We wanted to have a look at the SiPM currents over all of FACTs lifetime. The aux files containing the calibrated currents (FEEDBACK_CALIBRATED_CURRENTS.fits) only exist since 9th august 2013, so they were out of question. We needed to look at the BIAS_CONTROL_CURRENT.fits files and do the current calibration ourselves.

I mean, the calibration constants were already there, we just needed to apply them to the uncalibrated data, but how exactly this is done, I was not able to find. So I reverse engineered it with the data of yesterday night and wrote it down here.

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I write it here in pseudo-python:

fb_cal_r8 = fits.open('20150628.FEEDBACK_CALIBRATION_R8.fits')[1].data
delta_i = fb_cal_r8['DeltaI'][0, :320]
r8 = fb_cal_r8['R8'][0, :320]

bias_cur = fits.open('20150628.BIAS_CONTROL_CURRENT.fits')[1].data
bias_dac = fits.open('20150628.BIAS_CONTROL_DAC.fits')[1].data
I8 = bias_cur['I'][:, :320] * 5e-3/4096. - delta_i[np.newaxis, :]
I9 = bias_dac['U'][:, :320] * (1e-3/4096) * 100 / r8[np.newaxis, :]
Iout = (I8 - I9) / 4e-6