WF/PC INSTRUMENT SCIENCE REPORT 90-10:
Technical Report on Wide Field Camera Observations of 2237+0305 (SV 3068)
By Donald P. Schneider and John N. Bahcall
February, 1991
Abstract excerpted from the report:
Our analysis of five Wide Field Camera observations of 2237+0305 yielded the following results:
1) The standard calibration performed by the
Space Telescope Science Institute's software
satisfactorily repairs the analog-to-digital
conversion errors in the raw data.
2) The standard calibration software
overestimates the bias plus preflash level
by nearly one electron.
3) The use of flat fields taken during the
vacuum testing of the camera has the potential
to produce misleading results.
4) The noise properties of the images can be
characterized by a readout plus preflash noise
of ~1.9 electrons and poisson statistics in
the sky.
5) Centroids of well exposed objects (several
thousand photons in the central pixel) can be
determined to an accuracy of a few hundredths of
a pixel.
6) The preflashs appear to remove low light
level charge transfer inefficencies.
7) Relative positions of objects measured from
Wide Field Camera and Faint Object Camera data
agree to a few milliarcseconds over an area a
few arcseconds across.
The complete report (PDF 2.1 MB) is available.