The New WFC3 Photometric CalibrationOutline1.) Step 1 – TV3 Calibration2.) Step 2 – SMOV4 (+ Cycle 17 Calibration)3.) Step 3 – Final Calibration (present analysis)

- More data- New flat fields- Astrodrizzle- Precise calibration

Apr 19th, 2012 TIPS Meeting

Thermal Vacuum 3 (TV3)- Calibrated lab response of components from GSFC, DCL, Ball.- CASTLE aperture photometry.

Components1.) The HST OTA2.) Pickoff mirror3.) CSM4.) Mirror reflectivity5.) Filter throughputs6.) Detector window7.) Detector QE

Results folded into the detector QE (for UVIS) and a “fudge” factor for IR T. Brown (WFC3-ISR-2008-48) T. Brown (WFC3-ISR-2008-09)

The New WFC3 Photometric Calibration

SMOV4 + Cycle 17 Calibration – UVIS and IR1.) Observations of HST spectrophotometric standards: SMOV: GD153 in 37 UVIS filters; GD153 and P330E in all 15 IR filters Cycle 17: All filters, GD153, G191B2B, GD71, P330E

- 1% absolute accuracy in medium and broadband filters.- 2-3% absolute accuracy in narrow band filters.

2.) Repeatability: Measure photometry stability, both temporal and spatial. High S/N subarray imaging, multiple dither positions.

Star B V J H Temp (K) Log(g)

G191B2B 11.45 11.77 12.55 12.66 61,193 7.492

GD153 13.06 13.35 14.07 14.19 38,686 7.662

GD71 12.78 13.03 13.74 13.86 32,747 7.683

P330E 13.62 13.00 11.88 11.60 G0V G0V

J. Kalirai (WFC3-ISR-2009-05)R. Bohlin et al. (2011, AJ, 141, 173)

The New WFC3 Photometric Calibration

The Strategy

The New WFC3 Photometric Calibration

UVIS: 5-10% boost in efficiency at blue/red ’s, 15-20% at 400-700 nm

IR: 10-15% boost in efficiency at all ’s

Results (SMOV)

Ooops, but this is great!

J. Kalirai (WFC3-ISR-2009-30)J. Kalirai (WFC3-ISR-2009-31)

The New WFC3 Photometric Calibration

First New Calibration (Cycle 17)

The New WFC3 Photometric Calibration

The Current Calibration

The New WFC3 Photometric Calibration

Two Independent Tests Suggest Issues with the Flat Field- Relative photometry across the detector reveals residual gradient.

Large campaign to fix this over the past two years

The New WFC3 Photometric Calibration

Step 3 – Final Calibration (present analysis)- New flat fields- Astrodrizzle- More data

- Reprocess all SMOV, Cycle 17, Cycle 18 data- Images: 2080 (GD153), 1260 (P330E), 1134 (G191B2B), 610 images

(GD71)- 2220 images of GRW+70

- Precise calibration

The New WFC3 Photometric Calibration

Step 3 – Final Calibration (present analysis)

A. Rajan: Astrodrizzle image of F606W (42 GD153 images)

The New WFC3 Photometric Calibration

The New WFC3 Photometric CalibrationStep 3 – Final Calibration (present analysis)

The New WFC3 Photometric CalibrationStep 3 – Final Calibration (present analysis)

The New WFC3 Photometric Calibration

Delivery Details- New filter transmission tables (updated history, fudge factor, pedigree, etc..)- Tables of the fractional change in ZP- Tables with the counts in 13 apertures in all filters for all stars- New photometric zero points- Everything is ingested into CDBS

Step 3 – Final Calibration (present analysis)

The New WFC3 Photometric Calibration

Extra Slides

Results- Temporal stability also looks good (~0.5%)

J. Kalirai (WFC3-ISR-2010-14)J. Kalirai (WFC3-ISR-2011-08)

The New WFC3 Photometric Calibration

7 weeks ago- New Keck data of all HST primary spectrophotometric standards

The New WFC3 Photometric Calibration