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The core of M106

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#1 meegja

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Posted 22 October 2021 - 05:51 AM

Since the clouds are here to stay it seems frown.gif  , I started to re-process captures I made over the last few months.
Also experimenting more and for the first time I did stack without any calibration files. In the case of M106 (from April this year) that worked great because it's in the center of the FOV.

 

The original capture with all the data is at https://www.cloudyni...lti-narrowband/

 

There was way less noise because of the not using of calibration files, so I could stretch more. Downside, less contrast.

And I did it "quick and dirty": stacked all the broad- and narrowband data in 1 go with Deep Sky Stacker.

One of the 2 secondary arms was conserved well too. It's the faint vertical lane in the middle left. The second arm is too faint for me to capture.

These jets are hot gasses that are spewed out by the black hole in the center of M106 and only realy showing in narrowband.

Going to see if I can capture the 2nd arm also in the future with the Optolong L-eXtreme filter (this capture is with the L-eNhance). Doubt if it will work cause of my Bortle 6/7 but I'll see :)

 

 

M106-Core-sm.jpg


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#2 Jon_Doh

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Posted 22 October 2021 - 09:04 AM

Vert nice!


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#3 meegja

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Posted 22 October 2021 - 03:54 PM

Vert nice!

Thank you! :)



#4 freestar8n

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Posted 22 October 2021 - 06:03 PM

If I understand this - it is unguided with a roughly $2000 mount and up to 9 minute exposures, with an OSC camera, and a mixture of narrowband and wide filters.  I think that's a nice summary of how things have changed in a few years, and how versatile an osc camera can be.  I guess that mount is exceptional in its price range. 

 

Nice work.

 

Frank


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#5 meegja

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Posted 22 October 2021 - 06:25 PM

If I understand this - it is unguided with a roughly $2000 mount and up to 9 minute exposures, with an OSC camera, and a mixture of narrowband and wide filters.  I think that's a nice summary of how things have changed in a few years, and how versatile an osc camera can be.  I guess that mount is exceptional in its price range. 

 

Nice work.

 

Frank

Thanks. And yes, that a good summary. Doing 10 minutes now but that only really works rather high in the sky. Which is fine cause being in the city, my skies start at 70+ degrees.

And yes, that mount is just insane. Mind you, I use the user-defined sidereal tracking, the defaults will not track that long. It's a rather active way of doing it but I like that and it gives great results :)



#6 Jared

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Posted 23 October 2021 - 08:24 AM

How do you determine the appropriate tracking rate since sidereal presumably leads to some minor elongation over longer exposures? And how do you do your polar alignment such that you can go 9min unguided even at the correct tracking rate? And, the ultimate question, why not just guide given the above challenges? Also, you mentioned that you are getting less noise when you don’t calibrate. That seems strange to me. Sure, darks can theoretically increase noise, but generally the removal of fixed pattern noise more than offsets the minute addition of the random noise embedded in a master dark. And the removal of dust from flats is almost always helpful, even if you don’t need the vignetting correction…

No arguing with the results, of course. Nice job!
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#7 meegja

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Posted 23 October 2021 - 11:00 AM

How do you determine the appropriate tracking rate since sidereal presumably leads to some minor elongation over longer exposures? And how do you do your polar alignment such that you can go 9min unguided even at the correct tracking rate? And, the ultimate question, why not just guide given the above challenges? Also, you mentioned that you are getting less noise when you don’t calibrate. That seems strange to me. Sure, darks can theoretically increase noise, but generally the removal of fixed pattern noise more than offsets the minute addition of the random noise embedded in a master dark. And the removal of dust from flats is almost always helpful, even if you don’t need the vignetting correction…

No arguing with the results, of course. Nice job!

  1. Because of my location, I am always high in the skies. So for starters I know roughly where to start, lets say 0.9984 of sidereal tracking. With doing some test captures I then can fine tune that. After that, during capturing, I keep an eye on 1 star. In SharpCap I use the bulls-eye overlay and zoom into a star with 400x. When I do 600 seconds exposures, I each time have to wait 600 seconds to see if there is movement. Roughly 2 to 3 times per hour I have to adjust the sidereal tracking then in steps of 0.0002. So it's a kind of manual guiding but very slowly :)
  2. For polar alignment I use the Ioptron Ipolar camera and its software. And if needed, I do an azimuth adjustment on the fly if I see the star mentioned above, move. This is just by gut feeling.
  3. And I don't guide because I like it this way :) I do like to take things (and myself) to their limit. Plus, the real long exposures are not that often. For example 120 or 300 sec exposures are perfectly done with tracking. It also saves weight: the Ioptron CEM25EC is a small, light mount and I am now at around 55% of it's max payload.
  4. And yes, the darks. Like I said, this was a first time for me that I didn't use calibration files and because of that, I discovered that there is something really wrong with my darks: they add really a lot of noise, they make my captures less sharp. It's not the amount of darks, I take 30 darks by default, even with 600 sec exposures. I suspect that it has something to do with the power. I am home based and I use power from the grid but from a non-grounded point. Generally the houses here only have grounded points in the kitchens and bathrooms but all other rooms are not grounded.
    And it is the darks: when I use only (dark)flats, then the noise is not there. The way I take darks is also as normal: leave every settings the same as with the subs, cover everything and capture darks.
    So still investigating that :)
  5. Thanks! :D



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