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UKIRT Spectral Images of Fragment C Impact


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Fragment C Impact Seen at UKIRT

The following message was sent to the Jupiter/comet news center at the University of Maryland. The image above combines an observation taken before (top) and about fifteen minutes after (bottom) impact. Both spectral images were obtained with the 1.1" wide slit aligned along 45 degrees south latitude. Spectral line graphs of these images can be found here.

CGS4 (with echelle at about 20 km/s resolution) on UKIRT detected dramatic changes in the spectrum near 3.5um at the location where the C fragment struck Jupiter. In addition to a bright continuum (where there previously was essentially none), the relative strengths of pre-existing emission lines of H3+ changed and many new lines appeared, very few of which are identified by us at present. In particular, at the wavelength of a previously undetectable "hot band" transition of H3+, a bright line appeared whose strength surpassed that of all other pre-existing H3+ lines. A second line, unidentified at present, succeeded in saturating its central pixel in a ten second exposure. Some of the lines seem considerably (Doppler) broadened, but, due to the high density of spectral features, confirmation will have to wait until after the observers get some sleep. The emission faded with a 1/e time of roughly 15 minutes.

Tom Geballe
Mary-Frances Jagod 
Steve Miller 
Tim Brooke

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