Indiana Astronomical Society

Observation Planning

Search for astronomical objects visible at a specified time and location.

Arp Galaxies

Halton Arp Arp Galaxies - A catalog of peculiar galaxies that do not fit into a conventional galaxy classification scheme, such as the Hubble tuning fork. Halton C. Arp began compiling this atlas in 1962. During that period, galactic morphologist wondered whether some evolutionary or astrophysical trend might become apparent if they were systematically assorted by shape. By and large, the kind of peculiar galaxies that Arp eventually turned up could not simply be pronged onto a tine of the Hubble tuning fork or dropped into the bins of Knut Lundmark's "bins".

Source - The Arp Atlas of Peculiar Galaxies - A Chronicle and Observer's Guide by Jeff Kanipe and Dennis Web.

Caldwell Objects

Caldwell Objects - A Catalog composed by Sir Patrick Alfred Caldwell-Moore that lists 109 object not identified by Messier arranged in order of declination, beginning in the far north and ending in the far south -- from Cepheus to Chamaeleon. All objects are accessible to amateurs using modern 4-inch and larger telescope under a dark sky, but some are more difficult than others. The catalog was first published by Sky & Telescope Magazine in its December 1995 issue.

Source - Sir Patrick Moore in Deep Sky Companions - The Caldwell Objects by Stephen James O'Meara

Herschel - 400

Herschel-400 Objects - The Herschel 400 catalogue is a subset of William Herschel's original deep sky catalogue of 2,500 deep sky objects, selected by Brenda F. Guzman (Branchett), Lydel Guzman, Paul Jones, James Morrison, Peggy Taylor and Sara Saey of the Ancient City Astronomy Club in St. Augustine, Florida, USA circa 1980. They decided to generate the list after reading a letter published in Sky & Telescope by James Mullaney of Pittsburgh, Pennsylvania, USA. In this letter Mr. Mullaney suggested that William Herschel's original catalogue of 2,500 objects would be an excellent basis for deep sky object selection for amateur astronomers looking for a challenge after completing the Messier Catalogue.

Source -

Charles Messier

Messier Objects - Charles Messier was a French comet hunter in the 1750s. In Messier's day, astronomers did not have the benefit of good start charts like we have today, showing th epositions of galaxies, star clusters, and nebulae - what the great twentieth-century comet hunter Leslie Peltier termed "comet masqueraders." these objects were largely unknown and uncharted. Thus Messier began to build a catalog of what he called these "embarrassing objects". By 1765, Messier had compiled a list of 41 such objects. Of those, only 17 or 18 were his own discoveries; the rest had been seen previously by others (whom he acknowledged). Before submitting the list for publication, he decided to round it out with a few more objects so on 4 March of that year he determined the positions of M42, M43, M44, and M45. He presented his list of 45 nebulae and star clusters to the Academy of Sciences in Paris in February 1771, and it appeared in the Academy's Memoirs for that year, which were actually published in 1774.

Source - Deep Sky Companions - The Messier Objects by Stephen James O'Meara

NOTE: The calculations used in the lists above do not account for atmospheric refraction or the earth's precession among other things that can cause positional inaccuracies. The calculations are based upon the sidereal date at the observer's location, and the right ascension and declination of the listed object. The calculations are not accurate enough to point your telescope at an astronomical object, but can be used to determine if an object is above 30 degrees to within a reasonable accuracy for visual observations. The results are not guaranteed, you should check your list against other sources.

Google Moon Map

Google Moon Map - View a visible light or elevation map of the Moon. You may scroll and zoom the map using your mouse. The maps allow you to zoom in on the apollo landing sites.

Google Mars Map

Google Mars Map - View a visible light, infrared or elevation map of Mars. You may scroll and zoom the map using your mouse. The maps show features such as Mountains, Plains, Spacecraft, Canyons, Ridges, Dunes and Craters.

Other Helpful Links

Moon Phase Calculator - courtesy of Stardate Online

Tonight's Sky - Helping the amateur astronomer plan their night by showing what you can see and what it will look like.

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