Author Topic: Pacman Nebula - NGC 281  (Read 192 times)

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JohnH

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Pacman Nebula - NGC 281
« on: Dec 30, 2020, 11:28:20 »


Sharpstar HNT 15028 (150mm aperture, 420 mm focal length) on iOptron CEM 25p
ASIair software.

1 December 2020: Green 5 * 20 secs; Blue 100 * 20 secs
Moon 97% (59 degrees sep.)

27 December 2020: H alpha: 20 * 300 secs; Red: 72 * 30 secs
Moon (95% at 37 degrees sep.)

Camera: ZWO ASI 1600 MM Pro at -15C

Processing:
Calibration and integration: APP
Gradient removal, deconvolution, combination and sharpening: PI

Location: Bromley (between Bromley South Station and Tesco) Bortle 7 - 8.

Disasters: Most of my green subframes had to be discarded because of dew formation (I back on to a playing field with the Ravensbourne culverted underneath and it tends to be extremely damp), I was able to use 5 of the 100!

Between session 1 and session 2 I recollimated the telescope which has given me a more evenly illuminated field but I accidentally moved the secondary mirror when fitting a dew band. As a result (I think this was the cause) I had an area of the image so out of focus that the Ha and Red stars were doughnuts. NGC 281 transited during the red frame run and I lost guiding after the meridian flip resulting in the loss of 28 subframes.

Hoping everybody enjoys a much better 2021,

John

Carole

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Re: Pacman Nebula - NGC 281
« Reply #1 on: Dec 30, 2020, 11:50:43 »
Excellent John and very nicely processed.

Well done.

Carole

The Thing

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Re: Pacman Nebula - NGC 281
« Reply #2 on: Dec 30, 2020, 13:34:47 »
Nice one John.

I've got a stream at the bottom of the garden and a water table at best 6feet under the surface so I sympathize with the dew/damp problems🙁. My solution was built my obsy floor 1m up! Works great and warmer on the feet.
We're all guinea pigs in the laboratory of life. Better a fluffy guinea pig than a lab rat!
¯\_(ツ)_/¯ (Gallic shrug :))

Hugh

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Re: Pacman Nebula - NGC 281
« Reply #3 on: Dec 31, 2020, 09:16:01 »
That's very nice John.

I'm not an astrophotographer but that's great colour and the nebula looks really sharp. 

A nice star field background.

Hugh

Roberto

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Re: Pacman Nebula - NGC 281
« Reply #4 on: Dec 31, 2020, 11:17:01 »
Excellent shot John!  8)  You have framed the nebula nicely in and blended the narrowband well into the star field.
Well done indeed!

Roberto

MarkS

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Re: Pacman Nebula - NGC 281
« Reply #5 on: Dec 31, 2020, 11:38:28 »
That's come out really well.  An excellent result for Bortle 7-8!

How are you finding the Sharpstar HNT 15028?  It must be very similar to my Tak Epsilon. By the way, I find it necessary to use both a dewshield at the front and a dew heating strap around the tube at the back near the primary.

Mark

JohnH

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Re: Pacman Nebula - NGC 281
« Reply #6 on: Jan 01, 2021, 11:15:17 »
Thank you everyone for the comments. I am still learning, experimenting (floundering around) all of the aspects of astrophotography.

I like the Sharpstar, I suspect it would like to be a Takahashi Epsilon when it grows up. I have made a dew shield from craft foam and it was when I fitted a dew heating band on the secondary that I upset collimation. Certainly, everything is extremely wet at the end of a session and I probably should add a band for the primary mirror.

I don't have an observatory (yet, I am working on it) and set up afresh on the lawn each time. Imaging time is precious and therefore I am reluctant to spend too much time experimenting with set up.

Wishing everybody a healthy New Year,

John