From jeff@astron.mit.edu Date: Mon, 27 Jun 1994 16:32:12 +0700 Subject: New SL9 impact time predictions [Courtesy of Paul Chodas, JPL] --------------- Attached is the June 24 edition of our Predicted Impact Parameters table. The predicted impact times continue to slide earlier, but generally only about 5 minutes earlier than those in our table of June 14. However, the impact times for A, B, R, and S made larger jumps (15 to 20 minutes earlier), and the times for T and U moved the most (half an hour and a full hour earlier, respectively). Fragment U's orbit is finally becoming reasonably well-determined, the last one to fall into line. Paul Chodas 1994 June 24 ============================================================================== Predicted Impact Parameters for Fragments of P/Shoemaker-Levy 9 --------------------------------------------------------------- P.W. Chodas, D.K. Yeomans and Z. Sekanina (JPL/Caltech) P.D. Nicholson (Cornell) Predictions as of 1994 June 24 Date of last astrometric data in these solutions: 1994 June 16 The predictions for all fragments except Q2 are based on independent orbit solutions; our orbit reference identifier is now given. The orbit solution for fragment Q2 was obtained by applying a disruption model to the orbit for Q1, and using astrometric measurements of Q2 relative to Q1. Except for fragment Q2, uncertainties in the impact parameters are given immediately below the predicted values. These uncertainties are 1-sigma values obtained from Monte Carlo analyses; we have made an effort to make them realistic: they are not formal uncertainty values. NOTE: To obtain a 95% confidence level, one should use a +/- 2 sigma window around the predicted values. The uncertainties for Q2 have not been quantified, but are probably comparable to those for fragment P2. The dynamical model used for these predictions includes perturbations due to the Sun, planets, Galilean satellites and the oblateness of Jupiter. The planetary ephemeris used was DE245. - ------------------------------------------------------------------------------- Frag- Impact Jovicentric Merid. Angle Satellite Longitudes ment Date/Time Lat. Long. Angle E-J-F Orbit at Impact (deg) July (UT) (deg) (deg) (deg) (deg) Ref. Amal Io Eur Gany - --------------h--m------------------------------------------------------------- A = 21 16 19:30 -42.87 162 62.87 99.92 A14 191t 341 105+ 76+ 20 .27 12 1.07 .81 10 3 1 1 B = 20 17 02:34 -42.95 59 62.68 100.03 B15 45+ 40+ 135+ 90+ 17 .25 10 .94 .71 9 2 1 1 C = 19 17 06:49 -43.09 211 64.42 98.76 C11 172t 76+ 153+ 99+ 17 .21 10 .93 .70 9 2 1 1 D = 18 17 11:13 -43.11 11 63.91 99.12 D12 305 113+ 171 108+ 20 .25 12 1.09 .82 10 3 1 1 E = 17 17 15:10 -43.42 152 66.09 97.50 E28 64+ 146+ 188 117+ 13 .08 8 .58 .42 7 2 1 0 F = 16 18 00:12 -43.41 122 63.72 99.17 F19 336 224 225 136+ 15 .16 9 .79 .58 8 2 1 1 G = 15 18 07:30 -43.59 24 66.62 97.08 G28 195t 286 255 151+ 11 .07 7 .51 .37 6 2 1 0 H = 14 18 19:26 -43.68 96 66.96 96.81 H26 194t 27+ 305 176 12 .07 7 .52 .37 6 2 1 0 K = 12 19 10:21 -43.79 276 67.85 96.15 K27 284 153+ 8+e 207 11 .07 7 .50 .36 6 2 1 0 L = 11 19 22:18 -43.84 349 68.66 95.55 L28 283 254 60+ 232 12 .07 7 .52 .37 6 2 1 0 N = 9 20 10:08 -44.13 59 67.27 96.48 N16 279 355o 111+ 257 20 .14 12 1.01 .72 10 3 1 1 P2= 8b 20 14:52 -44.45 233 65.81 97.44 P14 62+ 35+ 131+ 267 17 .12 10 .88 .62 9 2 1 1 Q2= 7b 20 19:37 -44.49 50 69.37 94.93 204 75+ 151+ 277 Q1= 7a 20 20:04 -43.99 57 69.54 94.89 Q30 218 78+ 153+ 278 11 .07 7 .50 .35 6 2 1 0 R = 6 21 05:31 -44.02 40 69.74 94.74 R26 143 158 192 298 14 .09 8 .62 .43 7 2 1 0 S = 5 21 15:18 -44.12 35 70.15 94.43 S35 78+ 242 232 318 13 .08 8 .53 .37 7 2 1 0 T = 4 21 18:01 -45.01 136 66.97 96.51 T10 159t 265 244 324 28 .18 17 1.30 .92 14 4 2 1 U = 3 21 21:52 -44.33 274 69.09 95.14 U12 275 298 260 332 40 .22 24 1.75 1.23 20 6 3 1 V = 2 22 03:44 -44.25 128 67.70 96.14 V11 92+ 348 284 344 25 .19 15 1.32 .94 13 4 2 1 W = 1 22 08:12 -44.20 287 70.79 93.96 W28 226 25+ 303 353 15 .10 9 .64 .44 8 2 1 1 Satellite Codes: + impact is visible from satellite o satellite is occulted by Jupiter at impact e satellite is eclipsed but not occulted at impact t satellite is in transit across Jupiter - ------------------------------------------------------------------------------- Notes: 1. Fragments J=13, M=10, and P1=8a are omitted because they have faded from view. The March'94 HST images show that P2=8b and G=15 have split; we do not as yet have sufficient data to obtain independent predictions for the sub-components. 2. The impact date/time is the time the impact would be seen at the Earth (if the limb of Jupiter were not in the way); the date is the day in July 1994; the time is given as hours and minutes of Universal Time. The impact time uncertainty is a 1-sigma value in minutes. 3. The impact latitude is Jovicentric (latitude measured at the center of Jupiter); the Jovigraphic latitudes are about 3.84 deg more negative. 4. The impact longitude is System III, measured westwards on the planet. The large uncertainty in impact longitudes is due to Jupiter's fast rotation. 5. The meridian angle is the Jovicentric longitude of impact measured from the midnight meridian towards the morning terminator. This relative longitude is known much more accurately than the absolute longitude. At the latitude of the impacts, the Earth limb is at meridian angle 76 deg and the terminator is at meridian angle 87 deg. 6. Angle E-J-F is the Earth-Jupiter-Fragment angle at impact; values greater than 90 deg indicate a farside impact. All impacts will be just on the farside as viewed from Earth; later impacts will be closer to the limb. 7. Satellite longitudes are given for Amalthea, Io, Europa, and Ganymede. The longitudes are measured east from superior conjunction (the anti-Earth direction). Longitude uncertainties listed as "0" are simply < 0.5 deg. 8. According to these predictions, the only impact certain to occur during a satellite eclipse is K=12 with Europa eclipsed.