Background Flux Calculator back

Only for SBIG ST7/8/9/10e Non AGB cameras.

To compare images from different setups it is necessary to normalize (make mathematically equivalent) the important elements: CCD efficiency (QE), telescope aperture, angular pixel size, filter, and exposure time.

The most problematic element for comparisons is spectral QE, but because the Kodak CCDs in the ST-7/8/9/10 e non-ABG cameras have very similar QE it is relatively simple to compare skies based on images from these cameras. For these cameras, Stan Moore has defined a standard measure of electron flux for unfiltered exposures:

e- / arcsec2 / meter2 / second

The calculator below will automatically normalize your system and compute the standard sky flux. The basic equation is:

Standard Flux = (background_ADU 100) * gain / (exp_time * angular_pixel_size2 * clear_aperture)

To use the calculator, simply change the appropriate fields to your particular values.

mm inches
Focal Length
% obstruction (diam)
clear aperture (m2)

unbinned bin 2x2 bin 3x3
gain (e-/adu)
linear pixel size (microns)
angular pixel size (arcsec)

Measurements from single unfiltered exposure (dark subtract and flat field)
exposure time in seconds
average ADU of background*
*including pedestal (do not pre-subtract 100 adu)

standard background flux

e-/arcsec2/meter2/second Add Your Value To My Flux Map