Here's having a go.....Attached some visuals,
Alpha Cen, Peacock, Saturn-Bow, Antares.
Afocal ie camera at eyepiece, with my no-skill astrophotography therefore these are a very poor representation of what were seen in reality. One 1st order spectrum was (designed in the grating to be) much brighter than all others.
Each viewed spectrum was narrower than shown, longer and much more colour-intense. Rainbow Optics (imaging+visual version, bought in the US) 200 l/mm grating, threaded like a filter to the bottom of a 15 mm eyepiece, focussing attempted on the spectrum and not the star, 10” Bintel Dobsonian, Canon S5 IS digital but not-DSLR. Moon 35%. Rainbow Optics Cylindrical lens not attached.
I believe in exploring and discovering! So purposely did not restrict (this time) to lining up the spectrum to the pixels nor avoiding certain objects. I explored alpha Cen., Antares, A Crux, Achernar, Peacock, but leaving gamma Vel and eta Car for next time. Then I got a moon-bow. I got Saturn-bow. It’s extreme fun.
**For better-quality profiles and processing I team up with astro-photographer colleagues.
Hope you’ll share here your better images. Suggest southern objects mostly please, only because they’re less explored :-)
Good intro....
You'll get more data from your spectra using a "converging beam" arrangement rather than the a focal method.
Focus on the spectrum rather than the zero order star image.
The next step is to be able to process the image to a spectral profile...
BASS Project is a Good and easy software package.
Thank you, Ken. I appreciate all the encouragement and advice.
Here, showing the visuals like for general observations, for new explorers and for when showing to the public I try to show what can be seen straight at the eyepiece firstly.
For data, my teammates have a lot better skills and equipment. One currently uses a black and white CCD with the grating in the converging beam; we get into the data and processing mode. That department we hope to share in the other forum.
I bought my Star Analyser SA 100 grating about a year ago. For a while, I was content to just use it visually, and look at all the pretty rainbows. At least on the brighter stars, you can certainly make out the main absorption and emission features of the spectra through the eyepiece, and see the difference between a cool red star and a hot blue star..
Then I put it onto my colour astro-camera, and discovered that you can share the spectra with a group of friends in real time - both as real-time video on your computer's screen, but also doing real-time spectral analysis using a program like RSpec, V-Spec or BASS. That was actually a "knock-out" moment for me - I have my camera set up on a flip-mirror, so you can go from a visual view through an eyepiece, to the camera, and back again, and swap between seeing the natural view of the target to a rainbow spectrum AND a real-time analysis of the spectrum, with an overlay of the library spectrum for the star's Class, key elemental emission / absorption lines, scrolling through the black-body temperature spectra overlaid on the real-time spectrum to get an idea of the star's temperature, etc. Even my non-astro friends agree that it is pretty cool, even if they don't fully understand it.
I now generally use my grating with a mono camera - in a way, I miss the coloured rainbows on the computer screen, a grey-scale streak just isn't as pretty, but it gives me better resolution spectra for analysis purposes. I'll still mount the grating on my colour camera when friends or family join me under the stars, as it is easier to grasp what the analysis is doing, when you can also see the coloured spectral image, and for social spectroscopy sessions, I don't mind losing a bit of resolution for the sake of ease of comprehension, and the "Wow" factor of being able to contrast the absorption lines on one star with the emission lines of another is hard to beat.
