1st Isis Processed Spectra! - Z CMa

[James Foster]

After working many many hours, through multiple trails, errors, here is my 1st Isis V5.80 processed spectra:

Of course, as seen, I plotted this in BaSS 1.96, since I'm not well versed in plotting in Isis.

I used SAO133651, a magnitude 6.9 A1V star about 6 degrees away, to calculate the instrument response; I used 5x30sec images of this star before shooting Z CMa.
I was using the LISA with a 19 micron slit and 90 second 1x1 bin exposures.

One of the issues with Isis was I could not use the "UV Calibration" option in Isis's repose assistant without getting tremendous errors. When I had this option off, my
RMS was around 0.13 angstroms. I understand that this might be because of my low signal since I was only doing 90seconds at 1x1 bin; will shoot this again at
2x2 bin to see if I can acquire data short-wards of 400 nm.

My next project with Isis will be reducing some 3C 273 LISA spectra I took a few nights ago......comments welcomed!

James Foster
Los Angeles, CA

[Francois Teyssier]

It looks very good, James
You can send me the Spectrum (fit)
UV is not easy with LISA due to chromatic abberation
How is the image of your Spectrum in the near UV? ("fish tail"?)

François

[Terry Bohlsen]

Well done.
What calibration lamp are you using?
I can usually get a useful spectrum down to 3800 with my LISA for bright targets. The UV does depend a bit on your focus and the type of scope. A refractor is poorer than a reflector.
see http://users.northnet.com.au/~bohlsen/L ... /Start.htm

[James Foster]

To: Terry,

I finally got good near UV spectra by tuning the grating angle and LISA Optics focused towards UV!
I re-positioned the slit along the x-axis using the technique shown in the LISA user guide, page 57-58. Instead of positioning the bright Ne line at 5852.488A
near the center of the CCD, I moved the grating so that this feature was just right of the center of the long axis of the CCD fov. Despite pushing the Red-IR past the righ-side of the CCD fov, I was still able to capture continuum past 7725A, where 2nd order effects start to rear their ugly head.

I then re-focused LISA's main optics on the Ne-Ar line region btw 4000 and 6000A using the procedure in LISA User's guide, page 14-15. Both of these re calibrations
resulted in a much better imaged near UV and gave sharper lines for Isis v5.80 to process against. Here is the spectral result of one of the A-stars I imaged:


Thanks for the advice!