Attached is our Predicted Impact Parameters table for the week of June 13. Our latest orbit solutions use astrometric measurements which have been reduced using a pre-release version of the very accurate Hipparcos star catalog. The predicted impact times are generally earlier than in our table posted June 5, by an average of about 12 minutes. The impact times for fragments B, F, and P2, however, moved over 20 minutes earlier, and that for fragment U jumped an hour and half earlier. Fragment U's orbit is still very uncertain. Paul Chodas 1994 June 14 ============================================================================== 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 12 Date of last astrometric data in these solutions: 1994 June 8 The predictions for all fragments except Q2 are based on independent orbit solutions; the 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 predictions for fragments E, G, H, K, L, Q, R, S, and W are the most accurate, as these have the best-known orbits; fragments T, U, and V have the most poorly-determined orbits, (especially U). The uncertainties for fragment 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 19:50 -43.12 173 63.57 99.37 A11 201t 344 106+ 76+ 22 .27 13 1.11 .83 11 3 2 1 B = 20 17 02:46 -43.16 65 63.01 99.75 B12 50+ 42+ 136+ 91+ 20 .26 12 .97 .74 10 3 1 1 C = 19 17 06:50 -43.15 212 64.33 98.81 C9 172t 76+ 153+ 99+ 20 .23 12 .99 .74 10 3 1 1 D = 18 17 11:11 -43.11 10 63.60 99.34 D10 304 113+ 171 108+ 23 .28 14 1.16 .87 12 3 2 1 E = 17 17 15:17 -43.56 157 66.02 97.52 E26 67+ 148+ 188 117+ 14 .09 9 .61 .44 7 2 1 0 F = 16 18 00:16 -43.49 124 63.58 99.25 F17 338o 224 225 136+ 18 .18 11 .85 .63 9 3 1 1 G = 15 18 07:36 -43.68 27 66.65 97.04 G26 198t 287 256 151+ 13 .08 8 .53 .38 7 2 1 0 H = 14 18 19:35 -43.77 102 67.08 96.71 H24 199t 28+ 306 176 13 .08 8 .54 .39 7 2 1 0 K = 12 19 10:26 -43.87 280 67.87 96.12 K25 286 153+ 9+e 207 13 .08 8 .54 .39 7 2 1 0 L = 11 19 22:24 -43.94 353 68.63 95.56 L26 286 255 60+ 232 13 .08 8 .53 .38 7 2 1 0 N = 9 20 10:09 -44.30 60 67.10 96.57 N13 280 355 111+ 257 22 .15 13 1.04 .74 11 3 2 1 P2= 8b 20 14:58 -44.57 236 65.84 97.40 P12 65+ 36+ 131+ 267 21 .13 12 .96 .68 11 3 1 1 Q2= 7b 20 19:40 -44.39 43 69.10 95.14 206 75+ 151+ 277 Q1= 7a 20 20:07 -44.09 59 69.52 94.89 Q28 220 79+ 153+ 278 12 .07 8 .50 .35 6 2 1 0 R = 6 21 05:47 -44.18 49 69.95 94.56 R23 151 161 193 298 17 .10 10 .68 .48 9 2 1 1 S = 5 21 15:39 -44.21 46 70.63 94.08 S33 88+ 245 234 319 14 .08 9 .55 .39 7 2 1 0 T = 4 21 18:28 -45.23 152 67.93 95.80 T8 173t 269 246 325 41 .21 25 1.66 1.16 21 6 3 1 U = 3 21 22:52 -44.69 309 70.30 94.24 U9 306 306 264 334 68 .28 41 2.46 1.72 34 10 5 2 V = 2 22 03:54 -44.38 133 67.88 95.98 V9 97+ 349 285 344 28 .20 17 1.39 .99 14 4 2 1 W = 1 22 08:21 -44.24 292 70.99 93.80 W26 231 26+ 303 354 17 .10 10 .67 .47 9 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 and M=10 are omitted because they have faded from view. Fragments P=8 and Q=7 each consist of multiple components. The March'94 HST image shows that P1=8a has almost completely faded away (so it too is omitted from the Table), and that P2=8b has split. We do not as yet have sufficient data to obtain independent predictions for the two components of P2=8b. 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. The probability that any fragment will impact on the near side as viewed from the Earth is < 0.01%. 7. Satellite data are given for Amalthea, Io, Europa, and Ganymede. Callisto is omitted, as it is too distant to act as a useful reflector of the impact flashes, and it has no occultations or eclipses during the impacts. Metis, Adrastea and Thebe are also omitted, due to the expected faintness of any flash reflections from them. The satellite 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.