Live Stacks 10-19-2018

A place to share images that you have taken with SharpCap.
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Please share the equipment used and if possible camera settings to help others.
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BlackWikkett
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Joined: Sat Jun 23, 2018 8:48 pm

Live Stacks 10-19-2018

Post by BlackWikkett » Sat Oct 20, 2018 4:33 pm

First clear night since Robin fixed the dark frame problem and hot pixel detection with the strong amp glow in the ASI183MC Pro.
You can read about it here: viewtopic.php?f=38&t=1205

Equipment: GSO RC6, ZWO ASI183MC Pro Bin2 , IDAS D1 LPS, .75 Reducer F6.8

SharpCap: Used Smart histogram Brain to measure sky brightness, suggested 236 sec Exp, 110 gain, 0 offset. Made a master dark with 5 frames which were used for all images. All images were live stacked and final .png images cleaned up in Photoshop: remove skyglow, remove horizontal banding and some remaining noise.

Image
IC1396 Elephant Trunk Nebula 11 x 236s

Image
NGC6888 Crescent Nebula 26 x 236s

Image
IC405 Flaming Star Nebula 24 x 236s

Image
B33 Horse Head Nebula 9 x 236s
Big crop on left side of image to remove a reflection of secondary housing caused by Alnitak

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turfpit
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Re: Live Stacks 10-19-2018

Post by turfpit » Sat Oct 20, 2018 5:22 pm

Very good images and write-up. This is the first informative post I have read regarding the use of the Smart Histogram. I note with great interest the exposure time of 4m and integration time of 1h 40m.

Would it be possible for you to do the following: take a single bias frame i.e. a dark frame with exposure set to minimum for the camera, load the frame into FITS Liberator and post back the display of Processing and Image Headers tab. I want to see the effect of offset=0 on the bias frame. The background is here viewtopic.php?f=9&t=1209&start=20 on page 3. I think you will understand.

Dave

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admin
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Re: Live Stacks 10-19-2018

Post by admin » Sat Oct 20, 2018 8:46 pm

Hi,

glad that everything is working now - great images too:)

4 minute exposure seem quite long - maybe you have a nice dark site as that tends to lead to longer exposure suggestions.

cheers,

Robin

BlackWikkett
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Re: Live Stacks 10-19-2018

Post by BlackWikkett » Sat Oct 20, 2018 9:21 pm

The IDAS D1 Filter may be at fault for longer exposures. I completed the original sensor analysis for the ASI183MC Pro on a refactor and did not use the LPS filter. Should I do the sensor analysis again on the RC6 with LPS filter? If I understand the sensor analysis procedure this shouldn't mater. The FWHM measurement in live stack was 5.5 to 6 the evening these images were taken.

turfpit I'll make the bias frame next time i'm at the scope. I image from my brother's place, my place has a canopy of oak and pine trees that doesn't give me enough sky.

The camera is still in place on the scope from this imaging night. I have clouds forecast for the next week so I may capture some more dark frames along with a set of flats. Noticed that i have finally started accumulating dust after 4 months of use. I'll stack the raw frames in DSS and give it pass through Star Tools or Photoshop and post results. We'll be able to compare Live stack with my limited stacking and processing ability.

Thanks Team, Wikkett

BlackWikkett
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Joined: Sat Jun 23, 2018 8:48 pm

Re: Live Stacks 10-19-2018

Post by BlackWikkett » Sun Oct 21, 2018 2:48 am

Image
Bin2 offset 0

Image
Bin2 offset 35

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turfpit
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Re: Live Stacks 10-19-2018

Post by turfpit » Sun Oct 21, 2018 8:44 am

Thanks for doing this.

From my understanding, for your telescope/camera and exposure/gain setting, an offset of 35 would be optimal. The min/max Image Statistics look healthier.

I would be grateful if you could supply the following using the exposure and gain above:
  • a FITS histogram display for a single light at offset=0
  • a FITS histogram display for a single light at offset=35
  • image and process one of the above objects with offset=35, same exposure and gain and post back
At the end of the day, there might be no visual difference between images captured using the 2 settings.

I am trying to come to terms with my own sky - east of the meridian is dark, west of the meridian gives me the sky glow of Manchester. As noted by Robin, darker skies can lead to recommendations for longer exposures.

Dave

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