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What to do on a moonlit night?

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#1 GoFish

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Posted 11 September 2019 - 03:07 PM

After several weeks' hiatus, I set up an EAA rig Monday night.  Working against me, as always, are my Bortle 6/7 skies, poor transparency, and a driveway plagued by streetlights and porchlights.  Throw in a bright moon and you have a recipe for staying inside.

 

Instead, I set up what I think might be my "goldilocks" configuration going forward for EAA:

  • OTA:  6" f/5 (Omni XLT 150)
  • Camera:  ASI294MC Pro, cooled to -5C for this session (~50% TEC load)
  • Mount and target acquisition:  Atlas, EQMOD, CdC, and AstroTortilla
  • Capture:  SharpCap Pro, with real time darks, flats applied (gain = 350 for all images)
  • Image scale:  1.27 "/px

This OTA seems ideal to me. It has the right image scale, tolerable coma across most of the sensor, light weight, and it cost me $100 as a CL find.  At f/5 it is fast enough, but also collimates easily. What's to not like?

 

So Monday night I decided to target some objects that might show well given the poor sky conditions.  For me, these are normally visual targets, but I thought it might be fun to see them on the screen.  I needed a trial run with the OTA/camera combo anyway.

 

All images were "saved with adjustments" from SC, then downsampled using PS from png to jpg for posting here.  No post-processing.

 

Caroline's Rose (NGC 7789 in Cassiopeia) is elusive from my driveway, just visible in a 10" Dob.  So that was my first target:  13 frames at 15s = 195s.  (Anyone else notice the dog's face?)

 carolines-rose-red-Stack_13frames_195s.jpg

 

The Coathanger ( Brocchi's Cluster, Cr399 in Sagitta) is a nice visual target in my 102ED refractor, but looked nice in the camera as well: 15 frames at 8s = 180s.

coathanger-red-Stack_15frames_120s.jpg

 

To be continued...


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#2 GoFish

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Posted 11 September 2019 - 03:15 PM

Continuing...

 

M45 (the Pleiades cluster in Taurus) has always been among my favorites for visual observation.  I have seen some great AP's as well.  It shows well no matter the sky conditions.  There is some skyglow in the lower left corner due to heavy light pollution near my horizon (sigh).  22 frames at 15s = 330s.

m45-red-Stack_22frames_330s.jpg

 

M39 (open cluster in Cygnus) has never been too inspiring visually, so I thought I would have another look.  It is about 1,000 LY away and the stars in the cluster are pretty bright.  15 frames at 8s = 180s.

m39-red-Stack_15frames_120s.jpg

 

To be continued...


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#3 GoFish

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Posted 11 September 2019 - 03:24 PM

Continuing...

 

So, I couldn't resist observing a couple of the more common EAA targets.  I chose not to closely crop the globular because I wanted a view that put the object in context with the surrounding starfields.

 

M15 (globular cluster in Pegasus).  33,600 LY away, 12 billion years old.  21 frames at 8s = 168s.

m15-red-Stack_21frames_168s.jpg

 

M31 (the Andromeda Galaxy).  Who can resist a quick look at M31?  Not me.  23 frames at 15 seconds = 345s.

m31-red-Stack_23frames_345s.jpg

 

The end.

 


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#4 GaryShaw

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Posted 11 September 2019 - 03:57 PM

Very nice goFish

 

What scope and camera  were used on the images you posted?

 

Never mind... I see now it was the 6" F5


Edited by GaryShaw, 11 September 2019 - 03:58 PM.


#5 mikenoname

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Posted 11 September 2019 - 06:47 PM

Nice!



#6 Ptarmigan

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Posted 11 September 2019 - 09:46 PM

I have gotten used to deal with doing EAA under the Full Moon. I have managed to get many objects including Abell 1656.



#7 Rickster

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Posted 11 September 2019 - 11:00 PM

I like it.  The image scale would be great for introducing kids to this kind of thing.  It gives a perspective that they would not get on the internet (our main competition, doncha know).  Nice clean images too, especially considering the LP.



#8 GoFish

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Posted 11 September 2019 - 11:15 PM

Thanks, all, for the comments.

 

Someday I may become more serious and spend more time doing traditional AP. But EAA gives instant feedback on what is going well, and what you are hosing up!



#9 39.1N84.5W

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Posted 13 September 2019 - 05:25 PM

There are loads of HII nebulae you can observe under a bright moon. For color I use a 294mc and idas NB1 filter. For mono I use an ultrastar mono and 7nm filter.
Tomorrow, full moon, I'm doing outreach with a 71mm zenithstar, 294mc, NB1, focal reducer, and the entire Veil nebula in one frame. Look for Goofi's Narrowband Target list, organized by season, elsewhere on CN.
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#10 GoFish

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Posted 13 September 2019 - 06:14 PM

I have an IDAS LPS-D1 filter.  Is that a substitute for the NB1, or will the LPS-D1 pass too many undesirable wavelengths?



#11 DSO_Viewer

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Posted 13 September 2019 - 07:17 PM

I see some on NSN using an Ha filter and their mono cameras obtaining excellent results.

 

Steve



#12 39.1N84.5W

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Posted 13 September 2019 - 07:24 PM

Try the D1 on ngc7000 and see what happens. Ideally you want narrowband filters which are very restrictive.
If you don't know the late honorable Maurice Gavin (cn user Nytecam) was using a mono filter and Lodestar cameras about 15 years ago in the middle of London, UK. Look back into his CN content and you will see some amazing results.

I miss that guy.
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#13 insistent

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Posted 14 September 2019 - 09:41 AM

Ay same prob here, best night mostly show up during full moon :(
I have a celestron c8 with meade 3.3 reducer, asi224, ir/uv block filter, DGM Npb filter wich only seem to work well with visual?

Those 350$ cad filters looks great but outta mt budget.

#14 39.1N84.5W

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Posted 14 September 2019 - 10:51 AM

Save your money and find a used 7nm or 12nm hii filter. It will really open up your observing schedule!

#15 GoFish

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Posted 14 September 2019 - 11:07 AM

Ok, Hii it is then. I’ve got an ASI178MM that could probably be put to good use with my Hyperstar C8. 


Edited by GoFish, 14 September 2019 - 11:11 AM.

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#16 GoFish

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Posted 14 September 2019 - 12:08 PM

Q:  is there a reason to prefer a 7nm or 12nm Hii filter over the IDAS NB1 for EAA?  In my present state of filter ignorance, I am imagining that seeing the Ha, Hb, and OIII lines together might be interesting with a OSC camera (versus just the Ha line in either mono or color). 

 

Edit: added graphs of NB1 and Celestron UHC/LPR filters. Do they perform significantly differently?

 

https://www.sciencec...ters/nb1-lg.htm

 

https://s3.amazonaws..._lpr_filter.gif

 


Edited by GoFish, 14 September 2019 - 12:59 PM.


#17 39.1N84.5W

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Posted 14 September 2019 - 01:15 PM

The short story: 5nm, 7nm, 12nm filters are usually used in mono cameras. NB1 are usually used in color cameras.
Of course nothing is going to explode if you swap these out... but ideally I'd use the NB1 for hii nebulae in a color cam.
Many of the hii targets are big wide field type objects. So a small refractor or camera lens is good for this. I've even used a 50mm finderscope with my 1.25" ultrastar. It really isn't about aperture anymore!
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#18 GoFish

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Posted 14 September 2019 - 03:49 PM

The short story: 5nm, 7nm, 12nm filters are usually used in mono cameras. NB1 are usually used in color cameras.
Of course nothing is going to explode if you swap these out... but ideally I'd use the NB1 for hii nebulae in a color cam.
Many of the hii targets are big wide field type objects. So a small refractor or camera lens is good for this. I've even used a 50mm finderscope with my 1.25" ultrastar. It really isn't about aperture anymore!

Thanks for your patience in walking me through this.

 

The Celestron UHC/LPR filter specs are somewhat similar to the NB1, but the Celestron’s passband at Hb/OIII is around 2X as wide as NB1. At Ha the Celestron looks to be around 3X as wide. I can imagine the performance of the NB1 may be a lot better based on its tighter passbands. 

 

The biggest difference between them, though, is that I have the Celestron version already sitting on my shelf lol.gif  I guess I really should give that a try with the 294 before buying either a new Hii or NB1 filter. 



#19 39.1N84.5W

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Posted 14 September 2019 - 04:47 PM

Oh yes. Just try it out and see! I've done so much observing in my city observatory with narrowband EAA. It's the business.

#20 GoFish

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Posted 16 September 2019 - 11:12 AM

Oh yes. Just try it out and see! I've done so much observing in my city observatory with narrowband EAA. It's the business.

Spent some time last night using the Celestron LPR/UHC filter, as suggested.  Interesting results.  Mostly good, some not so much.

 

Skies:  full Moon (nearly), Bortle 6/7, good transparency

OTA:  AT8IN (8" f/4 imaging Newtonian); no coma corrector

Camera:  ASI294MC Pro @ -5C, gain = 350

Filter:  Celestron 2" LPR/UHC

Mount:  Atlas, EQMOD, no guiding

Capture: SharpCap Pro, darks and flats calibration in real time

 

All images posted here were "saved with adjustments", downsampled, and converted to JPG using PS.  No post-processing.  North is generally up in all images.  Scale before downsampling was 1.18 "/px.

 

An annoying gradient in the green channel is evident in all of the frames.  The gradient seems to be consistent in each image so I don't think it is from the sky.  It seems to be internal to the 294 camera.  Of course, in the highly stretched images it is much more evident.

 

Suggestions on cause and remedy are most welcome!

 

Western veil nebula (Witches Broom, NGC6960).  6 frames @ 60s = 6 minutes.

veil-west-1000-Stack_6frames_360s.jpg

 

Pelican nebula (a portion, IC5070 and IC5076).  6 frames @ 60s = 6 minutes.

pelican-1000-Stack_4frames_360s.jpg



#21 GoFish

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Posted 16 September 2019 - 11:16 AM

Continuing...

 

North American Nebula (a portion of NGC7000).  7 frames @ 60s = 7 minutes.

ngc7000-1000-Stack_7frames_420s.jpg

 

Pacman Nebula (NGC281 in Cass).  7 frames @ 60s = 7 minutes.

pacman-1000-Stack_7frames_420s.jpg

 



#22 39.1N84.5W

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Posted 16 September 2019 - 11:27 AM

Before I stack I analyze the digital rgb readout in the top menu>histogram window. (I only do 30s subs with my narrowband filter and 8s subs with my general lp filter, btw).
In this pop up histogram window you will see r, g, b digital readouts while your camera is running with your desired filter in place. Ideally you want the r and b channels to have the same digital readout as the g channel. In the right column of sharpcap you can adjust the white r channel and the white b channel. You can't adjust the g channel. So move these sliders bit by bit until all rgb channels have the same number. It doesn't have to be spot on exact.
Close the histogram window.
Now click live stacking.
After about 5 minutes of stacking I'll do final color adjustments with the live stacking histogram rgb sliders.
I learned all of this from CN user Saguaro. Her knowledge of sharpcap is far beyond mine... but this technique has worked fine for me.
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#23 GoFish

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Posted 16 September 2019 - 12:50 PM

Before I stack I analyze the digital rgb readout in the top menu>histogram window. (I only do 30s subs with my narrowband filter and 8s subs with my general lp filter, btw).
In this pop up histogram window you will see r, g, b digital readouts while your camera is running with your desired filter in place. Ideally you want the r and b channels to have the same digital readout as the g channel. In the right column of sharpcap you can adjust the white r channel and the white b channel. You can't adjust the g channel. So move these sliders bit by bit until all rgb channels have the same number. It doesn't have to be spot on exact.
Close the histogram window.
Now click live stacking.
After about 5 minutes of stacking I'll do final color adjustments with the live stacking histogram rgb sliders.
I learned all of this from CN user Saguaro. Her knowledge of sharpcap is far beyond mine... but this technique has worked fine for me.

I hope you don’t send me a bill for all of this consulting lol.gif

 

I understand exactly what you describe, and when I first started I would do something similar. I liked my unstacked images to have a good color balance, and stacked images required less correction.

 

But then ... I read somewhere to just set both the red and blue levels to 50 and leave ‘em alone, along with brightness set at 0. IIRC, this was so that you could create a dark library and always have consistency between darks and lights. (I have been shooting flats at 50/50, too). 

 

A 50/50 R/B balance gives a strong green cast to my images, even after dark/flat calibration. It never felt right, but it seemed to make sense to be consistent with settings for the darks library. 

 

What color balance settings do you use for darks?  Flats?

 

Also, probably not related, but what color space do you use?



#24 iam1ru12

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Posted 16 September 2019 - 01:08 PM

...

Caroline's Rose (NGC 7789 in Cassiopeia) is elusive from my driveway, just visible in a 10" Dob.  So that was my first target:  13 frames at 15s = 195s.  (Anyone else notice the dog's face?)

 attachicon.gif carolines-rose-red-Stack_13frames_195s.jpg

...

Jim,

yes, I see the dogs face, like he/she is looking straight at you - the floppy ears give it away.

 

-Mike



#25 39.1N84.5W

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Posted 16 September 2019 - 01:13 PM

I should note... before I create darks or flats I do my previously described "rgb digital readout step" first. That way my library is all lined up.
I use 0 brightness.
I use RAW16.
Color space I don't remember off hand... I will look next time.

I've also read about the "50/50 don't touch it" idea. After trying both techniques I've found Saguaro's workflow to work better for me. This isn't rocket science... I feel that trying different things and seeing the results is the best way to move forward.

I'm happy to share my experience. Trust me... I've asked (and still ask) loads of questions to folks smarter than me!

Edited by 39.1N84.5W, 16 September 2019 - 01:14 PM.

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