SIGNAL calculates the number of object and sky photons which will be detected during imaging exposure of a point or extended source with one of the common-user instruments of the ARISTARCHOS telescope.

Instrument setup	Instrument: Detector: Band: Bandwidth: Exposure time (sec):
Object information	Object: Point Extended Apparent magnitude: (/arcsec2 if extended)
Sky conditions	Seeing (FWHM in arcsec): Airmass: Extinction(mag/airmass): Sky brightness: (mag/arcsec2) (D, G or B for typical dark, grey or bright)
Output options	Format: Text Text + graph Graph: S/N vs Exposure time Magnitude from to Multiple Curves None Moon (B/G/D) Airmass Seeing (FWHM) curve 1: curve 2: curve 3:

If bandwidth, extinction and sky brightness are left set at zero, SIGNAL assumes sensible defaults (click on parameter name for details).

For details of the assumptions made by SIGNAL, or to access the code, please see the SIGNAL help page, or click on a parameter name above (NB the help page may open in a separate tab).

This is version AR1.0 of SIGNAL. Last Updated: 21 Oct 2013.

© Isaac Newton Group of Telescopes
© of Modifications for Helmos Observatory, National Observatory of Athens
Developed by Chris Benn and Robert Greimel and modified for ARISTARCHOS by Thanassis Katsiyannis