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Old 10-11-2019, 03:33 PM
JimIrish (Jim)
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JimIrish is offline
Join Date: Oct 2016
Location: Junabee, Q., 4370
Posts: 8
airglow photometric spectroscopy

Hi all,

Has anyone used a telescope and grating to obtain spectra for airglow? I have an eleven inch Celestron SCT, which I'm planning to point at the South Celestial Pole (so I can leave the mount off, while permanently observing a narrow field of view in which there are few stars.

I'd expect to see the usual suspects for airglow line emissions and hopefully be able to get relative intensities for these and the continuum throughout a night and to compare nights. I expect a cooled camera will be needed to manage thermal noise.

I could be persuaded, however, to use an f/5 refractor.

Or am I dreaming? Will I only get faint spectra from the dim stars? To stack, or not to stack? Exposure times?

My copy of the recent Cambridge University Press book on astronomical spectroscopy hasn't been returned, so I'm in the dark, so to speak.

The alternative is extremely costly narrowband filters for each spectral line and/or standard photometry for at least B and V filters (possibly using Johnson-Cousin filters and Sloan filters in an electronic filter wheel to get some of the airglow emission lines by subtraction).

I'd rather not have to go the fully Monty with calibration every night using standard stars. One alternative is to measure the extinction coefficient at several wavelengths in the daytime with solar photometer.

Thanks in anticipation of your thoughtful reply.

Jim Irish (near Warwick, in SE Queensland - badly affected by bushfire smoke for more than a month, and counting)
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