WFC3 Instrument Monitoring

UVIS

Bowtie

1 to 3 plot
Median flatfield (image1/image3) ratio levels as a function of day since June 11th, 2009; crosses are for chip 1 and circles are for chip 2.

1 to constant plot
Median flatfield (image1/image1) ratio levels as a function of day since June 11th, 2009; crosses are for chip 1 and circles are for chip 2.

3 to constant plot
Median flatfield (image3/image3) ratio levels as a function of day since June 11th, 2009; crosses are for chip 1 and circles are for chip 2.

References
WFC3 ISR 2009-24: WFC3 SMOV Proposal 11808: UVIS Bowtie Monitor. Baggett and Borders

Contamination

HST spectrophotometric standards are routinely observed to monitor throughput stability. Analysis of the high signal-to-noise photometry in W and M bands indicates that the instrument is photometrically stable, with measured variations that are <0.4%.

References
WFC3 ISR 2010-14: The Photometric Performance of WFC3/UVIS: Temporal Stability Through Year 1. Kalirai et al.

Charge Transfer Efficiency (CTE)

The EPER (Extended Pixel Edge Response) method can be used to measure CCD detector Charge Transfer Inefficiency (CTI)-induced losses via internal exposures. EPER data consist of short tungsten lamp flat field exposures in several filters in order to obtain a large range of illumination levels (from ~100e- to 4000e-). By measuring the signal profiles as they extend into the trailing overscan region, an assessment can be made of the CTE level. Please see the most recent report for current plots.

Tabulated data of EPER CTE levels as a function of signal and time
Columns are filename (date encoded as ddmmyy), Modified Juilan Date, average signal across all four amps at five different levels (cols 3-7), CTE for those average signals (cols 8-12), and the error bars for the EPER CTE measurements (cols 13-17).

References
WFC3 ISR 2011-17: WFC3/UVIS CTE-EPER Measurement: Cycle 17 & 18. Khozurina-Platais et al.

Internal Monitoring of WFC3/UVIS Charge Transfer Efficiency. Khozurina-Platais et al., 2010 HST Calibration Workshop

WFC3 ISR 2009-10: WFC3/UVIS CTE-EPER Measurement. Khozurina-Platais et al.

WFC3 ISR 2007-13: UVIS CCD EPER CTE measurements performed during the April 2007 Ambient Calibration campaign (SMS UV02S01). Robberto

Darks

UVIS Hot Pixels
WFC3/UVIS (Chip 2, Amps C & D)
This plot shows the hot pixel growth between anneals for WFC3/UVIS. The number of hot pixels are plotted as a function of time since the installation of WFC3 on HST, where the yellow lines represent the SIC&DH failures, when WFC3 was safed, the red lines represent the anneals, and the brown vertical line is the switch between SMOV dark (1800 sec) and Cy 17 darks (900 sec).

Dark Current
WFC3/UVIS (Chip 2, Amps C & D)
Shows the dark current vs. time for WFC3/UVIS. The yellow lines represent the SIC&DH failures, when WFC3 was safed, the red lines represent the anneals, and the brown vertical line is the switch between SMOV dark (1800 sec) and Cy 17 darks (900 sec).

Dark Current with linear fit to Cy 17 data
Shows the dark current vs. time for WFC3/UVIS. A linear fit to the Cy 17 data is show in magenta, the yellow lines represent the SIC&DH failures, when WFC3 was safed, the red lines represent the anneals, and the brown vertical line is the switch between SMOV dark (1800 sec) and Cy 17 darks (900 sec).

References
WFC3 ISR 2009-16: WFC3 SMOV Proposals 11419, 11426, 11431, and 11446: On-Orbit Darks. Borders and Baggett

Gain

Cycle 17 Gain Plot
Cy 17 mean-variance plot for Quad A, B, C, and D.

SMOV Gain Plot
SMOV mean-variance plot for Quad A, B, C, and D.

TV3 Gain Plot
TV3 mean-variance plot for Quad A, B, C, and D.

References
WFC3 ISR 2011-13: WFC3 Cycle 17 Proposal 11906: UVIS Gain. Borders, Pavlovsky, and Baggett