To: All SL9 Observers and Participants in the IAU Colloquium 156:
The Collision of Comet Shoemaker-Levy 9 and Jupiter
From: Don Yeomans and Paul Chodas
Subject: Synthesis of fragment impact times
During the upcoming conference at the Space Telescope Science Institute, there will be a workshop to determine, as best we can, the actual times that the fragments collided with Jupiter. Since the workshop time is limited we'd like to create a strawman table of impact times prior to the workshop. With this in mind, we would appreciate your comments on, and corrections to, the following table. In particular, we'd appreciate hearing from you if you have:
Much of the impact time data available is summarized in this Table. All times are UTC times as seen at the Earth (ie, they are corrected for light time). The first column of times contains the predicted impact times from the last pre-impact orbital solutions by Chodas & Yeomans. These are the times at which the fragments were predicted to reach the 1-bar level in Jupiter's atmosphere. The predictions for the poorly-observed fragments J, M, and P1 are very uncertain.
Impact times inferred from Hubble Space Telescope (HST) observations were determined using one of three following methods as outlined in Hammel et al., 1995, Science, vol. 267, pp. 1288-1296. One-sigma uncertainties (in min.) are given in parentheses.
p Plume observations. The times of the first images showing bright pixels
above Jupiter's limb. These are assumed to be direct observations of the
meteor or plume.
w Wave observations. The impact points were assumed to be at the center of
the wave features seen in HST images. The differences between the measured
and predicted impact longitudes were used, along with the rotation rate, to
correct the predicted impact time.
s Site observations. Same as the method used for the wave observations
except that the impact sites were identified without the aid of the
wave phenomena.
In the columns labeled "Observations", we compile reported times of precursor, flash, and plume observations that were often used to estimate an observed impact time.
Our best estimates of the impact times are given in the final column, with approximate uncertainties appearing in parentheses immediately below each estimate. The alignment of the uncertainties indicate their units. We have determined these times using various sources, weighted in the following order of priority:
Table. Impact Times for Fragments of Comet Shoemaker-Levy 9
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D.K. Yeomans and P.W. Chodas (JPL/Caltech)
Mar. 18, 1995
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Date Predict. HST-Inferred Observations Best Estimate
July (UTC) (UTC) (UTC)
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A 16 19:59:42 p 20:13:16 (0.2) 20:11:30 Precursor (Calar Alto) 20:13:00
w 20:15:54 (1) 20:18 Plume (Calar Alto) (2)
s 20:13:24 (3)
B 17 02:54:15 s 02:56:09 (3) 02:50 Io reddens (L. Campanas) 02:53:00
02:50 H3+ ionosphere (4)
brightening (UKIRT)
02:56 Plume (Keck)
C 17 07:02:16 s 07:13:51 (3) 07:18 Plume (IRTF) 07:12:00
07:17 Plume (Okayama) (3)
07:11:57 Fireball (AAT)
D 17 11:47:02 s 11:52:50 (3) 11:54:46 Precursor (AAT) 11:54:00
12:00 2nd flash (AAT) (3)
12:01 Plume (Okayama)
E 17 15:04:54 w 15:12:11 (1) 15:17:30 Plume (Calar Alto) 15:12:00
s 15:12:11 (3) 15:18 Plume (SPIREX) (3)
F 18 00:29:39 00:33 Spot on terminator at 00:33:00
01:10 suggests impact (5)
at 00:33 (CTIO)
G 18 07:28:56 p 07:33:16 (0.5) 07:33:32 GLL PPR (1st) 07:33:32
w 07:33:17 (1) 07:34:36 GLL PPR (2nd) (30)
s 07:35:11 (3) 07:33:37 GLL NIMS
07:33:32 GLL UVS
07:32:58 Precursor (AAT)
H 18 19:26:09 s 19:33:21 (3) 19:31:59 GLL PPR 19:31:59
19:33 Precursor (Calar Alto) (30)
19:33:04 Flash (Pic du Midi)
19:32:31 SPIREX
19:32:57 Flash (La Silla)
19:32:58 Flash (Vatican)
J 19 02:40 Not observed since Dec. 1993
K 19 10:18:23 s 10:30:58 (3) 10:24:14 GLL SSI 10:24:14
10:22:42 Precursor (AAT) (30)
10:24:33 Bright fireball (CASPIR)
10:24:02 1st brightness rise (Okayama)
10:25:08 2nd brightness rise (Okayama)
L 19 22:09:09 s 22:21:44 (3) 22:16:48 GLL PPR 22:16:48
22:16:30 Precursor (Calar Alto) (30)
22:17:30 Plume (Calar Alto)
22:17:35 1st of 3 flashes (Pic du Midi)
M 20 05:45 No observations since July 1993
06:08 Impact site obs. (Keck)
N 20 10:20:05 s 10:30:09 (3) 10:29:17 GLL SSI 10:29:17
10:35:23 Fireball (ANU) (30)
P2 20 15:16:21 No impact observations reported 15:23:00
(7)
P1 20 16:30 No observations since March 1994
Q2 20 19:47:19 s 19:46:31 (3) 19:44 Flash (Pic du Midi) 19:44:00
19:44 Precursor (Calar Alto) (4)
Q1 20 20:04:47 w 20:14:42 (1) 20:13:52 GLL PPR 20:13:52
s 20:18:24 (3) 20:13 Flash (Pic du Midi) (30)
20:13 Precursor (Calar Alto)
R 21 05:28:26 w 05:41:18 (1) 05:35:08 GLL NIMS 05:35:08
s 05:36:06 (3) 05:36:36 Precursor (AAT) (30)
05:34:52 1st flash (Palomar)
05:35:48 2nd flash (Palomar)
05:34:45 1st flash (Keck)
05:35:46 2nd flash (Keck)
05:35 1st notice (McDonald)
S 21 15:12:46 s 15:17:46 (3) 15:16 Brightening (SAAO) 15:16:00
15:22 2nd brightening (SAAO) (4)
15:19:20 Flash (Kavalur)
T 21 18:03:49 No impact observations reported 18:11:00
(7)
U 21 21:48:32 No impact observations reported 21:56:00
(7)
V 22 04:16:52 04:23:03 Flash (Palomar) 04:23:00
04:23:13 Fireball (AAT) (4)
W 22 08:00:50 p 08:06:16 (0.1) 08:06:17 GLL SSI 08:06:17
s 08:08:46 (3) 08:06:56 Precursor (AAT) (30)
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