SPHERE Quality Control: ZIMPOL detector calibration

SPHERE ZIMPOL Quality Control:
detector calibration

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Trending & QC1
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trending & QC1

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QC1 database
Paranal autrep database
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QC PLOTS
	CURRENT	HISTORY
IMG bias
IMG ron
IMG dark

POL bias
POL ron
POL dark
QC1 database (advanced users): browse \| plot
Click on CURRENT to see the current trending (Health Check). Click on HISTORY to see the historical evolution of the trending.

The ZIMPOL optical CCDs are operated synchroneously in a special shift-and-add mode (see the User Manual and the pipeline user manual for details). ZIMPOL has two detectors (DET.CHIP.NAME= Callas and Bartoli), each one with 1156 x 2014 pixel. Raw frames come with two extensions, for each detector one fits cube. ZIMPOL detectors can be operated in one of the three modes (DET.READ.CURNAME) StandardImaging, SlowPolarimetry and FastPolarimetry.

top bias, ron, rms

ZPL_BIAS_IMG_CAM1 ZPL_BIAS+_IMG_CAM2 ZIMPOL raw bias frames (one plane of the cube) in StandardImaging readmode. Left is for Callas and right is for Bartoli.

ZPL_BIAS_SPOL_CAM1 ZPL_BIAS_SPOL_CAM2 ZIMPOL raw bias frames (one plane of the cube) in SlowPolarimetry readmode. Left is for Callas and right is for Bartoli.

ZPL_BIAS_FPOL_CAM1 ZPL_BIAS_FPOL_CAM2 ZIMPOL raw bias frames (one plane of the cube) in FastPolarymetry readmode. Left is for Callas and right is for Bartoli.

QC1 parameters

parameter	QC1 database: table, name	procedure
bias	sphere_zimpol_bias_img, qc_bias sphere_zimpol_bias_pol, qc_bias	median of the first plane of the raw fits cube in ADU
ron	sphere_zimpol_bias_img, qc_ron sphere_zimpol_bias_pol, qc_ron	The first five planes of the data cube are considered. For each pixel the standard deviation out of the five planes is calculated. The median of all stdev values between x=[300,850] and y=[100,900] is taken.
rms	sphere_zimpol_bias_img, rms_I_CAM1, rms_P_CAM1, rms_I_CAM2, rms_P_CAM2 sphere_zimpol_bias_pol, rms_zero_odd, rms_zero_even, rms_pi_odd, rms_pi_even	rms of the bias product frame.

Trending

bias, ron and rms are trended for

for both detectors (CAM1 and CAM2)
in imaging mode for both cycles (I and P).
in polarimetry mode for all four cycles (phase zero odd subcycle, phase pi odd subcycle, phase pi even subcycle, phase zero even subcycle).

top dark level

Optical dark frames are acquired once a month in all three read modes to monitor the dark radiation. The exposure time is 100 asec.

QC1 parameters

parameter	QC1 database: table, name	procedure
dark level	sphere_zimpol_dark_img, median_I_CAM1, median_P_CAM1, median_I_CAM1, median_P_CAM2 sphere_zimpol_dark_pol, median_zero_odd, median_pi_odd, median_pi_even, median_zero_even	dark level after 100 sec

Trending

In imaging mode the QC parameters come per CCD (CAM1, CAM2) and per phase (I, P). The pipeline generates a product in DOUBLE format (see the SPHERE pipeline user manual for details) with eight extensions of which the first four extensions are called IFRAME, but mean the signal coming from the odd rows of the raw frames which are illuminated. The second four FITS extensions are labeled PFRAME but mean the signal coming from the even rows of the raw frames, which are not illuminated in imaging mode and contain only a bias signal.

The polarimetry mode is operated with two different read modes: SlowPolarimetry and FastPolarimetry. Due to the special CCD cycle, the products contain sixteeen FITS extensions and the signals are divided in two polarimetric phases (zero and pi) and two cycles (odd end even). The dark values are monitored in all four setup combinations.

History

Due to a contamination issue dark values in 2015 are higher. Details are given on the problems page.
As occured on 2016-09-23, the saturated modemeff calibration acquired directly in advance of the ZIMPOL imaging mode dark calibration left a double as large dark current on the detector, a kind of persistence.