Rediscovering the Bedford Catalogue for the 21st Century

by Rob Peeling

In 1844, Captain William Henry Smyth RN published two volumes entitled A Cycle of Celestial Objects. Volume 1 or Prolegomena described in detail Smyth’s observatory in Bedford and his observing techniques. It is volume 2, The Bedford Catalogue, which is still of interest to the 21st century amateur astronomer.

This volume was a forerunner to Thomas William Webb’s Celestial Objects for Common Telescopes, first published in 1859 and dedicated to the now Vice Admiral WH Smyth. William Henry Smyth’s work is therefore, arguably, the first popular guide sky published. Indeed, Webb states in part three of his work, in the chapter, The Starry Heavens, where he deals with double stars, clusters and nebulae that he examined all of the 850 double stars and nebulae of the Bedford catalogue, and only retained those which, seem to possess sufficient general as well as scientific interest, together with a number of other objects largely taken from Frederick Wilhelm Struve’s Mensurae Micrometricae, usually referred to by Smyth as the Dorpat catalogue.

Sadly, the Bedford Catalogue is no longer well-known. This is a shame because of the detailed but easy style in which Smyth writes his notes for each of his 850 objects. The style is reminiscent of Patrick Moore in the famous The Observer’s Book of Astronomy, 1962 or Stephen O’Meara’s Deep-sky Companions series, 1998 onwards.

The aim of this project is to rediscover the Bedford Catalogue for use in the 21st century by updating Smyth’s object names or designations to enable the modern observer to rapidly locate them with their own telescope.

The problem for the astronomer using Smyth’s guide at the telescope today is simply the publication date.

Smyth uses what are often anachronistic designations for his objects making them hard to identify in modern sky atlases either printed or electronic. His carefully measured positions were all reduced to the epoch 1840.0 instead of the 2000.0 used by almost everything to hand today. There are constellation names which no longer exist following the standardisation to 88 constellations by the IAU in 1922.

Smyth uses Bayer letters and Flamsteed numbers but he also uses numbering from the Palermo catalogue published by Giuseppe Piazzi (the discoverer of Ceres) from 1814. Piazzi was the godfather of one of Smyth’s sons, Charles Piazzi Smyth, later Astronomer Royal of Scotland.

Smyth does use Messier numbers, but most of his clusters and nebulae are referred to using the catalogue numbers of either William or John Herschel. For these at least modern NGC numbers can be easily recovered with the help of Wolfgang Steinicke’s excellent work.

The double and multiple star systems are harder to recover. This requires precessing Smyth object positions to the 2000.0 epoch, checking using Aladin and against the Washington Double Star Catalogue. Facsimiles of the original works by the Herschel’s and also the Palermo catalogue were also useful for checking object identities.

Smyth gives detailed descriptions of the star fields around many of his objects and so the updating has not been restricting to identification of the 850 entries in the Bedford Catalogue but extended to identification of all the other objects and stars described by Smyth in his notes.

This leads to the question of why a modern observer might choose Smyth as his companion for the Deep Sky. The answer for a visual observer is that identifying all the additional objects mentioned by Smyth when looking at one of his objects will help develop their observing skills.

Smyth will encourage you to estimate orientation, position angle, object separations and better understand the movement of the sky and the relationship between your telescope’s optics and the star atlas. He will also encourage his reader to take much more notice of relative magnitudes and colour. Imagers may find inspiration to try new projects such as measuring multiple star systems and interpreting the fields around the objects they image.

Updating the Bedford Catalogue

Smyth’s object positions where determined by him using the equipment installed in his Bedford observatory. He reduced his positions to an epoch of 1840.0. Hence first step in this project being to precess all Smyth’s coordinates to epoch 2000.0 to enable confirmation of Smyth’s identities against modern catalogued positions.

The necessary formulae in spherical trigonometry were implemented in an Excel spreadsheet and checked for consistency using objects (Messier objects, bright stars) where the designation used by Smyth has not changed with the passage of time such as alpha Andromedae or 33 Messier (Smyth’s version).

The clusters and nebulae were updated first.

In 1844, the separate classification of galaxy was not used and objects we now know to be galaxies were referred to simply as nebulae. This change in classification did not occur until after Hubble’s work to show that the Andromeda Nebula lay outside the Milky Way and therefore became the Andromeda Galaxy. In Smyth’s time, the term Galaxy was only used for the Milky Way.

Smyth used three sources for these clusters and nebulae. These included the final version of Messier’s catalogue from 1781 (up to M103 only), the three papers to the Royal Society from William Herschel, detailing 2500 objects in all, and John Herschel’s Stroud catalogue.

Smyth’s notes for individual objects describe the star fields around the objects. During this research, it has become clear to the author that Smyth did personally observe the objects in the catalogue and thought carefully about what he saw. There are however some cases where his description either omits to mention obvious nearby stars or it is difficult to relate his description to what is seen in the Digital Sky Survey as visualised using CDS’s Aladin applet. These lead to a fairly short list of objects requiring further investigation.

Where to find a copy of the Bedford Catalogue

The Bedford Catalogue: From a Cycle of Celestial Objects, Admiral William Henry Smyth, Willmann-Bell (April 1986), ISBN-10: 0943396107. This is a good quality facsimile version of the original 1844 publication.

Free downloadable versions can be found in PDF format on the internet. However, be aware that there is also a second edition, published in 1881, edited after Smyth’s death by George F Chambers. Unfortunately, Chambers chose to expand the list of objects to 1603 and completely renumbered them making cross-referencing to the original version tedious.

Finally the author has made his updated version of The Bedford Catalogue available in PDF format for anyone to download via this link. It is complete with modern designations and positions right alongside Smyth's original data and comments.