Using very low dispersion gratings is an interesting area. I get quite a few enquiries about my ALPY200 but the 200l/mm grism was specially made and Paton Hawksley/Shelyak do not supply them commercially. The fast focal ratio optics of the ALPY also helps with faint objects, keeping the dispersion low for a given resolution but trying a very low dispersion grating with say the SOLEX or UVEX could be interesting. For supernovae I suggest a target of R~100-150, similar to that I use in the ALPY200Hamish Barker wrote:I see a really low dispersion option in their list, only 41lpmm, blazed for 500nm. Could be good for extending faint, low res performance down to mag 17+ SN candidates. there are a lot more of them than there are of mag 14-15 which is approximately my limit with 180lpmm grating in my L200 spectrograph.
http://www.threehillsobservatory.co.uk/ ... opy_20.htm
and also similar to that of the SED machine
https://nickkonidaris.com/sed-machine/
Cheers
Robin