ISIS bug - predefined dispersion used with reference line

Post Reply
Robin Leadbeater
Posts: 1926
Joined: Mon Sep 26, 2011 4:41 pm
Contact:

ISIS bug - predefined dispersion used with reference line

Post by Robin Leadbeater »

ISIS has a useful feature where the predefined dispersion equation mode can be used with a single reference line which uses the same dispersion equation but recalculates the offset coefficent A0 based on a single reference line (Normally you enter 0,0 for the reference line which forces ISIS to use the full predefined dispersion equation. If you enter the wavelength of a line and the approximate position in pixels in the calibration image it uses this instead.)

This correctly shifts the calibrated spectrum as expected but it calculates the spectrum over the original wavelength range. This produces incorrect constant values on one edge and crops the other edge of the spectrum.

ISIS V5.9.3
ISIS_predifined_dispersion_bug.png
ISIS_predifined_dispersion_bug.png (18.28 KiB) Viewed 2659 times
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Ken Harrison
Posts: 197
Joined: Thu Oct 25, 2012 5:45 am
Location: St Leonards, Australia
Contact:

Re: ISIS bug - predefined dispersion used with reference li

Post by Ken Harrison »

I thought it was only me......
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before....
"Imaging Sunlight - Using a digital Spectroheliograph" - Springer
http://www.astronomicalspectroscopy.com
Post Reply