I have made arrangements with Paton Hawksley, the manufacturer of the SA200 diffraction grating that fits into your filter wheel, to make a group purchase of these gratings (or a mix of SA100 and SA200 gratings). For U.S. purchases, I can get these gratings for about $160 at the current exchange rate including postage; it will be somewhat higher for foreign shipping. If there is sufficient interest (and monetary pledges), I'll go ahead and set up the group purchase. There will only be one such purchase. Hawksley says that there will be a small price increase for 2015.
My recommendation in the future for filter selections is going to be either B,V,R,I,GR or B,V,I,C,GR or even U,B,V,I,GR for those with 5-position wheels. I think the grating is an excellent substitution for the Rc filter, as it gives you a much better feeling for emission/absorption at Halpha than does the wideband filter, and V/Ic pretty much give you the rest of the astrophysical information.
Arne
Please put me down for a SA200.
Thank you.
Paul
I would like to purchase one also!
Thanks!
Jim
I will commit to a 200. Thanks for the footwork.
Tom
I'd like to sign up for a SA200.
Phil Sullivan spp
Hi Arne,
I'll order a SA200, Cheers,
Mark
I'm extremely pleased to see the level of interest in the gratings.
This could be a watershed moment in the AAVSO, the transition to spectroscopic observations.
While you're waiting on your gratings to arrive..... this would be a good time to assess what activities would be appropriate and how we could establish a basic support mechanism to resolve the issues/ problems which I know will arise.
Unfortunately life is never simple (but you know that already ;-) ) Just dropping a grating in a filter wheel is not very effective...for best resolution the spectal image MUST be aligned with the horizontal axis of your CCD chip.
The spectral image MUST be focused, NOT the zero image star. Shorter focal lengths and smaller (down to f5) ratios give the "best" ie smallest star images and hence resolution..... The exposures should max out (in the spectrum) within the linear region of your CCD, and can be stacked to improve SNR.
It is strongly recommended that you start with a A type star spectrum - this shows prominent hydrogen Balmer lines - makes it easier to check focus, and establish the dispersion/ resolution. It also allows you to practise developing an Instrument response curve (which you'll definately need later!)
Check out the freeware processing software listed above and find one you are comfortable with....
After these "preambles", you will be far more confident moving forward.....
I know I can speak for all the other amateur spectroscopists when I say "We're here to help!"
Onwards and Upwards
Put me down for one also. I hope it can be used with a DSLR camera instead of a ccd+filter wheel.
Chris
If your not restricted
Chris,
If your not restricted by the spacing of a filter wheel, then the SA100 is probably a better bet.
Yes, it works with a DSLR......
Hi Chris,
Examples of Star Analyser + DSLR
With a telescope (Christian Buil)
http://www.astrosurf.com/buil/staranalyser/obs.htm
Without a telescope (My website)
http://www.threehillsobservatory.co.uk/astro/spectroscopy_11.htm
The Star Analyser will work with colour cameras eg DSLR on brighter targets for quick look identification but a long exposure capable monochrome camera, preferably cooled is preferable for the following reasons.
Spectroscopy needs a lot more light than photometry (A rough rule of thumb with the Star Analyser is that to get a spectrum you need a star 5-6 magnitudes brighter than the equivalent for photometry)
The response of the filters on the pixels and the different sensitivity of the pixels to the different colours reduces sensitivity and resolution and can give artifacts which makes it more difficult to do any quantitative analysis.
Colour cameras have UV/IR cut filters which unless removed restricts the spectral range
Robin
After reading the posts (thanks Ken and Robin) and checking the SA and other websites, I think my best bet would be to order a SA100. I could certainly use one for education, but would also like to use the grating for science. Is this a reasonable expectation?
Chris
I would like to get SA200 suitable to mount in 1.25" filter wheel. Please send me the payment terms and conditions. If there is PayPal possibility it will be greate.
Velimir Popov (PVEA)
Put me down for a SA200, also, Boss!
Tim Crawford, CTX
I would like one as well. Someone in my area has been drumming up interest and may submit a request for several. But he seems to be out of town briefly and so I didn't want to depend on him getting the order in on time. I'm trying to follow up with him to see what progress he's made.
Rick Wagner
WCR
Ottawa Centre/Kingston Centre
RASC
The low resolution of
Chris,
The low resolution of the grating and need for stellar target objects can restrict the scope of scientific work.
Having said that there has been some excellent work done in the early identification of SN type and the all-sky survey of Be candidates (especially in the northern hemisphere).
Torsten Hansen's work with a SA100 and an 8" f6 newtonian - WR stars, Methane spectra of the outer planets etc, are outstanding examples of what can be achieved.
Maurice Gavin, using a grating, was the first amateur (in 1998) to record the redshift of a quasar - 3C273
We are only limited by our imagination................
Please let me know by 2400UT today if you want to join the group purchase for an SA100/SA200 or mounting kit. I will collate the requests that I have and start the purchase process tomorrow. Thanks!
Arne
Hello Arne
I was waiting for you to announce that the orders were open on the web page per your original post, I did not indicate that I wanted on on the Forum for that reason. Can you add me to the list for the SA200?
Thanks
WGR
Sorry for duplicate question:
has anyone here tried SA200 with an Apogee FW50 (9 round filters) filter wheel and Apogee Alta U42 camera? Does the grating fit into the wheel?
Cheers,
Tõnis
Hi Tõnis
The SA200 develoment was partly prompted by a request from an owner of this model wheel, so yes I believe it will fit in the FW50 using the mounting kit based on the dimensions he gave me, though he decided against using the SA200 in this configuration in the end and is using the Star Analyser on a different instrument. If you email me direct at robin_astro at hotmail.com I can put you in touch with him if you like
Robin
I have a complete list of those ordering the SA200 gratings. I want to confirm the other orders.
I have the following people down for purchasing SA100 gratings:
Neil Simmons
Doug Welch
Mike Miller
Chris Maloney
I have the following people down for purchasing the 50mm adapter kit:
Frank Schorr
Lew Cook
If anyone else has ordered an SA100 or the mounting kit, please let me know ASAP. Thanks!
Arne
I thought I sent an email about this yesterday. I apologize for the confusion!
Thanks,
Chris
Hi Chris,
I remembered you changing your request, but on first glance, I didn't see the email. I do now - and you have been changed from SA100 to SA200. Thanks for the reminder!
Arne
Folks,
I use an Astro-physics AP16T 2" nosepiece on my Apogee AP-7. The nosepiece has 48mm 2" filter treads in the front. The kits that adapt the 1 1/4" SA200 to 2" filters require that you provide your own blank 2" filter housing. Anyone know where these might be found?
Thanks,
Walt
Hi Walt,
There are a couple of possible routes.
You could use the mounting kit as you propose to mount the SA in a 2 inch filter cell. One source of blank cells is Baader, here for example
http://www.baader-planetarium.de/sektion/s44a/s44a.htm
Filterfassung 2" 245 9252 L near the bottom of the page
Alternatively and probably easier in this case where you are not having to fit it in a low profile filter wheel is to just use a 1.25 to 2 inch adapter like this one
http://www.teleskop-express.de/shop/product_info.php/language/en/info/p…
Robin
Edit: Actually looking more closely at the 1.25 to 2 inch adapter, this could also be an alternative way to mount the SA200 in a filter wheel for 2 inch screw in filters provided there is enough clearance in the wheel for the height of the adapter
Thanks Robin. The adapter from Telescope Express would be just perfect. I had looked for something like that but had been unable to find it on google. Let me keep looking to see if I can find one available in the US. The shipping cost from Germany is way more than the cost of the adapter itself. :-)
Walt
And I was able to find one...
http://agenaastro.com/blue-fireball-m48-male-m28-5-female-adapter-m-01…
It's on order. It's not the same as the offering at Telescope Express but it looks like it will do the trick. Thanks!
Walt
Yeah, I missed the deadline on this one. I was hoping to get an SA200, so if there are extras, let me know and I will purchase one.
Scott
Hi Scott,
There may be one spare; I'll have to see after everyone pays for their order. The gratings should be in next week, and I'll set prices once they arrive and have passed through customs.
Arne
The gratings that have been paid for were shipped today (with a few to go out tomorrow). Those that pledged to purchase gratings should visit the online store and complete payment within the next week. Thanks!
It looks like foreign postage is low enough with these lightweight packages that we can provide foreign shipping for the same price. Those that have ordered only need to pay the listed prices and we'll get them shipped out to you.
Arne
I received mine today.
Thank you!
Paul
There are over a dozen people who pledged to buy gratings, who have not made the final purchase. Please do so before the end of 2014, or I may give your grating to the next person in line.
Arne
Mine finally arrived yesterday, not sure where the delay was. I'll get it installed in my filter wheel and try it out next clear night. Too bad it didn't arrive a couple of days earlier - we had two clear (and cold!) nights in a row. Almost unheard of. Oh well, at least I was able to spend time getting some really nice pretty picture images of Comet Lovejoy and a couple of deep sky objects. Yes, I know, good photometry time wasted, but one sometimes has other interests. These particular images will be projected as backdrops for a local astronomy-themed play.
Thanks again Arne for arranging this purchase.
Rick Wagner, WCR
Finnaly it arrived. most curious apointment, it took 7 days to arrive to portugal than another 15 days to be released by customs that did the fine job of appliyng fees as if the price was in EUROS, so the aftermath was a big loss.
anyway im pleased that i can start to do the math for the Spectroscope calculations. mid year and results will come, finally can go for the Radial Velocities at low resolution in Binaries!
Thank you Arne, and all the aavso team that made this group purchase happen.
Kind regards
JAC