Astrograph


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astrograph

[′as·trō‚graf]
(astronomy)
A telescope designed to be used exclusively for astronomical photography.
(mapping)
A device for projecting a set of precomputed altitude curves onto a chart or plotting sheet, the curves moving with time such that if they are properly adjusted, they will remain in the correct position on the chart or plotting sheet; used in mapping the heavens.

Astrograph

 

an astronomical instrument for photographing celestial objects. Astrographs are constructed according to the designs of refractors, reflectors, or mirror-lens telescopes (Schmidt telescope, Maksutov telescope, and others). A filmholder with a photographic plate is fitted on the eyepiece end of the astrograph. The rotation of the astrograph in synchronism with the daily motion of the celestial sphere is achieved by an accurate timing mechanism and is controlled by the observer with the aid of a guide—a second optical tube which is fixed parallel on the same mounting. Some astrographs just use a photoelectric guide to automatically hold the star at a fixed point on the photographic plate.

The astrograph’s main feature is the focal length of the lens or the main mirror and the aperture size of the instrument. Short-focus, wide-angle astrographs are used to photograph stars over large areas of the sky, meteors, artificial earth satellites, comets, and asteroids. These astrographs have focal lengths of less than 1 and cover several tens or more square degrees of the sky. For more accurate measurements of the positions of stars and planets as well as of the proper motion of stars, astrographs with focal lengths of several meters are used. These are the so-called normal astrographs (focal length 3.5 m) and zonal astrographs (2.0 m). Astrographs with the longest focal lengths (7–19 m) are used for the highly accurate work of determining star parallaxes and measuring binary stars. The main advantage of mirror astrographs is their high aperture, which allows relatively short exposure times for photographing very faint objects, specifically of space probes receding from the earth.

A. N. DEICH

References in periodicals archive ?
Another Sobral telescope, known as an astrograph, also produced lots of star images, but they were blurred and out of focus, perhaps because heat from the sun had affected the telescope mirror.
From the specifications above, the study chose a design using a Takahashi CCA250 astrograph ($17,000 each) paired with an e2V CCD230-42 camera ($42,000 each) as a reference that meets the system specifications.
The Pohl Observatory has a 24-inch Corrected Dall-Kirkham Astrograph telescope that was made possible by a donation from Emeritus Chemistry faculty--Dr.
With more and more photographers looking to point their DSLR cameras at the cosmos, Celestron engineers created the new Rowe-Ackermann Schmidt Astrograph. Although it might look like a telescope, this new instrument cannot be used with an eyepiece, and was designed specifically for astroimaging with DSLR and astronomical CCD cameras.
Zacharias, "Radio-optical reference frame link using the US Naval Observatory Astrograph and Deep CCD imaging," The Astronomical Journal, vol.
Lopez reported that CCD observations obtained on Apr 25.2 at El Leoncito (0.5m f/7.5 double astrograph) also showed the object to be diffuse [IAUC 7613, 2001 Apr 25].
Q: I read that a new survey camera was incorporated into the astrograph telescope.
Chinese clones of the venerable Vixen Great Polaris German equatorial mount pictured here are available for around $400, and the Astro-Tech 6-inch f/9 Ritchey-Chretien astrograph retails for $795.
Celestron announces the newest addition to its line of ultra-fast astrographs. The 8-inch Rowe-Ackermann Schmidt Astrograph ($1,699) is an f/2 optic designed exclusively for deep-sky imaging.
On this occasion, he used a 0.51m f/6.8 astrograph and wide-band clear filter at a remotely-operated observatory near Mayhill, New Mexico, USA.
DETAILS: 210-millimeter Takahashi Epsilon astrograph and SBIG STL-11000XM camera.
It escaped detection until 1938, when Harlow Shapley noticed it on a 24-inch Bruce astrograph plate taken at Harvard's Boyden Station in South Africa.