Hoi Ed,
bij deze de uitleg over calibratie van je light frames die uit je EOS 550D komen:
Allereerst bekijken we de bias frames en de masterbias die we daaruit kunnen maken. Zie screenshot van de masterbias van 5 bias frames.
Deze masterbias heeft in 16bit een Bias pedestal/offset van ongeveer 8000 ADU (zie de bovenste slider waarmee je zwart punt zet). In 14bit is dit 4 keer zo laag, de statistiek van de 14bits data van de masterbias staat in de fits header, dus daarin zie je dat de bias offset in 14bits net iets boven 2000 ADU ligt:
FITS HDUs: 1
HDU1 – SIMPLE = T / Java FITS: Tue Jul 04 13:47:31 CEST 2017
HDU1 – BITPIX = 16 / bits per data value
HDU1 – NAXIS = 2 / number of axes
HDU1 – NAXIS1 = 5344 / size of the n’th axis
HDU1 – NAXIS2 = 3516 / size of the n’th axis
HDU1 – EXTEND = T / Extensions are permitted
HDU1 – BSCALE = 4.000183116645303 / scaling to 16bit
HDU1 – BZERO = 32768.0 / offset data range to that of unsigned short
HDU1 – DATE = ‘2017-07-04T11:47:31’ / creation date of master bias
HDU1 – SOFTWARE= ‘Astro Pixel Processor by Aries Productions’ / software
HDU1 – VERSION = ‘1.048 ‘ / Astro Pixel Processor version
HDU1 – CALFRAME= ‘master bias’ / master bias frame
HDU1 – INSTRUME= ‘CANON EOS 550D’ / instrument name
HDU1 – CFAIMAGE= ‘GBRG ‘ / Color Filter Array pattern
HDU1 – GAIN = 800.0 / gain or ISO depending on instrument
HDU1 – EXPTIME = 0.00025 / exposure time (s)
HDU1 – MEAN-R = ‘ 2,05E+03’ / mean of channel-R
HDU1 – MEAN-G1 = ‘ 2,05E+03’ / mean of channel-G1
HDU1 – MEAN-G2 = ‘ 2,05E+03’ / mean of channel-G2
HDU1 – MEAN-B = ‘ 2,05E+03’ / mean of channel-B
HDU1 – MED-R = ‘ 2,05E+03’ / median of channel-R
HDU1 – MED-G1 = ‘ 2,05E+03’ / median of channel-G1
HDU1 – MED-G2 = ‘ 2,05E+03’ / median of channel-G2
HDU1 – MED-B = ‘ 2,05E+03’ / median of channel-B
HDU1 – SIGMA-R = ‘ 7,78E+00’ / standard deviation of channel-R
HDU1 – SIGMA-G1= ‘ 7,95E+00’ / standard deviation of channel-G1
HDU1 – SIGMA-G2= ‘ 7,43E+00’ / standard deviation of channel-G2
HDU1 – SIGMA-B = ‘ 7,58E+00’ / standard deviation of channel-B
HDU1 – NOISE-R = ‘ 7,43E+00’ / MRS gaussian noise estimate of channel-R
HDU1 – NOISE-G1= ‘ 7,62E+00’ / MRS gaussian noise estimate of channel-G1
HDU1 – NOISE-G2= ‘ 7,20E+00’ / MRS gaussian noise estimate of channel-G2
HDU1 – NOISE-B = ‘ 7,33E+00’ / MRS gaussian noise estimate of channel-B
HDU1 – END
