WF/PC Instrument Science Report 92-02:
Determination of the Position Dependent Zero Point Magnitude Correction
for the Core Aperture Photometry with WF/PC-1
by Ellyne Kinney and Roberto Gilmozzi
October, 1992
Abstract excerpted from the report:
The method for developing a position dependent zero point magnitude correction is outlined. In general, it has been found that the magnitude obtained using Core Aperture Photometry tend to increase toward the edges of the FoV, and magnitudes are brightest near the center of the chip. It is shown that the magntiude variation can be very easily corrected using a linear relation delta mu = a_1 r + a_o, where r is the radial distance from the most sensitive part of the camera. The magnitude correction makes it possible to measure magnitudes to an accuracy of 0.05 mag or better. This improvement is re- assuring, especially considering that the flats for the WFC were not accurate enough for this calibration, and were not used in determining the correction. It is expected that the correction will reach even higher accuracy once improved flats are obtained.
For a copy of this report, please contact help@stsci.edu.