Messier of the Month - March 2020

Original article appears in GuideStar March, 2020.

by Jim King

This is the first installment of a series of columns revolving around observing the Messier Catalogue.  The intent is to provide the reader a small sampling of the Messier objects that are most visible in the time frame the column is published.  Hence, these objects should be easily identifiable in and around the month of February and early March.

M1.PNGM1: The Crab Nebula.  The Crab was formed in July 1054, when its progenitor star blasted away most of its mass in a supernova explosion.  The event was recorded in several locations around the globe, but there are no known European references to the explosion.  It is still expanding at a rate of over 600 miles per second…almost 50 million miles per day!  Although created by an event similar, but more violent than that which creates a typical planetary nebula, the Crab does not have a typical planetary nebula’s form.  It is classed instead, as a supernova remnant.  The Crab’s pulsar rotates at 30 times per second.  First identified by John Bevis in 1731.

Object: Messier 001, aka NGC 1952, aka The Crab Nebula
Type: Supernova Remnant             
Con: Taurus
RA: 5.34.5   Dec: +22.01   Mag: 8.4  Dist: 6,500 ly
Opt view (February) 08.00pm. Very bright, very large, extends roughly along position angle 135 degrees; very gradually, a little brighter in the middle, mottled.

M103.PNGM103: One of the less notable open clusters in Messier’s Catalogue, it was originally identified by Mechain in 1781.  Challenge: it has a definite fan shape as do two other open clusters in Cassiopeia, M52 and NGC663.  See conflict below.  This the last object listed Messier’s original catalogue.  Numbers 104 through 110 have been added in recent years on the basis that Messier did observe them and that they would have been included had another Messier supplement been published.

Object: Messier 103, aka NGC581
Type: Open Cluster     
Con: Cassiopeia
RA: 01.33.4    Dec: +60.39.5
Mag: 7.4   Dist: 8,130 ly
Opt view (February) 07.30pm
Conflict: NGC663 has an appearance like M103.  NGC 663 also shows well in a finder scope, while M103 may not show at all.  Instead, M103 appears as three small stars.  NGC 663 is frequently mistaken for M103.  M103 is smaller, more compact and has a more regular fan shaped outline than NGC 663.

M42.PNGM042:  a nebulous star cluster in Orion.  Messier certainly did not “discover” this prominent naked-eye object; but he did determine its exact position, along with M43, M44, and M45 in March of 1789.  M42 is possibly the most rewarding deep sky object for a telescope of any size.  It has a wealth of eye detail and shows some color in a telescope of moderate aperture.  A prominent feature is the Trapezium, a bright, compact cluster of four stars in the shape of a trapezoid within the nebula. 

Object:  Messier 042, aka NGC 1976
Type: Emission Nebula and Cluster
Con: Orion
RA: 05.35.4   Dec: -05.27
Mag: 3.7   Dist: 1,500 ly
Opt view: (February) 7:52pm
True eye candy…perhaps the best in the northern hemisphere.  Do not be in a hurry.  Take your time and savor the view.

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