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Hubble Space Telescope
FOCSIM Parameters Fill-out Form

This form will calculate the count rates for a simulated direct image of ONE point source in a 512X512 FOC image with an average value for the background. If you have trouble using this form, please contact Warren Hack at STScI.

Relay: F/151 F/96 (Pre-COSTAR)


Calculate exposure time to reach a S/N of
Calculate S/N reached in an exposure time of

Use an Observed -or- a Theoretical PSF.

Choose a spectra:
from the UCB catalog of Kurucz model spectra:

from the Calibration catalog of observed spectra:

or, created by FOCSIM that is either:
  • a Black-body with T=
  • a Power-law: F_lambda(ergs cm-2 s-1 Å-1) = lambda ** ()
  • a Flat continuum.
The spectra will be normalized to a flux of
at Angstroms.

Note: Simply specify a reference wavelength of 0 for U,B, or V magnitudes.