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Hi Robin, thanks for the reply. Yes, I did see your presentation on Shelyak’s YouTube webinar. That’s what inspired me to look into the possibility of using an Alpy 200. Now to save up some pennies!
JohnHi Robin, you mentioned in your post that ideally a reference star should have a low interstellar extinction. In terms of E(B-V) what upper limit would you recommend? Thanks, John
This is Monday night’s spectrum with bright helium emission lines.
There are P Cygni profiles in the hydrogen Balmer series and the helium lines With a velocity of about 1400 km/ sec.
I’ve just installed a permanent pier in my garden. I keep the mount on it with a Telegizmos 365 scope cover. It makes it so much easier to set up. I no longer have to carry my heavy mount and counterweights outside and polar align it. If it’s possible to have a permanent pier rather than a tripod I think it is worthwhile. My pier was from Altair Astro.
It looks as if there are P Cygni profiles in sodium. Is the sodium interstellar, and if so, what causes the P Cygni profile? Is the emission component due to photoexcitation by UV from the white dwarf or some other mechanism? Thanks.
Last nights spectrum shows P Cygni profiles in He I, Fe II, Na I and [O I] which have deepened or appeared since 5th September.
1920p
Thanks very much for that. Maybe next year you will be able to teach us how to do this, perhaps in another spectroscopy workshop.
H alpha is still prominent, possibly even brighter. It needs someone cleverer than me to do a flux calibrated spectrum. I’ve attached a plot of three spectra taken over the last three weeks to show the changes. This object continues to fascinate me. Any interpretation of what we are seeing would be welcome.
The H alpha line has become very prominent again and the P Cygni profile has disappeared. There appear to be emission lines for Fe II, He I and [O I]. The spectrum was recorded around midnight on 18th/19th August with an Alpy 600 and the resolution is ~ 550.
This is a spectrum from the early hours of 12th August. It looks very different from those of the 30th and 31st July in this thread. The H alpha line is much reduced and there appears to be a P Cygni profile, presumably due to expansion of the nova. I haven’t tried to identify the other broad absorption features. I would be interested in other people’s comments on what this spectrum tells us about the evolution of the nova. I see from the database that others have also noticed the changing profile.
This is a photo taken with an astro-modified Canon 350D on a tripod on 13th July at 0100. Exposure 3 secs, F4, ISO 6400, focal length 55mm.
Hi Robin, What exposure time did you need to capture the spectrum of the tail and what scope and camera did you use?
Thanks
John
Hi, I live on the Essex marshes with views almost to the horizon, so managed to get a spectrum of the coma of this comet on Tuesday am. Didn’t try for the tail. The Swan Bands are stunningly beautiful (to a spectroscopist). The image is the raw unprocessed spectrum.
This is an annotated plot of the spectrum, the relative intensity of the emission lines is not reliable because the instrument response was calibrated using Merak which was at an altitude of 20 deg but the comet was at only 10 deg. Neither the sky background or the solar spectrum was subtracted when processing the spectrum. The emission lines were labelled according to data in Richard Walker’s Spectral Atlas and on the following website http://web.gps.caltech.edu/~mbrown/comet/all.txt
The full size images are attached.
Robin can advise on whether the annotations are reasonable. John.
Dear Hugh, I read that you work in alt-az mode to avoid the effects of atmospheric dispersion. I’d be interested to know how you do this. I have an AZ-EQ6 Mount but haven’t tried the AZ mode. I normally guide on a different star to the target. Does field rotation interfere with your guiding? Do you have more difficulty synchronising your telescope to your planetarium software? I’ve been put off trying AZ mode because I had heard that it’s “go to“ function was not so accurate.
