From spencer Mon Jul 11 21:02:43 1994 From spencer Mon Jul 11 21:02:43 1994 Return-Path: Date: Mon, 11 Jul 94 20:55:32 MST From: spencer (John R. Spencer) To: oleroemer Subject: Latest impact predictions Cc: spencer Content-Length: 9052 X-Lines: 173 Status: RO >From PWC@GRAVI.JPL.NASA.GOV Mon Jul 11 20:36:02 1994 Return-Path: Date: Mon, 11 Jul 1994 20:29:35 -0700 (PDT) From: PWC@GRAVI.JPL.NASA.GOV To: "naif::dky"@GRAVI.JPL.NASA.GOV, nicholson@astrosun.tn.cornell.edu, mcghee@astrosun.tn.cornell.edu, "cfaps1::brian"@GRAVI.JPL.NASA.GOV, "gllsvc::sedberg"@GRAVI.JPL.NASA.GOV, "muon::wmo"@GRAVI.JPL.NASA.GOV, zs@sek.jpl.nasa.gov, go@orton.jpl.nasa.gov, cchapman@psi.edu, shigeru@tone.jpl.nasa.gov, eric@styx.jpl.nasa.gov, f.odonnell@jpl.nasa.gov, james.h.wilson@jpl.nasa.gov, kbeatty@cfa.harvard.edu, trettig@comet1.phys.nd.edu, DunhamDW@space2.spacenet.jhuapl.edu, jscotti@lpl.arizona.edu, rwest@eso.org, ohainaut@eso.org, festou@srvdec.obs-mip.fr, slarson@lpl.arizona.edu, dhlevy@lpl.arizona.edu, spencer@lowell.edu, lhw@lowell.edu, "astrog::GShoemaker"@GRAVI.JPL.NASA.GOV, alice@nofs.navy.mil, davidr@clrs1.ciw.edu, tholen@hubble.IFA.Hawaii.edu, weaver@stsci.edu, storrs@stsci.edu, alw@astro.as.utexas.edu, ray@scn5.jpl.nasa.gov, "issac::pweissman"@GRAVI.JPL.NASA.GOV, doug_smith@starbase1.caltech.edu, 72000.2704@compuserve.com Subject: New Predicted Impact Parameter Table Here's the July 11 edition of our Predicted Impact Parameters table. The orbit solutions for these predictions incorporate several new highly- accurate measurements reduced using the Hipparcos star catalog. Except for fragment V, the predicted impact times are holding steady, within 5 minutes of those in our previous table, dated July 5. The impact time for fragment V, however, jumped 17 minutes later, due to the excellent new Hipparcos- based measurements. We have very little new data on fragments T and U because they are so faint and difficult to observe; their orbit solutions are not improving much. The impact time uncertainties for most of the fragments are now down in the 5-7 minute range (1-sigma). Paul Chodas 1994 July 11 ============================================================================== 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 July 11 Date of last astrometric data in these solutions: 1994 July 10 The predictions for all fragments except Q2 are based on independent orbit solutions; our orbit reference identifier is 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 T. 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 (UTC) (deg) (deg) (deg) (deg) Ref. Amal Io Eur Gany ------------h--m--s------------------------------------------------------------ A = 21 16 19:57:34 -43.11 177 64.28 98.87 A20 205 345 107+ 77+ 8.2 .19 5 .76 .56 4 1 1 0 B = 20 17 02:54:02 -43.15 70 63.78 99.21 B19 55+ 43+ 136+ 91+ 6.8 .20 4 .75 .56 3 1 0 0 C = 19 17 06:59:25 -43.31 217 65.05 98.27 C16 177t 77+ 153+ 100+ 7.0 .17 4 .74 .55 4 1 0 0 D = 18 17 11:45:30 -43.40 29 65.47 97.95 D17 321 118+ 173 110+ 7.5 .18 4 .77 .57 4 1 1 0 E = 17 17 15:05:00 -43.45 149 65.78 97.71 E33 61+ 146+ 187 117+ 5.6 .08 3 .46 .33 3 1 0 0 F = 16 18 00:26:39 -43.52 130 64.40 98.67 F24 343o 226 226 136+ 6.0 .12 4 .57 .41 3 1 0 0 G = 15 18 07:27:36 -43.58 23 66.58 97.10 G31 194t 286 255 151+ 4.8 .07 3 .38 .27 2 1 0 0 H = 14 18 19:25:55 -43.72 96 66.85 96.88 H30 194t 27+ 305 176 4.7 .07 3 .38 .27 2 1 0 0 K = 12 19 10:17:50 -43.79 275 67.72 96.24 K32 282 152+ 8+e 207 4.8 .07 3 .40 .28 2 1 0 0 L = 11 19 22:07:07 -43.90 343 68.09 95.95 L32 278 253 59+ 232 5.1 .07 3 .39 .28 3 1 0 0 N = 9 20 10:21:15 -44.27 67 67.87 96.03 N21 286 357o 112+ 257 6.7 .12 4 .68 .48 3 1 0 0 P2= 8b 20 15:09:51 -44.59 243 66.57 96.88 P19 71+ 37+ 132+ 268 6.6 .09 4 .59 .41 3 1 0 0 Q2= 7b 20 19:32:02 -44.34 39 68.83 95.33 202t 74+ 150+ 277 8 2 1 1 Q1= 7a 20 19:59:29 -44.04 55 69.25 95.08 Q35 216 78+ 152+ 278 5.4 .07 3 .41 .29 3 1 0 0 R = 6 21 05:24:17 -44.07 36 69.35 95.00 R30 139 157 191 297 6.2 .08 4 .47 .33 3 1 0 0 S = 5 21 15:09:53 -44.16 30 69.78 94.69 S41 74+ 241 232 318 5.9 .08 4 .42 .29 3 1 0 0 T = 4 21 18:05:50 -45.00 139 67.44 96.18 T14 161t 266 244 324 13.2 .16 8 1.00 .70 7 2 1 0 U = 3 21 21:52:39 -44.45 274 68.98 95.20 U15 276 298 260 332 14.5 .19 9 1.13 .79 7 2 1 1 V = 2 22 04:14:43 -44.41 145 69.32 94.96 V16 107+ 352o 286 345 10.3 .16 6 1.00 .71 5 1 1 0 W = 1 22 07:56:53 -44.16 278 70.38 94.25 W32 218 23+ 302 353 7.2 .10 4 .53 .37 4 1 1 0 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 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.