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WFPC2 Flat Field Normalization Error
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Hubble Space Telescope
WFPC2 Flat Field Normalization Error

Following the installation of a new delivery of WFPC2 flat fields to the archive and pipeline databases, it has been discovered that a small number of these flat fields were incorrectly normalized. The problem occurs in PC frames for UV filters F122M thru F336W. This note is to warn you that the calibration images incorrectly normalized PC flats are:

Prop ID: 5563
 
u2a70609t   u2a7060bt   u2a7060dt   u2a7060ft   u2a7060ht   
u2a70909t   u2a7090bt   u2a7090dt   u2a7090ft   u2a7090ht   
u2a70c09p   u2a70c0bp   u2a70c0dp   u2a70c0fp   u2a70c0hp 

Prop ID: 5612

u28x6308t  u28x6309t  
u28x7108t  u28x7109t  
u28x7308t  u28x7309t  
u28x8108t  u28x8109t  
u28x8308t  u28x8309t

The problem has been corrected and new PC flat fields for F122M thru F336W have been already installed. The archive filenames for the flats incorrectly normalized for the PC are:

      Flatfile          Filter

      e380933du.r4h     f122m.r4h   
      e380933fu.r4h     f160bw.r4h   
      e380933iu.r4h     f170w.r4h   
      e380933mu.r4h     f185w.r4h   
      e380933qu.r4h     f218w.r4h   
      e380933tu.r4h     f255w.r4h   
      e3809341u.r4h     f300w.r4h   
      e3809344u.r4h     f336w.r4h

The new replacement archived flat field files are:

      e4510333u.r4h   f122m.r4h   
      e4510337u.r4h   f160bw.r4h   
      e451033au.r4h   f170w.r4h   
      e451033du.r4h   f185w.r4h   
      e451033gu.r4h   f218w.r4h   
      e451033lu.r4h   f255w.r4h   
      e451033pu.r4h   f300w.r4h   
      e451033su.r4h   f336w.r4h

Finally, correction may also be made to images already flat fielded with the incorrectly normalized PC flats by multiplying the images by a scale factor of 28.3/12.92.

Note that when the science images above, or any science image, are retrieved from the HST archive using OTFR (On The Fly Reprocessing), the proper calibration files, including the correctly normalized flats listed above, will be applied to the data.