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The Double Stars Sirius and Izar with a Takahashi FC-100DZ

Astrophotography CMOS Double Star Imaging Refractor
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#1 james7ca

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Posted 05 February 2023 - 10:47 AM

Taken on two different nights using a Takahashi FC-100DZ fluorite doublet with a ZWO ASI183MM Pro camera. Both images used a Takahashi 1.04X Multi Flattener that increased the focal length to 815mm (f/8.15).

 

The seeing conditions were stable enough on the night that I imaged Sirius that most of the subs showed some evidence of Sirius B (the so-called "Pup") and it was consistently visible in the liveview frames from the camera. However, I captured 5000 frames for each color filter and then let AutoStakkert! select the "best" 256 for each of the final R-G-B masters. I'm fairly confident (based upon past work) that if I did a manual selection I could get a somewhat better looking image but Autostakkert! seems to have done a good enough job by itself.

 

The components of Izar are usually described as being yellow and greenish blue and this double is often described as being one of the prettiest in the sky. In fact, this star was called "Pulcherrima" (meaning "most beautiful") by its discoverer F. G. W. Struve, the famous Baltic German astronomer.

 

Both of these images were drizzled but for the shot of Sirius I reduced the final image down to that of the original capture scale. For Izar, because of its closer spacing, I left the scaling as output by the 3X drizzle.

 

Image capture using SharpCap Pro, processing with AutoStakkert!, PixInsight, and Photoshop 2023.

 

Thanks for looking and C&C welcomed.

Attached Thumbnails

  • Sirius and the Pup with FC-100DZ.jpg
  • Izar with FC-100DZ.jpg

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#2 wizbang396

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Posted 05 February 2023 - 11:54 AM

NICE SHOTS



#3 james7ca

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Posted 05 February 2023 - 12:20 PM

I blinked the first 100 frames from the green sequence (of 5000 frames) and selected nine that seemed to be the best to make a short animation. This had no processing other than a 90 degree rotation, a crop, and a histogram transformation done in PixInsight along with a one star registration in SiriL. Each frame was exposed for 30ms.

 

You may have to click on the image to get the animation to run (also best seen against a darker background).

Attached Thumbnails

  • Sirius_Animation.gif

Edited by james7ca, 05 February 2023 - 01:02 PM.

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#4 james7ca

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Posted 12 February 2023 - 05:30 AM

Here is an RGB animation showing Sirius A and B (the "Pup"). Same sequences as used in the original post but I allowed PIPP to run through all 5000 frames for each color channel and select what it considered to be the nine best frames. Then I took those and aligned them in SiriL followed by an RGB combination, Arcsinh and histogram stretch, and crop in PixInsight. Lastly, I used Photoshop to create a GIF animation that used the nine RBG frames.

 

Since the red, green, and blue frames were taken separately and at different times there is a lot of color scintillation but I thought that would make an interesting color image.

 

So, here is Sirius and the "Pup" in a full-color animation. You may have to click on the image to get the animation to run.

 

Attached Thumbnails

  • Sirius and the Pup.gif

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#5 james7ca

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Posted 01 February 2024 - 12:30 AM

My image of Sirius has just appeared in the American Astronomical Society's "This Month in Astronomical History: January 2024" as authored by CN member Michael Marotta.

  https://aas.org/post...ry-january-2024

There is, however, one very minor mistake in the caption supplied in the article, my image was taken on January 27, 2023, not September 14, 2018. By pure coincidence I captured this image almost exactly 161 years after the first sighting of Sirius B (discovered on January 31, 1862 with a new 18.5" refractor make by Alvan Clark & Sons).


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#6 rgsalinger

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Posted 01 February 2024 - 12:33 AM

Unbelievable. I really thought that you need tons of aperture to be able to separate them out. I have to try this sometime with one of my smaller scopes. 

 

Rgds-Ross



#7 Spaceman 56

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Posted 06 February 2024 - 08:57 AM

Unbelievable. I really thought that you need tons of aperture to be able to separate them out. I have to try this sometime with one of my smaller scopes. 

 

Rgds-Ross

James lovely Takahashi FC100DZ doublet seems to do very well Ross.  waytogo.gif

 

I noticed its fluorite too.  smile.gif




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