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Interesting EAA evening

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#1 nicknacknock

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Posted 16 January 2021 - 03:08 AM

Since I am stuck home due to Covid-19 restrictions, I can only use my back yard for some EAA. I live in a city of about 300,000 people, smack right into the center of it. LED lights all around, building lights etc.

 

Given the circumstances, I am loath to take out my Borg 90FL or Celestron C5, since it is a) winter time and b) the skies are pretty bad, so I am currently playing around with a Borg 60ED and a GSO 0.6x reducer, for effective focal length of 210 mm and a fast f3.5 ratio.

 

I have two cameras for EAA, the ASI 533MCPro and the ASI 290MM. Last night, I had first light with the 290MM with the Baader 7nm Ha filter and then with the Baader Moon & Skyglow filter. Observing report to come up, but all images are unprocessed 20 exposures x 10 sec each at gain 300. I use the ASIAir Pro, SW AZ GTi in EQ mode and my iPad for fun :)

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#2 nicknacknock

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Posted 16 January 2021 - 03:12 AM

First, I played with the Ha filter, taking two shots - Pac Man and Cave Nebula. The 290MM at that focal length gives great image scale for small nebulae and I was quite surprised with the volume of data presented. 

 

The ASI290MM is really very sensitive and the images were there from the first frame. Up to frame 7, each additional frame gave more and more detail as the image was stacked. From frame 8, I would say it was mostly a reduction in noise.

 

These two did not have any calibration frames used, and the 290 IS quite noisy apparently, as evidenced especially in the top right corner.

 

I had to pop in for dinner, but came out again later and switched to the Baader Moon & SkyGlow for some galaxy work mostly, and took calibration frames.

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#3 nicknacknock

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Posted 16 January 2021 - 03:14 AM

After I took calibration frames, I did the Pac Man again to see how the dark subtraction worked. The Master Dark showed a lot of noise, but when applied, and despite less signal on the nebula as the filter used was broadband, the amp glow artifacts cleared out.

 

Lesson learned - always take darks and bias. Flats are not needed if you keep a clean sensor and image train, as the sensor size is such that vignetting was negligible. So, after this comparison, I decided to do some other than nebula work!

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#4 nicknacknock

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Posted 16 January 2021 - 03:18 AM

M33 is always a splendor to behold! I am sure that had I let this stack go for 10 minutes instead of three, there would have been a ton more signal.

 

Given the FOV of 1.53° x 0.87°, it was enough to fit this in. If I want more, I can always switch to my 533.

 

I then switched to a favorite when Andromeda is up. Nope, not Andromeda, but Mirach's ghost. It's always a tiny speck in my scopes, but it showed up nicely framed with Mirach.

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#5 nicknacknock

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Posted 16 January 2021 - 03:19 AM

I decided since I was in the neighborhood, to see Caroline's Rose. Again, great image scale, but this one is something better seen with a color camera, as there are stars of all colors!

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#6 nicknacknock

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Posted 16 January 2021 - 03:20 AM

Then the Pleiades - to check out what nebulosity I could pull out with this camera. Pleasantly surprised at the detail and reminiscent of traditional eyepiece views!

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#7 nicknacknock

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Posted 16 January 2021 - 03:21 AM

M1 was close by... Not much detail as I was a bit out of focus, but there it is, that remnant of a supernova!

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#8 nicknacknock

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Posted 16 January 2021 - 03:23 AM

Finally, a test to see what galaxies this baby could pull in. I also used Astrometry.net to annotate (no post-processing, just annotation). I noticed that Astrometry.net ignored some galaxies, but still, NGC 672 and friends was a welcome surprise and encouraged me to go a bit deeper...

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#9 nicknacknock

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Posted 16 January 2021 - 03:36 AM

I switched to Abell 262 and friends. Abell 262 is 12.7 magnitude and if you look carefully, there are many galaxies not marked by Astrometry.net which are even fainter!

 

I include a screenshot from SkySafari, my companion at any astronomical viewing, which helped me identify a ton more galaxies. I am still working at identifying galaxies, but for example, UGC 1336 is clearly visible at Mag 15.6!

 

To say that I am thrilled with the performance of this small rig that I can transport outside with one hand is the understatement of the year.

 

I am also excited because by using a monochrome camera, the views of galaxies look EXACTLY how I perceive them at the eyepiece! And I look forward to seeing what the ASI 290MM can do with the C5 at f4.5 (I have the Starizona Night Owl) from a dark site! The FOV of 0.51° x 0.29° is just perfect for galaxy work!

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#10 nicknacknock

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Posted 16 January 2021 - 03:38 AM

Comments / criticism / questions most welcome!



#11 Tyson M

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Posted 16 January 2021 - 04:15 AM

Well done.  I really like the idea of EAA with a small portable rig like that!  I might dabble some day in the city if I get too lazy to go out to my dark site.

 

I like these images.  They are done well.


Edited by Tyson M, 16 January 2021 - 04:16 AM.

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#12 nicknacknock

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Posted 16 January 2021 - 05:10 AM

Thanks Tyson!

 

Seems my luck has ran out as it’s raining cats and dogs now!!!



#13 alphatripleplus

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Posted 16 January 2021 - 08:58 AM

Nick, that is a great set of captures with your spanking new 290MM - welcome to the club! As you've noticed, with longer sub-exposure and a H-alpha filter, amp glow is noticeable but is easily calibrated out with darks. 

 

As I've mentioned in another topic, on really hot summer nights, even with good dark calibration, the background thermal noise in H-alpha shots is noticeable. The good news is that at reasonable temps, dark calibration gives nice results in H-alpha. Your shots demonstrate that very well.

 

As you've found this little camera is great for galaxies. I'm working through all the Arps with it at the moment and having a good time. Looking forward to seeing more.smile.gif


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#14 alphatripleplus

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Posted 16 January 2021 - 08:59 AM

Thanks Tyson!

 

Seems my luck has ran out as it’s raining cats and dogs now!!!

You can't win them all. lol.gif


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#15 alphatripleplus

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Posted 16 January 2021 - 09:02 AM

Comments / criticism / questions most welcome!

Forget to ask - how long were your sub-exposures on the H-alpha targets? (I usually go for at least 15sec subs when at f/3.5 to f/4.)



#16 nicknacknock

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Posted 16 January 2021 - 09:13 AM

Both Ha shots are 20 images x 10 secs each. ASIAir Pro only allows 10 sec / 30 sec and more intervals, but next update will allow setting the exposure time to whatever one feels like .



#17 nicknacknock

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Posted 16 January 2021 - 09:15 AM

Errol,

 

It’s a whole different ball game indeed with a mono camera with such sensitivity! The C5 with this camera should be a galaxy buster indeed!


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