Friday, October 22, 2021

Veil Nebula (a.k.a. Cygnus Loop)

The Veil Nebula also goes by the Cygnus Loop or the Filamentary Nebula. It refers to the visible structure of a supernova remnant located in Cygnus. The progenitor star was 20 times more massive than the Sun and exploded between 10,000 and 20,000 years ago. The nebula is quite large at 120 light-years in diameter (3 degrees) and approximately 2400 light-years across. An excellent article in the September 2021 Sky & Telescope by Howard Banich focuses on the Veil Nebula. Banich describes how the region’s interstellar dust was cleared prior to the explosion by the star and may not have been much to look at until the shock wave encountered farther out interstellar dust clouds a few thousand years ago.

The Veil Nebula is so large that it consists of several different NGC numbers describing different parts but I like the way Banich separated it into five parts.

1 - The First Veil - NGC 6960 located on the western side is also known as the Witch’s Broom.

2 - The Second Veil - Fleming’s Triangle (formerly Pickering’s Triangle) also known as Simeis 3-188 was discovered by Williamina Fleming in 1904 at the Harvard College Observatory but credit was given to her director E. C. Pickering until recently.

3 - The Third Veil - Southern Blowout Region is very faint and located at the bottom edge of Fleming’s Triangle.

4 - The Fourth Veil - NGC 6974, NGC 6979, and Assorted Filaments are located just east of Fleming’s Triangle and are also quite dim.

5 - The Fifth Veil - NGC 6992, NGC 6995, IC 1340, and the Southeastern Knot are all located on the eastern side. The portion is very bright and to me, resembles a claw.

Note: My image is rotated 90 degrees so west is top, south is right, east is bottom, and north is left (most images of the Cygnus Loop are rotated like this). 

I spent many nights trying to capture enough data between the clouds in order to bring out the Ha gas and extra dust but did not capture what I had hoped in that regard, however, I am happy with what I did get main nebula wise.  I captured 436 three minute subframes after and initial inspection but did another inspection with the PI Subframe Selector and trashed another 137 frames - I have to be very careful as the sky conditions here in southern CT are not that stable.  There are hints of the faint Ha in my image specially on the left side of my image but I believe longer exposure subframes such as 10 minutes are needed to bring that out (at least that is what Jeffrey Horne did with his recent image of this).



Veil Nebula (a.k.a. Cygnus Loop)
Dates: 9-10, 9-11, 9-13, 9-18, 9-19, 9-20, 9-24, 9-26, 9-27, 9-30, 10-1
Camera: ZWO ASI294MC-Pro
Telescope: Canon EF 200mm f/2.8L II USM Lens
Barlow: None
Focal Length: 200mm
f/4.0
Focal Reducer: none
Mount: Orion Atlas Pro
Filter Adaptor: ZWO EOS Filter Drawer
Filter: IDAS NBZ (2-inch)
Focuser: None
Autoguiding: ASI120 Mini attached to a ZWO Mini guidescope - None
Exposure: L 299 x 180
Gain: 139
Offset 0
Temp: 0 C
Processing: NINA, PixInsight, Photoshop, Gradient Exterminator, Topaz DeNoiseAI.

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Monday, October 11, 2021

C14 - An Unusual Look For The Double Cluster in Perseus

This lovely star cluster is actually two clusters but since they are so close to one another they are together known as the Double Cluster. Located in the Constellation of Perseus they go by other designations such as h and chi Persei, NGC 869 and NGC 884, and also Caldwell 14 (C14). They are approximately 7,500 light-years away and visible with the naked eye as hazy patches but stars can be resolved with binoculars. Like most open-clusters, C14 contains hot mostly hot young stars which are blue in color but there are some orange stars scattered throughout as shown on the image.

I imaged the Double Cluster in the past which is considered an easy target, but not with the red tinted hydrogen alpha (Ha) clouds in the background. There is a reason there are not many images with the Ha clouds because it is exceedingly faint - this was one of the hardest images I have done, almost a month of collecting data. Twenty three hours of total exposure (138 x 10min) using hyperstar (f/1.9) was used to capture these clouds and this is all I obtained. I tried to capture Ha data last year when I did this object with my AT115 at f/5.6 and there was not even a hint even after 17 hours so I bagged it until I had a faster system. If you do attempt to capture the nebulosity I would recommend a fast system (f/4 or less), at least 10 minute exposures, and dark skies. I have Bortle 5 skies at best here in southern Connecticut and crappy weather so not the best conditions for this.

Capturing itself went fine with the ASIAir and Atlas Pro but I did have difficulty with the star shapes as mentioned from my previous image post, however, after adjusting the corrector plate a second time the stars showed significant improvement. Still not great on the edges but much better.  In addition to trashing a lot of Ha data, my first set of RGB data was taken on one of those 'fake' clear nights so there were halos in the green channel stars plus it was before I readjusted the corrector plate.  Consequently I redid it another night with much better results.  I decided to use Chuck's 15 second approach for collecting f/2 data.  As a backup I collected a third set of RGB data using the Canon 200mm F2.8 II USM and ASI294MC Pro which came out OK but the stars were noticeably better with the hyperstar.

Processing was very difficult as well because although I did get some Ha, it was not good looking, certainly not what one would normally expect with over 20 hrs. with hyperstar. I had to do a lot of stretching and noise reduction to make it look presentable. I had dreams of getting some nebular detail but so far the only person to do that is Andreas (Equinox). Probably was the best idea going after this with my limited experience with the hyperstar but I am satisfied with it and am ready to move on to something not as challenging.



C14 - Double Cluster in Perseus
Dates: 9-10, 9-11, 9-18, 9-19, 9-24, 9-27, 9-30, 10-1, 10-6, 10-7
Camera: ZWO ASI1600MM-Pro 
Telescope: Celestron EdgeHD 800
Barlow: None
Focal Length: 2032mm (native)
F/10 (native) F/1.9 (Hyperstar)
Focal Reducer: Starizona Hyperstar
Mount: Orion Atlas Pro
Filter Adaptor: Starizona Filter Drawer
Filter: Baader Highspeed F/2 Ha CMOS, Optolong R, Optolong G, Optolong B 
Focuser: ZWO EAF
Autoguiding: ASI120 Mini attached to an Agena 50mm Helical Guidescope
Exposure: Ha 138 x 600s, R 99 x 15s, G 98 x 15s, B 99 x 15s
Gain: 139
Offset 20
Temp: 0 C
Processing: Asiair app, PixInsight, Photoshop, Topaz DeNoiseAI.

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Friday, October 8, 2021

NGC 281 - Pacman Nebula

NGC 281 is a gorgeous nebula and a very popular object with astrophotographers. I only imaged it once before many years ago and it was the first object where I used a hydrogen alpha filter (Astronomik EOS Ha-Clip). NGC 281 also goes by IC 11 or Sh2-184 and is a bright emission nebula in the constellation of Cassiopeia. It is 48 light-years across and contains numerous Bok globules visible in the image. Bok globules are small dark nebulae where stars are likely to form. It is nicknamed the Pacman Nebula due to its similar appearance to the popular 1980s video game that I spent many quarters on.

This was the third image I used with the EdgeHD 800/hyperstar and I am quite impressed with how quickly it obtains photons. Although not shown on this image because it is cropped, there seems to be some alignment problem with the corrector plate, collimation, or possibly tilt as the stars on the edge of the FOV are misshapen. Fortunately the stars for most of the FOV are pretty good. 

I also used the IDAS NBZ dual band filter and seems to work really well with the hyperstar and OSC cameras. The processing was not difficult except for adding the stars back but I did spend some time deciding how far to go with color enhancements. In the end I decided not to do much at all as the natural color seems to produce the greatest amount of detail plus I kind of like it.  I really like detail of outer regions of this nebula and also the dark canyon looking region in the lower area of the nebula.


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NGC 281 - Pacman Nebula
Dates: 9-4, 9-6, 9-7
Camera: ZWO ASI294MC-Pro
Telescope: Celestron EdgeHD 800
Barlow: None
Focal Length: 2032mm (native)
F/10 (native) F/1.9 (Hyperstar)
Focal Reducer: Starizona Hyperstar
Mount: Orion Atlas Pro
Filter Adaptor: Starizona Filter Drawer
Filter: Baader IDAS NBZ (2-inch)
Focuser: ZWO EAF
Autoguiding: ASI120 Mini attached to an Orion ST80
Exposure: NBZ 121 x 120
Gain: 120
Offset 0
Temp: 0 C
Processing: Asiair app, PixInsight, Photoshop, Topaz DeNoiseAI.

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