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Zero Points
Updated July 23, 2007The in-orbit photometric zero points are reported in the UVOT calibration document of 2007-05-22 are listed below. See the UVOT Calibration Documents Page, which is part of the Swift CALDB for detailed discussion of the photometric zero points. The current (as of 2007-05-22) photometric zero points for UVOT are
Filter Zero Point Error V 17.89 0.01 B 19.11 0.02 U 18.34 0.02 UVW1 17.49 0.03 UVM2 16.82 0.03 UVW2 17.35 0.03 White 20.29 0.04
These zero point convert instrumental magnitudes measured in a circular aperture with a radius of 5 arcseconds into a UVOT system magnitude. To convert UVOT system ubv magnitudes to Johnson UBV magnitudes apply the color transformation equations described in the "Color Correction" document available at the Swift UVOT Calibration Documents page, which is part of the Swift CALDB Web site.
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