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fireworks galaxy under severe light pollution

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#1 joelin

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Posted 20 August 2019 - 12:30 AM

So I did the area around the fireworks galaxy yesterday, mag 18.5 skies...

 

15 frames of 30 seconds each

80mm f/6 SV80ST refractor, ASI1600MC-cool at 0C

 

so yeah 7.5 minutes under really bright skies...does it look ok or can i do better under those constraints?

 

fireworks-out.jpg

 

Here is a closeup of the galaxy

IjZSbL6.jpg


Edited by joelin, 20 August 2019 - 12:31 AM.

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#2 jerahian

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Posted 20 August 2019 - 01:22 AM

I know what Saratoga is like...I used to live in SF :)  Here is what I would do if I were you:

 

1) Cool you camera to -15 (reduces your read noise)

2) Up your exposure to 60s

3) Set your gain to 75, offset 10

4) Take about 150 exposures

5) Dither every 3 frames (2 would be better if you have the time)

 

...7.5 mins is not nearly enough.

 

Also, at some point, you might want to look into what is going on with your stars; they seem streaky along the 10-4 o'clock line.  What mount are you using?

 

GL&CS,

Ara


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#3 happylimpet

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Posted 20 August 2019 - 03:39 AM

Looks good! Just need a load more subs!!!!  Its a great field.

 

 

1) Cool you camera to -15 (reduces your read noise)

Just to be pedantic (but why not) cooling reduces dark current and hence shot noise from that dark current; it doesnt reduce read noise. You'll need different darks if cooling. I expect you know that!


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#4 jerahian

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Posted 20 August 2019 - 08:03 AM

Just to be pedantic (but why not) cooling reduces dark current and hence shot noise from that dark current; it doesnt reduce read noise. You'll need different darks if cooling. I expect you know that!

You’re absolutely right.  Thank you for the correction!  waytogo.gif


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#5 bobharmony

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Posted 20 August 2019 - 08:07 AM

Agreed - this is a good start, and yes, you will do better with more subs and more time.  Great recommendations thus far on cooling and dithering.  Nice framing, BTW!

 

Bob



#6 joelin

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Posted 20 August 2019 - 12:32 PM

actually i did dither...im sure the noise would be much worse otherwise

 

as for the messed up stars....i blame that on the field flattener




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