Updates for three Asteroidal Occultations Next Week, & Aldebaran Occ'n
1. Apr.28 am, Pamela & 8.2-mag. star, SEMI-ACCURATE path now s. Fla. & along East Coast (New York City) & New England. The uncertainty is estimated to be 250 km or about 3 path-widths, so observers throughout the Florida Peninsula, Mid-Atlantic states, New York, New England, populous parts of Quebec, Ottawa area, Honduras, and Guatemala have a chance to see this relatively bright occultation. The prediction will be improved soon using better (ACT) reference data to reduce the available observations, so watch for further updates. 2. Apr.28 pm, Kolga & 8.8-mag. star, ACCURATE path now over southern Mexico and Guatemala, but enough uncertainly remains that central Mexico and the rest of Central America have a chance, but not the USA.
3. Apr. 30 am, Kleopatra & 10.8-mag. star, APPROXIMATE path is now over Maine and Quebec just n. of Maine, as well as almost all of Chile (it's a north-south path), western Venezuela, and Puerto Rico, but observers in all of New England, and probably the rest of the eastern USA (especially Midatlantic states and New York), Quebec, and Ontario should look for later updates, which should be much better.
4. Apr. 28, there will be a daytime occultation of Aldebaran for most of North America. More will be distributed about it later, and information about it will be on IOTA's lunar occ'n Web site at http://www.sky.net/~robinson/iotandx.htm The event will be spectacular in the early evening in central Europe. _____________________________________________________________________
Finder charts and general information for the Pamela and Kleopatra occultations are on pp. 94-95 of the April issue of Sky and Telescope, and on the skypub.com Web site occultation page; they also give general information about these events. More detailed charts from the IOTA Occ'n Newsletter North American Asteroidal Occultation Supplement for 1998 for all 3 occultations are (or soon will be) on IOTA's Web sites at http://www.sky.net/~robinson/iotandx.htm and also at http://www.anomalies.com/iota/splash.htm in the table of North American events at the top of the "upcoming events" section. Maps of the Pamela and Kolga events based on Pedro Valdez Sada's calculations using the Occult program are also there. His computations for Pamela are based on his own CCD observations made at Monterrey, Mexico, on April 1 and 21, reduced with GSC 1.2 data, but shifted to minimize the residuals for two Tycho stars present in both fields. An earlier prediction based just on the April 1st observations and not shifted to agree with the Tycho stars placed the path over s.e. Georgia, the central Carolinas, western Pennsylvania, western New York, and just east of Toronto, but that prediction is now known to be less accurate.
Information about the Pamela and Kleopatra occultations are (or soon will be) available on both IOTA occultation Web sites, as described above, so we will await more astrometic observations of these occultations before providing more details here. The new information about the Kleopatra occultation is given below.
David Dunham, IOTA, 1998 April 25 _______________________________________________________________________
The path of the occultation of an 11th-mag. star by the unusually shaped M-class (metallic) asteroid 216 Kleopatra the morning of April 30th will shift east of my nominal path shown on p. 86 of the February issue of Sky and Telescope by 3.4 path widths, putting it over eastern Maine (at 8:25 UT or 4:25 am EDT) and part of Quebec just west of the Gaspe Peninsula. This north-south path also crosses South America, passing over almost the whole length of Chile as well as western Venezuela and Puerto Rico. This new prediction is based only on an improved position for the star measured in the ACT reference frame by Gordon Garradd; there is no update yet for Kleopatra, whose 1989 orbit may now be in error, especially with the event being near a stationary point. So the actual path could easily be in error by 0.3" or 5 path- widths (or even more), giving observers throughout New England, New Brunswick, and Nova Scotia a chance to see the occultation. Hopefully soon someone will measure Kleopatra in the ACT reference frame (or adjusted to it) and then a considerably more accurate prediction will be possible. Garradd's J2000 position for the star is RA 18h 36m 29.699s +/-0.003s, Dec -10 deg. 54' 28.95".
For those who have the IOTA LOCM asteroidal appulse local circumstance predictions, the shifts are less, since the slightly better GSC 1.2 position of the star was used for them, while the GSC 1.1 position was used for the map in the Feb. issue of S&T. The corrections to the LOCM predictions are +1.1 min. for the U.T. and 0.12" or 2.0 diameters east for the path.
Some details of the occultation and the path are given below.
David Dunham, IOTA, 1998 April 24
OCCULTATION OF 10.83-MAG. GSC 5696 1723 BY 216 Kleopatra ON 1998 APR 30
MAGNITUDES OF Kleopatra = 12.51 V AND 13.21 B, PHYSICAL TYPE= M
IN VISUAL, COMBINED MAG. OF STAR PLUS Kleopatra = 10.62
AND MAG. DROP AT DISAPPEARANCE= 1.89 EPHEMERIS SOURCE = Goffin89
DIAMETER= 113. KM = 0.062 SECONDS OF ARC, CENTRAL OCCN. = 15.807 SECONDS
CENTER PATH IS ABOUT 114. KM WIDE AT THE COORDINATES LISTED BELOW
UNIV. TIME Kleopatra SUN MOON
LONGITUDE LATITUDE H M S ALT. AZI. ALT. AZI. ALT.
150.82 W -76.68 7 58 21.8 9.9 95.4 -26.1 213.2 -19.2
112.43 W -73.93 7 59 1.6 19.8 58.1 -30.7 171.0 -29.1
91.67 W -66.78 8 0 6.6 29.8 38.5 -34.6 145.3 -39.0
81.56 W -58.06 8 1 34.9 39.7 29.8 -37.7 129.0 -49.0
76.07 W -48.77 8 3 23.7 49.5 26.2 -39.7 116.4 -58.9
74.57 W -44.97 8 4 12.2 53.5 25.7 -40.2 111.9 -62.9
73.34 W -41.14 8 5 3.3 57.4 25.8 -40.5 107.5 -66.9
72.81 W -39.22 8 5 29.7 59.3 26.0 -40.6 105.4 -68.8
72.32 W -37.29 8 5 56.6 61.3 26.4 -40.6 103.3 -70.8
71.87 W -35.36 8 6 24.1 63.2 26.9 -40.6 101.3 -72.8
71.47 W -33.43 8 6 52.0 65.1 27.7 -40.5 99.3 -74.8
71.10 W -31.49 8 7 20.4 67.0 28.6 -40.4 97.4 -76.8
70.76 W -29.55 8 7 49.1 68.9 29.9 -40.2 95.5 -78.7
70.44 W -27.60 8 8 18.3 70.8 31.5 -39.9 93.6 -80.7
70.16 W -25.65 8 8 47.7 72.6 33.5 -39.7 91.8 -82.7
69.89 W -23.71 8 9 17.5 74.4 36.1 -39.4 90.0 -84.6
69.65 W -21.75 8 9 47.5 76.2 39.5 -39.0 88.3 -86.5
69.43 W -19.80 8 10 17.8 77.8 44.0 -38.6 86.6 -88.2
69.04 W -15.89 8 11 18.8 80.8 57.9 -37.6 83.4 -87.0
68.56 W -10.01 8 12 51.1 83.0 97.6 -35.9 79.0 -81.3
68.00 W -0.19 8 15 24.3 77.8 151.6 -32.3 72.6 -71.4
67.83 W 3.74 8 16 24.6 74.4 159.7 -30.6 70.4 -67.5
67.75 W 5.71 8 16 54.4 72.6 162.5 -29.8 69.4 -65.5
67.69 W 7.68 8 17 23.8 70.8 164.8 -28.9 68.4 -63.5
67.62 W 9.65 8 17 53.0 68.9 166.6 -28.0 67.5 -61.5
67.56 W 11.62 8 18 21.7 67.0 168.1 -27.1 66.6 -59.5
67.51 W 13.60 8 18 50.1 65.1 169.4 -26.1 65.8 -57.6
67.42 W 17.54 8 19 45.5 61.3 171.4 -24.2 64.2 -53.6
67.37 W 19.52 8 20 12.4 59.4 172.2 -23.2 63.5 -51.6
67.33 W 21.49 8 20 38.8 57.4 172.9 -22.1 62.9 -49.6
67.17 W 31.38 8 22 41.7 47.6 175.3 -16.9 60.2 -39.7
67.14 W 33.36 8 23 4.2 45.7 175.7 -15.8 59.8 -37.8
67.12 W 35.34 8 23 26.0 43.7 176.0 -14.7 59.4 -35.8
67.05 W 41.28 8 24 26.6 37.8 176.7 -11.4 58.4 -29.8
67.03 W 43.27 8 24 45.2 35.8 176.9 -10.3 58.2 -27.9
67.01 W 45.25 8 25 2.9 33.8 177.1 -9.2 58.0 -25.9
67.00 W 47.23 8 25 19.6 31.9 177.3 -8.1 57.8 -23.9
66.98 W 49.22 8 25 35.5 29.9 177.4 -7.0 57.6 -21.9
66.97 W 51.21 8 25 50.4 27.9 177.5 -5.9 57.5 -19.9
66.97 W 53.19 8 26 4.4 25.9 177.6 -4.8 57.4 -17.9
66.97 W 55.18 8 26 17.5 23.9 177.7 -3.7 57.3 -16.0
66.97 W 57.17 8 26 29.5 22.0 177.8 -2.6 57.3 -14.0
66.98 W 59.15 8 26 40.5 20.0 177.9 -1.5 57.2 -12.0
CENTER FOR 216 Kleopatra DATE 1998 APR 30
W. LONG. LAT. W. LONG. LAT. W. LONG. LAT. W. LONG.
LAT.
67.269 25 0.0 67.147 33 0.0 67.052 41 0.0 66.985 49
0.0
67.252 26 0.0 67.134 34 0.0 67.042 42 0.0 66.980 50
0.0
67.236 27 0.0 67.121 35 0.0 67.033 43 0.0 66.975 51
0.0
67.220 28 0.0 67.109 36 0.0 67.023 44 0.0 66.971 52
0.0
67.205 29 0.0 67.097 37 0.0 67.015 45 0.0 66.968 53
0.0
67.190 30 0.0 67.085 38 0.0 67.006 46 0.0 66.966 54
0.0
67.175 31 0.0 67.074 39 0.0 66.999 47 0.0 66.966 55
0.0
67.161 32 0.0 67.063 40 0.0 66.992 48 0.0 66.966 56
0.0
AT U.T. 8 22 0, W. LONG.= 67.222, LAT.= 27.869
AT U.T. 8 23 0, W. LONG.= 67.148, LAT.= 32.980
AT U.T. 8 24 0, W. LONG.= 67.078, LAT.= 38.580
AT U.T. 8 25 0, W. LONG.= 67.015, LAT.= 44.922
AT U.T. 8 26 0, W. LONG.= 66.969, LAT.= 52.547
(if path shifts 0.3" west of the new prediction; it could shift even
more)
TRACK 300 WEST FOR 216 Kleopatra DATE 1998 APR 30
W. LONG. LAT. W. LONG. LAT. W. LONG. LAT. W. LONG.
LAT.
72.733 25 0.0 73.054 33 0.0 73.623 41 0.0 74.557 49
0.0
72.761 26 0.0 73.110 34 0.0 73.716 42 0.0 74.710 50
0.0
72.793 27 0.0 73.170 35 0.0 73.815 43 0.0 74.873 51
0.0
72.828 28 0.0 73.234 36 0.0 73.921 44 0.0 75.047 52
0.0
72.867 29 0.0 73.302 37 0.0 74.033 45 0.0 75.233 53
0.0
72.908 30 0.0 73.375 38 0.0 74.152 46 0.0 75.432 54
0.0
72.953 31 0.0 73.452 39 0.0 74.279 47 0.0 75.644 55
0.0
73.002 32 0.0 73.535 40 0.0 74.414 48 0.0 75.872 56
0.0
(if path shifts 0.3" east of the new prediction; it could shift even
more)
TRACK 300 EAST FOR 216 Kleopatra DATE 1998 APR 30
W. LONG. LAT. W. LONG. LAT. W. LONG. LAT. W. LONG.
LAT.
61.844 25 0.0 61.281 33 0.0 60.526 41 0.0 59.467 49
0.0
61.782 26 0.0 61.199 34 0.0 60.414 42 0.0 59.305 50
0.0
61.717 27 0.0 61.114 35 0.0 60.296 43 0.0 59.134 51
0.0
61.650 28 0.0 61.025 36 0.0 60.173 44 0.0 58.955 52
0.0
61.582 29 0.0 60.933 37 0.0 60.045 45 0.0 58.765 53
0.0
61.510 30 0.0 60.838 38 0.0 59.910 46 0.0 58.566 54
0.0
61.437 31 0.0 60.738 39 0.0 59.770 47 0.0 58.355 55
0.0
61.360 32 0.0 60.634 40 0.0 59.622 48 0.0 58.132 56
0.0
MIN. GEOCENTRIC Shifts from nominal Prediction comparison
U. T. SEP. Time Path Kleopatra ephemeris: Goffin 1989
h m " m " widths Prediction (only star data updated)
8 14.4 0.64W 0.0 0.00 0.0 Nominal, GSC 1.1, p. 86 of 1998 Feb. S&T
8 11.8 0.54W -2.6 0.09E 1.4E Stellar data from GSC 1.2 used by LOCM
8 12.9 0.43W -1.5 0.21E 3.4E Garradd's star position in ACT frame