I recently wrote about the wonderful dark Bortle 4 skies at my new home in Somerset and, for the moment, the trstricted views to the west and north; I hope to establish a new location further down the garden this summer which will provide a southerly view and thereby longer transits of objects.  Meanwhile, I am enjoying imaging northern circumpolar targets regularly for the first time and some suitable western objects, which is exactly what I did on this occasion.        

Messier 35 AKA Shoe Buckle Cluster (?), is a bright open star cluster in the constellation of Gemini.  M35 lies about 2,800 light-years from Earth and is approaching us at 5 km/sec.  It is estimated to be between 100 and150 million years old, making it a relatively young open cluster in astronomical terms and spans 24 light-years across.  As the stars are formed from the same giant molecular cloud, they are roughly the same age and chemical composition; some post main-sequence are yellow and orange giants of spectral type G and K, while its hottest main sequence star is of spectral class B3. 

A notable feature of imaging M35’s is its apparent proximity to NGC 2158, which however, is a much older and more distant, metal-poor open star cluster located some 11,000 to 16,000 light-years from Earth.  It contains over 3,000 stars of some 2 billion years age, which are dominated by yellower stars.

Intriguingly, when commencing to image these clusters, the guiding software could not recognise a star to lock onto as there were just too many close together!  I’m pleased to say that over three nights I managed to obtain some excellent data that resulted in this exiting image.   

IMAGING DETAILS
Object	M35 AKA Shoe Buckle Cluster & NGC 2158
Constellation	Gemini
Distance	M35 2,800 light-years & NGC2158 16,500 light-years
Size	M35 28 arc minutes (24 light-years) & NGC2158 5 arc minutes (16 light-years)
Apparent Magnitude	M35 +5.0 & NGC2158 +8.6
Scope	William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount & Control	ZWO AM5 + ASIair
Guiding	William Optics 50mm guide scope
	+ ZWO 120MM Mini
Camera	ZWO ASI294MM CMOS sensor
	FOV 2.87o x 1.96o Resolution 2.50”/pix  Max. image size 4,144 x 2,822 pix
EFW	ZWOx8 EFW & 31mm Chroma Ha, OIII, SII 3nm & RGB filters
Capture & Processing	ASIair, Deep Sky Stacker & PixInsight v1.9.3 Lockhart
Image Location              & Orientation	Centre = RA 06:08:51.94      DEC +24:15:16.9                        Bottom Right = North
Exposures	L x142 @ 60sec + L x30 &30sec + R x37, G x35, B x30 @ 120sec    Total Integration Time: 6hr 1min
	@ Gain 120 & 30 Offset 21 @ -15oC
Calibration	10 x 120 sec, 20 x 60 sec & 20 X 30 sec Darks + 10 x  NB Flats & Dark Flats          @ ADU 32,000
Location & Darkness	Castle Farm Observatory, Wookey, Somerset – UK      Typically Bortle 4
Date & Time	17th 18th * 19th March 2026 @ +21.30h
Weather	Approx. <5oC   RH >=<60%                  🌙 approx. New Moon