Hi Steven,
Sorry, this is a very long post but these issues come up with most people new to astronomical spectroscopy and the Star Analyser so I have tried to be as comprehensive as possible.
Forget Planck curves. Despite what you may read, stars are nowhere near being black bodies and the effective temperature Teff usually quoted is a theoretical construct which has little to do with the actual surface temperature of the star, if such a thing could even be defined. This diagram in Wikipedia nicely shows the problem using Vega for example
https://commons.wikimedia.org/wiki/F...comparison.png
If using the camera response gives you roughly the right answer this is purely luck, due to the fact that the response of the grating if roughly similar to that of the camera. To be honest you might as well have sketched out an instrument response freehand and used that. Here are some examples of the typical efficiency curve for a transmission grating here.
http://www.optometrics.com//App_Them...s_t_graph1.gif
The Star Analyser will be similar. The response excluding the atmosphere and other optical components in the system will be very roughly this x the CCD response.
Working with such a simple slitless system like the Star Analyser means we have to accept some limitations but the document I mentioned on my website
http://www.threehillsobservatory.co....t_response.pdf
gives a good idea of what you should be able to achieve in terms of response correction on bright targets using a monochrome astro camera and a Star Analyser. It does take practice though so I recommend beginners choose a few known reference stars to hone their skills on in the same way as I described there. (Note faint objects are tougher to get an accurate instrument response with slitless systems, mainly due to difficulties in subtracting the sky background accurately, which can be large compared with the signal, particularly at the blue end.)
The method of using a reference star to measure the instrument response (hot A or B types are chosen as they are relatively line free so it is easier to divide them and eliminate any remaining artifacts from residuals from the lines) is the same as used by professionals, except that they usually measure the instrument response and atmospheric extinction separately. To avoid that complication amateurs generally use a reference star at similar elevation. (Provided you are observing above ~40 deg, within 10deg altitude is good enough to get a reasonable accuracy down to 3800A which is as far is you can reasonably expect to go with a Star Analyser given the camera and grating response. At higher elevations you can be further away but at lower elevations you need to be closer in altitude. If you want to explore this further I can suggest for example Christian Buil's website. (In French but Google for example translates well)
http://www.astrosurf.com/buil/extinction/calcul.htm
http://www.astrosurf.com/buil/atmosp...ansmission.htm
I am not an RSpec user but you can see the steps I used to achieve the results shown using ISIS and Vspec. in the presentation "Low Resolution Slitless Spectroscopy (Star Analyser)- Observing a fast transient of a T Tauri star." Particularly slides 5-33 downloadable from this page
http://www.threehillsobservatory.co....roscopy_10.htm
The procedure will be similar in Rspec.
Hints and tips:
1. When making the observation, plan where your spectrum will lie relative to other stars and spectra to avoid cross contamination between star spectra. Rotate the camera plus grating if necessary to avoid this.
2. It is better to use if possible reference stars with an actual measured professional spectrum eg MILES stars. (The Pickles stars in the Vspec and Rspec libraries are generic of a particular spectral type and can differ from the actual spectrum of a particular star due to interstellar extiction, metallicity or inaccuracies in spectral classification for example)
3. Make sure you make your binning zone wide enough to include all the spectrum signal (turn up the gain in the image) Don't make it too wide though otherwise you just add extra noise
4. Make sure the zones for background subtraction above and below the spectrum are close to the measured spectrum but not so close that there is contamination from the target spectrum (turn up the gain in the image) The zones also need to be free of contaminating stars and spectra. This is particularly important in regions of the spectrum where the signal may be low eg the blue where the instruments response is low and small errors in background subtraction can give large errors in the final spectrum.
5. After wavelength calibration crop your spectrum to 3800-7800A. ( Below 3800A the sensitivity is too low to give reliable data and above 7800A you risk contamination from the second order spectrum.)
6. Rescale your measured spectrum to approximately 1 on average and filter your library reference spectrum to roughly match the resolution of your measured version. This makes the division easier and the resulting raw spectral response more accurate. Don't be afraid to wavelength shift your measured spectrum slightly if necessary to bring the lines in the two spectra into line
7. After division, remove any remaining artifacts where the lines have not divided accurately before smoothing the result This is particularly tricky in the blue region where the H Balmer lines crowd together and merge. (I normally remove the telluric lines at the red end too so they do not appear in the response and will therefore remain in the measured spectra but that is a personal choice)
8. The smoothing stage is critical. You are aiming to smooth out any remaining noise artifacts while still keeping the underlying instrument response. Take care not to over smooth. This is a common beginners fault. In particular look carefully at how well the smoothed curve fits the raw curve at the blue end. The instrument response is low here so what look like insignificant errors become magnified. Also take care not to smooth out broad ripples which may actually be in the camera response. (Kodak KAF and some CMOS sensors can be particularly prone to these)
9. The first acid test of a good instrument response is to apply it to the measured reference spectrum. The result should of course ideally exactly match the library version. If it does not, look closely at where it differs, try to understand why and if necessary redo the response calculation.
10. Check your skills by measuring other stars with known spectra and differing spectral types and correcting them with your instrument response. The results should be close to the library version for all stars.
