Celestial hemisphere:  Northern  ·  Constellation: Gemini (Gem)  ·  Contains:  HD251847  ·  HD252197  ·  HD41940  ·  M 35  ·  NGC 2158  ·  NGC 2168
M35 and NGC 2158 Open Star Clusters, Mark Germani
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M35 and NGC 2158 Open Star Clusters

Revision title: Extra Hour + Drizzle Upsample

M35 and NGC 2158 Open Star Clusters, Mark Germani
Powered byPixInsight

M35 and NGC 2158 Open Star Clusters

Revision title: Extra Hour + Drizzle Upsample

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Description

I've been doing astrophotography since Fall 2020 and I've never had a stretch this long without being able to do astrophotography - it's been virtually non-stop rain and cloud here in Vancouver Canada since early October. So when the skies cleared early December I grabbed my gear and got as much time on M31 as I could, and then I decided to spend whatever time remained after M31 hit the trees to grab a quick target that would work with the 0.8 reducer and 15-degree rotation I was using for M31.

M31 hit the trees at midnight, so I switched to these two adjacent and contrasting open star clusters, which hit my chimney around 2AM, netting me 90 minutes of good subs. I did a test stack a few days later and was so buoyed by the result and so desperate to share something here that I decided to process and post. There's a lovely blueish glow around M35 which could benefit from more integration time (we'll see... nothing forecast yet) but it's there nonetheless.

Note: I added another 55 minutes and reprocessed, making this revision my final version. The blueish glow is less pronounced (perhaps due to the fuller moon on the second night) but more stars are resolved, and NGC 2158 contains a broader range of star colours rather than the overall yellow glow from the 90-minute version.

M35 OPEN STAR CLUSTER

Relatively young (150 million years old) and relatively close (2,800 light years away), M35 is thought to contain about 500 stars. Younger open clusters such as M35 often contain brilliant blue stars, and M35 does not disappoint.


NGC 2158 OPEN STAR CLUSTER

I wasn't sure if this was a globular cluster while imaging it, as it's very dense and contained very few of the short-lived brilliant blue stars typical of open clusters. NGC 2158 is four times more distant and while it occupies roughly the same area in space, it contains about 800 stars - significantly more than M35. The brilliant blue stars have long since been extinguished, as the cluster is estimated to be around 2 billion years old.


SOURCES:

Messier 35 and NGC 2158, BBC Sky at Night Magazine, https://www.skyatnightmagazine.com/astrophotography/stars/star-clusters/messier-35
APOD: 2021 May 10 - Star Clusters M35 and NGC 2158,  Robert Nemiroff (MTU) & Jerry Bonnell (UMCP), https://www.skyatnightmagazine.com/astrophotography/stars/star-clusters/messier-35
Open cluster NGC 2158 investigated in detail, Tomasz Nowakowski , Phys.org, https://phys.org/news/2020-12-cluster-ngc.html

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  • M35 and NGC 2158 Open Star Clusters, Mark Germani
    Original
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    M35 and NGC 2158 Open Star Clusters, Mark Germani
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B

Title: Extra Hour + Drizzle Upsample

Description: I had the opportunity to add a little extra time to this image, and opted to drizzle 1.7x. More stars resolved, and NGC 2158 contains a mixture of star colours rather than the overall yellow glow in the previous version. The blue glow around M35 is less pronounced - the moon was fuller on the second night.

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M35 and NGC 2158 Open Star Clusters, Mark Germani