Fame

On the 30th September 1880 Henry Draper obtained the first photograph of any deep sky object - Messier 42 - the 'Great Orion' nebula. The length of the exposure was 57 minutes. Draper used an 11" (28cm) refractor built by the famous telescope maker Alvan Clark, supported by an equatorial mount also built by Clark. He made use of the new Gelatine-Bromide Dry Plates which were of greater sensitivity than the earlier wet collodion plates. This he thought would decrease the exposure required and minimize the degree of star trailing due to imperfections in the telescope's drive mechanism The telescope was originally intended for the Lisbon Observatory, and had the added benefit of being fitted with a photographic corrector lens. Draper took two other photographs of Messier 42 in March of 1881 and on 14th March 1882, but this time with longer exposures of 104 minutes and 137 minutes respectively. It is a remarkable photograph and truly deserves it place as one of the greatest of all early astronomical photographs. Indeed it reminds me of many 'first attempts' at M42 by novice imagers! As of 1996, Draper’s House, along with the Observatory and the 11” Refractor has been preserved, and is now home to the Hastings Historical Society (see photographs above).

Sponsor

Henry Draper (1837-1882) was one of the great pioneers of Astrophotography. He was the first person to photograph a Deep Sky Object, when he imaged M42 in 1880 above left). His earliest efforts were in the imaging of the Sun and Moon in the early 1860’s (see image above right), and the results obtained were amongst the finest taken at that time. From 1872 he began his great work in spectroscopic astrophotography, being the first person to obtain an image of a star’s spectrum (Vega). He was also the first to detect the presence of Oxygen in the Sun’s atmosphere. In the years 1879 to 1882 he obtains the spectra of 50 of the brightest stars. He tragically died at the early age of 45 years old from a severe chill caught on a shooting trip to the Rocky Mountains.

Construction

In order to compare the performance of his own 28” mirror with a large Refractor, he ordered in the winter of 1875 a 12” refractor from the famous telescope maker Alvan Clark. From the outset Draper was not happy with its performance. In 1880 he swapped it for an 11” Refractor from Alvan Clark originally destined for the Lisbon Observatory, which had the additional advantage in that it was fitted with a Photographic corrector lens. Draper was very happy with this instrument, and it was with this telescope that he photographed the Great Orion Nebula (M42) on the 30th September 1880 with an exposure of 57 minutes. The Clark 11” Refractor was housed in the Observatory Draper had built in the spring of 1860 at Hasting-on-Hudson, New York on land owned by his father. The equatorial mount for the telescope was constructed by Draper himself. Alvan Clark (March 8, 1804 – August 19, 1887), born in Ashfield, Massachusetts, the descendant of a Cape Cod whaling family of English ancestry, was an American astronomer and telescope maker. He was a portrait painter and engraver, but at the age of 40 become involved in telescope making. Using glass blanks made by Chance Brothers of Birmingham and Feil-Mantois of Paris, his firm Alvan Clark & Sons ground lenses for refracting telescopes, including the 36” Refractor at the Lick Observatory, and the 40” Refractor (still the largest) at the Yerkes Observatory.

Specification

The success of Draper in obtaining his famous photograph of M42 was due not only to the quality of the Clark Refractor and his foresight in using Dry Plates, but more importantly to the Clock Mechanism of the Mount. Draper was obliged to construct no less than seven driving clocks before he succeeded in getting one that was perfect. The regulator of the last one was a heavy conical pendulum, or rather pair of pendulums, weighing some fifteen pounds, and so hung that their revolutions were sensibly isochronous through quite a range of inclination. Whenever by increase of driving power or decrease of resistance one of the balls rose above a certain limit it acted, without affecting the radial motion of the ball, upon a friction spider which absorbed the superfluous energy. This regulator revolved once in a second. The gearing and driving screw were constructed, for the most part, by Draper himself, with the utmost care and accuracy. In its perfected condition the driving clock was as good as any in existence, keeping a star centred for an hour at a time.