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And Another M51 - around 1k subs....


RolandKol

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Hi guys...

I am struggling to image in LRGB from my location due to the Light Pollution.... :(
Bortle 8-9... London....
So I decided to go for a short exposures (15 and 30sec) and gain 200 to reduce noise and influence of LP.

Ended up with around 2k subs (62.4GB of data) to Blink/Stack and etc...

I thought my PC gonna die... 

At the end, almost half of the images went to the Bin :( 

And sadly, I lost most of the Green Channel due to the clouds.... 

You can see the result below...  Heavily cropped due to the LP artifacts.

Not sure if I want to go through all of that again :) 

But if you have any suggestions how to optimise the exposure/gain settings, - Would be very grateful.

2k of images to blink is not a joke! :)

Data: L 435x15sec, R 337x30sec, G 69x30sec, B 298x30sec.

130PDS+SW CC +ASI1600MM + Baader LRGB

 

P.S.

How do people get that "brownish" background colour?
I tried to add a bit of Red without any acceptable results...

P.P.S.

Did something wrong to the stars... 
 

 

M51

 

 

Edited by RolandKol
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Wow, what an amount of data to process!  Shame you lost so many, but it sounds like you were being careful to only include what you thought were good subs 👍

It's come out really well, nice one for following through so diligently with so much data!

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Thanks guys for the compliments :)
But I am not yet happy, - especially with the stars... 
Will try to re-process next week....
Plus, few clear nights are in the forecast for this weekend... maybe I will end up with 4k of subs to play with :) (insane...)


Sadly my new Ha filter is not yet delivered :(

Edited by RolandKol
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This is RolandKol Dairy:

Linear Fit Clipping stacking started on Monday at 10:30...

2013 Light subs in total. (Lucky, as I have all master Calibration subs.)

Question N1: how long it going to take? - My guess: 5 hours probably... (PC is quite slow... Need a new one...)
Question N2: some subs were a bit cloudy... How many will get rejected by Pix script? - My guess: around 300 probably... (I need a DYI cloud sensor to save HDD space for sure.... will google about it again) 

Edited by RolandKol
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This is RolandKol Dairy:

11:46 PixInsight got frozen...

Decided to wait and see if it will get back to work....

12:00 PixInsight alive and back in action!  
it was close! :)

Current process, - "Integration of R channel". Soon I will have 1 file to compare with the previous one.

Untitled.thumb.png.53767a21e1201ba46a917e6e68f7bf02.png

Edited by RolandKol
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This is RolandKol Dairy:
15:27 The first one, R channel, not yet integrated....
(I was way too optimistic thinking 5 hours will be enough....)

15:34 R channel Finished... (goodness)

Edited by RolandKol
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This is RolandKol Dairy:

G channel was finished at 18:43

Next day on 28/04/2020: 

L  @04:51 

B @13:27

Totals

2010 subs split into:

L30s x 68 = 34min (hmmm should be around 1 hour... clouds... I hate clouds)

L15s x 570 = 142.5min

R30s x 461 = 230min

G30s x 368 = 184min

B30s x 543 = 271.5 min

All in all, - 862min or 14.37 hours

Stacking took 26 hours.... Lets see what it brings.....

Will not repeat that ever again for sure :)

(However, - maybe I should stack 20% best of the best, they probably have less high-level clouds??? and compare??? hmm... But how to choose them?  OK, - not now... someday... PC needs some rest...)

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Many moons ago (around 20), I lived in Dulwich, so can sympathise with you. You best bet is to concentrate on narrowband imaging of nebulae, of which there are many many targets. There are some bright objects like open star clusters and globular clusters that are worthwile imaging. Then secondly, if you can, take you kit out of London to a much darker sky and image broadband objects.

As long as you are enjoying your hobby, then it doesnt matter how much light pollution you have and I think you have done very well with the above image from near central London.

Adrian

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On 28/04/2020 at 19:34, CCD Imager said:

Many moons ago (around 20), I lived in Dulwich, so can sympathise with you. You best bet is to concentrate on narrowband imaging of nebulae, of which there are many many targets. There are some bright objects like open star clusters and globular clusters that are worthwile imaging. Then secondly, if you can, take you kit out of London to a much darker sky and image broadband objects.

As long as you are enjoying your hobby, then it doesnt matter how much light pollution you have and I think you have done very well with the above image from near central London.

Adrian

Thanks Adrian,

And you are correct, - I do mostly go NB way, but in the current period of the year, all possible Nebulas are heavily guarded by my back-garden trees ;)

Plus, At LAST, I had some clear and Moonless skies, - so it was worth a try ;) 

I am almost sure, - I will manage to improve this image by selecting better subs to stack, plus... I still suffer from the "two left hands" syndrome in the pixinsight area....

Edited by RolandKol
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Did my best...

Anyway still very noisy.....

I don't think I can do any better....

(all initial images used.... no time to sort best of the best for the next stack)...

M51_LRGB-A2

 

Edited by RolandKol
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Great narrative and image. Unfortunately you can't dodge LP photons, the stream in along with target photons, and after dbe/abe, you're left with their associated noise.

A diy cloud sensor isn't too difficult.

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6 hours ago, wimvb said:

Great narrative and image. Unfortunately you can't dodge LP photons, the stream in along with target photons, and after dbe/abe, you're left with their associated noise.

A diy cloud sensor isn't too difficult.

Thanks,

Anyway, l have a feeling, it can be done better ;)

Manual stacking is probably the way to go with a proper sub rejection formula.

I hoe to find a free evening for that.

As per cloud sensor, - unfortunately l am not bright enough to create one myself from scratch... And l cannot yet find any drafts online to reproduce... 

 

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8 hours ago, RolandKol said:

Thanks,

Anyway, l have a feeling, it can be done better ;)

Manual stacking is probably the way to go with a proper sub rejection formula.

I hoe to find a free evening for that.

As per cloud sensor, - unfortunately l am not bright enough to create one myself from scratch... And l cannot yet find any drafts online to reproduce... 

 

Just use the mlx ir thermometer, if you don't want a complete weather station. It's possible to swap the esp32 for an arduino and connect through usb in stead of wifi.

On 28/04/2020 at 14:58, RolandKol said:

But how to choose them?

"Blink" in PI, is your best friend here. Do 100 - 200 at a time if you think all at once may be too much. Don't even try subframe selector, unless you got time on your hands.

Edited by wimvb
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