The Unicorn’s Finger

SH2-284 is an HII star forming region of dust and gases, sculpted by the radiation and interstellar winds emanating from the young (3 to 4 million years) open star cluster Dolidze 35 located near its centre. Along the inner edge of the main ring structure are numerous dark dust pillars and Bok Globules, not unlike those of the Elephant’s Trunk nebula, of which the largest seems to resemble a hand with a large bony finger at the end pointing inwards (see cropped + rotated image below).

Despite its close resemblance to the Elephant’s Trunk and the nearby Rosette nebula, the emission nebula SH2-284 is by comparison somewhat overlooked. Being some x8 times further away it’s apparent size is a good deal smaller and much fainter in nature but still forms an excellent late winter image target.

	IMAGING DETAILS
Object	SH2-284 or LBN 983
Constellation	Monoceros
Distance	18,000 light-years
Size	0.50^o
Apparent Magnitude	Faint

Scope	William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount	SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding	William Optics 50mm guide scope
	+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera	ZWO ASI294MM CMOS sensor
	FOV 2.87^o x 1.96^o Resolution 2.50”/pix Max. image size 4,144 x 2,822 pix
EFW	ZWOx8 EFW & 31mm Chroma LRGB filters
Capture & Processing	Astro Photography Tool + PHD2 + PixInsight v1.8.9-1
Image Location & Orientation	Centre = RA 06:45:20.506 DEC +00:18:12.758 Right = North Top = East
Exposures	Ha 53 x 300 sec, OIII 36 x 300 sec, SII 36 x 300sec = 11hr 30 min R 35 x 60 sec, G 35 x 35 sec, B 34 x 60 sec = 1hr 44min Total Integration Time: 13hr 14 min
	@ 120 Gain 30 Offset @ -15^oC
Calibration	5 x 300 sec & 20 x 60 sec Darks + 15 x LRGB & Ha, OIII, SII Flats & Flat Darks @ ADU 32,000
Location & Darkness	Fairvale Observatory – Redhill – Surrey – UK Typically Bortle 5-6
Date & Time	6th^th + 7^th + 8^th + 9^th + 13^th February 2023 @ +19.30h
Weather	Approx. <=3^oC RH >=70% 🌙 Full Moon – waning