Aciqra (uh-SEE-kruh) is a free and open source virtual planetarium and sky mapping program which tracks celestial bodies including planets, deep sky objects and stars to an accuracy of a fraction of a degree for thousands of years into both the future and the past.
Nightshade is free, open source astronomy simulation and visualization software for teaching and exploring astronomy, Earth science, and related topics. Nightshade is a fork of the award-winning Stellarium software, but tailored for planetarium and educator use.
The emphasis is on usability
... [More], realism, feature stability, and performance. It is backward compatible with scripts for Stellarium 0.8.2 and earlier using the StratoScriptTM language developed and maintained by Digitalis Education Solutions, Inc.
It is available for Linux, Windows, Mac OSX, and other platforms. [Less]
DSO Tonight is a Java application which aims to help plan an observing session.
It contains a list of 14000 Deep Space Objects, which are interactively searchable on name, apparent-size, brightness, right-ascension, declination, constellation, and object type
You can quicklly download images
... [More] from a variety of sources to determine whether an object is interesting to you.
DSO Tonight will calculate sidereal time, and set reasonable RA/Dec limits based on your Latitude and Longitude [Less]