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This spectrum (taken using the C11 and ALPY600 spectrograph) is of magnitude 15 star IRAS 00500+6713 in Cassiopeia. It is believed to be the result of a merger between two white dwarfs, kept from complete collapse by a powerful magnetic field and may be the stellar remnant of the supernova seen by Chinese astronomers in 1181. It is a star of extremes with a temperature of 200,000 K and 16,000 km/s winds. More about this star and references on my BAA page here
I am looking into making a hobby out of spectroscopy but don't exactly know where to start.
All I can really go off is a high school education of physics and the various reading that one usually does when looking into something new.
The main questions are, essentially;
1. What is the best spectrometry equipment for an amateur like myself?
I have little to no knowledge on all the necessary equipment, so any recommendations would be very much appreciated. For any suggestions, if you wouldn't mind giving a reason as to why you recommend a said product, I will take this information with great appreciation.
In terms of a camera, I've read that CCD monochrome cameras are the best. How does a DSLR rank against this though?
In terms of a telescope, should I be looking at one with a specific aperture range? If so, are there any other properties I should be looking at?
Is a grating better than a prism? Why?
What software is the most effective and easiest to use?
Do I need some sort of focusing device?
2. How do you collect spectral data using the technology?
Is it as simple as pointing at a star and recording the acquired data?
How long should I view the chosen star? Is it a photo or a video?
I would assume that these questions have been asked plenty of times, so any links to other forums which discuss the same questions and topics I am raising will be very helpful as well.
Any type of reply is welcome. As an amateur, anything is helpful.
Looking forward to discussing this with you all.
I've called it LOWSPEC.2 as it's the updated version of Paul Gerlach's LOWSPEC, a DIY 3D printed spectrograph. I built the first version but had trouble aligning the guide mirror (which was fixed), and locating the slit by waving a torch down the scope made it difficult to use.
The updated version is a vast improvement, for me at any rate.
1. The guide mirror can now be adjusted forward and backwards and side to side. I can now actually guide the spectrograph.
2. Adding an Illumination device (Baader). The slit can now be illuminated and the overlay in PHP2 used to locate it. No more trouble getting the star on the slit.
There is also the option to use a 30mm dia camera lens instead of 24mm. The camera lens used is 100mm focal length; I had a 30mm dia lens left over from a previous diy project which is 90mm focal length so I used that. I'm not sure of its quality as I bought it for £15 from ebay, but it seems to work ok.
I also had a defraction grating of 600 l/mm from a previous project so used that. Paul reckons LOWSPEC will now cope with anything up to a grating of 1800 l/mm.
For calibration I used a Philips S10 starter bulb because I found some calibration charts for it, (I think on one of the French websites) and these bulbs are about £1 in B & Q, significantly less than the Relco ones (if you can get them). I made a hole in the top cover, made a container on the 3D printer and now I simply insert it when I need to get a calibration reading. Not the most practical solution but again, it seems to work. If Paul manages to add a calibration unit inside LOWSPEC, that would be the icing on the cake. And if it could just be attached to the existing body that would be a bonus, as it took me 29 hours to print!
Here's a couple of shots of the thing itself.
The long tube houses the Philips lamp.
Here the calibration unit is inserted into the top cover.
The first reasonably clear night was moonlit and there was high cloud coming and going, but I went first for Vega as it's easy to image and calibrate with the Hydrogen lines.
The salmon coloured line is the A0V reference.
The image of Vega looked quite good on the laptop, so I moved on to P Cygni, one of my favourite subjects, and here are the results.
I've taken some of the readings from a PDF version of Richard Walker's 'Spectroscopic Atlas for Amateur Astronomers'. It doesn't seem to be available for download any more, I think there's now a book which you have to buy.
I may need to get a better guide camera; I'm using an Altair Astro GPCAM mono and when guiding it used a star with a S/N ration of 9.8, the brightest available. But having said that, it managed to keep P Cygni on the slit for 5 minutes at a time.
LOWSPEC is a great project if you've started out using the StarAnalyser and want to move to a higher resolution. It takes a lot of patience and persistence, but worth it. I reckon the total cost for LOWSPEC is about a quarter of the cost of an equivalent 'off the shelf' spectroscope, so if you can't justify spending loads of dosh then this is a viable option.
I completed a small 3D printing project yesterday to have a cap for my Star Analyser 100 filter while it is permanently fit on DSLR lenses. Here it is the 3D model if anybody else wants to print such cap for a filter:
I know that astrophotographers can use diffraction gratings and filters to image a star's spectra. However, is there a filter or eyepiece that a visual observer can use to see a star's spectra? Like, look through an eyepiece and instead of seeing points of light you see each star's spectra? Or am I going stir crazy from a lack of observing ?