Overview

IR photometry is currently based on derived quantities from observations of the three HST white dwarf standard stars,  GD153, G191B2B, GD71, and the G-type star,  P330E,  acquired between 2009 and 2012. Data were reduced with CALWF3 and  processed with AstroDrizzle.The independent calibrations from the four stars agree to within 1% in most filters.  The inverse sensitivity per filter,  PHOTFLAM, is based on the average of the measurements.

The tables below are the derived quantities from observations of GD153, G191B2B, GD71, and P330E acquired between 2009 and 2012. The independent calibrations from the four stars agree to within 1% in most filters, and the photometric zeropoint is set to the average of the measurements. The data sets were processed with AstroDrizzle.

IR Inverse Sensitivity (Zeropoint) Tables

The 2012 PHOTFLAM values are provided for the infinite aperture (defined as having a radius of 6 arcseconds) and  for an aperture of radius r=0.4 arcseconds (corresponding to a radius of about 3 pixels)

IR values of the inverse sensitivity (photflam) and photometric zeropoints in the STmag, ABmag and VegaMag systems

Prior Calibration

Delivery Calibration Reference File CALWF3 version Description Change Documentation
Dec 10, 2008 Ground Flats s*pfl.fits v1.4+ Thermal vacuum data   2008-28

Nov 18, 2009

In-flight Zeropoints

(infinite)

   

Polynomial correction with wavelength

GD 153, P330E

FLT*PAM

10-15% higher sensitivity than ground test data

2009-30

Nov 10, 2009

In-flight EE

   

F098M, F105W and F160W

Other filters from optical models

 

2009-37

Dec 7, 2010

In-flight Flats

u*pfl.fits

 

Ground flats corrected by a 'grey' delta-flat

Computed from average sky flat for all filters

+/- 2% correction

2011-11

Mar 06, 2012

Revised Zeropoints

(Infinite and 3 pix)

   

Filter-dependent correction

GD153, GD71, G191B2B, P330E

Master DRZ frames, per filter

 

Available via this WFC3 webpage only: Kalirai et al.

(see above tables)

Nov 19, 2012

First IMPHTTAB for IR

(infinite)

wbj1825ri_imp.fits

v3.1.6+

HSTCAL replaces calls to STSDAS/synphot in calwf3 to populate PHOT keywords

 

HSTCAL Webpage

 

LAST UPDATED: 05/22/2019

Please Contact the HST Help Desk with any Questions

https://hsthelp.stsci.edu.