Forum der Vereinigung der Sternfreunde

I have made good progress processing my spectra with IRAF but seem to be falling at the last step.

I have been using apall to define the apertures and, as a separate step, extract the spectra. All goes well with setting up the apertures and for the first 22 spectra extractions but it then crashes with "Polynomial separation too large".

The aperture data does not show any issues or obvious changes at transition between extraction working and failing.

Google searches led me to a reference to a hidden parameter "polysep" but being a novice I could not follow how to find or change it. even if it is the cause of the problem

I have the latest versions downloaded from the IRAF site.

Any ideas on how to proceed would be welcome.

Regards Andrew

PS I think I may have solved the problem. I found a reference to apall1 and using epar changed polystep to 0.5 and it now seems to work. Is there anything more I should do?

I know it also appears in apdebug, apfit1, apnoise1 apnorm1 and apparams should I try and change these?

Hi Andrew,
when you google 'iraf polysep' you will find
http://iraf.net/forum/viewtopic.php?showtopic=115886
Maybe that helps you.
Regards Christian

Thanks Christian, I think it is working ok and so will leave it alone unless I have another error message.

I have now finished mapping the Th Ar lines to the different orders so I can complete the wavelength calibration.

Thanks for your continued help.

Regards Andrew