Plotted entries from OPSLOG files in VISIR report BACKGD, plot 2, data set bgd_iP:

DATE       MJD-OBS      parameter values
==========================================================================
2008-09-15 54724.339807 -4718.77474	bgd_iP
2008-09-18 54727.176104 527.4175781	bgd_iP
2008-09-28 54737.038419 -4727.407031	bgd_iP
2008-09-29 54738.973927 8903.05599	bgd_iP