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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. Eric.
Star Analyser 100 in pristine condition + spacer (to give correct spacing with CCD chips). Details (including a calculator to enable you to determine whether it is suitable for your system): http://www.patonhawksley.co.uk/staranalyser.html Reason for sale: I have upgraded. £80 (Normally retails for £105.71 + P&P), includes GB insured p&p. Bank transfer preferred; PayPal (net of fees) accepted. Advertised elsewhere.