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M57 spectrum


nytecam

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This is a field shot of M57 from last week with the Rainbow Optics grating before the CCD. It shows three emission lines eg the dominant OIII+OIII+H-beta blend in the centre, the H-alpha to left [longer wavelength] and right of OIII a feeble line in UV that Torsten Hensen also records here @ 382nm [=Hansen]- presumably Balmer 10->2 ? The 4th image to the right is the real [zero order] image of M57.

I don't think I've recorded this far into near-UV before before on CCD and wonder if my change of CCD [sX_H9 mono cam] is responsible. M57 was near the zenith at the time so perhaps minimum atmospheric absorption comes into play.

Have you recorded this UV emission line and extracted its wavelength :police:

post-21003-0-33406300-1379025342_thumb.j

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Love that view for spectra, far batter than looking at basic lines! How do you differentiate between the image (x,y) and the wavelength shifted image (x,y)? So if you pick a point in the image, how do you know only that part of the spectra for that specific (x,y) is sampled? Reason I ask is that it appears, with almost circular stars overlaid with the spectra image of the stars.

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Love that view for spectra, far batter than looking at basic lines! How do you differentiate between the image (x,y) and the wavelength shifted image (x,y)? So if you pick a point in the image, how do you know only that part of the spectra for that specific (x,y) is sampled? Reason I ask is that it appears, with almost circular stars overlaid with the spectra image of the stars.

Nick - a transmission grating is partially transparent and records both the real [zero order] star and nebular images with their spectrum offset to one side - the separation defines their wavelength within the spectrum. Here I've ovelaid, as best I can, the spectrum of Altair with known lines mostly hydrogen Balmer lines for calibration. Ideally a slit is need for a difuse object. :police:
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Nick - a transmission grating is partially transparent and records both the real [zero order] star and nebular images with their spectrum offset to one side - the separation defines their wavelength within the spectrum. Here I've ovelaid, as best I can, the spectrum of Altair with known lines mostly hydrogen Balmer lines for calibration. Ideally a slit is need for a difuse object. :police:

Here is M57 taken with a slit spectrograph (by Christian Buil using an Alpy 600 spectrograph) which I have found has very good performance into the UV (good grating efficiency and sharp focus.) I think the main feature you are seeing in the UV  is perhaps the N[iII] forbidden line at 

http://www.astrosurf.com/buil/alpy600/data4/m57_3.png

from this page

http://www.astrosurf.com/buil/alpy600/performances.htm

Cheers

Robin

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Here is M57 taken with a slit spectrograph (by Christian Buil using an Alpy 600 spectrograph) which I have found has very good performance into the UV (good grating efficiency and sharp focus.) I think the main feature you are seeing in the UV  is perhaps the N[iII] forbidden line at 

http://www.astrosurf.com/buil/alpy600/data4/m57_3.png

from this page

http://www.astrosurf.com/buil/alpy600/performances.htm

Cheers Robin

Thanks Robin - N[iII] in violet it is for my third emission line ! 

I presume the Alpy600 is a grism arrangement?  Unusual for Christian he's named H-beta twice in his M57 spectrum ! :police:

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