ROAST :: 06 2026

Update, June 13/14
Another go last night, and here’s a mega stack of the two sessions:

Some more detail, and the surrounding nebulosity has been brought out a bit more. I tried raising the gain to 70 and reducing exposure time to 15 seconds, mainly to see what diference it made; the increased noise is probably due to the extra gain, so I won’t be trying that again. There were 36 failed shots this time, some satellites but mostly because it was very windy resulting in smeared stars.

Details:
Target: C34, Witch’s Broom nebula
Time:
A: 2026-06-11 00:17..01:23
B: 2026-06-14 00:11..01:39
Equipment: Dwarf Mini, Duo-Band filter
Integration:
A: 49mins (98×30secs, +7 failures), gain 60
B: 66mins (264×15 secs, +36 failures), gain 70
Total: 1hr 55mins
Conditions: Clear but windy, Bortle 7
Processing: PhotoDesk equalisation, gamma (blue and rgb), balance

Original post
June 10/11, another few hours of clear skies. After doing the wide mosaic of the Veil Nebulae recently, we were intrigued by the colours in the Witch’s Broom part. They weren’t very prominent so here’s another go, this time concentrating on the Broom, Caldwell 34.

The Dwarf Mini has two main filters available: Astro, which enhances infrared and is mainly used for galaxies and solar system objects, and Duo-Band, which is designed to emphasise the Hα and O III parts of the spectrum — that is, ionised hydrogen at 656.3nm and oxygen at 500.7nm. These emissions are prominent in nebulae and are shown as reddish and bluish colours respectively. This filter also reduces glow from moonlight and general light pollution (street lighting and so forth), so is pretty useful.

I didn’t have time for many exposures, so this is intended as the first tranche of a mega-stack. It’s a fairly faint object and needs hundreds of shots — perhaps 3 or 4 hours of integration — to really bring it out. I’m also not too happy with the processing, but it’s a start.

Details:
Target: C34, Witch’s Broom nebula
Time: 2026-06-11 00:17..01:23
Equipment: Dwarf Mini, Duo-Band filter
Integration: 49mins (98×30secs, +7 failures), gain 60
Conditions: Clear, Bortle 7
Processing: PhotoDesk equalisation, gamma (blue and rgb), balance

And so to bed…

June 8/9, and at last a couple of hours of clear sky. We’re approaching the solstice now, and observing is limited to between 11pm and 3am or so.

I started with a perfect EQ alignment just before 11pm, and aimed the scope at the star Sadr, the central star in Cygnus, when it finally moved out from behind a tree. On the right is the view to the east at about 11:00 pm; Sadr is the star under the “g” of “Cygnus”, and it’s in the centre of a large area of nebulosity known as the Gamma Cygni Nebula, the Sadr Region, or IC 1318.

Below is the result of the session. Sadr itself is the fairly bright (magnitude 2.2) star in the centre of the image.

The small group of stars at top centre is the Inchworm Cluster, NGC 6910.

The long dark lane at lower left is the “body” of the Butterfly Nebula (the Cygnus one — there are a number of similarly named features elsewhere in the sky). The large “wings” are at centre left and (off-screen mostly) bottom left. This area is so large it really needs a mosaic!

It’s interesting to compare my effort with this image, taken with much more expensive equipment.

Details:
Target: Sadr, HD 194093
Time: 2026-06-08 22:50..00:18
Equipment: Dwarf Mini, Duo-Band filter
Integration: 1hr 15mins (150×30secs, 1 failure), gain 60
Conditions: Clear, Bortle 7
Processing: PhotoDesk equalisation, gamma

Just after midnight the Elephant’s Trunk nebula also became visible (that damned tree!); it’s halfway between Cygnus and Cepheus but is technically in Cepheus. I aimed the scope slightly off to get a bit more of the surrounding nebulosity in the picture.

The “Trunk”, or IC 1396A, or Sh2-131 — there are a hell of a lot of these sky catalogues, aren’t there? — is the curly bit at lower right. It’s embedded in the large nebula known as IC 1396, and is being illuminated by the brightest star at centre bottom, HD 206267.

Details:
Target: Elephant’s Trunk Nebula, IC 1396A
Time: 2026-06-09 00:23..01:32
Equipment: Dwarf Mini, Duo-Band filter
Integration: 1hr (120×30secs, 5 failures), gain 60
Conditions: Clear, Bortle 7
Processing: PhotoDesk equalisation, gamma

This is a bit noisy, and would benefit from more exposures. I’ll try it again (skies permitting) and stack them all together.

And so to bed…