Filename                               Reason     Bkg         V      RCAM      TCAM   Sigma
20210921.184025.ucomp.706.l1.p7.fts        16    17.2     13.76       0.7       1.7     NaN
20210921.190504.ucomp.706.l1.p7.fts        16    17.1     13.62       2.1       1.9     NaN

GBU bitmask codes
Code    Description
    1   spar guide control loop is below threshold (0.99)
    2   spar guider intensity below threshold (0.9 * 6.551 * exp(-0.05 * secz))
    4   median background is above threshold (35.0)
    8   median background is below threshold (5.0)
   16   spurious Stokes V signal is above threshold (8.0)
   32   the chi-squared of the occulter fit is above threshold (800.0)
   64   the difference of the image with the median is above threshold (1.5)

* indicates that the threshold values changed on the day