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  Ghosts in MIR-L data

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                                                2010/01/05
Dear AKARI phase 2 observers,

   As you may have already noticed, ghost images may be seen in the 
MIR-L data, in particular in the L24 band, when you have very bright 
sources in the field-of-view. There seem to be at least two kinds of
ghost in the data, one relatively compact and the other quite extended.
Based on detailed analysis of the ghosts, we found that the extended 
ghost component affected the flat data now included in the toolkit.
The present flat shows a steep decline at the edges of the field-of-view.
The decline is found to be due to this extended ghost. Thus sources
near the edges could be overcorrected by about 20% at most in L24.
The effect on sources near the center should be much smaller. We are
trying to prepare the revised flat data and are going to release
them as soon as we confirm them. For the time being, please be
aware of this problem and the large uncertainty associated with the
photometry of sources near the edges in the MIR-L. Figure associated
with this note are available on the AKARI Observers Page:

Sincerely yours,
IRC team
Associated Figure:
MIR-L Ghost