Photometric Calibration

From: Roc Cutri
To: jarrett

Tom,
Here are the median photometri offsets for each coma scan on 970418 and 970423 relative to Scan 003 on 970418. The values are the median if M(s003) - M(N), where N is the other scan number. Thus, to convert The J data in scan 004 on 970418n to the scan 003 zero point, you would need to ad 0.006 mags. Note that I did not filter on source brightness, or exclude limits, so the rms values are artificially high. The medians are robust, though. All in all, there are remarkably little differences in the photometry.
Roc

Photometric Offsets Relative to Scan 003 - 970418n

970418n 004
J npts= 999 median= 6.000000e-03 rms= 6.232391e+00
H npts= 999 median= -1.900000e-02 rms= 8.191232e+00
Ks npts= 999 median= -1.100000e-02 rms= 6.985174e+00

970418n 005
J npts= 968 median= 1.400000e-02 rms= 1.919244e-01
H npts= 968 median= -4.000000e-03 rms= 6.743033e+00
Ks npts= 968 median= -5.000000e-04 rms= 7.217280e+00

970423n 049
J npts= 945 median= -1.800000e-02 rms= 8.033554e+00
H npts= 945 median= -5.900000e-02 rms= 2.156081e-01
Ks npts= 945 median= -2.800000e-02 rms= 1.352507e+01

970423n 050
J npts= 907 median= -1.300000e-02 rms= 5.811420e+00
H npts= 907 median= -6.700000e-02 rms= 6.278577e+00
Ks npts= 907 median= -2.700000e-02 rms= 1.184904e+01

970423n 051
J npts= 967 median= -3.000000e-03 rms= 5.155533e+00
H npts= 967 median= -6.000000e-02 rms= 5.792946e+00
Ks npts= 967 median= -2.100000e-02 rms= 1.343485e+01

970423n 052
J npts= 926 median= -1.700000e-02 rms= 6.797559e+00
H npts= 926 median= -6.200000e-02 rms= 5.778801e+00
Ks npts= 926 median= -3.600000e-02 rms= 1.242199e+01

970423n 054
J npts= 952 median= -2.100000e-02 rms= 2.454339e-01
H npts= 952 median= -6.200000e-02 rms= 3.505084e+00
Ks npts= 952 median= -2.200000e-02 rms= 9.260145e+00

The zero point correction to scan 003 is:

delta_J = 0.050 +/- 0.029
delta_H = 0.209 +/- 0.034
delta_K = 0.134 +/- 0.038