STScI Logo

Space Telescope Imaging Spectrograph
STIS-07

ACTIVITY TITLE: STIS CCD Bias and Dark Monitor

ID: STIS-07

APPLICABLE SMOV REQUIREMENTS: L.10.4.5.4.1

DESCRIPTION: This activity is the first in a series of measurements to characterize and monitor the CCD biases and darks. It is a combination of the Cycle 17 CCD bias monitor program and the Cycle 17 dark monitor program. Both the programs are continuations of Cycle 12 calibration programs to characterize and monitor CCD biases (Cy12 Cal 10019) and darks (Cy12 Cal 10017).

Bias program: This activity will take full-frame bias exposures in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4 to monitor the bias and to build up high-S/N superbiases and track the evolution of hot columns. At gain=1: 14 bias frames are acquired with 1x1 binning and 2 bias frames are acquired with 1x2, 2x1, and 2x2 binning. At gain=4: 3 bias frames are acquired with 1x1 binning. All exposures are internals and fit in occultation orbits. This program executes daily.

Dark program: This activity will obtain 1 long (1100s) and 2 short (60s) unbinned darks per visit at GAIN=1 to monitor CCD behavior and chart growth of hot and bad pixels. Acquiring dark exposures of different durations provides a test of low-level instrument noise over a wide range of observing conditions, provides high S/N calibration frames for Cycle 17 science, and permits hot pixel reference file updates on appropriate time scales. All exposures are internals, less than 1800 seconds long, and fit in occultation orbits. This program executes twice daily.

IMPLEMENTATION METHOD: Stored commanding

DEPENDENCIES: Should begin after STIS-06, the CCD functional test.

DURATION: 3 Orbits (Internal) and executes daily. The bias monitor is 1 internal orbit (<1800 seconds) and executes daily. The dark monitor is 1 internal orbit (<1800 seconds) per visit and executes twice daily.

DATA REQUIREMENTS: 0.5 Gbits/day.

ANALYSES & EXPECTED RESULTS: This SMOV4 activity comprises the initial visits of the Cycle 17 program that will produce weekly and biweekly superbias reference files. It will also produce weekly dark reference files and test for low for low level sources of noise.

COMMENTS: This activity is part of the Cycle 17 calibration program for daily monitoring of CCD biases and twice-daily monitoring of CCD darks.

AUTHOR/telephone/email: Mary Elizabeth Kaiser/401-516-5088/kaiser@pha.jhu.edu

DATE: September 28, 2007