Feburary 10, 2018: Patrick Moore and the Caldwell Catalogue

A few months back, I highlighted Charles Messier and his famous catalogue.  But because of a number of omissions – you might even say some of them were, ahem, glaring – it was felt that another catalogue was needed for amateurs to hunt down, to expand beyond Messier’s 110 objects.  At the request of Sky and Telescope magazine, about 20-odd years ago, Patrick Moore, British astronomer, prolific author, and BBC television presenter, drafted another catalogue containing an additional 109 DSOs.*

Patrick Moore, the be-monocled man

Moore could be considered to be the British Carl Sagan, but that would be doing him a bit of a disservice.  Sagan was only on The Tonight Show a couple/three times a year; he had his limited-run (although excellent and mind-expanding) series, Cosmos, and he was the go-to guy for reporters regarding anything to do with astronomy and the space program, especially the planetary probes that were sent out in the 70s and 80s.  

Moore, on the other hand, had his very own show, The Sky at Night, which ran monthly for over 50 years on the BBC, beginning in 1957 until Moore’s death in 2012.  That’s over 700 shows; his show was the longest continuously broadcast television show with the same host.

Just as Sagan was the go-to guy for space missions of the seventies and eighties, Moore was for space missions for the entire space-faring era.  Where Sagan wrote about 20 science books, Moore authored over 70 books on astronomy, including many popular guides for beginners.  I own one of his books, called Astronomer’s Stars, and it’s terrific.  To most Brits, Patrick Moore WAS astronomy, and he is forever engraved upon the British collective consciousness.  Well, at least until the British Neil deGrasse Tyson comes along, anyway.

Moore’s interest in astronomy began because he had heart problems as a child.  Because he had to stay home, his mother gave him a book on astronomy, sparking a lifelong interest.  His fiance died during a German bombing while he served as a navigator with the Royal Air Force during World War II, and he never married thereafter.

Although he held no degree in astronomy, or even science, and always described himself as an amateur astronomer, he was made director of the Armagh Planetarium in Northern Ireland, and he was elected president of the British Astronomical Association.  His television show started before Sputnik and ended after the Space Shuttle.  He was a BBC commentator on the space program, both the American and Russian programs, for all the years in between.  For his efforts in popularizing science, he was knighted in 2001.  Moore passed away in 2012 at the age of 89.

Moore was certainly an eccentric.  He was noted not only for his ever-present monocle, xylophone playing, cricket bowling, but also for holding some, well, let’s say “interesting” political views, particularly on immigration and Britain’s membership in the EU.  This most likely stemmed from the loss of his fiance at the hands, or, well, the bombs of the Germans during the war.  Even in 2012, almost 70 years after the war, and only six months before his death, he was still expressing his intense and abiding hatred for the Germans.

Image result for patrick moore astronomer
Patrick Moore, with his good friend, another famous astrophysicist, Dr. Brian May.  Dr. May won third prize at a “Newton look-a-like” contest.  He may also have won a Grammy or two playing with some rock group or something.

The Caldwell Catalogue

He named his list the Caldwell Catalogue after his family’s true last name, Caldwell-Moore, because if he called them the Moore objects, the “M” designation would be confused with the Messiers.  Instead, they’re referred to with the letter C, as in C41, the Hyades.  Sky & Telescope, the premiere astronomy magazine, published the catalogue in 1995.  While it hasn’t reached anywhere near the recognition of the Messier Catalogue (yet), the Caldwell Catalogue has been disseminated widely.  If you have a computerized telescope, the Caldwell Catalogue might appear on the handset right up there with Messiers.  (Another catalogue appears there as well, which I’ll get to later.)

Some of the Caldwell objects are Messier’s goofs, oops, omissions; the brighter objects in the Northern Hemisphere skies that somehow or another did not make it into Messier’s Catalogue.  The most prominent of these are:

  • The Owl or E.T. Cluster (C13);
  • The Double Cluster (C14);
  • The Veil Nebula (C33 and C34 for the East and West sections, respectively);
  • The Hyades (C41);
  • The Sculptor Galaxy (C65).

Around 40 of them are more or less Southern Hemisphere objects.

Moore numbered his catalogue in order of declination.  The first Caldwell objects are located closest to the North Pole (nearest to Polaris) and go down from there.  This makes it very easy to figure out which objects not to bother with.  For me, at almost 40 degrees north latitude, I don’t try for the last 40 or so, because they just never rise high enough above the horizon to be seen, or at least, to be seen well.  Messier obviously could not see these at all from Paris, as he was located at 50 degrees north latitude.  The more prominent of these southerly objects include:

  • Centaurus A Galaxy (C77);
  • Omega Centauri (C80);
  • The Jewel Box Cluster (C92);
  • 47 Tucanae Cluster (C106).

Some of the rest of the objects are deeper, fainter objects than the ones Messier put on his list.  The Caldwell Catalogue contains 35 galaxies, 25 open clusters, 18 globs, 13 planetary nebulae, 9 nebulae, 6 combination open clusters and nebulae, 2 supernova remnants – the East and West Veil Nebulae, which he counted twice – and 1 dark nebula (the Coal Sack Nebula, in Crux, C99).

Caldwell Catalogue Criticism

Moore’s Catalogue was also criticized.  It includes a number of galaxies that, while beautiful, are extremely challenging visually with even medium aperture scopes of around 8 inches or so, which is about the largest size most amateurs use, and which his list is supposedly designed to permit them to see.  Moore generally observed with modern 12 1/2-inch and 15-inch reflectors, both of which are far larger than what most average amateurs have access to.  The Catalogue is inconsistent that way, containing many brighter objects but also these rather dim ones.

For example, take the pair of Antennae Galaxies, C60 and C61, discovered by William Herschel in 1785.  (Why Moore felt the need to give each of these a separate number, while he didn’t do so with the Double Cluster, but did with the Veil, is unknown and annoyingly inconsistent.)  They are generally considered interesting because of their shape in photographs, as they are interacting and colliding with each other, and generally tearing each other apart.  Have a look:

The Antennae Galaxies, C60 and C61, in the constellation Corvus.

However,  they are only 11th and 13th magnitude, respectively, making them very difficult for anyone but amateur astrophotographers to really “see”.

Another criticism is that his Catalogue is simply a list of DSOs that Moore himself personally found beautiful or interesting.  These are just one person’s favorite non-Messier objects, although, certainly, that one person was an important force in astronomy.  Some objects that others consider to be worthy of inclusion didn’t make his cut.  As Moore himself said of his Catalogue, “It was just a bit of fun.  I never dreamed it would be so popular.”


So, between the Messier and Caldwell Catalogues, that gives you about 150-180 objects to look for, depending on your latitude, if you live somewhere in the Northern Hemisphere. However, during any one season of the year, that’s roughly only about a third of the DSOs – maybe 50-60 on any given night.  (Yes, I know there are four seasons, but you can typically see at least a third of the sky at a decent altitude above the horizon during any one observing session.)

What if you do have that bigger scope, or you do have those darker skies, or you’ve got both, and you want to go deeper?

Stay tuned for my blog post on William Herschel and the Herschel 400!  

*  You may wonder why there are 110 Messiers, but only 109 Caldwells.  This is because there “aren’t” 110 Messiers.  There were “really” only 104, and additional objects got added to his list over the years in the 20th century as researchers reviewed Messier’s observing notes, and saw that he had “discovered” additional objects.  Some old school types – including, obviously, the monocle-wearing Patrick Moore (and if there’s anything more old school than a monocle, someone tell me what that is) – didn’t fully consider the Messier catalogue to include the 110th item, a satellite galaxy of Andromeda (M31).  Moore therefore cut his list off at 109.


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