Detection of fragment "L" flash at the Whately Observatory 
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At 22:17UT on July 19 UT we observed the beginning of the fragment "L" flash. 
Within 13 minutes the emission from the impact site saturated our NICMOS3 array 
through a 1% filter at 2.29um with an 0.6s integration time. By 22:40 the spot 
had faded to be twice as bright as Io. At 23:00 the impact site was similar in 
appearance to site "K" through a 2.23 -- 2.29um filter. We continued observing 
the development of site "L" at the usual set of wavelengths until Jupiter set 
below the trees. 
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The images show a time sequence of the "L" impact observed through a 
2.23 -- 2.29um filter in daylight with the NICMASS camera at the 0.4m Whately 
Observatory. The sequence begins at the upper left and ends at the lower right. 
Each frame is an average of 10 0.6s exposures lasting 25 seconds in total. 
The sequence of mid-frame times is 22:15:43, 22:16:51, 22:17:35, 22:18:40, 
22:19:40, 22:20:15, 22:21:12, 22:22:10, 22:54:10, 22:24:00, 22:24:53, 22:26:50. 
By frame 22:54:10 the brighness of the impact region matched that of Io. 
By the last frame in this sequence (just before the array saturated in 
the 2.23 - 2.29 filter) the impact region was 10 times brighter than Io. 
The bright spot to the right (west) of the "L" impact region is the "K" 
impact site. The region continued to brighten after 22:27, reaching a peak 
at 22:31. At peak brightness, observations through a 1% 2.29um filter saturated 
as well, suggesting that the peak was at least 30 times brighter than Io.