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Elephant’s Trunk - CDK12 - f/5.3 - QHY268m

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#1 Rouzbeh

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Posted 25 September 2021 - 09:51 PM

Taken with the CDK12.5 and the PW 0.66 reducer from our backyard over 3 nights through semi-cloudy skies.

 

The AP1100GTO performed admirably, tracking the target unguided  through the clouds and allowing data to be captured throughout the night. The subs(exposures) blocked by clouds were then deleted.

 

The QHY268m  with its very low Read Noise and very high quantum efficiency is a perfect candidate for the task.

 

Link: https://astrob.in/o831ao/D/

 

Details:
Imaging telescopes or lenses: Planewave CDK 12.5
Imaging cameras: QHYCCD 268M
Mounts: Astro-Physics AP1100 GTO CP4

Guiding: Unguided APCC
Focal reducers: Planewave Instruments 0.66x Reducer
Software: NINA - Nighttime Imaging ‘N’ Astronomy  ·  PixInsight 1.8.6 Ripley Pixinsight 1.8
Filters: Chroma 3nm Sii  ·  Chroma 3nm OIII  ·  Chroma 3nm H⍺
Dates:Sept. 15, 2021

Frames:
Chroma 3nm H⍺: 52x300" (4h 20')
Chroma 3nm OIII: 45x300" (3h 45')
Chroma 3nm Sii: 40x300" (3h 20')

Integration: 11h 25'

Pixel scale SHO: 1.020 arcsec/pixel
Field radius: 0.479 degrees

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  • Ic 1396-brighter2 CN.jpg

Edited by Rouzbeh, 25 September 2021 - 11:06 PM.

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#2 Rouzbeh

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Posted 25 September 2021 - 09:58 PM

Hi-res Ha Pixel scale: 0.574 arcsec/pixel

 

 

Link: https://astrob.in/hz5u8e/0/

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Edited by Rouzbeh, 25 September 2021 - 10:36 PM.

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#3 Rouzbeh

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Posted 25 September 2021 - 10:01 PM

I had a bunch of renders, this one with a more saturation, but I did like the "pop" it had.

 

Overall quite a dime object, specially in Oiii and Sii.

 

The fast f/ratio helped a lot.


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#4 Peter in Reno

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Posted 25 September 2021 - 10:21 PM

The QHY268m  with its very low sensitivity and very high quantum efficiency is a perfect candidate for the task.

I thought QHY268m has pretty good or high sensitivity sensor with QE to as high as 90% at around 525nm and drops down to about 64% at 700nm which is pretty darn good.

 

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#5 Rouzbeh

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Posted 25 September 2021 - 10:41 PM

Its right up there at 76%

 

 

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#6 Rouzbeh

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Posted 25 September 2021 - 10:42 PM

Also

 

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#7 Rouzbeh

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Posted 25 September 2021 - 10:48 PM

The Kaf3200 seems be(was) higher but that was a 17mm diagonal chip with 9e- of read noise.

 

For years people imaged with the Panasonic (1600) at some 46% at Ha.

 

I find this a nice step up.

 

 

 

 

 

 

 

 

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#8 Peter in Reno

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Posted 25 September 2021 - 10:54 PM

Your sensor uses Sony IMX-571 which is the same as your last graph which is exactly what I said. Your 1st two graphs don't use the sensor in your QHY268M which I'm confused why you posted the 1st two graphs. Your sensor QE has maximum of 90%.

 

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#9 Rouzbeh

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Posted 25 September 2021 - 11:07 PM

I thought QHY268m has pretty good or high sensitivity sensor with QE to as high as 90% at around 525nm and drops down to about 64% at 700nm which is pretty darn good.

 

Peter

Typo, I meant low read noise :)

 

 

 

"Your sensor uses Sony IMX-571 which is the same as your last graph which is exactly what I said. Your 1st two graphs don't use the sensor in your QHY268M which I'm confused why you posted the 1st two graphs. Your sensor QE has maximum of 90%.

 

Peter."

 

Yes the IMX571, the other graphs are for comparison. The 571 is actually very high compared to many popular sensors.



#10 Peter in Reno

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Posted 25 September 2021 - 11:42 PM

OK, yes your camera has low read noise depending on the gain used.

 

Peter



#11 rockstarbill

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Posted 26 September 2021 - 12:58 AM

The 3200 was also popular with folks because it was a NABG sensor with high QE, which for some scientific endeavors was very beneficial. RN for them was of zero concern. 



#12 Rouzbeh

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Posted 26 September 2021 - 03:19 PM

OK, yes your camera has low read noise depending on the gain used.

 

Peter

I'm running it on gain56, read noise 1.55, FWC 30k or so.

 

Initall LRGB images I used the same settings  but it will be better to go for gain0 - RN3.5 - FWC 62k. 



#13 Rouzbeh

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Posted 26 September 2021 - 03:21 PM

The 3200 was also popular with folks because it was a NABG sensor with high QE, which for some scientific endeavors was very beneficial. RN for them was of zero concern. 

Don't know much about that sensor, just saw the hi QE it had.

 

I didn't like the 183 sensor as it was far too noise with very small pixels. Ok for a short FL widefield stuff otherwise compared to these new chips its way inferior. 



#14 Yilia Yu

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Posted 26 September 2021 - 10:14 PM

Very beautiful Elephant’s Trunk!


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