Photometry of SN 1974G from Photographic Plates Using a Kodak DCS200 Camera
at the Annual Meeting of theAAVSO, October 15, 1994
have investigated the use of a Kodak DCS200 camera, which mounts a 1524 x
1012-pixel uncooled CCD as the detector in a conventional Nikon 8008s camera,
to digitize and obtain photographic photometry from typical plates in the Maria
Mitchell Observatory (MMO) plate collection. We tested the photographic
stability of the camera system on photographic standard sequences in several
fields, finding a linear correlation between instrumental aperture magnitudes
and standard photographic magnitudes, with an rms deviation of 0.1 magnitude.
We then applied the methods to digitize a 1 cm square area surrounding SN 1974G
in NGC 4414 on a series of five plates taken within a week of maximum light.
The major source of the 0.2magnitude uncertainty in SN 1974G magnitude
measurements was determining the local background surrounding SN 1974G.
However, the photographic magnitudes we derived agree within 0.2 magnitude of
points interpolated from published light curves. We conclude that the Kodak DCS
200 camera is an excellent and economical device for digitizing small areas of
plate collections for special study.
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