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Finally a night out with the new Hyperstar


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Got the HS for my C8 almost a month ago, but weather and work have kept me from really exploring its potential until now.  I tried it out on both galaxy and nebula targets, the latter with an H-alpha filter (I got the filter-drawer option on the HS, me being a committed mono camera kind of guy and all).

First up was a small spiral gx, NGC6946 in Cygnus.  Nicknamed the Fireworks Galaxy for the plurality of supernovae that have happened there in recent decades:

NGC6946_2016.8.27_23.49.07.png

Two minutes worth of 10 sec subs.  Lots of stars in Cygnus...

Next a quick look at globular cluster M71, shortened to 5 sec exposures to try and keep the stars under control:

M71_2016.8.27_23.58.20.png

Then on to the Deer Lick group (NGC7331).  My general feeling is that the short FL (400mm) is not ideal for a lot of these smaller galaxies.  It seems attractive to try and frame them, or get lots of galaxies in one shot, but the surrounding stars are so bright relative to GX that they tend to wash things out, at least near the plane of the Milky Way.

NGC7331_2016.8.28_00.12.08.png

So how about a big galaxy instead?

M31_2016.8.28_00.20.40.png

That's but 5 minutes total of exposures.  But I need a bigger sensor, even at 400mm.  I'm thinking about one of the new ZWO micro-4/3 cooled CMOS jobs.  Mono, natch.

Next post, we'll shift to the H-alpha filter.

 

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Adding the H-alpha filter requires a substantial change in focus.  Fortunately the Bahatinov mask makes this quick and precise.

First up, and two-part tour of the Western part of the Veil, NGC6995:

NGC6995.2_2016.8.28_00.49.35.png

NGC6995.1_2016.8.28_00.39.16.png

Up to 60 sec subs now, with the narrowband filter.

Here is a section of IC1848, the Soul nebula:

IC1848_2016.8.28_01.12.33.png

Again, bigger sensor required here...

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Finally, back to unfiltered starlight, for another try at a galaxy cluster, around NGC507 in Pegasus:

NGC507_2016.8.28_01.29.25.png

With 60 sec subs you can see a lot of galaxies, but the stars are so big as to lessen the impact.  Finally, left a stack of three minute subs on M33 running while I wrote the preceding.  This is 6x60 plus 9x180.  Yes I am guiding for the 60 and 180 sec subs.

M33.2_2016.8.28_02.06.50.png

Overall an entertaining three hours of EAA with the new toy.  Definitely adds a lot of potential to the basic C8, especially for narrowband viewing of emission nebulae.  But I need a bigger sensor :-)

  

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If you look at the last but one image, there is a faint line all the way through from top to bottom, is this a satellite passing, or some other artefact.

its also visible on other images but just in the bottom half...!

fantastic images though.. :)

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These are really fine captures Alex, the mono seems unbeatable for bringing out the fine detail, and these objects look really special in black and white somehow.  Although NGC7331 is quite small there is still plenty of detail visible. When you say you need a larger sensor (I am assuming your captures are with the Ultrastar) is this because it is not wide enough for the large emission nebulae? Do you feel that 400mm FL lends itself to a wide enough range of objects to be useful in the long run?

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5 hours ago, Bonnylad said:

Lovely images, but what's causing the exceptionally fine streaks in the bottom third of most of the pics? All in the same place.

Cheers

Bad column of pixels in the my Ultrastar.  A defect it did not have when I bought it but has developed over time.  If I was using dark subtraction it would be less visible.

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50 minutes ago, RobertI said:

These are really fine captures Alex, the mono seems unbeatable for bringing out the fine detail, and these objects look really special in black and white somehow.  Although NGC7331 is quite small there is still plenty of detail visible. When you say you need a larger sensor (I am assuming your captures are with the Ultrastar) is this because it is not wide enough for the large emission nebulae? Do you feel that 400mm FL lends itself to a wide enough range of objects to be useful in the long run?

Thanks Rob.  At least for the "summer classics" in Cygnus and adjacent regions of the Milky Way, the FOV with the Ultrastar just isn't going to frame to whole subject (it is about 1 by 1.3 degrees).  This would include the Veil, the N.A. Nebula, M31, The Heart and Soul Nebulae, California Nebula, etc.  Even come winter, that FOV will be crowding the Rosette and will clip the outer bits of M42.  Conversely, a micro-4/3 sensor like in the ZWO ASI1600 would afford a 2 by 2.6 degree field (with smaller pixels as well), and would handily capture all of those objects, save the entirety of the Veil, in a single frame.

With a bigger chip, 400mm is a great FL - that's why all the serious AP guys love their 70mm APO refractors.  I still like the Cassegrain-focus 1260mm too, for small galaxies, and would actually love to have something in-between around 800mm as well.

 

Alex

 

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That's nice. Isn't that tempting? :D
As for the bigger sensor - I can't recall exactly but I am pretty sure that Hyperstar imaging circle is quite small, at least for 6". Not sure about 8" but if true then going for bigger chip You might experience some issues with equal illumination of the frame.

PS.
Just found more info
Hyperstar 6" - up to 16mm diagonal sensor
Hyperstar 8" (11" and 14" aswell) - up to 27mm diagonal sensor

Edited by MrOD
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Alex, very nice images. I have been toying with the idea of a C8 HS for a while. But have been debating the right camera.

The 825 sensor produces great images but due to the under-sampling smaller objects are challenging.

I have also been investigating the ASI1600MM. Should be a very good fit wrt sampling. The 3.75 micron pixels provide an almost perfect 1.84"/pixel sampling which means you can zoom in on the acquired image and view smaller objects at almost the same detail as a Ultrastar at ~750mm FL. Plus the field of view covers a huge 2.4 deg FoV.

But the one downside is that the EAA software is not as good as SLL. Should do well for imaging though.

 

 

 

 

 

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3 hours ago, Astrojedi said:

 

But the one downside is that the EAA software is not as good as SLL. Should do well for imaging though.

 

 

 

 

 

Yes, that is indeed a problem.  From my browsing of the CN forums when the ASI1600 launched, any software to run the camera, even for AP on a Windows machine, was a pretty dicey proposition.  Seems like the rush to get new hardware out tends to leave software development behind.  I've been thinking about testing out AstroLive USB.  They guy who writes it seems to have a deal with ZWO such that it is free for folks who purchase ZWO cameras.  It also has a 30 day free trial offer, and will also work with SX cameras, and importantly for me has a native Mac implementation.  My major concern is that I have to find a 30 day period when I'm pretty sure I can get out 2-3 times to test it, which is not easy to do.

 

 

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I have found that software to be very promising but the stacking is not robust enough yet. Needs a few more development iterations.

This is not a ding on the SW. Given the variety of cameras supported it takes a lot of testing and refinement to make it robust. Just the nature of the beast.

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Very nice images Alex!

Over the weekend I was wishing I had a C8 with Hyperstar. 400mm is the ideal focal length for many objects, including NGC6992-6995. You may want to explore, if a rotator like this https://www.optcorp.com/teleskop-service-t2-quick-changer-360-rotator-tst2rot.html could be added to your optical train. It's only 5mm of thickness and has T-threads on both sides. The entire NGC6995 fits into the field of the 825 chip at 400mm, if rotated to be positioned diagonally. (The long thumbbolts of the rotator could be replaced by shorter ones to avoid additional diffraction spikes. Other than that, the entire rotator would probably hide in the shadow of the filter slider.)

Clear Skies!   --Dom

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