Friday, September 22, 2017

centred on NGC 7023 (Halifax)

The Iris Nebula aka NGC 7023 seems a popular target of late. Steve captured it beautifully from the CAO. I viewed it briefly at the Merritt Reservoir in the 20" Dob and wanted to revisit. I ordered the BGO robot to aim to it. It's big! The nebula extends far away from the bright double star V380 Cep.

diffuse nebula NGC 7023 around double-star in luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

I wondered if 60 seconds would be too much. Certainly it blows out the central region (like in Orion's Trapezium).

V380 Cephei itself SkyTools shows as a double. I'll have to rework the image in FITS Liberator to see if I can draw out the pair. I doubt however this will work in the 60 second exposure. A and B are 6 arcseconds apart and multiple magnitudes different...

The dark regions surrounding nebula are thick. Few stars on the east can pierce the darkness. SkyTools notes the dark nebula LDN 1174 in the area.

There is a delicate cluster of a dozen or so stars to the west. This is Collinder 427.


SkyTools says that double V380 has a PA of 31° and a separation of 6.0" as of 1992.

The WDS says theta is 164° and rho is 2.3" as of 1996. Very different. And closer to the primary! In other words, the faint, mag 13 star, should be very tight to A and oriented to the south-south-east.

Even when I alter the stretching in the image I cannot see the companion.


Never noticed it before but there's a little wisp to the east-south-east. Detached from the main nebula. Learned via SkyTools 4 Imaging that's reflection nebula GN aka PID 1070.


Wikipedia link: Iris Nebula.

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