spectro-aras.com

A C11 + LISA observation of comet Garradd C/2009 P1 (coma region) - March 26.8 2012:



The comet is well positionned and bright but not a so easy object for me because
sky pollution...

The 2D image of comet + sky (6 x 300 s):



The comet is faintly visible relative to sky intensity. The pollution intensity is
dramatic. Now a 6x 300 s exposure of a sky field (no comet):



The substraction of the two images reveal the comet:



ISIS processing. Details here:

http://www.astrosurf.com/buil/garradd/obs.htm

Christian B

OK - here is my spectrum of C/2009 P1 Garradd in 1h exposure with LISA + Televue 85. Not as good but features well visible...

To process it, I created a dummy dark & offset frame (note: I had to do it in AudeLA and not ISIS as I had to set the exposure time for the dark). I then substracted the comet 2D images with the sky background images and added them together into a single 2D image to process.
This worked but I still have strong emission lines visible in my image - some pollution I couldn't remove.

Anyway, here is the spectrum profile:
Cordialement,
Olivier Thizy