Double Stars at the U.S. Naval Observatory

Transcription

1 Page 12 Alan L. Behall 1 U.S. Naval Observatory 3450 Massachusetts Avenue, NW, Washington, DC, Abstract: Micrometer measures of double stars made with the 24-inch reflector and the 26- inch refractor of the U.S. Naval Observatory from 1973 to 1990 are presented. Introduction Alan Behall ( ) worked at the US Naval Observatory from in the Astronomy & Astrophysics Department in work primarily involving double stars. From 1968 to 1970, he made measures of 159 pairs with the 12 inch Clark refractor on the roof of Building 1 and obtained 68 mean positions with a median separation of 1.39 a.s. After his training period with the 12 inch, Alan began work with the 26 inch Clark refractor. From 1970 to 1974 he made measures of 1295 pairs with the 26 inch and obtained 370 mean positions with a median separation of 1.20 a.s. In 1974 he also made measures of 60 pairs with the 24 inch Boller & Chivens reflector, resulting in 24 mean positions with a median separation of 1.01 a.s. All of these measures are found in the second series of USNO Publications (Behall 1977). However, his in-depth analysis of orbit pairs is probably of greater significance. In 1963 he determined a very accurate orbit for 13 Ceti (Behall 1963), and returned to it a decade later (Gatewood & Behall 1975) with George Gatewood to investigate the residuals in parallax measures due to the unseen spectroscopic companion in this overluminous star. He later collaborated with Charles Worley (Worley & Behall 1973), determining the orbit of the faint red double L726-8 observed with the 61 inch parallax program. He continued his work on this pair, collaborating with Bob Harrington (Harrington & Behall 1973) determining their mass ratio. Also with Harrington (Harrington & Behall 1976), he investigated the Keplerian perturbation of the 1 Deceased: 11 June 2009 Figure 1. Alan Behall, USNO staff photo (August 1968).

2 Page 13 Table 1. Statistics of Samples Name Dataset Behall Years Figure 2: Alan Behall, USNO luncheon (September 2002). faint red dwarf pairs, G96-45 and G146-72, determining orbits that are still the standard. This was done in conjunction with his work on the parallax program (Harrington et al. 1976). After Alan retired, he had subsequent careers as a computer programmer for two other branches of the Federal Government, the Office of Personnel Management and the Veteran Administration. But even after Alan left the USNO, he maintained an interest in double star research and returned periodically from 1984 to 1990 to observe and make micrometer measures. His observing program on the 26 inch only ended when the USNO mothballed it s visual micrometry program in favor of speckle interferometry. Results After the cutoff date of his earlier publication (Behall 1977), additional measures were made before he left the USNO: 36 mean positions with a median separation of 1.13 a.s. with the 24 inch and 231 mean positions with a median separation of 0.82 a.s. with the 26 inch. The final set of post-retirement measures were delayed for some time. Of the 44 nights he observed from 1984 to 1990, Alan retained observing reports for only 12 of them. The reports for the remaining nights were apparently mishandled and the publication of these data have been delayed in a vain search through the USNO archives and double star papers of Charles Worley, who was in charge of the visual double star program. All of the mean positions in the pre and post retirement are presented in Table 2. In this table, the first two columns identify the system by providing its epoch-2000 coordinates and discovery designation. Columns three through seven give the parameters of the mean position, the epoch of observation (expressed as a fractional Besselian year), the position angle (in degrees), the separation (in seconds of arc), the magnitude difference (in visual, when determined), and the number of individual measurements in the mean. Column eight gives the telescope aperture in inches indicating either the 24 inch Boller & Chivens reflector or the 26 inch Clark refractor. Finally, column nine is reserved for notes which are listed at the end of the table. Compilation of the measurements and brief description prepared by Brian Mason. References Behall, A.L. 1963, AJ 68, 432 Behall, A.L. 1977, Pub. USNO 24, Pt.2 Behall, A.L. & Harrington, R.S. 1976, PASP 88, 204 Gatewood, G.D. & Behall, A.L. 1975, AJ 80, 1065 Harrington, R.S. & Behall, A.L. 1973, AJ 78, 1096 Harrington, R.S., Dahn, C.C., Behall, A.L., Priser, J.B., Christy, J.W., Riepe, B.Y., Ables, H.D., Guetter, H.H., et al. 1975, Pub. USNO 24, Pt.1 Worley, C.E. & Behall, A.L. 1973, AJ 78, 1973

3 Page 14 Table 2. Measurements of Double Stars 281 AB 281 AB 281 AB 1.57 MLB 429 AB 1929 AC 3056 AB 3056 AB 1250 AB AB J J AB AB AB D 2 AB BC 1.35

4 Page AB 208 AB AB 536 AB

5 Page AB AB AB 2 A,BC BC 729 AB AB AB AB AB 112.3

6 Page STT AB 2534 AB,C J KUI AB AB 1426 BC

7 Page A J AB AB AB AB

8 Page HU AB U AB AB Aa,Ab Aa,Ab AB,C AB AB BC AB AB AB

9 Page STF AB 2055 AB AB AB AB AB AB AB AB AB AB AB AB,CD

10 Page AB AB AB AB AB AB 2570 AB,C AB 2576 FG AB AB AB AB 2624 AB AB J J 5.51

11 Page AB CD 64 AB SE 2729 AB AB A,BC 3 BC AB AB 989 AB AB AB 154.7

12 Page AB AB BC AB 2950 AB AB Aa,Ab AB J HLD BC AB AB 503 AB AB AB

13 Page STF3050 AB STF3050 AB Editors Note: Alan Behall did the measures listed in this article, which was written by Brian Mason of the U.S. Naval Observatory.