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I'm looking for my galaxie? (SN2011by)

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#1 Jef De Wit

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Posted 01 May 2011 - 02:16 AM

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

Greetings, SN2011by

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

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#2 IVM

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Posted 01 May 2011 - 03:00 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.

#3 JakeSaloranta

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Posted 01 May 2011 - 03:12 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

#4 cpl43uk

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Posted 01 May 2011 - 06:07 PM

Congrats Jef- an excellent catch!

#5 frank5817

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Posted 01 May 2011 - 10:37 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 :)

#6 JayinUT

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Posted 02 May 2011 - 12:01 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.

#7 Jef De Wit

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Posted 02 May 2011 - 01:51 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...ELM2BCalc.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 :whistle: I let the machine do the work!

#8 JakeSaloranta

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Posted 02 May 2011 - 02:07 PM

@ Jake: I know there's a lot of debate about it. I used the formula on http://unihedron.com...ELM2BCalc.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 :whistle: 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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