The Anglo Australian Telescope



    Introduction


    During a previous close encounter with Jupiter a small comet fragmented. Due to the slightly different forces that the resulting components experienced, they assumed slightly different orbits and appeared to arrange themselves in a line of small comets that was discovered by Carolyn and Eugene Shoemaker and David Levy in 1993. They recognized it as a fragmented comet and, since this was the ninth comet this team had discovered, it was named Comet Shoemaker-Levy 9. The fragments were named A, B, C, etc. in order of anticipated arrival at Jupiter or of detection.

    Published estimates of the impact times and locations of the fragments of SL9 are given below (see Table 5 in Chodas, P.W. and Yeomans, D.K. IAU Colloquium 156',1996, eds. K.S. Noll, H.A. Weaver and P.D. Feldman (Cambridge and New York: Cambridge University Press). The impact was defined to occur at the 100 mbar level of Jupiter's atmosphere. The impact for all fragments except J and M are based on independent orbit solutions given by Chodas and Yeomans (1996). The estimates for the 'lost' fragments J and M were obtained by applying the tidal disruption model to the orbit for fragment Q1 and matching the astrometry of these two fragments relative to Q1. The third column of the table contains the final pre-impact prediction for each of the fragments The fourth column lists the final best estimates, which were inferred directly from impact phenomena for 16 fragments, and computed from the orbit solutions for the rest. All times are as viewed from the Earth, and therefore include the light travel time. The impact time uncertainties are rough estimates which indicate a confidence level in the accepted time; they are not formal 1-sigma uncertainties. The impact latitude is jovicentric, while the longitude is System III, measured westward on the planet. The meridian angle is the jovicentric longitude of the impact point measured from the midnight meridian towards the morning terminator. At the latitude of the impacts, the limb as viewed from the Earth is at meridian angle 76 deg, and the terminator is at meridian angle 87 deg. The final column gives the angular distance of the impacts behind the limb.

    Impact Time (UTC)Impact LocationMeridian AngleAngular Distance
    FragmentDatePredictedAcceptedLagLat.Long      
                            Behind Limb
       (July)(h m s)(h m s)s(deg)(deg)(deg)(deg)
    A1619:59:4020:10:4060-43.3518465.47.7
    B172:54:132:50:00180-43.226763.928.8
    C177:02:147:10:5060-43.4722266.147.1
    D1711:47:0011:52:3060-43.533366.167.1
    E1715:05:3115:11:40120-43.5415366.46.9
    F180:29:210:35:45300-43.6813565.37.7
    G187:28:327:33:333-43.662667.096.4
    H1819:25:5319:31:591-43.799967.476.1
    J192:401:353600-43.75~31668.05~6
    K1910:18:3210:24:172-43.8627868.325.5
    L1922:08:5322:16:491-43.9634868.865.1
    M205:456:00600-43.93~26469.25~5
    N2010:20:0210:29:202-44.317168.685.1
    P22015:16:2015:21:11300-44.6924967.585.8
    P12016:3016:32:35800-45.02~29365.966.9
    Q22019:47:1119:44:0060-44.324669.264.7
    Q12020:04:0920:13:531-446369.854.3
    R215:28:505:34:5710-44.14270.214.1
    S2115:12:4915:16:3060-44.223370.344
    T2118:03:4518:09:56300-45.0114167.735.7
    U2121:48:3022:00:02300-44.4827869.544.5
    V224:16:534:23:2060-44.4714969.964.2
    W2217:59:458:06:161-44.1328371.193.4


    References:


    Meadows, Victoria; Crisp, David; Barnes, Jason; Orton, Glenn; Spencer, John, AAT Observations of the SL9 Fragment C, D, G, K, N, R, V, and W Impacts with Jupiter: Lightcurves and Imaging, Icarus, Volume 152, Issue 2, pp. 366-383 (2001).

    Measurement Objectives
    The InfraRed Imaging Spectrometer (IRIS) on the Anglo-Australian Telescope was used to monitor the July 1994 impacts of Comet Shoemaker-Levy 9 with Jupiter. Spectral image cubes were obtained for the impacts of fragments C, D, G, K, R, and W. These data provide time sequences of spatially resolved spectra in K-band (1.98 to 2.40 μm), with a spectral resolution of 300 (λ/∆λ) and a spatial sampling of 0.6 arcsec/pixel.

    Fast-rate 2.35-μm filter photometry was used to monitor the impacts of fragments N and V. The imaging and spectral observations track the entire evolution of each impact, from the time the fragment entered the jovian atmosphere, until the impact site rotates into view.

    Useful Mission Documents


    Additional Information


    Archived Datasets
    This dataset contains imaging, spectroscopy, and spectral mapping of Jupiter from July 16, 1994 through July 23, 1994 in FITS format with detached labels. This includes data from the C, D, G, K, N, R, and W impacts in addition to before and after observations for baseline and comparison.

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    Data Set Description

    Fragments C & D in volume sl_0008
    Fragment G in volume sl_0009
    Fragments K & N in volume sl9_0010
    Fragment R in volume sl9_0011
    Fragment W in volume sl9_0012


    Citing Data



    Other Useful Products for Interpreting the Data
    Literature Search -  using the Astrophysics Data System (ADS) and searching  on author (see. Reference above) and Shoemaker-Levy in the abstract should yield additional references.