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 1.8 path widths, putting it over central
Maine (at 8:24 UT or 4:24 am EDT) and part of Quebec just west of the
Gaspe Peninsula. This north-south path also crosses South America,
passing over much of the length of Chile as well as western Venezuela
and Puerto Rico. This new prediction is based on 9 CCD images including
both Kleopatra and the asteroid taken about 10 hours ago and measured in
the ACT reference frame by Gordon Garradd; this "last-second" astrometry
should be quite accurate, with the formal error being +/-0.03" or +/-
half a path width, although I expect the actual error could be double or
possibly even triple this. But it is now doubtful that the event will
be seen west of New England. Garradd's J2000 position for the star is
RA 18h 36m 29.699s +/-0.003s, Dec -10 deg. 54' 28.95". Gordon also
measured the magnitudes of the objects, and found that Kleopatra is
close to 1.0 mag. fainter than the star, meaning that the occultation
magnitude drop will be about 1.1 magnitudes. But it could be more or
less, depending on which part of the 1-mag.-amplitude light curve the
event occurs; that has not been checked. Garradd obtained 24 CCD
images, but due to e-mail problems with my primitive laptop while now
on travel, I was not able to obtain these measurements by e-mail, and
had to work with a fax copy of them, so used only the first 3 and the
last 6 measurements (Garradd said that conditions were better
towards the end of his observing run, although there were no obvious
differences in the residuals between the early and late observations).
For those who have the IOTA LOCM asteroidal appulse local
circumstance predictions, the shifts are less, being +0.1 min. for the
U.T. and 0.04" or 0.5 diameters east for the path.
Some details of the occultation and the path are given below.
David Dunham, IOTA, 1998 April 30, 5h U.T.
OCCULTATION OF 11.0-MAG. GSC 5696 1723 BY 216 Kleopatra ON 1998 APR 30
MAGNITUDES OF Kleopatra = 12.01 V AND 13.21 B, PHYSICAL TYPE= M
MAG. DROP AT DISAPPEARANCE= 1.11 EPHEMERIS SOURCE = Goffin89
DIAMETER= 113. KM = 0.062 SECONDS OF ARC, CENTRAL OCCN. = 15.807 SECONDS
CENTER PATH IS ABOUT 141. KM WIDE AT THE COORDINATES LISTED BELOW
UNIV. TIME Kleopatra SUN MOON
LONGITUDE LATITUDE H M S ALT. AZI. ALT. AZI. ALT.
150.25 W -75.52 7 57 24.9 9.9 95.3 -27.1 213.2 -19.2
109.10 W -71.82 7 58 15.7 21.8 55.6 -32.6 167.2 -31.1
79.45 W -52.12 8 1 40.4 45.4 29.7 -40.2 122.8 -54.9
78.42 W -50.27 8 2 2.8 47.4 29.2 -40.5 120.3 -56.9
77.50 W -48.40 8 2 26.0 49.4 28.8 -40.8 117.8 -58.9
76.66 W -46.52 8 2 49.9 51.3 28.5 -41.1 115.4 -60.9
75.90 W -44.64 8 3 14.4 53.3 28.4 -41.3 113.1 -62.9
75.21 W -42.74 8 3 39.6 55.2 28.4 -41.5 110.8 -64.8
74.58 W -40.84 8 4 5.4 57.1 28.5 -41.6 108.6 -66.8
74.01 W -38.93 8 4 31.7 59.1 28.8 -41.7 106.4 -68.8
73.49 W -37.02 8 4 58.6 61.0 29.3 -41.7 104.2 -70.7
73.01 W -35.10 8 5 26.0 62.9 29.9 -41.7 102.1 -72.7
72.58 W -33.17 8 5 53.8 64.8 30.8 -41.6 100.0 -74.7
72.18 W -31.25 8 6 22.1 66.6 31.9 -41.5 98.0 -76.6
71.82 W -29.31 8 6 50.8 68.5 33.3 -41.3 96.0 -78.6
71.48 W -27.38 8 7 19.8 70.3 35.1 -41.1 94.1 -80.5
71.17 W -25.44 8 7 49.2 72.1 37.4 -40.8 92.2 -82.4
70.89 W -23.50 8 8 18.9 73.9 40.2 -40.5 90.3 -84.2
70.64 W -21.56 8 8 48.9 75.5 43.9 -40.1 88.6 -86.0
70.40 W -19.61 8 9 19.0 77.1 48.6 -39.7 86.8 -87.3
70.18 W -17.66 8 9 49.4 78.6 54.6 -39.2 85.1 -87.5
69.98 W -15.71 8 10 19.9 79.9 62.5 -38.7 83.5 -86.4
69.80 W -13.76 8 10 50.5 80.9 72.4 -38.2 81.9 -84.7
69.48 W -9.86 8 11 51.9 81.8 97.8 -37.0 78.9 -81.0
69.22 W -5.94 8 12 53.3 80.9 123.3 -35.6 76.1 -77.2
68.90 W -0.06 8 14 24.8 77.1 147.4 -33.4 72.3 -71.3
68.66 W 5.82 8 15 54.5 72.1 159.1 -30.8 69.0 -65.4
68.60 W 7.79 8 16 23.9 70.3 161.6 -29.9 68.0 -63.5
68.54 W 9.75 8 16 53.0 68.5 163.6 -29.0 67.0 -61.5
68.49 W 11.72 8 17 21.7 66.7 165.3 -28.1 66.1 -59.5
68.45 W 13.69 8 17 50.0 64.8 166.7 -27.1 65.2 -57.5
68.41 W 15.66 8 18 17.8 62.9 168.0 -26.1 64.4 -55.6
68.38 W 17.63 8 18 45.2 61.0 169.0 -25.2 63.6 -53.6
68.35 W 19.60 8 19 12.1 59.1 169.9 -24.1 62.9 -51.6
68.32 W 21.57 8 19 38.4 57.2 170.7 -23.1 62.2 -49.6
68.28 W 33.41 8 22 3.4 45.5 173.7 -16.8 58.8 -37.8
68.28 W 35.38 8 22 25.1 43.6 174.0 -15.7 58.4 -35.8
68.37 W 43.29 8 23 44.1 35.7 175.0 -11.3 57.0 -27.9
68.41 W 45.27 8 24 1.7 33.7 175.1 -10.2 56.7 -25.9
68.45 W 47.25 8 24 18.5 31.8 175.3 -9.1 56.4 -24.0
68.51 W 49.23 8 24 34.3 29.8 175.4 -8.0 56.2 -22.0
68.57 W 51.22 8 24 49.2 27.8 175.5 -6.9 56.0 -20.0
68.65 W 53.20 8 25 3.1 25.8 175.5 -5.8 55.8 -18.0
68.74 W 55.18 8 25 16.1 23.9 175.6 -4.7 55.6 -16.0
CENTER FOR 216 Kleopatra DATE 1998 APR 30
W. LONG. LAT. W. LONG. LAT. W. LONG. LAT. W. LONG.
LAT.
68.294 25 0.0 68.275 33 0.0 68.334 41 0.0 68.499 49
0.0
68.288 26 0.0 68.278 34 0.0 68.348 42 0.0 68.530 50
0.0
68.283 27 0.0 68.282 35 0.0 68.364 43 0.0 68.564 51
0.0
68.279 28 0.0 68.288 36 0.0 68.381 44 0.0 68.601 52
0.0
68.276 29 0.0 68.294 37 0.0 68.400 45 0.0 68.642 53
0.0
68.274 30 0.0 68.302 38 0.0 68.422 46 0.0 68.686 54
0.0
68.273 31 0.0 68.311 39 0.0 68.445 47 0.0 68.735 55
0.0
68.274 32 0.0 68.322 40 0.0 68.471 48 0.0 68.788 56
0.0
AT U.T. 8 21 0, W. LONG.= 68.279, LAT.= 27.984
AT U.T. 8 22 0, W. LONG.= 68.276, LAT.= 33.102
AT U.T. 8 23 0, W. LONG.= 68.309, LAT.= 38.715
AT U.T. 8 24 0, W. LONG.= 68.402, LAT.= 45.077
AT U.T. 8 25 0, W. LONG.= 68.631, LAT.= 52.741
(if path shifts 0.06" west of the new prediction; it could shift some
more)
TRACK 60 WEST FOR 216 Kleopatra DATE 1998 APR 30
W. LONG. LAT. W. LONG. LAT. W. LONG. LAT. W. LONG.
LAT.
69.385 25 0.0 69.454 33 0.0 69.645 41 0.0 70.009 49
0.0
69.387 26 0.0 69.471 34 0.0 69.679 42 0.0 70.071 50
0.0
69.392 27 0.0 69.489 35 0.0 69.717 43 0.0 70.138 51
0.0
69.398 28 0.0 69.510 36 0.0 69.757 44 0.0 70.211 52
0.0
69.406 29 0.0 69.532 37 0.0 69.800 45 0.0 70.289 53
0.0
69.415 30 0.0 69.557 38 0.0 69.847 46 0.0 70.373 54
0.0
69.426 31 0.0 69.584 39 0.0 69.897 47 0.0 70.464 55
0.0
69.439 32 0.0 69.613 40 0.0 69.951 48 0.0 70.561 56
0.0
(if path shifts 0.06 east of the new prediction; it could shift even
more)
TRACK 60 EAST FOR 216 Kleopatra DATE 1998 APR 30
W. LONG. LAT. W. LONG. LAT. W. LONG. LAT. W. LONG.
LAT.
67.206 25 0.0 67.099 33 0.0 67.026 41 0.0 66.993 49
0.0
67.191 26 0.0 67.088 34 0.0 67.020 42 0.0 66.993 50
0.0
67.176 27 0.0 67.078 35 0.0 67.014 43 0.0 66.993 51
0.0
67.162 28 0.0 67.068 36 0.0 67.008 44 0.0 66.995 52
0.0
67.148 29 0.0 67.059 37 0.0 67.004 45 0.0 66.999 53
0.0
67.135 30 0.0 67.050 38 0.0 67.000 46 0.0 67.004 54
0.0
67.123 31 0.0 67.041 39 0.0 66.997 47 0.0 67.010 55
0.0
67.111 32 0.0 67.034 40 0.0 66.994 48 0.0 67.018 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
8 12.9 0.43W -1.5 0.21E 3.4E Garradd's star position in ACT frame
8 11.9 0.50W -2.5 0.14E 1.8E Garradd, 1998 Apr. 29, 9 obs. of both