E.13 The Cycle 27 Calibration Plan

The Cycle 27 calibration plan is being executed from November 2019 through October 2020. The individual programs are listed in Table E.14 and are described in more detail on the WFC3 Calibration Plan webpage. Following the link to Cycle 27 Calibration, a similar table may be found with direct links to the phase II programs and observation dates. This information may alternately be accessed via the HST Program Information webpage by entering the Proposal ID.

The WFC3 Cycle 27 webpage also links to a PDF presentation summarizing WFC3 usage in the latest cycle and comparing the current plan with the prior cycle. This document contains more details on the calibration justification and in many cases includes supporting figures with the latest results from regular monitoring.
 The Cycle 27 calibration plan was designed to:

  • Maintain and update the standard reference files (biases, darks, linearity, CTE traps, UVIS anomalous QE pixels, post-flash)
  • Monitor the health of the instrument (throughput, gain, hysteresis, bad/hot pixels, sink pixels, CTE decline, stability of the post-flash LED, filter transmission, state of the CSM, number of IR blobs, wavelength and flux stability of the grisms)
  • Support new initiatives and obtain supplemental (non-routine) calibration data

In this cycle, two standard monitoring programs have been restructured from Cycle 26. These programs (16021, 16030) were designed to:

  • Quantify losses in the UVIS sensitivity using spatial scans (previously called ‘UVIS Contamination Monitor')
  • Monitor the ‘UVIS and IR Photometric Calibration’ via staring mode observations of HST standards

Five new calibration programs will supplement the standard monitoring. These programs (16020, 16022, 16023, 16029, 16031) were designed to:

  • Measure the stability of the tungsten lamp output immediately after turn-on
  • Refine the UVIS grism wavelength calibration across the entire detector with better 2D sampling
  • Finalize the flux calibration of the UVIS grism with similar spatial sampling as for the wavelength calibration
  • Recheck the optimal UVIS background level to mitigate CTE losses
  • Check for time dependent sensitivity in the IR detector grisms and filters

The results of these calibration programs will be documented in Instrument Science Reports on the WFC3 website at:
http://www.stsci.edu/hst/instrumentation/wfc3/documentation/instrument-science-reports-isrs

Table E.14: The Cycle 27 Calibration Programs

Program ID

Title

15712

WFC3 UVIS Anneal

15713

WFC3 UVIS Bowtie Monitor

15714

WFC3 UVIS CCD Daily Monitor (Darks and Biases) Part 1

15715

WFC3 UVIS CCD Daily Monitor (Darks and Biases) Part 2

15716

WFC3 UVIS CCD Daily Monitor (Darks and Biases) Part 3

15717

WFC3 UVIS CCD Unflashed (CTE) Monitor

15718

WFC3 UVIS Post-flash Monitor

15719

WFC3 UVIS CCD Gain Stability

15720

WFC3 UVIS CTI Monitor (EPER)

15721

WFC3 UVIS CTE Monitor (star cluster)

15722

WFC3 Characterization of UVIS traps with Charge Injection

15723

WFC3 IR Dark Monitor

15724

WFC3 IR Linearity Monitor

15725

WFC3 IR Gain Monitor

15726

WFC3 UVIS Shutter Monitoring

15727

WFC3 IR Grism Wavelength Calibration

15728

WFC3 IR Grism Flux/trace Calibration

15729

WFC3 UVIS Pixel-to-Pixel QE Variations via Internal Flats

15730

WFC3 UVIS Internal Flats

15731

WFC3 IR Internal Flats

15732

WFC3 CSM Monitor with Earth Flats

15733

WFC3 Astrometric Scale Monitoring

16020

WFC3 Tungsten Lamp Warmup

16021

WFC3 UVIS Time Dependent Sensitivity

16022

WFC3 UVIS Grism Wavelength Calibration

16023

WFC3 UVIS Grism Flux Calibration

16029

WFC3 UVIS Background Check

16030WFC3 UVIS & IR Photometry Monitor
16031IR Time Dependent Sensitivity