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Observing >> Variable Star Observing and Radio Astronomy

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nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Nova Cep 2013
      #5679987 - 02/14/13 06:12 PM Attachment (44 downloads)

Learned of Nova Cep 2013 [discovered 10 days ago] at London Astrofest last Friday and first clear night since for 30s shot below going down to ~m17. The nova is fading and est ~m11.3[R?] from my pic against Sloan DSS. Any other obs of this object Some nice chains of stars nearby

Edited by nytecam (02/15/13 03:12 AM)


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Nova Cep 2013 new [Re: nytecam]
      #5680365 - 02/14/13 10:49 PM

Visually the nova is a lot fainter than your estimate. I got it at 12.6 on Feb 11.05UT and the latest CCD V observation gave 13.0 . Both determinations are based on the AAVSO sequences for the star.

BrooksObs

Edited by BrooksObs (02/14/13 10:50 PM)


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nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Re: Nova Cep 2013 new [Re: BrooksObs]
      #5680623 - 02/15/13 03:09 AM

Quote:

Visually the nova is a lot fainter than your estimate. I got it at 12.6 on Feb 11.05UT and the latest CCD V observation gave 13.0 . Both determinations are based on the AAVSO sequences for the star.BrooksObs


Do I detect a hint of disapproval? I must admit I was more interested in recording the object to show on various fora than providing a V mag which mine is not as unfiltered and perhaps closer to R mag - amended above.

I did consider taking a spectrum but it was too much hassle last night. I'd already seen a 100 l/mm [probably Staranalyser] lo-res spectrum on the internet that shows the radiation was dominantly in near-IR from strong H-alpha peak and completely invisible to you eyes - hence the discrepancy perhaps. I won't blinker my camera to conform to 'visual'


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starquake
sage


Reged: 02/02/08

Loc: Nádasdladány
Re: Nova Cep 2013 new [Re: nytecam]
      #5680628 - 02/15/13 03:18 AM

I've observed this nova on 7 Feb, here's my observation posted in the Sketching forum:

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5668279/page...

My estimate of 12.7 might be totally wrong as I've measures it only to other stars in the FoV, and the closest star in brightness might be a variable. Anyhow, I've seen some interesting photographical captures of this nova where it has a somewhat redish colour. Guess that would explain the high difference between visual and photographical brightness estimates.


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Rich (RLTYS)Moderator
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Reged: 12/18/04

Loc: New York (Long Island)
Re: Nova Cep 2013 new [Re: nytecam]
      #5680726 - 02/15/13 06:21 AM Attachment (21 downloads)

Here's an image of N Cep 2013 I took on 2/11 (red star toward center). In green light I estimated it's mag as 12.5.

Rich (RLTYS)


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Nova Cep 2013 new [Re: nytecam]
      #5680855 - 02/15/13 08:39 AM

Quote:

Quote:

Visually the nova is a lot fainter than your estimate. I got it at 12.6 on Feb 11.05UT and the latest CCD V observation gave 13.0 . Both determinations are based on the AAVSO sequences for the star.BrooksObs


Do I detect a hint of disapproval? I must admit I was more interested in recording the object to show on various fora than providing a V mag which mine is not as unfiltered and perhaps closer to R mag - amended above.

I did consider taking a spectrum but it was too much hassle last night. I'd already seen a 100 l/mm [probably Staranalyser] lo-res spectrum on the internet that shows the radiation was dominantly in near-IR from strong H-alpha peak and completely invisible to you eyes - hence the discrepancy perhaps. I won't blinker my camera to conform to 'visual'




Hardly critical of such an observation, but the situation does point out the need for qualifying the nature of any posted magnitudes from CCD camera images (i.e. image mags are "unfiltered with an R bias").

As it stood, any less experienced visual observer looking for the nova with a modest scope after seeing the image would almost surely miss it at an actual "v" magnitude of 13.0 (as opposed to the mid 11's). As you've subsequently noted, novae often show a very strong H-alpha emission making them appear strongly red shortly after maximum, although looking white in your image, and thus appearing far brighter in unfilted CCD images than they do visually.

BrooksObs

Edited by BrooksObs (02/15/13 08:45 AM)


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nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Re: Nova Cep 2013 new [Re: BrooksObs]
      #5681163 - 02/15/13 11:02 AM Attachment (17 downloads)

Quote:

...novae often show a very strong H-alpha emission making them appear strongly red shortly after maximum, although looking white in your image, and thus appearing far brighter in unfilted CCD images than they do visually.
BrooksObs


Thanks - for your possible interest below are a couple of colour spectra of V4743 Sgr = Nova Sgr 2002 No.3 from my webpage - diffraction grating spectra are essentially linear with half the spectra [right of red H-alpha] recorded colourless as this invisible radiation can't have colour! Thus a dominantly near-IR object can appear white in an unfiltered colour image.

Of course spectra of Miras etc are almost entirely in near-IR even at apparent visual minimum a strong spectrum is record so the star only dramatically fades visually - spectra are great fun



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ZielkeNightsky
Pooh-Bah
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Reged: 10/01/06

Loc: Denmark
Re: Nova Cep 2013 spectrum new [Re: nytecam]
      #5684889 - 02/17/13 10:18 AM

Hi

Here's my spectrum of Nova Cep from feb. 10th.

I've tried to identify some of the important lines.





The OI line at 8446 forced me to learn about "Bowen resonance fluorescence mechanism"
Now I have a headache, rather complicated stuff.

I still need an explanation for the 7116 line ?

Edited by ZielkeNightsky (02/17/13 10:26 AM)


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