^ Ü.23Ü0 0.2^ i.l3b-0l 1.7&E-Ü9 4.2ifc-ll 2b d 0.239b l.lbt t-0-y 5. j3 t-11 30Ü dl O.2JÖ t:-Cl 1.49t-C7 3.6bt-0 9 3b öd 0.23öb l.4lt-ül 3.03E-C6 7.44t-0d 'tooo 0.216b Ü.22b9 U.23b l.bot-ll 2.97fc-03 t.zit-^1 ^büo b2 u.0193 l.b4t-0l l^tt-t 4.24fc-06 bco.2l:)'» C.22tü 0.23'»6 ü. J192 l.böe-ol 7.22t-04 l./6e-0b!)30c 0.21b lt-0i 2.3iE-0i i.öbe O^IW 0.223d 0.233b t-ül 6.18fc t-u4 FLAT 0.212b Jla 0.J19J 1.7bE-Cl 9.7 7b-Ol 2.32fc-u2 iün 0.21b2 0.22'.'» 0.233b O.OlKö l.b9fc CE-Ü3 1.Obb-U4 TEMP K b C laoü j.obe-l< '. '».9bE-C9 200y l.b9e-ll L 1.65E-0b C-1 I 1.66E-08 2t7J 1.69E-1J L 1.66t-Üd 2b E-i L 1.65fc-Üb 3ÜÜÜ 1.6ÖE-1J L 1.62t-0b 3b00 i.6e-l l 1.63c-0b 4ÜJ0 1.6bt-i L 1.64E-0b 4300 l.b7t-i 1. l.ö4e-0d 5000 l.7e-l i. 1.64t-0b bdoü 1.bdb-H l.ö4t-0b OOO 1.6bE-l] 1.65E-06 t-lat 1.7iE-li 1.6aE-0b bu.^ 1.75L-li l 1.71b-Cb

50 B9 Table B-2. CHANNEL GT7-2, CURVE NO. 2 T-LAMbUA(O) 2.0ÖOE-Ü1 LAMbUA(A) 0.2tt)b ii l.c20t-q3 LAMtlUA(Q) OUitO LAMUUA(b) C.Z'iöS i/rt y.tiute C2 LAMBDAiU L.ZiTs UtLIA LAMbJA O.Ü220 A(cHP1 '.OöOt-l J LAMdUA(S) C.^i^O 4.ü60b-lJ 3.980E-10 EMP K LI LO L2 ütlta L 1 (LO) H(l.Ol H( tt-h) O.2t)70 J.0250 ö.5dt-02 l.//t-l3 * U.23/0 0.2^3 0.25öä l.lüt-l 2.30t-li 6.3ÜE G.25bd J b -01 ^.356-0^. 3 2 t d fc-01.36t fc ^:437.J t-01 B t-lC ^33«0.^:43^ E-01 t.l3t-ö7 l.lle-ufl 3 5G V 0.2^ i.63t-0l 7.0lfc-O l.dbt a.2hlb 0.252/ O.J205 i.73e-l fc-C fll U.2 52Ü l.b4fc-ul 3.2 5fc t-0t O fc-03 3.Jt L C« COt-Ol 3.d4b-3 9.0dt-03 büoo d U.02CI 2.0Jt >8t t-04 FLAI Ü.220V 0.237d u.24ä6.i'y? 1.vbt-ul 9.3tb t-02 SUN 0.2J ^ ^ t-ül. 3'tt-C 3 l.lb-04 remp K b E-1 l l.49b-0d üE-1 I l.33e-ob L 1.4bb-Cö t-l L 1.4bb-0b E-i L 1.4öE E-1 L 1.4äfc-0d t-l L 1.50E-Jri 4000 i.5öb-l I l.53b-0b fc-li I 1.59E-Cb E-1 L 1.64E-0Ö b-l l l.öb-oö 60 JO 1.73E-li l.9e-0ö f-lat 1.64E-1] 1.6lE-0b SLM 1.60b-l 1.57fc-0b

51 RIO Table B-3. CHANNEL GT7-3, CURVE NO. 3 T-LAMUÜA(O) l.-tioe-ql LAMbOA(O) 0.^970 LAMÖL)A(C) LAMbUA(SI LAMtJUA(A) LAMBOA(B) DELTA LAMBDA C.02ÖÜ M l/m ACEFF» b(eff-) C(bFF) 1.020E E E E-12 2.Ü69E-09 TEMP K Ll LO L2 JELTA L I (LO) H(LO) H(EFF) ISOO C E-C1 4.58t AE-14 20ÜO.28aa E-01 1.ö2E E O E E E-Ü E E-U E ^ E-C1 2.22E E Ü E E E-G C E E E J ) L C E E E-06 4b C E E-03 2.dOE-05 50C0 C b E-n3 8.33E U I8E E E C E-C1 2.14E E-04 FLAT 0.28U C E E E-02 SUN C.3C E E E-04 TEMP K IsOO eooo FLAT SUN 7.80E E E E E E E-10 I.UE-IO 1.09E E E E E E-10 7.O4E E E-C8 9.65E E-08 1.O2E E E-07 1.O7E E E E E-C8 1.07E-07

52 nn Table B-4. CHANNEL GT7-4, CURVE NO. 4 r-lambualqj 1*<iXXQ -a2 LAMBUA(O) 0.262U LAMbUA(C) O.ZbtZ LAMBUA(SI C.2600 LAMUUACAi LAMBUA(b) ühlta LAMöüA G ^ W 1/H A(fcPF) ü(tff) C(EFF) 1.02ÜE E E E E-09 EMP K Li LC L2 UfcLTA L I (LOi H1L0) H( tff) IbOG C E E-1* 5.85E E-C *.26E-12 2J * Ü E-Ü2 1.38E ÜE-10 2A7J * 7.WE-Q2 3.43E E-10 2bOO E E-C8 9.18E-ia E E E-08 31) Ü E E-C5 *.41E-C C E E E-06 4i00 0.^ <» Ii9 7.72E-C2 Ö^IE-O^f 1.38E ^ E E E-05 SMJO t E-C3 I.2*E-0* * E E E-G* FLAT u E E E-C2 SUN P E E b-C4 TEMP K L 7.88E-C *E-11 L 7.59E E-11 I 7.41E-08 2* E-1 ' 7.37E-0e l] 7.37E E-il 7.28E E-U L 7.28E E-11 I 7.31E E E E-11 7.*0E E-1J 7.44E E E-08 FLAT 7.86E E-08 SLW 7.89E-n 7.7*E-08

53 B12 T.ibh B-5. CHANNEL GT7-5, CURVE NO. 5 T-LAMbUA(ü) LAMbDA(ü) LAMOOA(L) LAMbUA{ bl,v40e-ü1 0.28^0 C LAMÖÜA(A) LAMt3DA(B) DELIA LAMBDA U L/W A(EFH B(EF(-) C(EFF) 1.020E-O3 9.80*E ÜE-13 ö.g've-^.büte-10 tmp K 11 LC L2 JELTA L r (LOJ H(LO) H(EFF) 15) ^ Bb E E E-15 2G0C C '' Id E E E E-C1 3.49E-08 7.t2E-10 2A ^ C.^91b E-Ü1 8.40E-Ü8 1.77E-09 2&0U C E E E-09 30C ? C E E E-CB SbCJ 0.2/ E-C1 3.91E E-07 ^ec L J.2797 C E E E-Ü6 4b0C Ü C E E-Ü3 2.0CE-05 booo t E E E-05 5&ÜC ^ E-C1 8.13E-03 l.ue C i.eie-i 1.78E E-Ü4 FLAT !> E-01 9.Ö3E ÜE-02 ion E E-Q2 6.33E-04 TEMP K a C E-1 I 2.86E E-1 L 3.07E E-1 I 3.20E E-1 I 3.23E E E E-1 I 3.36E-C E-1 I 3.47E E-1 I 3.47E E-1J L 3.46E t-lJ L 3.45E E-1J I 3.45E E-1] I 3.44E-08 FLAT 3.52E-11 L 3.45E-Ü8 SUN 3.55E-1J 3.48E-08

54 B13 Tab If B-6. CHANNEL GT7-6. CURVE NO, 6 T-LAMbUA(O) LAMBL)A(Ci LAMbUAICi LAMBDA«Si l.i)sioe-ol 0.247S LAMbUA(A) LAMüOA(B) UtLlA LAMÖUA 0 UilQ 0.2b6(j M Aitee t a<e(-h CIEPH 1.0^0E-O3 V.bü^t 02 b.300t-lj 6.30üE-li. 17c.t-lC TEMP K LI LÜ L2 OtLTA L TiLOJ H(LO) H( EH b 0.2dl0 C E-U2 1.15E-lt n.-+?l-16 2Ü d bl t E E O E-02 b.62t-ü9 2.alE-iO 2^ Ü.U3Ü7 9.47fc E E-iO J E b E bül Ü.2 7öO E-01 ä.75e E-üb dl l.löe E E u ^ E E E-Ü d C C fc t E-Ü «l 2 54d ÖE E-U3 5.3ÜE ü.242d E E bE G.26b E E aE-04 FLAT ötb E-Ü1 9.46t-Jl 2.80t-02 SUN d C E-Ü1 9.29E-ÜJ E- u 4 TEMP K b C E-i I I.ICE-Od 2000 i.58e-l] l 1.55E-GÖ E-1 l 1.63E-Ü bE-i L 1.65E E-1] L 1.66E i.7öt-l L 1.73E l.80e-li l 1.77E-üd E-1 L 1.Ö1E VE-1J i l.d6e-0d 50 JO 1.93E-iJ L i.a9e E-1] i.vie-a E-1] I 1.93c-08 FLAT 2.13E ä SUN i.77e-l] 1.73t-Cb

55 B14 Table B-7. CHANNEL GT7-7. CURVE NO. 7 r-lamtiüa(c} ^.t>^t-^ LAMöDAU) O.^/BC * I.O^OE-03 LAMöUA(O) 0.2dii LAMbüA(B) Kj.lÜbtL 1/W y.o'tb 02 LAHbUAlL» C.2610 UtLIA LAMbUA 0.00^2 A(EFH 2.3a0t-l2 LArtbUAiä) C.2ÖIC b(el-(-) 2.3düfc-12 C(et-Fi 2.3Jit-0V TtMP K Li LO Li ublia L 1 (LO) HILO) H(bEE) /87 0.2b t-C2 1.4öt-l3 1.2 lb C.27Ö3 O.^Ölö u7 I /.'.ab-02 /.41b E-12 2J C.2b5l O.0070 /.52t E Ub-10 2^73 U.2/8U a.28lt O.0071 /.50e b-d /.d^b Ö0 0.^ U.00/1 /.50t b-0/ 9.d7b-10 30ÜÜ C.277d /.4/t E b U Ü ^b /0 7.45t b b-0/ /2 7.42t:-Ü2 2.O8t-04 2.i3b-Oö t b<« /.40E b-03 8.a5E Ü Ö45 O.OO/l /.4O't-02 3.'.8b-03 2.//b Ü.280J C.2Ö /2 /.3ut bE-03 /.03b-05 öogo ^84'» 0.00/ U2 1.91E E-04»-LAr C C t E E-Ü3 SUN u.^all 0.2b4 u.j t-ü2 3.52E-02 2.d0E-04 TEMP K b C a3E E E b-07 23/3 2.99E E-07 t^ll 2.99E E-07 2DOO L:.99b JE E-iO 2.93E Jb-07 4U E E-07 4D L b-07 DOOJ 2.99E-i0 2.94E E-07 boo J 2.y7b b-07 FLAT iO 2.84E-0/ buim 2.99b b-0/

56 B15 Table B-8, CHANNEL GT7-8, CURVE NO. 8 -LAMUüA(ü) a.iae-a2 LANdUA(A) 0.J022 M 1.02ÜE-03 LAMaL)A(G) C.3J5 5 LAMbOA(d) C /rt 9.Ö04E 02 LAMUÜA(C) UbLTA LAMBOA A(EFF) 1.090E-11 LAMäOA(S) 0. JObO B(fcFF) C(EFF) 1.090E-11 l.cb'je-ob TEMP K LI LO L2 OtLTA L HLO» H(LO) H(EFFI 1500 O C59 u E-02 i.4le CC C E E E C C E E E-09 2^73 U.3C C93 J.0O E E E-J L.iOCd E E E-09 3C0u C E E-06 d.76e C.2997 'J.304a C.3& E-02 ti.91e E-C C E E E-Ü E E-C3 1.72E-C5 500C C E E-C3 4.99E-05 55Ü E E-C2 1.19E E-C2 2, eE-04 FLAT Ü.3078 D E E-C1 1.16E-02 SUN w E E E-04 TEMP K b C E E CE E E E E E E E E- r J9 1.17E Ü 1.16E-D9 1.14E E E E-Ü9 1.09E E-Ü9 1.06E C6E E t E-06 FLAT 7.99E E-07 SUN 1.15E E-06

57 B16 TabU' B-9. CHÄMHEL GT7-9, CURVE NO, 9 I-L AMlJUAlO) 7.560t-02 L..MtjUA(A) 0.28f0 H 1.U20E-03 LAHUUAI0) c.täa LAMÜUA(Q) 0.29JC 1/M y.acte J2 LAMbOAlU C.2dB^ ÜLLIA LAMbDA 0.CC90 A(fcFh» J.iyOE-U LAMrtuAC S) r.2ö70 U(EFF) C(tFF» i.l-vufc-w ItMP K LI LO L2 OfcLIA L I (LO) HILO 1 H ( EH F ) b J.üü9b 7.35b E E-lb 2C00 t., :ö3d 0.2öbi f b3t-^2 1.14E E C.2a3^ C.2b7-J 0.292b t-C2 b.82e-08 b.91e-10 2^73 Ü.2Ö33 C.^b7d ) E E U.2Ö E-C2 1.70E E-09 3CC0 C b 0.2y21 0.OC t-C2 4.80E bE-08 3t>CC ' ^ ) t-J2 5.21E-05 b.28e-ü7 4U ^ 0.-: E-Ü2 3.14E E-Ü C E-C2 1.27E-03 l.28e-0b 5CCC b C.0C9b 7.36E-L2 3.86E E-05 bbco E-02 9.öbE f7e-0b 60C / ^91H E E-O2 2.09E-04 FLAT L.28C b E-Ü2 9.70E-01 l.cbe-02 SUN 0.262t C C.^918 J t-02 4.C4E E-04 TEMP K B C IbOO 2.99E E E-1Ü 3.06E E aE E-07 2bOO 3.1t E E-07 3b00 3.1bE E E CE OE CE-07 booo 3.15E-10 3.Ü9E-Ü7 bboo 3.1bE E E E-07 FLAT 2.94E E-07 SUN 3.12b-10 3.C6E-C7

58 B17 Table B-10. CHANNEL GT7-10, CURVE NO. 10 LAMbUA(G» i. rüüb-i LAMbUA(A) 0.21i H l.u20t-c3 LAHbüA( 0) 0. ^ l * 0 LAMdDM(b) O^itO 1/w 9.butt ^ LAMöUAC* ü.^21 J UtLlA LAMUUM. J «i 1 C Alti-H t.ldüt-ij LAMUUA(S) 0. ^ 14 U Ülthfi CitfF) '.lujl-l J.09db-l 0 JhMP K LI LO L^ OtLTA L 1 ttct H(LÜJ M( bl-b» IbOO U.i29V O^'td v>. ->Ul ö0b-u3 5.29b b C t) 0.^:440 J.021u b.l4fc b-l^ 1.09t-l3 237i 0.220J c Jl9y l.c5h-l 6.00b b-ll 2'W3 0. ^ 1 > ^ 0.22^3. 2J97 j.jl9b 1.09t-ül 1.74b-U9 4.13E-il V ^7 ü.t3v5 J.Ü197 l,&9e-0l 2.29b b-11 3C00 ü.21b,: 0.22dÜ L.<i c lb fc-09 35ÜÜ C.2172 Ü.2207 L. i36 5 j t-l 3.04b fc-0b d Ü lb-^l 2.94b E U O.^-WV Db-Ul 1.73b öt U HÜ U.^J44 J.O190 1.tbb-l 7.16b E tl 0.^340.l b-ül 2.31b b u.<:i / 0.233O 0.01b9 1.53b-ül Ö.12b-C3 1.4bE-04 FLAT 0.2U C.^J13 j.01«v 1.64b-Jl 9.6ab E-02 iun t 0.23JO J.Jlb <.4Ob E-04 IbMP K ü i, isoo ).4dE-l2 3.41E E-11 i ub 2373 J 1./6L-1 I 1.73b-Cb i L.77b-i) 1.73E-Cb I«77E-1 I d 300 i..76b-l) 1.72E-0b c-lJ 1.70b-0b HOOO l.73b-l I 1.70E-0b 450J ).73b-i I 1.69t-0b 5u00 J.73E b J.73b-l) 1.70b-Ob OO J.73b-li 1.70E-0b FLAT 1.75b-i b SUN 1.bGt-U 1./7-0b

59 B18 Table B-ll. CHANNEL GT7-U, CURVE NO. 11 l-lambda(o) UMBDA(O) LAMBDA(0) LAMBDA(S) 4.070E LAMBDA(A) LAMBDA(B) DELTA LAMBDA W 1/W A(EFF) B(EFF) C(EFF) 3.860E E E E E-02 TEMP K. LI LO L2 DELTA L T(LO) H(LO) H(EFF) FLAT SUN , E E E E E-01.20E-01,22E-01,23E-01,23E-01,24E-01,25E-01,25E-01,25E E E-01,17E-05.37E-05, 10E-04,47E-04.18E-04.25E-04.06E-03 2,05E E E E E E E E E E E E E E E E E E E E E E SE-03 TEMP K E E E E E E E E E E E E E E E E E E ,92E E E E E E E E-01 FT AT 6.88E E-01 SUN 6.93E E-01

60 B19 Table B-12. CHANNEL GT7-12, CURVE NO. 12 T-LAMBDA(O) 5.710E-01 LAM3DA(A) W 3.860E-04 LAMBDA(0) LAMBDA(B) /W 2.591E 03 LAMBDA(C) DELTA LAMBDA A(EFF) 5.200E-06 LAMBDA(S) B(EFF) C(EFF) 5.200E E-02.'EMP K LI LO L2 DELTA L T(IX)) H(LO) H(EFF) E E E E E E E E E U E E E E E-04 J.59E E E E E E E E E E E E E E E E E E E E~ E E E E E-03 FLAT E E E-01 SUN , E E E-03 TEMP K E E E E E E E E E E E E E-05 l.ooe E E E E E E E E E E E E-02 FLAT 3.93E E-01 SUN 3.83E E-02

61 B20 Table B-13. CHANNEL GT7-13 CURVE NO. 13 T-LAMBDA(0) 5.300E-01 LAMBDA(A) W 3.860E-04 1AMBDA(0) LAMBDA (B) /W 2.591E 03 LAMBDA(0) DELTA LAMBDA A(EFF) 3.550E-06 LAMBDA(S) B(EFF) C(EFF) 3.550E E-03 TEMP K LI LO L2 DELTA L T(LO) H(LO) H(EFF) FLAT SUN ,5140, , E E E E E E E E E E E E E E E E E E E E E E E E E-03 3,18E E E E E E E E E E E E E E-04?..76E E E E E E-03 TEMP K E E E E E E E E E E E E E E E E E E E E E E E E E E-02 FLAT 3.27E E-02 SUN 3.21E E-02

62 B21 Table B-14. CHANNEL GT7-14, CURVE NO. 14 T-IAHBDA(O) 4.060E-01 LAMBDA(O) AMBDA(C) LAMBDA (S) LAMBDA (A) 1,3020 LAMBDA (B) DELTA 1AMBDA W 3.860E-04 1/W 2.591E 03 A(EFF) 6.020E-06 B(E?F) 6.020E-06 C(EFF) 1.560E-02 :iimp K Ll LO 1,2 DELTA L T(LO) H(LO) H(EFF) E E E , E E E , E E E , F-01 3,45E E E E-n/! 5.21E E-01 5,24E E E E E ,3170 1, E E E E-01 2,64E E E-01 3,63E E E-01 4,71E E E E /E E 'E E-04 FLAT l^.oo E E E-01 SUN E-01 3,31E E-03 TEMP K B C E E E E E E E E E E E E E E-0I E E E E E E E E E E E E-01 FLAT 4.85E E-01 SUN 4.69E E-01

63 B22 Table B-15. CHANNEL GT7-15, CURVE NO. 15 T-LAMBDA(0) 7,:40E-01 IAMBDA(0) LAMBDA(O) 2,9370 LAMBDA(S) LAMBDA(A) W 3.860E-04 LAMBDA(B) /W 2.591E 03 DELTA LAMBDA A(EFF) 8.020E-O6 B(EFF) 8.020E-06 C(EFF) 2.078E.02 TEMP K LI LO L2 DELTA L T(LO) H(LO) H(EFF) FLAT SUN ,7030,7000,6970,6940,6910,7230, , , ,2270 0,2200 6,54E E-01.51E-01.45E-01.45E-01.45E-01.33E-01.27E-01.22E-01,16E-01,11E-01.65E-01.99E-01.60E E E E E E E E E E E E E-04 6,36E E-04 9,37E-01 3,22E E E E E E-05 08E-05 64E-05 34E-05 16E-05 01E-04 20E-04 41E E E E-04 TEMP K FLAT SUN B 3.71E E E E E E E E E E E E E E E E E E-02 9,84E E E E E E E E E E E E-02

64 B23 Table B-16. CHANNEL GT8-16,, CURVE NO. 16 T-LAMBDA(0) 4.600E-01 UMBDA(A) 1.,8180 W 3.860E-04 LAMBDA(0) LAMBDA(B) /W 2.591E 03 LAMBDA(0) DELTA I.4MPOA A(EFF) 3.700E-06 LAMBDA(S) B(EFF) C(EFF) 3.700E E-03 'EMP K LI LO L2 DELTA L T(LO) H(LO) H(EFF) E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-04 FLAT E E E-01 SUN E E E-03 TEMP K E E E E E E E-05 7,16E E E E E E E E E E E E E E E E E E E-02 FLAT 2.83E E-02 SUN 2.70E E-02

65 B24 Table B-17. CHANNEL GT7-17, CURVE NO. 17 T-UMBDA(O) 4.30OE-O1 L\MBDA(0) LAMBDA (0) LAMBDA(S) LAMBDA(A) W 3.860E-04 LAMBDA(B) I/W 2.591E 03 DELTA LAMBDA A(EFF) 3,800E-06 B(EFF) 3.800E-06 C(EPF) 9.845E-03 TEMP K LI LO L2 DELTA L T(LO) H(LO) H(EFF) FLAT SUN ,1380,1370,1370,1370, , ,1800, E-01 11E-01 UE-Ol 11E-01 16E-01 16E-01 16E E E-01 22E-01 22E-01 22E-01 22E-0] 06E-01 22E E E-04,21E-04.83E-04.12E-04.46E E E E E E E E E E E E E E E E E E E E E E E E E-04 TEMP K E E E E E E E E E E E E E E E E E E E E E E E F E E-02 FLAT 3.16E E-02 SUN 3.29E E-02

66 B25 Table B-18. CHANNEL GT7-18, CURVE NO. 18 T-IAMBDA(O) 5,050E-01 LAMBDA(0) LAMBDA(0) LAMBDA(S) LAMBDA (A) W 3.860E-04 LAMBDA(B) /W 2.591E 03 DELTA LAMBDA A(EFF) 5.300E-06 B(EFF) 5.300E-06 C(EFF) 1.373E-02 TEMP K LI LO L2 DELTA L T(LO) H(LO) H(EFF) FLAT SUN E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-03 10E-06.OOE-06.85E-06,llE E E E E E E E E E E E-04 TEMP K E E E E E E E E E E E E L E E E E E E E E E-Ü E E E E-01 FIAT 5.29E E-01 SUN 5.35E E-01

67 B26 Table B-19. CHANNEL GT7-19, CURVE NO. 19 T-LAMBDA(O) 4.810E-01 LAMBDA(A) W 3.860E-04 UMBDA(O) LAMBDA(B) 2,8550 1/W 2.591E 03 LAMBDA(C) DELTA LAMBDA A(EFF) 1.100E-05 LAMBDA(S) B(EFF) C(EFF) 1.100E E-02 TEMP K LI LO L2 DELTA L T(LO) H(LO) H(EFF) FLAT SUN , ,7750, , , , E E E-01 3,88E-01 3,88E-01 3,88E-01 3,88E-01.89E-01.89E-01.89E-01,89E-01.89E-01.89E-01.91E-01.89E-01 2,72E-C5 6.05E E-05 9,52E-05 l,06e-04 l,20e-04 l,81e-04 2,49E-04 3,18E-04 3,90E-04 4,64E-04 5,39E E-04 8,02E-01 2,74E-03 3,58E E E-06 l,25e-05 l,39e E-05 2,37E E E E E E-05 8,04E E-01 3,57E-04 TEMP K B C E E E-Ü5 2.17E E E E E ,38E-05 2,17E E E E E E-05 2,19E E-05 2,19E E E E-05 2,19E E E E E-01 FLAT 8.32E E-01 SUN 8.43E E-01

68 B27 Table B-20. CHANNEL GT7-20, CURVE NO. 20 T-LAMBDA(0) 5.120E-01 LAMBDA(A) W 3.860E-04 LAMBDA (0) LAMBDA (B) /W 2.591E 03 LAMBDA (0) 2.8A00 DELTA LAMBDA A(EFF) 1.980E-05 LAMBDA(S) B(EFF) C(EFF) 1.980E E-02 TEMP K LI LO L2 DELTA L T(LO) H(LO) H(EFF) FLAT SUN , ,7680,7680, Ü ,100C.99E-01.01E-01.01E-01.01E-01.01E-01.01E-01.02E-01.02E-01.02E-01.02E E E E E-01 3,04E E E E-05 1.O1E E E E E E E E E E E E E E E E E E E E E E E E E E E-04 TEMP K E E E E E E E E E E E E E E E E E E E E E E E E E E-01 FLAT 1.41E E-01 SUN 1.48E E-01

69 B28 SECONDARY MIRROR V'CASSEGRAIN COLLECTING OPTICS STRIPED ALUMINUM VIBRATING V\BEAMSPLITTER CHOPPER- BEAMSPLITTER ^v ä FRONT SURFACED ALUMINUM MIRROR OPTICAL INTERFERENCE FILTERS SOLAR BLIND PHOTOMULTIPLIERh- TUBE I FRONT SURFACED ALUMINUM MIRROR KRS5 WINDOW I LEAD SULFIDE DETECTOR Figure B- 1. Radimeter Schematic Diagram EQUIVALENT LINEAR VOLTAGE, V E (vlts) 7.5 Figure B-2. V T vs. V E

70 B29 NORMALIZED POWER, f(p) Figure B-3. V T vs. f(p) 10* p 10 X s a > IS K 10" O'ZIOO'C CD. 2200* C CHANNEL NO G " 10" EFFECTIVE IRRAOIANCE, H (f( (watt-cm' 2 ) 10" Figure B-4. V-pG vs. Effective Irradiance

71 B30 ICT et 10' > < *0 G.220O"C CHANNEL NO I0 _ 10" IO-'» IO-" 10-" EFFECTIVE IRRAOIANCE, H, ff (wlt-em' 2 ) 10" Figure B-5. V^G vs. Effective Irradiance 10' lo'«i > (9 < 10'»2IOO*C Q«2200*0 CHANNEL NO. G " -II in-10 in-«effective IRRADIANCE, H t(f (wlf-cm -2 ) 10"' Figure B-6. V T G vs. Effective Irradiance

72 B aicc Q.2200"C CHANNEL NO. G-7-4 EFFECTIVE IRRAOIANCE, H (ff (wall-cm' 2 10" Figure B-7. V-pG vs. Effective Irradiance 10* s 10' ui 5.0- s IE < " lo'" 10"" 10" EFFECTIVE IRRAOIANCE. H, ff (watl-cnt*) O'Z\Q0'C Q.ZZOO'C CHANNEL NO G " Figure B-8. V^G vs. Effective Irradiance

73 B32 i 10' I0 4! I At UJ s < > K UJ 10 X < 10" - -ZIOO'C Q.2200'C s CHANNEL NO. G-7-6 / 1.0 X i i 1 10" 10" I0 - I0 _ 10 EFFECTIVE IRRADIANCE. H, (f (wtl-cnt 2 ) Figure B-9. VrpG vs. Effective Irradiance 10' P Z ' 10 «2100*0 E)«2200*C UJ (9 ( I- CHANNEL NO. G-7-7 i- I0 _ EFFECTIVE IRRADIANCE, H lff (wott-cm" z ) Figure B-10. V T G vs. Effective Irradiance IO"'

74 B33 O'ZIOO-C a ^ZZOO'C CHANNEL NO. G-7-8 EFFECTIVE IRRADIANCE, H eff (wtf-cm" 2 ) IO-' Figure B-ll. VpG vs. Effective Irradiance 10' IT p 10* UJ I > Ul < 10 0 = 2I00 8 C Q'ZZOO'C CHANNEL NO. G-7-9 I0 _ 10" 10'" 10"" 10"' EFFECTIVE IRRADIANCE. H, f,(«ft-cm -z ) i-! Figure B-12. V-pG vs. Effective Irradiance

75 B34 10" IE O <J 2 p (0 O > UJ O K < 10" 0>2I00 0 C Q.2200*C CHANNEL NO. G-7-10 ID'' lo" 15 EFFECTIVE IRRADIANCE, H etf (watt-cm -8 ) 10" Figure B-13. V T G vs. Effective Irradiance 5.0 e ui (9 > 3.0 g »C D 2000*0 A. 1700* CHANNEL NO " I0 _ » EFFECTIVE IRRADIANCE, H.ff (wlt-cm'*) 10" Figure B-14. V vs. Effective Irradiance

76 B I 4.0 III t 3.0 > UJ gz. < t- O. 2100»C Q. ZOOO^C A. 1700»C CHANNEL NO. G ' r» 10-10" EFFECTIVE IRRADIANCE. H, ff (watt-cm'*) lo" 8 I0 _ B-15. V vs. Effective Irradiance »C G -ZOOO'C A 1700'C CHANNEL NO. G-7-13 EFFECTIVE IRRADIANCE, H^f (wtt-em 1 ) 10" B- 16. V T vs. Effective Irradiance

77 B »C Q.2000*0 A. 1700»C CHAN N i NO " EFFECTIVE IRRADIANCE. H eff (watt-cm' 1 ) Figure B-17. V T, vs. Effective Irradiance 5.0 Z4.0 Mi 19 Ü 30 O > Ul g2.0 < 2100 «C E). 2000*0 A 1700 «C 1.0 CHANNEL NO ' IO-«lOT» 10' lo" 10,-B EFFECTIVE IRRADIANCE. H^f (wtt-cm"*) Figure B-18. V T vs. Effective Irradiance

78 B «C Q ZOOO'C A 1700*0 CHANNEL NO. G-7-16 EFFECTIVE IRRAOIANCE, H,,, (wff-cm" 1 ) I0 _ Figure B-ig. V T vs. Effective Irradiance 5.0 O 2100»C D ZOOO'C A I700*C CHANNEL NO. G-7-17 EFFECTIVE IRRAOIANCE, H^f (wtt-em f ) 10" 10" Figure B-20. V T vs. Effective Irradiance

79 B O 2100»C ü ZOOO'C A. ITOO'C CHANNEL NO » lo"» lo" 7 10"«EFFECTIVE IRRADIANCE, H tff («tt-cm'') 10" Figure B-21. V T vs. Effective Irradiance »C > 2000*C A. I700*C CHANNEL NO. G-7-19 EFFECTIVE IRRADIANCE, H, ff (wll-em^) 10" 10" Figure B-22. V T vs. Effective Irradiance

80 B O > 2100 *C Q.ZOOO'C A. 1700*0 CHANNEL NO «lO" 7 10-«10-» EFFECTIVE IRRADIANCE, H^f (wtt-cm* 1 ) 10-* Figure B-23. V.p vs. Effective Irradiance Temp («F) Figure B-24. Radimeter Respnsivity vs. Temperature »1.9 ANGLE-DEGREES FROM OPTICAL AXIS Figure B-25. Radimeter Field f View Phtmultiplier Sectin

81 B »IJO 1.5 ANGLE-DEGREES FROM OPTICAL AXIS Figure B-26. Radimeter Field f View - PbS Sectin , WAVELENGTH (micrns) Figure B-27. System Respnse Curves Phtmultiplier Channels CHANNEL NO. G-7-2 X» 2340/1 AX S ' 0228M WAVELENGTH (micrns! WAVELENGTH (micrns) 034 Figure B-28. System Respnse Curves Phtmultiplier Channels Figure B-29. System Respnse Curves Phtmultiplier Channels

82 B41 % Q ui N -I < 5 IT O 7? CHANNEL NO G-7-5 X s " 2760 fj. AX S ' 0168 M 0 -»L _U I 1 li WAVELENGTH (micrns) I I I L WAVELENGTH (micrns) 032 Figure B-30. System Respnse Curves Phtmultiplier Channels Figure B-31. System Respnse Curves Phtmultiplier Channels 1.0 CHANNEL NO G M XS'.0068M 2 a: S IQ" in >- tn ui f-j _l < a WAVELENGTH (micrns) 10'' WAVELENGTH (micrns) 0 32 Figure B-32. System Respnse Curves Phtmultiplier Channels Figure B-33. System Respnse Curves Phtmultiplier Channels

83 B42 CHANNEL NO G-7-9 X $.2870^ &X S > 0082 M WAVELENGTH (micrns) Figure B-34. System Respnse Curves - Phtmultiplier Channels WAVELENGTH (micrns) Figure B-35. System Respnse Curves Phtmultiplier Channels i. 1.0 ml«/) in z 2 in UJ a in UJ < 2 IT O Z clc a. UJ a. 2 IO' UJ i- in > in N _i «t 2 IT O Z i-' Q WAVELENGTH (micrns) Figure B-36. System Respnse Curves Phtmultiplier Channels 10' WAVELENGTH (micrns) Figure B-37, System Respnse Curves PbS Radimeter Channels

84 B in\i/t a. <n r < 5 a WAVELENGTH (micrn») UJ" en z 0. <rt UJ 1 2 UJ (- >- i/i a UJ IM J < 2 1 O z 10" 10' I CHANNEL NO. G-7-I3I X s = h AX S = n WAVELENGTH (micrns) 1.70 Figure B-38. System Respnse Curves PbS Radimeter Channels Figure B-39. System Respnse Curves PbS Radimeter Channels '* ISWt a. VI z UJ t- 10" in -I 2 CHANNEL NO. G-7-14 X s = /4 AX S = ^ 10" I WAVELENGTH (micrn») Figure B-40. System Respnse Curves PbS Radimeter Channels : WAVELENGTH (micrn») Figure B-41. System Respnse Curves PbS Radimeter Channels

85 B a. in > hi h- U) >- Q UJ < 5 a: i- CHANNEL NO G-7-16 \ X s M \ AX S = 0I35 p \ UJ v> z 2 «UJ cc S UJ E Ü1 Q UJ M Ct O 10" lo ' I I WAVELENGTH (micrns) Figure B-42. System Respnse Curves PbS Radimeter Channels \ 10'' WAVELENGTH (micrns) Figure B-43. System Respnse Curves PbS Radimeter Channels </) c/) cl«uj a: S 10" > in Q UJ N D «I > cc a. 5 IO' < 5 a: 10"' WAVELENGTH (micrns) Figure B-44. System Respnse Curves PbS Radimeter Channels 10' WAVELENGTH (micrns) Figure B-45. System Respnse Curves PbS Radimeter Channels

86 B Q. 5 UJ (- >- </) a UJ tf < 2 ct i- 10' WAVELENGTH (micrns) Figure B-4fi. System Respnse Curves PbS Radimeter Channels

87 BLANK PAGE

88 Cl Appendix C Gemini 7 Interfermeter Calibratins 1. DESCRIPTION 01 l-l I INTERFEROMETER The physical installatin f the 1-14 interfermeter n the spacecraft required an ptical axis that was at 90 with respect t the lng dimensin f the electrnics package. This was accmplished by placing a plane frnt-surfaced aluminum mirrr at a 45 angle behind the barium fluride lens (Figure C-l). The mirrr reflected the incident radiatin thrugh a barium fluride transfer lens t the interfermeter beamsplitter cmpensatr which reflected ne-half f the incident radiatin t a fixed mirrr and transmitted the ther half t a mving mirrr. The tw signals were then recmbined t prduce an interference pattern n a dichric beamsplitter that reflected 0. 5 t 3. 5 M radiatin t the PbS detectr and transmitted the lnger wavelength radiatin t the blmeter. The utputs f bth detectrs were fed t linear amplifiers equipped with fur utput gain settings which were switched autmatically t accmmdate the recrding equipment. The gain settings were set s that the interfergrams wuld nt saturate the recrder and wuld assure that the nise recrded n the tape wuld be the utput nise f the interfermeter. The latter bjective was accmplished fr the n-bard FM recrdings, but sme f the real time telemetered data appeared n tapes that were extremely nisy. Five year's experience with interfermeters f the type flwn n Gemini-7 has shwn that an abslute calibratin perfrmed in the labratry seldm yields accurate results when applied t data btained in the field; this applies t bth wavelength and amplitude. It has been fund, hwever, that the relative spectral

89 ca re-spnse is stable; thus, the relative spectral radiance distributin f an unknwn target based n labratry calibratin can be determined accurately prvided that the frequency f the tnal cmpnent crrespnding t a given wavenumber is measured in the field. The vji factr used in cnverting snic frequency (f) t wave-number (v) has been bserved t drift as much as 7 percent in 6 hurs. This is a slw mntnic drift that seems t crrelate t sme degree with temperature. The prblem is recgnized by Blck Assciates, and they usually prvide a lw-level scillatr that was designed t mnitr' the gain f the system and t assure that the frequency crrespnding t a given wavenumber will be knwn fr the envirnment in which the measurements are made. The lw-level scillatr has nt been fund par- ticularly useful fr either functin since it des nt mnitr the ptical cmpnents f the system. Hwever, an scillatr tne was incrprated int the Gemini-7 interfermeter as an aid in lcating the surce f the truble if a malfunctin ccurred. We seldm use an interfermeter withut a bresighted radimeter equipped with a narrw interference filter; althugh we calibrate the interfermeter abslutely and reduce the data n the basis f this calibratin, the usual prcedure in the final analysis is t adjust the abslute level f interfermeter spectrum t agree with the radimeter data. Since we had n cnfidence that the instruments munted n the Gemini-7 spacecraft wuld in fact be bresighted during the flight, and since ur usual prcedure f checking the respnsivity and vjl factr n the spt with a knwn stand- ard culd nt be accmplished, a calibratin light filtered by a narrw interference filter was installed behind an aperture in the interfermeter mirrr. This light was turned n fr a perid f 5 secnds at 71-secnd intervals. When the Gemini-7 ON BOARD recrded tape was checked, it was fund that the vltage btained with the calibratin light agreed with the value btained at the time f calibratin t within 1 db (13 percent). It was als fund that the scillatr tne appeared at a frequency f 1745 Hz, as cmpared t the labratry value f 1790 Hz, amunting t a reductin f 2. 5 percent, while the frequency crrespnding t the calibratin light changed frm 642 t 659 Hz, amunting t an increase f 2. 7 percent. Interfermeter spectra f earth backgrund radiatin taken during the flight shwed that the O, CO.,, and H 0 absrptin bands appeared at the crrect wavelengths if the vji determined frm the calibratin light were used. The calibra- tin light was used bth fr determining the wavelength and the abslute level in the data reductin; ur usual prcedure f adjusting the interfermetric spectra in abslute level t agree with the radimetric data near 2. 2 M was nt fllwed because the tw instruments were nt bresighted.

90 C3 2. Uli: IIICIIItOK FILTER PROBLEM The dichric filter used in the Gemini-7 interfermeter was a lng wavelength, pass interference filter depsited n a barium fluride substrate. Lng wavelength, pass interference filters f this type invariably have "bumby" transmittance characteristics in their pass regin', this is als true f very wide band pass interference filters. A rise in the transmittance f the Gemini-7 interfermeter dichric filter near 1,4 /n caused a dip in the spectrum reflected t the PbS detectr. Scheduling cnditins made it impssible t change the filter in time t meet the delivery date fr installatin n the spacecraft fr initial system check-uts; hwever, permissin was btained t change the instrument in Flrida a few days befre the scheduled flight. Cnsequently, the dichric was replaced by a striped mirrr in a spare instrument that was calibrated and taken t Flrida; this instrument lst sensitivity just after the substitutin was made and a decisin was made t g with the dichric. The dichric filler prblem is the familiar ne in which the data are either ver-crrected, prducing a false rise in the reduced spectrum, r undercrrected, leaving a residual false dip in the reduced spectrum. It is a prblem, since the signal can be reduced sufficiently t be affected by the nise and, at best, the assumptin f a randm phase additin f signal and nise, which is used in ur data reductin prcedure, yields accurate results nly if the signal-t-nise radi is 3 r mre. 3. INTERFEROMETER CALIBRATION DATA A plt f vltage versus spectral irradiancefr the Gemini-7 interfermeter PbS sectin is given in Figure C-2 fr a wavelength f 2, 2 ß. The circled pints were btained with cllimated radiatin, using the cllimatr described in Appendix B. The psitins f the fur lines n the figure indicate the changes in sensitivity crrespnding t the fur autmatic attenuatr settings used in the interfermeter. The triangles given in Figure C-2 represent the values btained by irradiating the interfermeter with a 12 x 12 inch, 200 C blackbdy surce and a 4 x 4 inch, 300 C extended blackbdy surce. This calibratin was perfrmed t check the effective field f view f the interfermeter when used against targets filling the field f view. The spread in the extended surce calibratin pints is partially due t errr in setting the temperature f the blackbdy. A small errr in surce temperature resulted in a much larger errr in radiance at 2,2 ß fr the temperatures used in the extended surce calibratin. In additin it was fund that the

91 C4 surces are nt very unifrm ver their surfaces and that the emissivity varies with psitin; cnsequently the cllimated irradiance calibratin was used in the data reductin. A plt f interfermeter inverse irradiance respnsivity versus wavelength based n the labratry calibratin is given in Figure C-3. The curve applies t a temperature f 82 F that was measured by the thermistr bead installed near the detectr at the time f calibratin. The dip in the respnsivity indicated by the rise in inverse respnsivity in Figure C-3 is due t the dichric filter that was discussed earlier. The curve in the cut-ff regin near 2,1 ß is pssibly t high by 25 percent due t water vapr in the ptical path during calibratin. t. RESPONSIVm VERSUS TEMPERATURE We have never fund as strng a dependence f respnsivity n temperature in Blck Assciates' PbS interfermeters as we have generally fund in PbS radimeters, and the Gemini-7 instrument was n exceptin (Figure C-4). This respnse curve was made at a wavelength f 2.2 ß and is representative f the entire instrument bandwidth except fr the 2.1 ß cut-ff regin where variatin with temperature is mre prnunced. S. INTERFEROMETER FIELD OF ME«The field f view curve fr the interfermeter given in Figure C-5 was measured by irradiating the instrument with cllimated radiatin and rtating it while the cllimatr remained fixed; the target subtended an angle f apprximately radian.

92 es FRONT SURFACED ALUMINUM MIRROR TRANSFER LENS ^^V^V FIXED MIRROR BEAMSPLITTER- COMPENSATOR, I,CUBE LENS KR S5 DETECTOR LENS INCIDENT RADIANT ENERGY =^2.14^ N^B. FILTER CALIBRATE LIGHT KRS5 DETECTOR LENS DETECTOR L_ /THERMISTOR C_r BOLOMETER Figure C-l. Interfermeter Schematic Diagram lo 4 i IT ft Cllimated Rdltm /-, Extended Area Surce \0*i 10-» _J I 1 1 I 1 1 I 1 10-» i- IO-«SPECTRAL IRRADIANCE at Z.Z^.Hj^watt em*> ') Figure C-2. Interfermeter Output vs. Spectral Irradiance at 2.2 M

93 CG WAVELENGTH (micrn») Figure C-3. Interfermeter Inverse Spectral Irradiance Respnsivity vs. Wavelength PbS Sectin TEMPERATURE, degrees F MO Figure C-4. Interfermeter Respnsivity vs. Temperature PbS Sectin

94 C7-2 -I ANGLE (DEGREES FROM OPTICAL AXIS) 4 Figure C-5. Interfermeter Field f View PbS Srctin

95 Unclassified Security C lassificai in DOCUMENT CONTROL DATA R.D (Security clajtsificatian j title, ''- (/% nj abstract and tndcxinß ttnn^tatum "insi In- entered when the verall reprt M classified) I, ORiüiNATiNC ACTIVITY (Crpurati imlhnr) Air Frce Cambridge Research Labratries (CRO) L.G. Hanscm Field Bedfrd, Massachusetts REPORT TITLE GEMINI 7 LUNAR MEASUREMENTS 20. REPORT SECURITY CLASSIFICATION Unclassified TBT GROUP «DESCRIPTIVE NOTES (Type f reprt and inclusive dates) Scientific. Interim. 5. AUTHOR(S) (First 'itanf, I'uihllr initial, last marti') T. P. Cndrn J.J. Lvett L. Marctte W.U. Barnes R. Nadile 6. REPORT DATE September 1908 SU. CONTRACT DR GRANT NO.^ J).Y Order 363 h. PROJECT. TASK, WORK UNIT NOS. 8GG2 10, TOTAL NO. OF PAGES 9(J. 92 Tb. ORIGINATOR'S REPORT NUMBEW^; AFCRL NO. OF REFS I. DOD ELEMENT ()250301R d. DOD SUBELEMENT 96. OTHER REPORT HOlS} (Any ther numbers that may be "'^^""^"ERPNO , OISTRIBUTION STATEMENT 1 Distributin f this reprt is unlimited. It may be released t the Clearinghuse Department f Cmmerce, fr sale t the general public. It. SUPPLEMENTARY NOTES Supprted by SSD 631A and ARPA Order ABSTRACT 12. SPONSORING MILITARY ACTIVITY Air Frce Cambridge Research Labratries (CRO) L.G. Hanscm Field Bedfrd, Massachusetts Radimetrie and interfermetric measurements were made f the lunar surface during a penumbral eclipse frm the Gemini 7 spacecraft. Data were btained in the regin frm t 2. 6 micrns. The bnd albed f the mn is cmputed fr the spectral regins measured. FORM S5 DD *"' ' NOV 1473 Unclassified Security Classificatin

96 Unclassified Security Classificatin KEY WORDS BOLE WT Gemini 7 Optical Measurements Mn Albed Measurements Interfermeter Unclassified Security (classificatin