Image centred at (nova.astrometry.net plate-solve):
RA: 21h 34m 17.296s
Dec: +57° 30′ 37.211″
Up is 2.19° E of N

IC1396 is a very large region of HII emission located in the Milky Way within Cepheus, which spans over 5 degrees of sky. Within IC1396, to the western side, is the Elephant’s Trunk Nebula, known as IC1396A, and VdB 142, which is a reflection nebula at the end of the “trunk”.

IC1396A itself is a dense globule of gas and dust that appears to be lined by bright pink emission from atomic hydrogen. This emission is due to excitation by the giant triple star system HD 206267 (off field to the left). The globule appears to be an area of star formation, and contains two young stars in the head of the globule that have created a cavity by the action of their own stellar winds. 

These F-type stars provide the illumination for the rare yellow reflection nebula seen in the head of the globule, as well as the radiation causing the pink hydrogen emission within the cavity. The combined action of HD 206267 and the two young stars has resulted in areas of high compression in the nebula, triggering the formation of protostars.

Data was captured on the night of the 21st September 2017 from West Oxfordshire. Image details are as follows:

L:R:G:B = 130:45:35:35
(L:10m subs, RGB: 5m subs, 2x bin)

Taken using a WO FLT110 @ f5.6 with SBIG ST2000XM, on Losmandy Titan.

Processing was performed in Pixinsight – control over the star sizes is tricky here, and I may try and improve on this later. There’s also a (relatively) small amount of data used here – this is certainly a subject that would benefit from adding more exposure (which may also help with star control), as well as H-Alpha data to increase signal and contrast in the emission nebula areas.

I had opportunity on the 19th/20th September 2017 to add another 3h40m of exposure to my previous image of the Propeller Nebula (Simeis 57/ DWB111/119) – see “A Crescent and A Propeller” for the previous version. Here is the reprocessed version of the data, taken through an H Alpha filter, which is centered at RA: 20h 16m 08s, DEC: +43° 40′ 42″ (plate-solve from nova.astrometry.net).

The extra time on this subject has brought out some of the fainter background nebulosity and enhanced dark nebulae in the field. The image at left is an annotated image (using the Image Solver and Annotate Image scripts in Pixinsight). As shown, the Propeller itself is catalogued as DWB111 (south) and DWB 119 (north), with DWB118 representing the surrounding nebulosity, with DWB 108 further to the south below the southern “prop”. There are a few catalogued dark nebulae in the field – Dobashi 2501; Dobashi 2511/TGU H469 P16 which sits between DWB118 and DWB 107 (off field to lower left); and TGU H469 P18 to the west of the main nebula. 

For more information about this region, and pretty much the only bit of published research I can find on it(!), see the paper “Israel, F.P. , Kloppenburg, M., Dewdney, P.E., Bally, J. (2003), The peculiar nebula Simeis 57, Astronomy and Astrophysics, 398, 1063 – 1071“.

All data was taken from West Oxfordshire on 9th/10th and 19th/20th September. William Optics FLT110 @f5.6 on a Losmandy Titan, SBIG ST2000XM CCD and an Astrodon 5nm HA filter.

Two nights of H-Alpha deep-sky imaging recently and in both cases this had the advantage of allowing imaging despite a bright moon being present.

This was also the first time I got to use a new adaptor which connects the threaded drawtube of the FLT110 to the corrector/reducer. This appears to have reduced the amount of vignetting present and potentially dealt with a source of internal reflections, but more importantly it has eliminated a potential source of flexture by removing the 2″ nosepiece from the imaging train.   

The first image is of the Crescent Nebula (NGC6888) in Cygnus (image centered at RA 20h 12m 08s, Dec +38° 19′ 44″). The Crescent is an example of a Wolf Rayet nebula – the bright star HD192163 (also WR136, centre) is a massive star nearing the end of its short life. When becoming a red supergiant several hundred thousand years ago, it blasted away a shell of material weighing about 5 times the mass of our sun. This shell of material is impacted by the fast stellar wind, and excited by X-rays from the star’s surface, causing the glowing shell of gas we see today.  

The image above consists of 11 x 20min exposures taken on the night of the 8th/9th September 2017, using an ST2000XM, WO FLT110 at f5.6 and an Astrodon HA filter. These were all taken with the moon at ~85%, which shows that the H-Alpha filter did a great job of filtering out the unwanted moonlight, and letting the required wavelengths pass. 

The second image is another region in Cygnus containing Simeis 57, the Propeller Nebula (image centred at RA 20h 16m 05s,
Dec +43° 41′ 05″). This is often mislabelled as DWB111, whereas that is only the southern (lower) half of the “propeller” (the other half is DWB119). Not a lot is known about the nebula – there isn’t a definitive distance, though it’s suspected that it is reasonably nearby, and it’s somewhat odd that given it’s distinctive shape and the fact it is reasonably bright in comparison to the surroundings, that it wasn’t included on other catalogues such as Sharpless-2. 

This image was 3h20min total (10x20min subexposures) with the same equipment as above taken on 10th/11th September 2017. These again were taken with the moon at ~75% full.  This could probably do with more exposure to help reduce the noise in the fainter regions (which are a bit marginal here), but cloud stopped play in the early morning for this one.