Hello everybody!

I am trying to learn how to estimate errors of line fluxes determination by SPLOT. As I understand from "ERROR ESTIMATES" part of description of SPLOT help it is needed to specify two parameters: "inverse gain" or invgain and "constant gaussian sigma " or sigma0. I understand what is invgain.

But what is sigma0 and how can I find this?

Thanks for your attention!

Andrey.

I've just been looking into this myself. sigma0 seems to be the equivalent of the readout noise, i.e. some sort of constant noise that every pixel has.

My question is instead this: What's the best way of estimating sigma0 (or for that matter invgain) from my spectrum? The help file says 'These parameters would need to be estimated in some way using the statistics of the spectrum', but doesn't make any suggestions.

See the explanation in http://iraf.net/phpBB2/viewtopic.php?t=83675&highlight=sigma0+invgain for more information (at least until Frank responds).

-Mike