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Who are you and what are you doing with the Ring?

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#1 deonb

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Posted 11 August 2020 - 07:35 AM

M57 below - I had a visitor tonight on the right that's only showing up on all my Hydrogen Alpha light frames (5 of them over 25 minutes). It wasn't present on any of the LRGB frames before that.

 

Any idea what it is? There are no streetlights nor any other light-source near there. The moon was behind me. I have IR lights all over my property, but nothing pointing in that direction. The neighbors have no IR lights up.

 

And there's of course no magnitude 0 stars or planets anywhere near M57. 

 

I tried swinging over the ring to the left of the frame, and the light source stays in the same position - it doesn't move into frame... It's also not showing up on Hydrogen Alpha dark frames.

 

Any idea?

 

Ring.jpg


Edited by deonb, 11 August 2020 - 07:39 AM.


#2 D_talley

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Posted 11 August 2020 - 07:39 AM

Looks like a classic case of amp glow but you did not tell us what camera you were using or the temp and exposure length, so it is only a guess until we get more info.



#3 astrodom

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Posted 11 August 2020 - 07:40 AM

Hi, that is what is called amp glow.  Its from the CMOS sensor you are using for your shots.  If you take dark frames at the same conditions and subtract them from your photos, this amp glow will be eliminated or at least significantly reduced.  I see this on my ASI183MC pro shots, but it completely disappears with dark frames.


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#4 Huangdi

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Posted 11 August 2020 - 07:40 AM

Looks like a classic case of amp glow but you did not tell us what camera you were using or the temp and exposure length, so it is only a guess until we get more info.


Wild guess: zwo asi 294

#5 deonb

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Posted 11 August 2020 - 07:41 AM

Ahh ok. It's a ASI183GT. Exposure time is 5 minutes. Camera temp was -15c. Ambient is 56f.

 

Why would it only do that under H-Alpha?


Edited by deonb, 11 August 2020 - 07:42 AM.


#6 SilverLitz

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Posted 11 August 2020 - 07:42 AM

It looks like normal 183 amp glow, and it will calibrate out, assume the exact same temp, gain, and exposure of dark frames.


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#7 SilverLitz

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Posted 11 August 2020 - 07:43 AM

This is very exposure time dependent.  Ha exposures would be significantly longer than RGB.


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#8 deonb

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Posted 11 August 2020 - 07:50 AM

Ahh, ok. Thanks! Heard the term, but never saw it in action.

 

I have a ASI1600 and picked up a ASI183GT mainly for planetary, but was testing last night see if it can compete against the ASI1600 for deep sky as well.

 

However, looks like the ASI1600 has a distinct advantage there.



#9 Huangdi

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Posted 11 August 2020 - 08:04 AM

Ahh, ok. Thanks! Heard the term, but never saw it in action.

 

I have a ASI1600 and picked up a ASI183GT mainly for planetary, but was testing last night see if it can compete against the ASI1600 for deep sky as well.

 

However, looks like the ASI1600 has a distinct advantage there.

As has been said, Amp glow is easily calibrated out and the ASI 183 definitely has some potential. Especially with wide field scopes(or very, very long focal lengths for planetary), I think the small pixels can work some real magic.




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