2023 March 18
Observer’s Challenge – Mini Messier Marathon – Open Clusters
March New Moon is the traditional time for the Messier Marathon challenge – to observe all the Messier objects in one night. This year 2023, New Moon will occur on Tuesday, March 21, 2023. This date suggests a primary weekend on March 18/19, and a secondary one on the weekend of March 25/26.
Of course there are many practical problems with a full Messier Marathon – not least that not all the Messier objects are visible from the UK, and as you head north in the country many become un-observable.
And as there are 110 objects in the Messier catalogue, it is also quite hard to get round them all. One of the best internet resources to help with a full Messier Marathon are these pages provided by SEDS.
For this ‘mini-marathon’ we’re just going to look for Messier’s open clusters – these should be easier to find and observe, and with more time available a chance for imagers or those using electronically assisted viewing to capture them too. There is still the big challenge of the objects with a southerly declination, so those objects in Scorpius and Sagittarius will be particularly difficult – even those in the south of the UK will still need a good southern horizon.
The list below of the 27 Messier open clusters is organised in a search order recommended by Don Machholz, whose book The Messier Marathon Observer’s Guide is excellent for anyone taking up the pursuit.
We will need a good clear night from dusk to dawn, though it might be possible to have a snooze or break half way through.
If you manage to observe or image these objects in one night, or even if you just manage a few – please post your observing report or images on your Members Page.
Good luck, happy Messier hunting!
No. | Messier | Constellation | RA | Dec | Visual Mag. | Size (arc-min) |
1 | M52 | Cas | 23 24.2 | +61 35 | 7.3 | 13 |
2 | M103 | Cas | 01 33.2 | +60 42 | 7.4 | 6 |
3 | M34 | Per | 02 42.0 | +42 47 | 5.5 | 35 |
4 | M45 | Tau | 03 47.0 | +24 07 | 1.6 | 110 |
5 | M35 | Gem | 06 08.9 | +24 20 | 5.3 | 28 |
6 | M37 | Aur | 05 52.4 | +32 33 | 6.2 | 24 |
7 | M36 | Aur | 05 36.1 | +34 08 | 6.3 | 12 |
8 | M38 | Aur | 05 28.4 | +35 50 | 7.4 | 21 |
9 | M41 | CMa | 06 46.0 | -20 44 | 4.6 | 38 |
10 | M93 | Pup | 07 44.6 | -23 52 | 6 | 22 |
11 | M47 | Pup | 07 36.6 | -14 30 | 5.2 | 30 |
12 | M46 | Pup | 07 41.8 | -14 49 | 6 | 27 |
13 | M50 | Mon | 07 03.2 | -08 20 | 6.3 | 16 |
14 | M48 | Hya | 08 13.8 | -05 48 | 5.5 | 54 |
15 | M44 | Cnc | 08 40.1 | +19 59 | 3.7 | 95 |
16 | M67 | Cnc | 08 50.4 | +11 49 | 6.1 | 30 |
17 | M29 | Cyg | 20 23.9 | +38 32 | 7.1 | 7 |
18 | M39 | Cyg | 21 32.2 | +48 26 | 4.6 | 32 |
19 | M6 | Sco | 17 40.1 | -32 13 | 5.3 | 25 |
20 | M7 | Sco | 17 53.9 | -34 49 | 4.1 | 80 |
21 | M11 | Sct | 18 51.1 | -06 16 | 6.3 | 14 |
22 | M26 | Sct | 18 45.2 | -09 24 | 8 | 15 |
23 | M16 | Ser | 18 18.8 | -13 47 | 6.4 | 7 |
24 | M18 | Sgr | 18 19.9 | -17 08 | 7.5 | 9 |
25 | M25 | Sgr | 18 31.6 | -19 15 | 6.5 | 40 |
26 | M23 | Sgr | 17 56.8 | -19 01 | 6.9 | 27 |
27 | M21 | Sgr | 18 04.6 | -22 30 | 6.5 | 13 |
Best of Luck. Any results are welcome within the Member Galleries, sent to the Deep Sky Section or on the Forum.
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