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Pacman Nebula - NGC 281

Started by JohnH, Dec 30, 2020, 11:28:20

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JohnH



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
Sir Isaac Newton should have said, "If I have seen further than others it is by inventing my own telescope".

Carole

Excellent John and very nicely processed.

Well done.

Carole

The Thing

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.

Hugh

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

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

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

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
Sir Isaac Newton should have said, "If I have seen further than others it is by inventing my own telescope".