William Herschel's catalog of Deep Sky objects

[herschel.jpg] Thanks to Bill Arnett, William Herschel's catalog is available online. Bill acknowledges David Bishop for making it available. You have the following options: More material on Friedrich Wilhelm (William) Herschel: William Herschel got interested in systematically looking for, and observing, "nebulae" and star clusters when he was presented a copy of the Messier Catalogue in December, 1781. Up to that time, he had recorded observations of only 4 nebulae (in particular, the Orion Nebula M42 and M43 as early as March 4, 1774). He started observing these objects about August, 1782, and made his first own original discovery on September 7, 1782 (of the Saturn Nebula, NGC 7009). After researching for some time how to do these observations, discoveries and recordings most efficiently, he started a systematical survey with considerable effort, assisted by his sister Caroline, on October 23, 1783, with his 18.7-inch aperture, 20-foot focal length reflector, with standard magnification 157 and a field of view of 15'4". He made his next discovery on October 28, 1783: NGC 7184, Herschel's H II.1, a little conspicuous galaxy in Aquarius of 11.2 mag.

At that time, Caroline had already started to make a number of own deepsky discoveries with her smaller Newtonian telescope; look at her list (of about 13).

In only 1 1/2 years until April 1785 he cataloged 1000 deepsky objects, a second catalog of 1000 objects followed to 1788 (published 1789), and a further 500 objects to 1802.

William Herschel was usually carefully avoiding to number the Messier objects, in appreciation of Messier's prior work. However, he of course numbered the missing and the additional (i.e., later added) objects, as he did not look at them as Messier's "nebulae". Erroneously, he also numbered some of the Messier objects though, and in some cases, parts of Messier objects. Look at the complete list.

Almost all of Herschel's objects (even the non-existing, erroneous entries) have also obtained an NGC number; there are only four or five exceptions.

As the most renowned astronomer of his time, William Herschel contributed significantly to most branches of astronomy: Besides searching clusters and nebulae, he discovered planet Uranus in 1781, two satellites of Uranus, Titania and Oberon, in 1787, and Saturn's moons Mimas and Enceladus in 1789, he investigated the proper motion of stars and derived the peculiar motion of the solar system toward the direction of constellation Hercules, modelled the Milky Way galaxy from stellar statistics, and speculated about the nature of the nebulae, including a discussion of the possibility of external island universes (galaxies) which had been brought up by Kant. He also contributed to physics (especially optics) and, e.g., discovered the infrared light.

Thanks to Arild Mikalsen from Norway for contributing some corrections to this page !

  • Other Deep Sky catalogs suitable for the amateur
  • History of the Discovery of the Deepsky Objects

    Hartmut Frommert (spider@seds.org).
    Christine Kronberg (smil@lrz.uni-muenchen.de)

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    Last Modification: 6 Aug 1999, 13:40 MET