Hodierna's Deep Sky Observations

Longly forgotten or neglected, Giovanni Batista Hodierna (1597-1660), astronomer at the court of the Duke of Montechiaro, compiled a catalog of some 40 entries, including at least 19 real and verifyable nebulous objects, found with a simple Galilean refractor of magnification 20, and printed in Palermo in 1654 (Hodierna 1654). This work was listed in the "Additions" of Lalande's "Bibliographie Astronomique" of 1803 (Lalande 1803), but otherwise neglected, until it was rediscovered only in the early 1980s, published by Serio, Indorato, and Nastasi (1985) and Kenneth Glyn Jones (1986).

Thanks to Fredi De Maria of the ORSA, Palermo, Italy, Hodierna's book "De Admirandis Coeli Characteribus", which contains his observations of nebulous objects, can now be found online (Italian language website). The book and the images were made available by the Osservatorio Astronomico di Palermo. The present author is grateful to Fredi for mailing him a copy of the article by Serio et.al.. This allowed me to revise this page appropriately.

Hodierna classified his objects according to what he thought they were resolvable into stars; he believed that all nebulous objects were actually cluster, which was a common view at that time, since Galilei had resolved the Milky Way, and e.g. the Praesepe cluster M44. The scheme was:

Luminosae: Stars visible to the naked eye
Nebulosae: Nebulous for the naked eye, but resolved in a telescope
Occultae: Unresolved nebulosity also in telescope

As for most early classifications, Hodierna's is of historical interest only and not related to physical object types.

Hodierna's observations include an independent rediscovery of the Andromeda Nebula (M31) and the Orion Nebula (M42), and at least 9 (probably 10) own true discoveries, as listed by Kenneth Glyn Jones: M6, the Lagoon Nebula M8, M36, M37, M38, M41, M47, NGC 2362, NGC 6231, and (possibly) NGC 2451. Hodierna was also the first who made a still preserved drawing of the Orion Nebula M42.

A list of the objects described by Hodierna follows. It was taken from Serio's original article, corrected for the misprint of NGC 2445 for NGC 2451, and contains several more objects not given above: It lists an original rediscovery of Brocchi's Cluster, an original "discovery" or first description of the Alpha Persei Moving Cluster, the probable original discoveries of M34, M33, and NGC 752, as well as possible original discoveries of NGC 2169 and NGC 2175.

Luminosae

Ha. I.1        M45 (Pleiades)
Ha. I.2        Hyades (Mel 25)
Ha. I.3        Coma Berenices Star Cluster, Mel 111
Ha. I.4    !   Alpha Persei Moving Cluster, Mel 20
Ha. I.5   (!)  M42
Ha. I.6        Asterism including Lambda, Phi1 and Phi2 Orionis
Ha. I.7    !   NGC 6231
Ha. I.8        Asterism in "the Water of" Aquarius

Nebulosae

Ha. II.1       M44 (Praesepe)
Ha. II.2       M7
Ha. II.3       NGC 869/884, h and Chi Persei
Ha. II.4   !   M6
Ha. II.5       Asterism of Nu1, Nu2 Sagittarii
Ha. II.6   !   M8 (Lagoon Nebula)
Ha. II.7   !   M36
Ha. II.7   !   M37
Ha. II.7   !   M38
Ha. II.8  (!)  "Al Sufi's Nebula", Brocchi's Cluster, Collinder 399
Ha. II.9       Asterism around 88 Herculis
Ha. II.10      Asterism in front of the head of Capricornus

Occultae

Ha. III.1      Asterism in Coma Berenicis
Ha. III.2      Asterism in Coma Berenicis
Ha. III.3 (!)  M31

Other Nebulae Listed in Text

Nebulosae

Ha. IV.1   !   M47
Ha. IV.2   !   M41
Ha. IV.3       asterism including Nu1, Nu2, Pi Puppis
Ha. IV.4   !?  probably M33
Ha. IV.4   !?  probably NGC 752
Ha. IV.5       ? insufficient description
Ha. IV.6       ? insufficient description
Ha. IV.7       ? insufficient description
Ha. IV.8       non-existent nebulosity near Hyades
Ha. IV.9       non-existent nebulosity near Pleiades
Ha. IV.10  !?? NGC 2169 ?
Ha. IV.11  !?? NGC 2175 ?
Ha. IV.12  !?  probably M34

Occultae

Ha. IV.13      ? insufficient description
Ha. IV.14      ? insufficient description
Ha. IV.15      ? insufficient description

Nebulae Shown in Maps Only

Ha. V.1    !   NGC 2362
Ha. V.2    !?  NGC 2451 ? (misprinted 2445 in Serio's article)
Ha. V.3        Asterism including k1, k2 Velorum (near NGC 2671)
Ha. V.4        Asterism in Canis Maior including star HD 58535

Links

References

Giovanni Battista Hodierna, 1654. This is actually the second part of a larger work, "De systemate orbis cometici, deque admirandis coeli characteribus" [About the systematics of the cometary orbit, and about the admirable objects of the sky]. Palermo. Available online (with Italian translation by Fredi de Maria)
Kenneth Glyn Jones, 1986. Some Notes on Hodierna's Nebulae. Journal of the History of Astronomy, No. 50 (August 1986).
Jérôme de la Lande, 1803. Bibliographie Astronomique; avec l'Histoire de l'Astronomie depuis 1781 jusqu'a 1802. Paris, 1803. Lalande describes Hodierna's work as follows:
1654. Panormi, in 4.deg. De Systemate orbis cometici, deque admirandis coeli characteribus (Hodierna).
"Montucla le cite comme ayant parlé des amas l'etoile qu'on appelait alors nébuleuses."
G.F. Serio, L. Indorato and P. Nastasi, 1985. G.B. Hodierna's Observations of Nebulae and his Cosmology. Journal of the History of Astronomy, Vol. XVI, No. 45, p. 1-36 (February 1985).

Please send me pointers to any errors, clarifications and/or comments, as well as any further info you have.

More Deepsky Observing lists

History of the Discovery of the Deepsky Objects

Some other historical catalogs

Hartmut Frommert
Christine Kronberg
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Last Modification: August 25, 2007