The Beauty of M35

Winter’s sky offers no shortage of showpieces, and for me Messier 35, the bright open cluster resting at the foot of Castor in Gemini, is one of those that I have to check in on. M35 has long been one of my favorite winter targets. It’s easy to find, bright enough to pop even from suburban skies, and rich enough to reward everything from binocular sweeps to deep imaging sessions.

Through binoculars or a small telescope, the cluster spills across the field as a loose spray of mostly white stars, though attentive observers will notice a few with a soft yellowish tint. It is an easy star hop at the base of the constellation, from 3^rd magnitude m and h out to Gem 1 (Propus). Once there our target is only a degree to the north. If you have dark skies (or a large enough scope) you are in for a double treat as just southwest of M35 lies the much fainter and more compact NGC 2158. Under suburban skies it often hides in the background glow, but from darker locations it resolves into a tiny, grainy knot resembling a globular cluster. This side-kick is a distant, older cluster five times farther away than M35 itself. I still remember the first time I caught it from a friend’s property in western Maryland’s dark countryside. Ever since, it’s been a personal benchmark for a dark sky.

This year, with Jupiter entering Gemini, I had hoped for a reprise of one of my favorite celestial pairings. M35 sits only a couple of degrees north of the ecliptic, and when Jupiter wanders through the constellation the giant planet can glide surprisingly close to the cluster. One such moment came in the spring of 1990, when Jupiter passed less than a degree south of M35 – a striking sight in a low‑power eyepiece of my 6” RV-6, creating a memory that stays with you for decades.

With a clear and not bitterly-cold January night unfolding, and with my HEM27 mount freshly repaired, I decided to test the repair as well as my plate-solving technique by targeting M35. After a quick polar alignment, I asked NINA to plate‑solve for M35 and – to my great delight – it did so flawlessly, undoubtably saving me time. As the first 15 second frame came in using the ASI2600MC I could make out not only M35 but that NCG 2158 was well within the frame. I kicked off a capture loop and checked in every 15 minutes or so to ensure things were still moving smoothly.

I ended up capturing 325 frames at 15 seconds each, and after tossing the outliers, 284 made it into the final integration. Processing the data in PixInsight was its own adventure. I leaned on Copilot for guidance, with mixed results – some guidance was helpful, others sent me wandering down dead ends or into outdated interface paths. But persistence paid off. After working through using the Weighted Batch Pre-processing (WBPP) script I ended up with a final image that I’m genuinely pleased with. The slight variety of colors in bright and showy M35 are seen and little NGC 2158 is fainter and yellower, reflecting its age and distance.

M35 never disappoints. Whether you’re sweeping with binoculars, hunting for NGC 2158 from a dark site, or capturing hundreds of frames through a modern imaging setup, it’s a reminder of how much beauty sits quietly in the winter sky, waiting for us to look up.