Star Analyser and RSpec Use In School (Physics Class)

[saac]

Hi folks, apart from a bit of lurking I'm new to this part of the forum so I thought I'd introduce myself before asking for your help and advice.

As well  enjoying astronomy as a  personal interest, mainly visual but experimenting with photography, I'm also a secondary school Physics Teacher in Fife.   A recent change in our Higher Physics curriculum has seen the welcome introduction of a cosmology unit in which we discuss stellar evolution/classification, and investigate the expansion of the universe through the context of Hubble's Law.  Spectrometry features as a means to measure  redshift and hence to discern the recessional velocity of  stars/galaxies.  I'm looking to introduce a practical dimension to the unit possibly looking to develop it if suitable for use as formal investigation which contributes to the pupils overall assessment.

I've looked at the possible use of the Star Analyser together with RSpec software.  I was wondering how practicable the proposition would be to use the star analyser to allow the student to obtain and then analyse the spectra from some of the brighter stars with a view to perhaps determining classification, temperature, identification of principal absorption lines for comparison against reference spectra, and if possible detection of red shift in the spectra.  Our department has available for use SW Equinox 80 APO Pro,  an 8 inch Newtonian reflector,  an imaging source DFK 21 AU04, and an DSLR (EOS 500D).  I've taken a look through some of the u tube tutorial on the use of RSpec and while I wouldn't be looking to use anywhere near its full capability I think we could use it to provide a basic analysis of any spectra we capture.

I'd be grateful for any thoughts: am I being too ambitious or perhaps am I limited in what I could achieve with the equipment we have available to us.  I haven't purchased anything yet but was looking to the Star Analyser 100 as perhaps being most suited to our SW 80 APO.  Grateful for any help or suggestions, thanks in advance.

Jim

[robin_astro]

Hi Jim,

Apart from  the redshift measurement of stars (too small for the resolution of the Star analyser)  the rest is doable, though having only colour cameras makes it significantly harder due to the different colour filtered pixels. Take a look at my website here for a link to an example of a simple technique using the SA mounted in front of a camera lens rather than with a telescope but the procedure is the same and you can use RSpec instead of  VSpec if you prefer

http://www.threehillsobservatory.co.uk/astro/spectroscopy.htm

Also Jim Ferreira's results with a DMK camera, an SA and a small APO refractor

http://www.lafterhall.com/spectroscopy.html

note this is a mono camera though

If you can get hold of a long exposure mono camera then cosmological redshifts of bright quasars and active galaxies are withing reach. Se my website for examples

Cheers

Robin

www.threehillsobservatory.co.uk

[saac]

Hi Robin,

Thanks for the reassurance, I have no real direct experience of spectroscopy so I wasn't sure how realistic I was being;  I'm reassured from your comments that there should be enough, even without the redshift ability, to do something meaningful.  I'm quite excited about the idea of the pupils being able to do real "science/analysis" with the data they collect.  I'll take a good look at your site over the next week (I'm off on mid term holiday) and the link to Jim Ferreira's work, thanks for that. 

I'm looking to place an order for the star analyser today so that I can hopefully get to play with it next week when I'm off work so if you don't mind I'll most likely come back with lots of questions.  Your technique of mounting the analyser in front of  the camera lens looks like a good place to start and certainly a good set-up for the kids.  Thanks again Robin.

Jim 

[robin_astro]

Hi jim,

if you are specifically looking to mount the Star Analyser in front of the camera, take a look at the objective grating section on the Star Analyser calculator page

http://www.patonhawksley.co.uk/calculator/

Depending on the focal length of the lens on your DSLR, you may find the SA200 rather than the SA100 might be the best bet for this specific application. The SA100 though might be better for the telescope application eg the SA200 on the nosepiece of the DMK camera might give too long a spectrum to fit in the frame.   Decisions.. decisions..  

Robin 

[Gazabone]

Hi Jim,

I just getting into this myself and it all looks very interesting. I'm using a star analyser 100 with Rspec too.

The BAA are running a Spectroscopy workshop tomorrow at the Norman Lockyer Observatory in Sidmouth. I do realise this is quite some distance for you and very short notice but saw your post and thought I'd mention it.

[saac]

Robin, thanks  for pointing out the Analyser calculator app.  I had a play around with it and the SA100/SW 80  combination looked ok.  I only have the standard kit lenses on my  DSLR so I think at the moment I'll make a start using the analyser with the refractor.  Decisions indeed, always  the way with astro equipment - compromise  upon compromise.  I'm already regretting opting for the  colour imaging source camera that I bought a few years ago, should have gone for the mono version. 

Gazabone that BAA workshop would be just what I need at the moment but your right about the distance - I'd never get back in time for Doctor Who!  I'll keep an eye on the BAA website just in case they post some notes.  Be good to hear of any tips or pitfalls you've came across in using the analyser or the software.

Jim