170 Lunar Occultations

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1 170 Lunar Occultations 2. GRAZing occultations: PREDICTIONS AND Star DATA by Eberhard Riedel and David W. Dunham Lunar graze predictions The table on pp lists lunar grazing occultation predictions for much of North America for The events are limited to stars of magnitude 7.5 or brighter that will graze the limb of the Moon when it is at a favourable elongation from the Sun and at least as high above the horizon in degrees as the star s magnitude (e.g. a third-magnitude star is included only if its altitude is at least 3 ). The star s USNO reference number is the ZC number, unless the number is prefixed with an X, which are not in the ZC; their numbers are from the XZ catalogue, a more extensive zodiacal catalogue first prepared at the U.S. Naval Observatory but now updated by D. Herald in Australia. The maps on pp show the predicted graze tracks. The maps are false projections, since the lat/long scales are both linear. This makes it much easier for measuring coordinates or plotting locations with known coordinates than is possible with any other type of projection. The longitude scale is compressed by a factor of cos. The maps are not detailed enough for locating oneself in the zone 2 3 km wide where multiple disappearances of a star may occur. To obtain detailed predictions of any graze for plotting on larger-scale maps of your region, write to (or ) IOTA (see p. 162). For many grazes, IOTA overlays the predicted limit line on the very detailed maps and imagery of maps.google.com, available at but further corrections are needed based on the predicted lunar profile and the observer s height above sea level. Each track is keyed to the sequential number in the table. The computer-drawn number appears at the east and west ends of the track and is aligned parallel to it. Some overlapping numbers have been omitted for legibility; in these cases, check the other end of the track for the number. Conditions are represented by three different types of lines: solid line = dark limb (night) dotted line = bright limb (night) perpendicularly dashed line = dark or bright limb (day) Thicker lines are drawn for first-magnitude stars and planets. Many tracks begin and/or end with the letter A, B, or S: A denotes that the Moon is at a low altitude, B that the bright limb interferes, and S that sunlight or twilight interferes. The tick marks along the tracks indicate multiples of 10 min of every hour. For example, if the time for the west end of the track is 3:16.2, the tick marks proceeding eastward correspond to 3:20, 3:30, etc. Time always increases from west to east along the path. The time ticks, track numbers, and the A, B, and S letters are on the side of the limit with an occultation, that is, north of southern limits and south of northern limits. The locations for the North American standard stations for lunar total occultation predictions are indicated by asterisks on the graze maps (see pp ).

2 The Moon 171 names of graze stars occulted in 2015 ZC Name ZC Name ZC/XZ Name Psc Gem Vir 354 ξ Ari Gem 2114 μ Lib 404 UV Ari 1106 λ Gem 2193 ο Lib Tau Cnc 2271 θ Lib 648 δ1 Tau (Hyadum II) 1341 α Cnc (Acubens) Lib Tau 1409 ξ Leo (Sco)/Oph Tau 1428 ο Leo (Subra) 2687 U Sgr 692 α Tau (Aldebaran) 1468 π Leo (Yu Neu) 2889 V4026 Sgr Tau Leo Cap Tau (Sex)/Leo 3015 τ Cap Tau Leo Aqr Tau Leo 3278 ρ Aqr Gem 1891 θ Vir (Apami-Atsa) Aqr Names of occulted stars The stars that are occulted by the Moon are stars that lie along the zodiac; hence they are known by their number in the ZC compiled by James Robertson and published in the Astronomical Papers Prepared for the Use of the American Ephemeris and Nautical Almanac, Vol. 10, Part 2 (U.S. Government Printing Office, Washington, 1940). Robertson s ZC has been out of print for several years. In 1986, Isao Sato, a member of the Lunar Occultation Observers Group in Japan, republished the ZC. This new edition is based on the epoch J2000 and includes much new data, particularly on double stars. Since stars are not usually recognized by their ZC numbers, the equivalent Bayer designations or Flamsteed numbers of the stars occulted during the year are given in the table above. The ZC and XZ (now version XZ80Q) catalogues, updated in 2005 by D. Herald using HIPPARCOS, Tycho-2, and UCAC-2 data, are available through IOTA s Web site. An XZ number is given for the last two non-zc stars. Occulted stars known to be double In the table on the next page are data on double stars for which graze predictions are given for This information is from DSFILE, a comprehensive file of zodiacal double-star data compiled by Don Stockbauer, Henk Bulder, Mitsuru Sôma, David Herald, and David Dunham; most of the data for the ZC stars are in the Sato ZC. The successive columns give the USNO reference number of the star, the Graze # of the track, the double-star code (d), the magnitude of the brighter (A) and dimmer (B) components, the separation (Sep.) in arcseconds, and the position angle (PA) of B from A measured eastward from north. If the star is triple, the third component s magnitude is given under C, and its separation and PA from A are given in the last columns. An XZ number is given for the last non-zc star. The parameters are given for the epoch of the occultation, computed from orbital elements when available or from extrapolations from a long series of observations. If there is little change in the available observations, the last-observed separation and PA are used. Most components fainter than magnitude 11.5 are not listed, and some very close doubles whose parameters are not known, generally with separations less than 0.2, are also not listed. The latter include spectroscopic binaries (code J, U, or sometimes V) and visual occultation doubles (most codes K and X, and many Vs).

3 172 Lunar Occultations stars occulted in 2015 and known to be double magnitude Sep. Pa sep. PA USNO Graze # d A B C P C V O C , 27, 65, T , , 113, 138 M M S Y , 34, Y , Y Y , 129 W M T M C G M , 86 A C , 130 I X M X K The double-star codes (d) have the following meanings: A, C, or G... visual double B or V...close double, usually discovered by occultation D...primary of wide pair; secondary has separate catalogue entry E...secondary star of wide pair F...prediction is for the following component of a visual double H...triple, with close occultation pair and third visual component; prediction uses a mean position I...data for B component computed from orbital elements, but B component is itself a close double, with data for C component referred to B rather than A K...possible double from occultation L...close triple star (only two stars often listed because inner pair is often spectroscopic) M...mean position (centre of light) of a close pair is used by the ZC and/or XZ catalogue N...northern component of nearly equal double star O...orbital elements available and used to calculate the separation and PA Q...= O, but A component may be close double (if triple, C-component data are computed from orbital elements) R...triple; close pair = O and C component also has orbit relative to centre of close pair S...southern component of nearly equal double star T...visual triple star W...= A or C, but A component is a spectroscopic binary X...probable double from occultation Y...triple, K or X (B component) and A or C (C component) Z...triple, O (B component) and V (C component) Some close pairs have rapid orbital motion so the current PA is unknown.

4 The Moon 173 GRAZING lunar occultations for 2015 This table lists lunar grazing occultation predictions for much of North America (p. 170). Graze tracks are shown in the 8 maps on pp For each graze, the table provides: No....a chronological sequential number used on the maps Date...the date USNO d... the star s USNO (U.S. Naval Observatory) reference number and its doublestar code (in the d column) (see the bottom of p. 171) m...its visual magnitude %sl...the percent of the Moon sunlit (+ for waxing, for waning, E for lunar eclipses) L...whether the track is a northern (N) or southern (S) limit W.U.T....the Universal Time at the west end of the track Lo., La....the longitude and latitude of the west end of the track No. Date USNO d m %sl L W.U.T. Lo. La. No. Date USNO d m %sl L W.U.T. Lo. La. 1 Jan L N 6: X N 7: K N 4: X16618 M N 5: C N 6: X N 7: Feb M S 9: K N 10: I S 13: N 6: A S 22: T N 22: X N 1: S N 4: Y N 4: N 6: Mar Y S 0: X N 3: X21192 K S 6: C S 6: N 1: N 4: J N 3: X 5691 V N 3: X N 4: X N 4: T N 6: N 1: M N 3: N 6: M N 7: K N 5: X N 6: Y N 9: K N 5: Apr N 4: K N 23: X E S 10: X E S 12: X E S 10: X E S 10: X18811 K E S 11: X E S 11: X S 3: S 8: M S 8: X S 8: Apr A S 10: S 9: X S 9: A S 15: V S 3: X N 1: V N 0: V N 1: N 1: K N 1: May S 6: X25452 A 7 82 S 7: T S 7: S 9: N 9: P S 9: C 5 4+ S 0: T N 1: Y S 1: Y S 1: W N 20: U S 5: Jun N 11: A S 10: S 5: Jul. 6 X S 3: S 5: X N 11: K S 7: A S 19: S 0: K S 3: X S 4: Aug V N 8: N 3: V N 23: S 1: S 6: A S 2: S 4: X S 5: Sep N 7: X N 6: A N 4: N 10: S 6: K S 11:

5 174 Lunar Occultations GRAZING lunar occultations for 2015 (cont d) No. Date USNO d m %sl L W.U.T. Lo. La. No. Date USNO d m %sl L W.U.T. Lo. La. 95 Sep V N 11: X S 4: N 2: V S 2: S 3: K S 3: S 2: X25452 A S 3: X S 5: C S 6: S 8: S 4: K N 6: Oct N 3: O 7 77 N 5: J N 7: A S 13: T N 9: M N 5: N 8: K N 7: Y S 10: N 9: X N 8: M N 9: X24976 K S 3: G S 4: Oct S 2: K N 3: Nov N 8: X N 9: K N 6: Y N 10: V 5 42 N 8: W S 14: I N 22: X S 2: X S 2: S 3: N 9: K N 5: A S 10: T N 5: M N 0: V N 14: N 9: Dec N 5: T N 10: X N 0: S 0: S 23: V N 4: N 7: Lunar occultation and graze observations refine our knowledge of the shape of the lunar profile and the fundamental star coordinate system. These observations complement those made by other techniques, such as Kaguya and Lunar Reconnaissance Orbiter laser ranging and photographs.

6 The Moon 175 Grazing occultation maps january 1 march 10 March 11 31

7 176 Lunar Occultations Grazing occultation maps (continued) April 1 25 april 26 June 30

8 The Moon 177 Grazing occultation maps (continued) july 1 august 31 Grazing occultation maps (continued) september 1 30

9 178 Lunar Occultations Grazing occultation maps (continued) October 1 november 15 november 16 December 31