Astrograph

Not to be confused with Celestial cartography.

A 13-inch (330 mm), f/5.3 astrograph at Lowell Observatory (a refractor with a 3 element Cooke triplet lens[1]) used in the discovery of Pluto.
A double astrograph consisting of two 6-inch (150 mm) astrographs and a central guide scope on display at Landessternwarte Heidelberg-Königstuhl observatory.
The Bruce double astrograph at the Landessternwarte Heidelberg-Königstuhl observatory.
This is a modern amateur Newtonian astrograph, specifically designed for astrophotography.

An astrograph (or astrographic camera) is a telescope designed for the sole purpose of astrophotography. Astrographs are mostly used in wide-field astronomical surveys of the sky and for detection of objects such as asteroids, meteors, and comets.

Improvements in photography in the middle 19th century led to designs dedicated to astrophotography, and they were also popular in the 20th century. As in other photography, chemicals were used that respond to light, recorded on a glass photographic plate or sometimes on photographic film. Many observatories of this period used an astrograph, beside instruments like the transit telescope, great refractors, and chronometers, or instruments for observing the Sun.

Astrographs were often used to make surveys of the night sky, and one of the famous projects was Carte du Ciel. Discoveries using an astrograph include then-planet Pluto. Rather than looking through the telescope, it was discovered by using a blink comparator with images taken by an astrograph.

By the late 20th century, electronic detectors became more common with the data being stored electronically.

  1. ^ Tombaugh, Clyde (5 April 1995). The Struggles to Find the Ninth Planet. NASA/JPL Outer Planets/Solar Probe Project, 5 April 1995. Retrieved from http://ircamera.as.arizona.edu/NatSci102/NatSci102/text/ext9thplanet.htm.