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NGC 4147 – Tiny Globular Cluster in Coma Berenices

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#1 jgraham

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Posted 06 April 2020 - 09:30 PM

Telescope: Meade SN10 @ f/4, Orion Atlas EQ-G
Camera: Full Spectrum Modified Nikon D5300, Baader Mk III MPCC
Filter: Orion Imaging Skyglow Filter
Guide scope: Williams Optics 50mm, Meade DSI Pro II, PHD
Exposure: 25x120sec, ISO 200, saved as RAW
Darks: Internal (Long Exposure Noise Reduction On)
Flats: 32x1/100sec, Tee shirt flats taken at dusk
Average Light Pollution: Red zone, Bortle 8, poor transparency, bright moonlight
Lensed Sky Quality Meter: 17.8 mag/arc-sec^2
Stacking: Mean with a 2-sigma clip.
White Balance: Nebulosity Automatic
Software: Backyard Nikon, Deep Sky Stacker, Nebulosity, Photoshop

 

NGC 4147 (4-2-2020)-1j.jpg

 

This was the 1st of 8 test images taken over 2 nights to evaluate the use of a Baader Mk III MPCC with my SN10 and my new D5300. I’m encouraged by these early results. The MPCC certainly helps the overall field, but I have a bit of a collimation issue that I need to straighten out. I’m thrilled with the performance of the camera particularly given the challenging imaging conditions. I’m still waiting for a night with good transparency to see what it can really do.

 

NGC 4147 is a tiny globular cluster near the border between Coma Berenices and Leo. The cluster appears small largely because of its great distance, an estimated 63,000 light years. That places it on the other side of the galaxy about as far from the galactic center as the sun. Note the little edge-on galaxy UGC 7170 (Mv 14.7) to the upper left of the cluster.


Edited by jgraham, 06 April 2020 - 09:32 PM.

  • Starman27, eros312, DuncanM and 6 others like this

#2 eyeoftexas

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Posted 06 April 2020 - 10:34 PM

Great image. I’ll have to look for it on my next clear night. Thanks for sharing.

#3 sunnyday

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Posted 06 April 2020 - 10:43 PM

very small but very well done
thank you.



#4 Tdesert63

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Posted 07 April 2020 - 12:11 AM

Putting both of those on my list , thank you ,nice pic👍

#5 F.Meiresonne

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Posted 07 April 2020 - 12:43 AM

Nice shot.

I wonder how you get the blackground no nicely dark considering your bortle 8 skies, and the moonlight.

 

Stars seems to show some drift of some kind...



#6 MHamburg

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Posted 07 April 2020 - 09:53 AM

Probably easier to turn off Long Exposure Noise Reduction in the camera and rely on taking dark frames for post-processing. You will save a lot of camera time.

 

Michael



#7 jgraham

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Posted 07 April 2020 - 12:48 PM

Yeah, I get that a lot. I run a research lab where we do a _lot_ of imaging and I spent the better part of a year investigating LENR. For me, I Love It! I delight in how clean and clear my subs are. It is also fun just loading lights and flats into DSS, easy peasy. For many years now it has carried me across warm summer nights with sensor temperatures well over 40C!

Use it. Love it. Always will. Whatever gives you the results that you are happy with is the right process for you. This is mine. :)

Enjoy!

#8 jgraham

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Posted 07 April 2020 - 01:50 PM

"I wonder how you get the blackground no nicely dark considering your bortle 8 skies, and the moonlight."

 

That's done in processing. The source calibrated image was a mushy gray. I pre-process in Nebulosity and finish the processing in Photoshop. I'd like to take a peek at some of the other tools floating around out there like GIMP.

"Stars seems to show some drift of some kind..."

 

Actually, my guiding was outstanding! What you are seeing is a combination of a bit of collimation and the MPCC. The collimation places the optical center of the imaging system off-center in this field. The MPCC gives the off-axis star images something of a "T" shape. Without the MPCC I get a more pronounced "V" shape. Fixing the collimation should move the region of sharpest focus to the center of the field and reduce the area of the off-axis image that is included in the field. I can reduce the appearance of these defects by leaving the field cropped wide, making the stars appear smaller. Once I get the collimation squared away I can make a better assessment as to the value of the MPCC. I suspect that I should move the MPCC a tad closer to the sensor, but at the moment I'm not sure how I could do that (Its at 55mm right now).

 

Lots of neat stuff!




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