William Herschel's catalog (original) (raw)

William Herschel's catalog of Deep Sky objects

[ ](../../Pics/History/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:

• The Astronomical League's selection of 400 Herschel objects, for which the AL grants the Herschel Award. This list was compiled by Brenda Branchett of Deltona, Florida.
• The full Herschel list of 2500 (actually 2514), which according to David was originally compiled by Fr. Lucian J. Kemble (1922-1999), a Franciscan Friar then living in Cochrane, Canada, who later moved to Lumsden, Saskaschewan, Canada, but the list partially lost; Richard Hook (astronomer from England, now at ESO) helped to restore. The list may still be somewhat buggy, though. Moreover, besides these (mostly typing) errors, Herschel's list is indeed considerably less reliable than Messier's smaller catalog: Herschel's catalog contains 36 duplications, 4 entries belong to two objects each, two further are listed twice as it is uncertain which object corresponds to them, and 87 objects marked as nonexistent in our lists (for whatever reason). Thus it seems that actually 2397 objects belong to the total of 2520 entries in our list (some of these objects are still multiple stars, or asterism).
• I extracted the "Notes" on Herschel's catalog of David Bishop from Bill's README
• Goto Bill Arnett's complete Herschel directory. The present author (hf) has revised some of these data and rearranged the list. Moreover, I decided to publish online my working list Herschel objects with discovery dates (by William Herschel) and remarks (discoverers etc):
• I have created a Herschel 2500 list sorted by Herschel number, availablein html (linked to our pages) or asplain ascii file.
• William Herschel's 2500 objects with discovery date and remarks, by Hartmut Frommert, based on the list of David Bishop (plain test only for the time being). More material on Friedrich Wilhelm (William) Herschel:
• Short biography of F.W. Herschel by Peggy Taylor & Sara Saey, maintained by Bert Stevens
• Astronomical League material on the Herschel objects; in particular, they have selected 400 objects which are suitable for observing by the better equipped amateur. These are compiled in two lists, which are available in numerical or in constellation order:
  • Herschel objects list 1 (NGC numerical order)
  • Herschel objects list 1 (constellation order)
    We have a local copy of thisHerschel 1 list of 400 in plain text, and and a local copy of the Astronomical League's old Herschel 2 list of 400
• The Herschel II Club: More Herschel objects for amateur observers [archival index local copy]
• NEW! The Herschel 3 list of 300 Herschel galaxies, by Tom Hoffelder
• The Herschel 400 list from the Astronomical League has become quite popular, so there are a number of further websites featuring this list:
  • Interactive star charts for Herschel 400 Objects, by Jim Cornmell
  • EVAC's Herschel 400 list
  • The Observing Webpage of The Astronomy Connection offers monthly lists of Herschel 400 objects to observe. They also offer a copy of theHerschel II list.
• An article on William Herschel has appeared in the Electronic Journal of the Astronomical Society of the Atlantic (EJASA), June 1991 (thanks to Larry Klaes for the hint !)
• The larger original of our picture of William Herschel (attn: >300 k image), was from the Planetarium Armargh historic collection (where it is no more available). This portrait is represented after a copper plate by James Goddy.
• William Herschel Museum: William Herschel discovered Uranus in 1781 from a house in Bath, England, which is now a museum.
• William Herschel's 20-foot reflecting telescope (NASM)
• William Herschel's Discovery of the Infrared (SIRTF/Caltech)
• William Herschel's Observations of Messier's Objects.
• Short biography of 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 Catalogin December, 1781. Up to that time, he had recorded observations of only 4 real and 2 non-existing nebulae:
• the Orion Nebula M42 and M43, together with two non-existing neighboring fainter nebulae, observed as early as March 4, 1774, of which he had learned from Robert Smith' book Opticks (Smith 1738),
• globular cluster M13 in Hercules on August 22, 1779, and
• the Andromeda "Nebula" M31 on August 6, 1780. See a list of William Herschel's Observations of Messier's Objects. He started observing these objects in August, 1782, first observing globular cluster M5 in Serpens on August 5. By chance, he made his first own original discovery on September 7, 1782, of the Saturn Nebula, NGC 7009. There followed a time of researching how to do these observations, discoveries and recordings most efficiently; during that time, William's sisterCaroline started to make a number of own deepsky discoveries with her smaller Newtonian telescope:look at her list (of eventually 20, including 8 original and 5 independent discoveries).

Probably inspired by Caroline's unexpected success with her small instrument, William looked for nebulae himself, and independently found the Tau Canis Majoris cluster, NGC 2362, on March 4, 1783 (e.g., Hoskin 2005). Eventually, he commenced a systematical survey with considerable effort, assisted by 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"; this telescope was used to discover most of William Herschel's deepsky objects. He made his next discovery on October 28, 1783: NGC 7184, Herschel's H II.1, a little conspicuous galaxy in Aquarius of brightness 11.2 mag.

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. The final 8 objects found in 1802 remained unpublished until 1847, when his son John Herschel published them in appendix to his catalog of observations made in South Africa (John Herschel, 1847).

The accumulation of discoveries in the earlier years of search, the decrease in the later 1780s, and the more occasional continuation thereafter, indicates that Herschel's hunt for nebulae and clusters was not carried through to "triumphant completion," but more an "unfinished business," as Michael Hoskin recently reported (Hoskin 2005a, Hoskin 2005b). This was due to the fact that after an enthusiastic and fruitful start in 1784 and 1785, other work arose and took more and more time, such as the construction of the great 40-foot reflector. William's 1788 marriage, 1792 birth of son John, as well as other discoveries and interests took even more time from the nebula project, so that finally Caroline and William needed full 14 years for the final catalog of 500 objects, leaving "un-swept" significant areas of the sky, in particular around the North Celestial Pole.

During this time, William Herschel also accumulated numerousobservations of most Messier Objects.

He invented the following classification scheme for nebulae and star clusters, based on the appearance of these objects as he perceived them, rather than physical properties:

1. Bright Nebulae
2. Faint Nebulae
3. Very faint Nebulae
4. Planetary Nebulae
5. Very large Nebulae
6. Very compressed and rich star clusters
7. Compressed clusters of small and large (i.e., faint and bright) stars
8. Coarsely scattered clusters of stars William Herschel compiled his lists with running numbers for each object type. Because of the missing physical meaning of this classification, it is of historical importance only.

William Herschel was usually carefully avoiding to number the Messier objects, in appreciation of Messier's prior work. However, he of course numbered the missingand 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 also 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, established the common existence of physical binary stars, 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 and evidently, to optics) and, e.g., discovered the infrared light.

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

References

• William Herschel, 1786. [XXVII.] Catalogue of One Thousand new Nebulae and Clusters of Stars. By William Herschel, LL.D.F.R.S. Read April 27, 1786. Philosophical Transactions of the Royal Society of London, Vol. LXXVI (76), pp. 457-499 [ADS: 1786RSPT...76..457H]
• William Herschel, 1789. [XX.] Catalogue of a second Thousand of new Nebulae and Clusters of Stars; with a few introductory Remarks on the Construction of the Heavens. By William Herschel, LL.D.F.R.S. Read June 11, 1789. Philosophical Transactions of the Royal Society of London, Vol. LXXIX (79), pp. 212-255. [ADS: 1789RSPT...79..212H]
• William Herschel, 1802. [XVIII.] Catalogue of 500 new Nebulae, nebulous Stars, planetary Nebulae, and Clusters of Stars; with Remarks on the Construction of the Heavens. By William Herschel, LL.D.F.R.S. Read July 1, 1802. Philosophical Transactions of the Royal Society of London, Vol. XCII (92), pp. 477-528. [ADS: 1802RSPT...92..477H]
• John Herschel, 1847. Results of Astronomical Observations made during the Years 1834, 5, 6, 7, 8, at the Cape of Good Hope. Smith, Elder and Co., London. Here p. 128, Appendix. Places and Descriptions of Eight Nebulae discovered by the late Sir William Herschel, but not published in his Catalogue. Appendix to the Catalog of Nebulae and Clusters of Stars.
• Michael Hoskin, 2005. William Herschel's Sweeps for Nebulae. Journal for the History of Astronomy, Vol. 36, Part 2, No. 123, p. 230 (May 2005).
• Michael Hoskin, 2005. Caroline Herschel as Observer. Journal for the History of Astronomy, Vol. 36, Part 4, No. 125, pp. 373-406 (November 2005).
• Michael Hoskin, 2005. Unfinished Business: William Herschel's sweeps for nebulae. History of Science, Vol. 63, in press.
• Robert Smith, 1738. A compleat system of opticks.

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

This webpage was selected as Houston Astronomical Society Site Of The Week for July 1, 2004

Hartmut Frommert
Christine Kronberg
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Last Modification: July 25, 2011