Photometric Keywords and Vegamag Zeropoints for 77.1K Detectors

(Appropriate for all data taken after January 1, 2000)

Last update February 2007.

The three tables below show NICMOS Photometric Keywords derived from principle calibration stars P330E and G191B2B for the three different cameras. The calibration values are the weighted averages of the values derived for the two stars individually. The relative error (sigma/mean) reflects the uncertainty in PHOTFLAM and PHOTFNU due to the individual star measurement errors and the discrepancy between the two stars. This error does not include the uncertainty in the absolute calibration of the reference star spectra, which are believed to be less than 5%. This reference spectrum uncertainty will also introduce a much smaller error in colors derived from NICMOS observations in different passbands, which are thought to be less than 3%, especially for the broad and medium band filters. The calibrations have been measured using apertures with a 11.5 pixel radius for NIC1,a 6.5 pixel radius for NIC2, and a 5.5 pixel radius for NIC3. They were then corrected to total flux with the listed passband dependent aperture corrections derived from TinyTim simulations. The fractional error values listed below are fractions of 1.0 (multiply this value by 100 to get the error in percent).