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With a long slit orientated appropriatelyand a suitable image scale you might be able to get all you need in one shot (Well 2, one exposed for the bright side) You would need a flat field illumination source which is nice and even in the slit direction so the subtractions work accurately.
Funnily I was just reading Paul Abel’s beginners article on Earthshine and musing about measuring that spectroscopically, perhaps mounting the spectrograph behind a camera lens to get a sensible image scale to match the slit. Much easier than Ashen Light though !
Robin
I have been runnng with my “ALPY 200” low resolution faint object spectrograph configuration again over the past few weeks and have been able to work my way down about a mag fainter to around 17.5.
http://www.threehillsobservatory.co.uk/astro/spectra_46.htm
I recorded the spectra of these two supernovae (asassn-15fa and asassn_15fz) a few weeks after discovery so they have evolved significantly compared the original spectra taken soon after they were discovered. The match with spectra of supernovae at a similar age is still clear though.
The supernova contribution is already much lower than the sky background which is significantly limiting the signal/noise. I am not sure if more aperture or darker skies will be needed to go much lower, probably a combination of both.
Robin
Hi Stan,
A couple of other safety tips.
Keep the front cap on the finder scope or make another filter for it from the offcuts of solar film
Be sure to put the filters on before aiming at the sun and remember to swing away from the sun before taking them off. (Seems obvious I know but I forgot once when packing up some time after an eclipse that the mount was still faithfully tracking the sun and within a couple of seconds of removing the filter the eyepeice cap had a nice neat pinhole melted through it! I keep it as reminder as to why you should never look at the sun through an unfiltered instrument.)
Robin
Hi Nick,
There is currently no centralised international database but the object specific database BeSS for professional and amateur spectra of Be stars makes an excellent model for such a general database.
http://basebe.obspm.fr/basebe/
This is a professionally funded high quality system with moderation of submitted data and a mentoring service for amateur contributors run by pros and amateurs. There were thoughts to expand it but it would need funding. I have been talking with AAVSO for many years about this (including advising several of the various working parties there have been over the years) and the people behind BeSS have offered the complete system to AAVSO to use but they appear to want to go their own way against the advice of other experienced amateurs in this area and I have currently given up on them.
In the meantime the most complete source of amateur spectroscopic data is the ARAS organisation who have been archiving spectra submitted to them on a range of objects
http://www.astrosurf.com/aras/
(although unofficial, ARAS is where most serious amateur spectroscopists can be found and they are currently the main force driving up standards in this area)
I plan to talk more about how ARAS is functioning at the upcoming VSS meeting using Nova Del 2013 as an example
Cheers
Robin
