From: Milton Aupperle <milton@outcastsoft.com>

Date: April 23, 2011 11:23:40 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Spectroscopy

Dear David;

On 23-Apr-11, at 10:48 AM, daffyddsant wrote:

Silent other here. (Not really, as I was the one who started the thread on the macastronomer group.)

I know that you have access to Windows. I would suggest that you download RSpec (30-day fully-functional trial) and see what it does <http://www.rspec-astro.com/>. There is a very short overview video at <http://www.rspec-astro.com/videos/overview/overview.html>.

I had a look at quite a few different packages (including RSpec) and read through their manuals to make sure I was covering the bases.

Thee are sample files available. Among other things, it can rotate the star image and spectrum to horizontal. After rotating one can manipulate two horizontal bars to select the region of interest (the star and its spectrum) and eliminate as many other stars and spectra as possible. A very neat feature is its ability to accept live input from video cameras such as Imaging Source, webcams, etc, and average for best curve. This is also a focusing aid, as focusing on the star does not do the job; one has to somehow focus on the spectrum, but the spectrum has fuzzy edges. Thus, in RSpec, one focuses for the best looking curve.

Those would be all standard features and is common to pretty much all of them packages I looked at. However I don't see the need to rotate the entire image. You simply draw a line(or click on 2 points)  over the center of the spectra, set the width of the area to measure (using a control) and then Astro IIDC would extract the area, rotate it into position and then generate the profile above it, in a separate sheet.

Stacking multiple frames and then working with the stack also improve the SNR too, much the same as stacking for detail on lunar / solar / planetary images.

And Astro IIDC can auto align and average the images and save it as frame on the fly too, for focus. But using the live Histogram Expand feature and then enlarging the live image to say 400% should increase the spectra contrast too, making it easier to focus and see absorption lines.

TTYL..

Milton Aupperle