THE ASTRONOMER Electronic Circular No 496 1991 Mar 17 14.30UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke,
Hants, RG22 4PP, England. Telephone: (0256)471074 Int:+44256471074
Telex: 9312111261 Answerback: TA G JANET BOXES:
GMH at UK.AC.CAM.ASTRONOMY.STARLINK or GUYH at UK.AC.SUSSEX.CLUSTER
TELECOM GOLD: 10074:MIK2885 PRESTEL 256471074
-------------------------------------------------------------------
PERIODIC COMET HARTLEY 1 (1991j)
Carolyn and Eugene Shoemaker and David Levy discovered another
comet on a pair of films obtained with the 0.46-m Schmidt at
Palomar on Mar. 12. The object was diffuse but condensed with a
tail > 1' long in p.a. 285 deg. Bad weather at Palomar prevented
convincing follow-up there, but Rob McNaught relayed preliminary
details to the Editor who relayed a request for confirmation to
selected observers throughout Europe.
Herman Mikuz and B.Dintinjana, Ljubjlana responded:
"We searched for the comet with the 0.25-m f/12 S-C and 576x384 CCD
camera at the University of Ljubljana Astronomical and Geophysical
Observatory. We have taken three 2-min CCD frames of the expected
field, centred at: 1991 Mar. 15.976UT, 16.050, 16.144.
We found a faint diffuse object of about mag 17 and of 15 arc sec
diameter on all frames. During the 4 hour observational interval,
the object moved 85 arc sec in PA 220deg. The comet approx position
at 1991 Mar. 16.050UT was RA 14h 14.9m DEC +12 20.0'."
Ted Bowell then relayed a precise position subsequently obtained
by Rob McNaught. Positions available:
1991 UT R.A. (1950) Decl. m1 Observer
Mar. 12.48888 14 16 12.59 +12 46 06.8 16.5 Shoemaker
12.51893 14 16 11.92 +12 45 55.8 "
16.050 14 14.9 +12 20 17 Dintinjana
16.70903 14 14 30.59 +12 16 34.7 McNaught
Brian Marsden, Harvard-Smithsonian Center for Astrophysics,
notes that the object is located some 16 deg from the nominal
prediction for P/Hartley 1 (1985 VII) on MPC 13045. A correction
of Delta(T) approximately +20 days reduces the residuals to no
better than 12', and there is a differential residual of more than
1' between Mar. 12 and 16. However, the comet made a close
approach to Jupiter in 1988 Feb., and a new linkage by Marsden
eliminates this discordance and satisfies 15 observations 1985-1991
with mean residual 1".1. The minimum separation from Jupiter was
0.36 AU.
Epoch = 1991 May 24.0 ET
T = 1991 May 17.6839 ET Peri. = 178.7489
e = 0.450686 Node = 38.2600 1950.0
q = 1.818390 AU Incl. = 25.7201
a = 3.310291 AU n = 0.1636458 P = 6.023 years
Ephemeris by G.Hurst using a program by N.James:
m = 14.0 + 5.0 log R + 10.0 log r
Date R.A. (1950) Dec. R r Elong Mag. Motion
h m o ' (AU) (AU) o "/hr P.A.
1991 Mar
15.00 14 15.30 +12 29.0 1.029 1.897 139.3 16.8 23 221
20.00 14 12.64 +11 50.3 0.988 1.886 143.8 16.7 31 228
25.00 14 8.89 +11 4.6 0.951 1.875 148.4 16.6 40 232
30.00 14 4.12 +10 10.7 0.919 1.865 153.0 16.5 48 233
1991 Apr
4.00 13 58.42 +9 7.8 0.893 1.856 157.4 16.4 57 233
9.00 13 51.94 +7 55.1 0.872 1.848 161.2 16.4 64 233
14.00 13 44.89 +6 32.7 0.857 1.841 163.7 16.3 69 231
19.00 13 37.55 +5 0.9 0.848 1.835 164.2 16.3 73 229
24.00 13 30.19 +3 20.8 0.846 1.830 162.3 16.3 75 226
29.00 13 23.11 +1 34.0 0.850 1.825 158.8 16.3 75 223
Guy M Hurst