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Beginner object?

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Bikeman
Bikeman's picture
Beginner object?

There is a very bright dwarf nova in Cygnus now:

http://www.cbat.eps.harvard.edu/unconf/followups/J21040470+4631129.html

I wonder if this could be a nice beginner's object for low-res spectroscopy with modest equipment (Star Analyser and upwards).

Thoughts?

Anyone else trying this and willing to share experiences?

CS

HBE

Robin Leadbeater
Cygnus dwarf nova

Yes this should be an interesting object for the Star Analyser with strong  H alpha ~10A FWHM. The other Balmer/He emisison lines might be tougher to see at typical Star Analyser resolution.There are some high resolution echelle and an R ~1100 LISA spectrum on the ARAS forum here

http://www.spectro-aras.com/forum/viewtopic.php?f=39&t=2355

Bikeman
Bikeman's picture
Cygnus dwarf nova in SA 100

Thanks for the encouragement, I'd like to briefly report back:

With just an 8" scope, probably not the ideal placement of the Star Analyzer 100 (I just put it in the filter wheel) and way too few photons collected (clouds...), I still got something that looks like a consistent spectrum on July 15th. With my setup I get about  8 Angstrom per pixel, not great, but ok-ish I guess for purposes of just learning spectroscopy basics at the moment. Working with the Star Analyser and RSpec software is quite some fun for the buck, I highly recommend it, especially because of the excellent tutorial videos for Rspec!

CS HB

File upload: 
Robin Leadbeater
Cygnus dwarf nova with SA100

Glad you were able to get something (The SA100 is my baby. I developed it back in 2005 and there are now almost 6000 of them out there somewhere).  Yes that is pretty much as I expected. The Star Analyser spectrum resolution in a typical configuration is around 40 Angstrom. (The maximum theoretical resolution is the dispersion (A/pixel) * The size of the in focus star image (in pixels), though the actual resolution can be lower because of the simple converging beam configuration.)  The hot continuum and the H alpha emision line is clear here, but if you look at the higher resolution spectra on the ARAS forum, you will see why the other lines are difficult to see because they are made up of a narrow emission line embedded in a broad absorption which at the Star Analyser resolution combine to give an almost flat result. "Proper" classical novae (and supernovae) give  better results with the Star Analyser as the lines are broader because of the higher velocities involved.  With an good astro camera and a longer total exposure, it is possible to go much fainter with the Star Analyser even with 8 inch aperture, to around mag 14.  There are some examples on my website

Cheers

Robin

www.threehillsobservatory.co.uk

Bikeman
Bikeman's picture
Ah right, I remember!

Ah right, I remember! Impressive success for the product, and I think it's now even more useful than "back in those days" with those hi-res, fast-readout, low-noise CMOS monochrome astro-cameras that are really affordable now.

CS

HB

stellakafka
stellakafka's picture
nice!

I am not familiar with star analyzer spectra and I am impresed that you can see the H-alpha line. Very nice! Could you try to observe SS Cyg? It is at 12 mag now, a nice target for your setup, and I am curious to see what you can get ...

Thank you in advance!

Best wishes - clear skies,

Stella.

 

PS: please remember to upload yoru spectra in our database 

bsr15
Re: nice!

Stella and any other interested peoples,

It is not only possible to see the hydrogen alpha line with the SA100 but also the H-beta and H-gamma. I published a paper in the Vol 47 No. 1 of the JAAVSO using the SA100 to observe Miras. While that paper doesn't include the particular Mira in which I observed the three H emission lines, the paper should show how useful adding an SA100 to a photometric observing programme can be in obtaining useful data on them.

 

Bill Rea

Bikeman
Bikeman's picture
SS Cyg

Sure, wanted to try that anyway...only problem is weather :-) I'll post here when I get something but would not be surprised if someone else with an SA 100 will beat me to it.

Clear Skies

Heinz-Bernd

 

Bikeman
Bikeman's picture
Taking data now with SA100...we'll see

I'm not sure whether the resolution will be sufficient to do anything useful, but it sure is easy to spot, you cannot miss it in outburst :-). 

Inverted preview image enclosed to motivate SA 100 beginners. It's the spectrum thru the middle.I'm trying 5 second exposures, to be stacked, with an 8" Newtonian for starters.

https://www.aavso.org/sites/default/files/live.png

File upload: 
Robin Leadbeater
SS Cyg with Star Analyser (Simulation)

I have not seen any SS Cyg Star Analyser spectra but it would be an interesting target to follow through an outburst.  There is a nice series of spectra in the BAA spectroscopic database from 2016 by Joan Guarro Flo using a LISA at R~1100. I pulled three of them out of the database at high, low and intermediate brightness and filtered them to R~130 to simulate what might be seen using the Star Analyser. It looks like it should be possible to follow the change from emission in quiescence to absorption during outburst.

Cheers

Robin 

stellakafka
stellakafka's picture
Very nice!

Very nice spectral sequence on SS Cyg ... and we are in luck: SS Cyg is in outburst now! I would like to encourage anyone who can observe to take data - it would be great to cover the outburst spectroscopically while TESS is acquiring photometry!

Best wishes - clear skies,

Stella

Robin Leadbeater
Original spectra at R~1100
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