After recently establishing Fairvale Observatory South AKA “The Shed” and dealt with some expected and unexpected problems, I was able to turn my attention to the object of my desire in this hitherto inaccessible part of the northern night sky. With the summer solstice approaching I had originally planned on imaging this astrophotographers’ favourite later in the year but I couldn’t resist an early look. A few nights after finishing Bodes galaxy from my new, northward looking location, I therefore swung the scope across the Meridian to the north east in order to obtain a few subs of this object just to see: (a) what it might look like with my equipment (b) bearing in mind the previous objective, to assess the best framing and (c) just for the fun of it, and was not disappointed!
The aforesaid object of interest was the Elephant’s Trunk Nebula or IC 1396, a very large emission nebula, which in narrowband shows wonderful colour and detail (HaSHO above). IC 1396 consists of glowing gas illuminated by an open star cluster, broken up by intervening lanes of dark interstellar dust clouds. The ‘trunk’ itself, designated IC 1396A, is the long dark area protruding from the lower edge of the image, spectacularly illuminated from behind by a bright star forming region; the image has been rotated 180o from its natural position. Top right on the edge is the red supergiant Mu Cephei or Herschel’s Garnet Star, one of the largest and brightest known stars in the Milky Way, which in the position of the Sun would extend out to Saturn’s orbit!
The large IC 1396 nebula will not fit my field-of-view but with some judicious framing, using the Garnet Star as a marker and helped by a few previously taken test subs, I achieved a pleasing composition with the aforesaid trunk and nearby billowing dark clouds well placed (HaOIIIOIII bicolour image above). Whilst I am pleased with my first attempt at the Elephant’s Trunk, the colour could be better and is too noisy – a consequence of too little integration time and high gain setting. Having had success before using similar settings for Ha-type features like the Rosette Nebula, I was a little surprised by this outcome but it just goes to show that each object is different. Notwithstanding, the Ha version is – I think – very promising (top of the page) but obviously there is too little OIII and SII in the composite wavelength images.
I used to live and have worked all over Africa but this is a very different type of elephant to what I have met before (the “trunk” HaSHO above). It forms an exciting imaging subject at this time of the year, made all the more rewarding being one of my first serious attempts to image the north sky. I hope to return to this object in a couple of months when astronomical darkness has resumed but in the meantime the Jumbo of the night sky has been a real joy on my first encounter.
| IMAGING DETAILS | |
| Object | Elephant’s Trunk Nebula IC 1396 |
| Constellation | Cepheus |
| Distance | 2,400 light-years |
| Size | 5o or “Trunk” only approx.. 45’ |
| Apparent Magnitude | +3.5 to +5.7 |
| Scope | William Optics GT81 + Focal Reducer FL 382mm f4.72 |
| Mount | SW AZ-EQ6 GT + EQASCOM computer control |
| Guiding | William Optics 50mm guide scope |
| + Starlight Xpress Lodestar X2 guide camera & PHD2 control | |
| Camera | ZWO1600MM-Cool (mono) CMOS sensor |
| FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix | |
| EFW | ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters |
| Capture & Processing | Astro Photography Tool + PS2, Deep Sky Stacker & Photoshop CS2 |
| Image Location | Centre RA 21:38:37 DEC 57:30:16 |
| Exposures | 12 x 300 sec Ha + 6 x300 sec OIII & SII (Total time: 120 minutes) |
| @ 300 Gain 50 Offset @ -20oC | |
| Calibration | 5 x 300sec Darks 20 x 1/4000 sec Bias 10 x Ha + OIII + SII Flats @ ADU 25,000 |
| Location & Darkness | Fairvale Observatory – Redhill – Surrey – UK Typically Bortle 5 |
| Date & Time | 22nd May 2018 @ midnight |
WATCH THIS SPACE(MAN) 