Quote:
Originally Posted by Jon
Nice one Terry. I've been finding your spectra of the Nova over on the Astronomical Spectroscopy forum incredibly useful for understanding what's going on.
Forgive a newbie's question but it seems to me that getting all of the continuum from 4000-7200 into one image on a 314+ sensor at R=1200 is really impressive. Other spectra seem to capture far less at that resolution. How do you do it?
One of the reasons I'm asking is because I've been trying to work out which gratings to order with my L200. I want at least one to capture as much of the continuum as possible but think I have to go down to R=300 or even R=150 to do so. Am I missing something?
Cheers
Jonathan |
The R figure is worked out by the processing software based on the FWHM of the neon lines in the calibration spectra as well as pixel size etc. It varies between 800 and 1500 depending on how I do the neon calibration. The actual range on the CCD is determined by the magnification of the spectra and the size of the pixels. I think it is 2.3A/pixel (Im at work so don't have the software infront of me).
For the Atik camera and the LISA this allows a spectra to range from 3800-7300 across the frame. It was much larger when I used my SBIG ST8 as it has a bigger chip but lower resolution due to it having bigger pixels.
The L200 is a different design and suffers more with field curvature making the ends of the spectra out of focus. This limits the practical width of the spectra. I think the L200 is better for medium resolution spectra and not to worry about trying to use it for full width spectra. Regularly changing the grating would be a pest to do and a but risky due to possible damage to the gratings. Drop it once and it is useless.
Terry