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Astrophotography and Sketching >> Sketching

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Jef De Wit
Carpal Tunnel


Reged: 03/06/09

Loc: Hove, Belgium
I'm looking for my galaxie? (SN2011by)
      #4554495 - 05/01/11 03:16 AM Attachment (38 downloads)

Hi, does anybody have seen my galaxie? I lost it because there was to much lightpollution Thanks for looking.

Greetings, SN2011by

30/04/2011, 22.00 UT, 30 cm dobson @ x240, SQM 19.0 (NELM 4.8), FOV +/- 20'

Edited by Jef De Wit (05/01/11 03:31 AM)


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IVM
Pooh-Bah


Reged: 01/07/08

Loc: Western New York
Re: I'm looking for my galaxie? (SN2011by) new [Re: Jef De Wit]
      #4555392 - 05/01/11 04:00 PM

Well, you saw more than I did, Jef. I was one eyepiece field away from it when the cloud front covered the Big Dipper, and that was it for the weekend. Congrats on seeing the SN.

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JakeSaloranta
Pooh-Bah


Reged: 09/18/08

Loc: Finlandia
Re: I'm looking for my galaxie? (SN2011by) new [Re: IVM]
      #4555410 - 05/01/11 04:12 PM

Bad light pollution indeed!

Your NELM estimate seems a bit too low when compared to the SQM reading. Using the typical conversion form, the NELM should be at least 5.5. I was observing last night and got SQM reading 18.5 and NELM 5.2 and we don't even have darkness up here anymore

Good catch anyway! Did you make any estimates of the brightness?

/Jake


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cpl43uk
sage


Reged: 02/09/08

Loc: Bristol, UK
Re: I'm looking for my galaxie? (SN2011by) new [Re: JakeSaloranta]
      #4555693 - 05/01/11 07:07 PM

Congrats Jef- an excellent catch!

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frank5817
Postmaster
*****

Reged: 06/13/06

Loc: Illinois
Re: I'm looking for my galaxie? (SN2011by) new [Re: cpl43uk]
      #4556225 - 05/01/11 11:37 PM

Jef,

The supernova without the galaxy. That's kind of sad.
Good you got your target.
A little bit of light pollution creates that sinking feeling when examining or looking for galaxies.

Frank


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JayinUTModerator
I'm not Sleepy
*****

Reged: 09/19/08

Loc: Utah
Re: I'm looking for my galaxie? (SN2011by) new [Re: frank5817]
      #4556338 - 05/02/11 01:01 AM

Jef,

I was in my backyard last night and was confirmed why I'll drive 40-45 minutes to a good dark site to observe. The Messier galaxies were visible but many others weren't. I like both your approach and your sketch.


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Jef De Wit
Carpal Tunnel


Reged: 03/06/09

Loc: Hove, Belgium
Re: I'm looking for my galaxie? (SN2011by) new [Re: JayinUT]
      #4557334 - 05/02/11 02:51 PM

Thanks everyone. No big deal, putting some points on the paper. But when you know that little point of light is a SN, it makes your day!

@ Jake: I know there's a lot of debate about it. I used the formula on http://unihedron.com/projects/darksky/NELM2BCalc.html. A well known Dutch observer uses another (more optimistic) formula: =8,5-5*LOG10(1+10^(4,4-(SQM/5))). But for me it is all Chinese.
And I must admit, I never check/control the NELM myself I let the machine do the work!


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JakeSaloranta
Pooh-Bah


Reged: 09/18/08

Loc: Finlandia
Re: I'm looking for my galaxie? (SN2011by) new [Re: Jef De Wit]
      #4557357 - 05/02/11 03:07 PM

Quote:

@ Jake: I know there's a lot of debate about it. I used the formula on http://unihedron.com/projects/darksky/NELM2BCalc.html. A well known Dutch observer uses another (more optimistic) formula: =8,5-5*LOG10(1+10^(4,4-(SQM/5))). But for me it is all Chinese. And I must admit, I never check/control the NELM myself I let the machine do the work!




What I use is a lot more simple NELM = (SQM reading - 8) / 2 -> So (19.0 - 8) / 2 = NELM 5.5.

I'm going to give the supernova a shot myself tonight if the skies clear up - a lot.

/Jake


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