By Jean Manfroid.
FNRS Director of Research at the University of Liège's Department of Astrophysics, Geophysics and Oceanography. This article was published in the Decemeber 2012 issue of the Liège Astronomy Society's journal, 'Le Ciel'.
The Belgian comets
Few places in Belgium are suitable for deep sky observation and even less so for observation near the horizon where comets that are hitherto unknown can appear. This explains the paucity of comet missions up to the present day in our country.
![(EN)comète C1956 R1]( "(EN)comète C1956 R1.")
In 1941, Eugène Delporte (1882®C1955), the Belgian astronomer who established the current limits of the constellations, co-discovered the comet 57P/du Toit-Neujmin-Delporte from the Uccle observatory. The sky was a lot darker at the time than it is now, given that light pollution had been largely eliminated due to the war in Europe. At that tragic time, communications in Europe were difficult and slow, which explains why three individuals are credited with discovering the same comet. The complicated history of this comet probably ended in 2002 when astronomers working on the 2m20 telescope in Hawaii noticed that it broke up into a chain of mini-comets covering half a degree in the sky which is equivalent to a million kilometers. This is not to forget the comet Shoemaker-Levy 9 which broke up while passing near Jupiter in 1992 with the resulting debris crashing into the giant planet two years later.
In 1951, a somewhat auspicious year, two periodic comets were discovered at Uccle:
49P/Arend-Rigaux and 50P/Arend. In 1956, it was again at Uccle that a new comet was discovered, the beautiful Arend-Roland.
Then there was a long period of inactivity before a new comet was found by a Belgian, the comet Heck-Sause (C/1973A1), which was named after Liege astronomer André Heck and his French assistant Gérard Sause. At the time astronomical observation was organized far from Belgium, and it was at the observatory of Haute-Provence that this discovery was made.
We mustn’t forget a sixth Belgian comet 133P/Elst-Pizarro which had the peculiarity of being a comet and asteroid at the same time, or neither one or the other and which recurrently displayed a spindly tail instead of the usual plume, 133P is part of the select category of the “main belt comets” (MBC). This discovery was made even further away, in the pristine skies of the Chilean Andes.
Tracking comets
It was only in the 18th century that it was established that apart from spectacular comets which are visible to the naked eye, there were others which were more numerous but so weak that the astronomers of the time, particularly Charles Messier (1730-1817), compiled lists of nebulous objects that could be confused with them. Tracking comets required a perfect knowledge of the sky which had to be tirelessly studied. Many amateurs have used this method which has become more and more neglected since the arrival of electronic sensors. Today, telescopes on the ground and in space comb the sky and comparison with databases quickly reveals the presence of a new “intruder” no matter how faint it may be.
The transition between these two methods was photographic imaging, and it was by means of this technique that all the Belgian comets were found. The advantage of photographic plates with an appropriate telescope was that a large field could be recorded. However, developing the photos took time and the comparison of negatives with atlases or previous negatives was very laborious. At that happy time, amateurs could still nurture the hope of visually discovering a beautiful comet while the professionals more or less systematically combed the sky with a Schmidt camera making it possible to record fields of several degrees at a time. Telescopes such as the Schmidt of the Mount Palomar observatory were abundantly used for this type of work with real success. Other lesser-known telescopes occasionally carried out such observations among other tasks which were imposed by the various research programs.
