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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. 

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.MessierConstellationRADecVisual Mag.Size (arc-min)
1M52Cas23 24.2+61 357.313
2M103Cas01 33.2+60 427.46
3M34Per02 42.0+42 475.535
4M45Tau03 47.0+24 071.6110
5M35Gem06 08.9+24 205.328
6M37Aur05 52.4+32 336.224
7M36Aur05 36.1+34 086.312
8M38Aur05 28.4+35 507.421
9M41CMa06 46.0-20 444.638
10M93Pup07 44.6-23 52622
11M47Pup07 36.6-14 305.230
12M46Pup07 41.8-14 49627
13M50Mon07 03.2-08 206.316
14M48Hya08 13.8-05 485.554
15M44Cnc08 40.1+19 593.795
16M67Cnc08 50.4+11 496.130
17M29Cyg20 23.9+38 327.17
18M39Cyg21 32.2+48 264.632
19M6Sco17 40.1-32 135.325
20M7Sco17 53.9-34 494.180
21M11Sct18 51.1-06 166.314
22M26Sct18 45.2-09 24815
23M16Ser18 18.8-13 476.47
24M18Sgr18 19.9-17 087.59
25M25Sgr18 31.6-19 156.540
26M23Sgr17 56.8-19 016.927
27M21Sgr18 04.6-22 306.513

Cover photo M103 by David Davies

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