7.5.13 LEAK_SUB

On 13-Nov-92, there was an entrance filter failure which caused visible light to contaminate the X-ray images. It is possible to have the leak image removed from PFI and FFI images by using the following command:
IDL> data_out = leak_sub(index,data)
  The routine will call DARK_SUB if it comes in as byte type. The technique at the time of writing this guide was to find the sunset leak image which matched the following criteria

• The same X-ray analysis filter.
• Using the ND filter if the input X-ray image used the ND filter.
• The nominal S/C pointing must be the same (there is one set of images between 13-Nov-92 and 19-Aug-93, and another set for images taken after 19-Aug-93)

The small changes in S/C pointing were not being accounted for as of Jan-94, even though there is a relatively strong dependence on pointing drift. Future modifications to LEAK_SUB might take this factor into account.

The leak image files must be in the directory $DIR_SXT_SFC.