Messier catalogue checklist

How to use the checklist

Pick a type of object, or tick "well up this month" to see only the ones that stand at least 20° above the horizon at 10pm this month. Tick each object as you find it. The count at the top keeps your tally, and your ticks stay in this browser on this device. Nothing is sent to us.

Press Print this list for an A4 sheet of whatever is showing, black on white, with a box to tick and space for the date and a note. Clubs often hand these out at observing evenings.

How to read each row

M is the number Charles Messier gave it in his list of fuzzy objects that were not comets, published between 1774 and 1781. Mag is its magnitude, a measure of brightness where smaller numbers are brighter. A spread-out galaxy of magnitude 9 looks much fainter than a star of the same magnitude, because its light is smeared over a wider patch.

Best months are the months when it crosses the meridian, the north-south line where it stands highest, between 9pm and 11pm UK time. The Orion Nebula, M42, comes out as January, the Andromeda Galaxy, M31, as October and November, and the Great Globular Cluster in Hercules, M13, as July. Highest is the most it ever climbs from the middle of the UK. Eight objects in Scorpius, Sagittarius, Ophiuchus and Hydra never get above 10° from there, and M7 reaches only about 2°.

How it is worked out

The positions, types and magnitudes come from OpenNGC, an open catalogue of deep-sky objects kept by Mattia Verga and shared under a CC BY-SA 4.0 licence. Where OpenNGC has no magnitude we use William Harris's catalogue of globular clusters and, for M35, NASA's Hubble Messier Catalog.

The months and heights are our own sums. For every day of the year we take 10pm on a UK clock, work out which part of the sky is due south at that moment from 53.5°N, and see which objects are within an hour of it. Astronomy Engine, an open astronomy library, does the star time and the slow wobble of Earth's axis since 2000. Our results match NASA's own notes: M31 best in November, M42 in January, M7 at 10pm in July.

Two objects that are not what they seem

M40 is two ordinary stars that happen to sit close together in the sky. Messier logged it while looking for a nebula someone else had reported there. M102 is a puzzle: his notes do not match any one object well. OpenNGC treats it as a repeat of M101, while most observing lists use the galaxy NGC 5866 in Draco. We list NGC 5866 and say so on its row.

From the eyepiece to the wall

Many of the brightest Messier objects are galaxies and nebulae. Our galaxy prints and nebula prints are made to order for a wall at home or the club room. For the story of what you are looking at, what a nebula is and the life cycle of a star explain planetary nebulae and the Crab Nebula's supernova, and the Orion guide shows where to find M42.

Written by Craig Fearn, Aphelion Prints. Last updated 29 October 2026.