Sh2-101 the 'Tulip' nebula

[RobertM]

Sh2-101 also know as the Tulip Nebula is an HII emission region located about 6000 ly away in the constellation of Cygnus. In the lower right you may be able to faintly make out the bow shock dome from the Cygnus X1 black hole as it ploughs through this region.

This is my first outing with the Optolong L-Extreme filter (7nm Ha+OIII) which I processed as an RGB image.  I'll post another once I've worked out how to get PI to correctly extract the Ha and OIII layers.

Image capture details:

Subs: 47 * 600s dithered
Camera: ASI2600MC Pro Colour camera (cooled to 1C)
Filter: Optolong L-Extreme
Scope: Skywatcher Esprit 150 with dedicated flattener (f/7)
Calibration: bias, darks and sky flats
Processing: Pixinsight (processed as RGB not Ha/OIII)
Location: Garden ROR observatory SE London
Fully automated capture over four nights from 20th-23rd July 2020 courtesy of Voyager Automation software.



Link to 4k version: https://live.staticflickr.com/65535/50181079562_e3f8b32a9f_4k.jpg
Link to 6k version: https://live.staticflickr.com/65535/50181079562_479993be3d_6k.jpg

Robert

[Carole]

Very nice Robert, funnily enough an image I am planning with my smaller camera including the nebulosity behind it, though pretty sure mine will be narrowband.

You got a great image out of just RGB - bit puzzled at the temp being cooled to only only 1C though, although it has been a struggle during this hot spell to get cameras down to the set point, but I have been managing -10 or more.

Nice to see you imaging again.

Carole

[RobertM]

Thank you Carole.

I set it to 1C purposely - the dark current is very low.  At 1C the dark current is 50 times lower than an Atik 383L at -10C; I dont consider a dark signal of 1.26e (600s * 0.0021e/s) for a 600s exposure statistically significant.  Another reason for 1C is that it is above freezing so no frost (not that there is a frost issue).

Robert

[Roberto]

Excellent image Robert.  That narrowband filter is definitely working with the RGB camera.

Roberto

[MarkS]

That's an excellent result Robert.

The filter seems to be working really well.

Mark

[Fay]

Well done Robert, back in the frame again!!

Fay

[RobertM]

Thank you all.  I have many more subs collected now but the OIII regions are faint so the Hubble palette colours are eluding me at present.

[NoelC]

Stars are really sharp right to the edge.  Very nice.
Is there much Oiii in there?

Noel

[RobertM]

Thanks Noel,

The Esprit is a very nice scope and enjoyable to use but quite slow at f/7.

In hindsight the Tulip nebula is probably not the best of targests to try a hubble palette on with a OSC.  I have managed to get some OIII to show but only on an extreme stretch which looks horrible.  I'll try Hubble on another target first then revisit this afterwards.

Robert