Are you up for the ultimate observing
challenge? Take a page out of the author’s
logbook and endeavour to observe the whole
Herschel catalogue.
I
n May of 1975 I completed my observations of all
110 Messier objects and received the certificate of
the Astronomical League’s (AL) Messier Observing
Program. There weren’t any other deep sky programs
within the reach of an amateur astronomer with a 15- or
20-cmh reflector until James ‘Jim’ Mullaney, in a letter to
the US edition of this magazine in April 1976, proposed
a new observing challenge: a list of the brightest objects
culled from William Herschel’s Catalogue of Nebulae and
Clusters of Stars. The Ancient City Astronomy Club of St
Augustine, Florida, reacted to Jim’s letter, and the AL’s
Herschel 400 Observing Program took off (https://is.gd/
Herschel400).
WTWO OBJECTS UNDER ONE NUMBER The Cone Nebula and
the Christmas Tree Cluster are both catalogued under a single
designation: NGC 2264. These double (or even multiple) designations
have led to confusion in the past. The nebula and the cluster lie at a
distance of about 2,600 light-years in Monoceros. This image, taken
with the European Southern Observatory’s Wide Field Imager at the
La Silla Observatory in Chile, spans some 30 light-years.
ESO
Herschel’s
categories
William Herschel
categorised eight
classes of object as
shown at right. Also
tabulated are the lower
and upper limits of
number of objects in
each category that the
author collated from
various publications, as
well as the total.
Herschel’s Classes of Objects
Class Type Lower Limit Upper Limit
I Bright Nebulae 288 289
II Faint Nebulae 907 912
III Very Faint Nebulae 978 987
IV Planetary Nebulae, Stars with Burs, with Milky
Chevelure, with Short Rays, Remarkable Shapes, etc.
78 80
V Very Large Nebulae 52 53
VI Very Compressed and Rich Clusters of Stars 42 43
VII Pretty Much Compressed Clusters of Large (Bright) or
Small (Faint) Stars
67 67
VIII Coarsely Scattered Clusters of Stars 88 89
Totals 2,50 0 2,520
http://www.skyandtelescope.com.au 57