• Wrong CD matrix WCS transformation coefficients : (2009-05-08)
    The keywords affected are CD1_1, CD1_2, CD2_1, and CD2_2.
    In what follows the keywords ESO.ADA.POSANG = A.
    Previous to 2008-11-03 the incorrect formula used to write the above keywords
    were:
    
    WRONG: before 2008-11-03T00:05:00.000
    
    CDELTA1 = -2.956388483633E-05
    CDELTA2 = +2.956388483633E-05
    CD1_1 = +CDELTA1*cosA
    CD1_2 = -CDELTA2*sinA
    CD2_1 = +CDELTA1*sinA
    CD2_2 = +CDELTA2*cosA
    
    The correct formulas are:
    
    CORRECT: after 2008-11-03T00:05:00.000
    
    CDELTA1 = -2.956388483633E-05
    CDELTA2 = +2.956388483633E-05
    CD1_1 = +CDELTA1*cosA
    CD1_2 = -CDELTA1*sinA
    CD2_1 = +CDELTA2*sinA
    CD2_2 = +CDELTA2*cosA
    
    Notice that 2.956388483633E-05 = 0.1064300/3600,
    is the value stored in the keyword ESO.INS.PIXSCALE.
    
    The CD keys have been repaired for the data in the archive but frames with HIERARCH ESO ADA POSANG not 0 and not 180, -180 being delivered before the fix might be affected.

    How to correct ? Change the sign of CD1_2 and CD2_1 in all four fits extensions of the HAWKI frame.