E.12 The Cycle 25 Calibration Plan

The Cycle 25 calibration plan was executed from November 2017 through October 2018. The individual programs are listed in Table E.13 and are described in more detail on the WFC3 Calibration Plan webpage. Following the link to Cycle 25 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 25 section also links to a PDF presentation summarizing WFC3 usage and comparing the Cycle 25 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 25 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, wavelength and flux stability of grisms, number of IR blobs, state of the CSM)
  
• improve the precision of the UVIS contamination monitor by using spatially scanned observations of photometric standards
  
• quantify color terms for the UVIS filters and recheck the photometric calibration at the center of the detector
  
• test a strategy to mitigate IR persistence using the calibration lamps to fill charge traps prior to obtaining science observations
  

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.13: Cycle 25 Calibration Programs.

¹New programs this cycle; others are routine monitors.