Classification of bad pixels of the Hawaii-2RG detector of the ASTROnomical NearInfraRed CAMera

TL;DR

This paper presents a method for classifying bad pixels in the Hawaii-2RG detector of the ASTRONIRCAM infrared camera, based on readout differences, and analyzes their behavior over cooldown cycles.

Contribution

It introduces a new classification scheme for bad pixels using histogram analysis of readout differences and studies pixel behavior over cooldown cycles.

Findings

99.6% of pixels are normal

Bad pixel counts are stable over cooldown cycles

Hot pixels remain constant, others may migrate groups

Abstract

ASTRONIRCAM is an infrared camera-spectrograph installed at the 2.5-meter telescope of the CMO SAI. The instrument is equipped with the HAWAII-2RG array. A bad pixels classification of the ASTRONIRCAM detector is proposed. The classification is based on histograms of the difference of consecutive non-destructive readouts of a flat field. Bad pixels are classified into 5 groups: hot (saturated on the first readout), warm (the signal accumulation rate is above the mean value by more than 5 standard deviations), cold (the rate is under the mean value by more than 5 standard deviations), dead (no signal accumulation), and inverse (having a negative signal accumulation in the first readouts). Normal pixels of the ASTRONIRCAM detector account for 99.6% of the total. We investigated the dependence between the amount of bad pixels and the number of cooldown cycles of the instrument. While hot pixels remain the same, the bad pixels of other types may migrate between groups. The number of pixels in each group stays roughly constant. We found that the mean and variance of the bad pixels amount in each group and the transitions between groups do not differ noticeably between normal or slow cooldowns.