iraf.net

Hi!

I know that the "m" keystroke in splot gives the rms and snr of a spectrum. However, I would like to understand how this is calculated, but there is nothing (obvious at least) at the help page of splot.

I did a searvh in the forum to see if there are relevant topics and I found these two (from archived mails) which remain unanswered:
https://iraf.net/forum/viewtopic.php?showtopic=132434
and
https://iraf.net/forum/viewtopic.php?showtopic=82803

I wonder if there is any documentation to look at.

Thanks
Grigoris

The source for the calculation can be found in noao$onedspec/splot/avgsnr.x. The calculation itself, however, is simply


snr = avg / rms

where the avg and rms are calculated from the points between the two cursor positions.