Downloading C2A 2.1.13 from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this software available. This PC program can be installed on 32-bit versions of Windows XP/XP Professional/Vista/7/8/10/11.
We recommend checking the downloaded files with any free antivirus. The most popular versions among the program users are 2.1 and 2.0. C2aw.exe and C2A.exe are the most common filenames for this program's installer. This free tool was originally developed by Philippe Deverchère. The program lies within Education Tools, more precisely Science Tools.
From the developer:
C2A (Computer Aided Astronomy) allows you to build detailed views of stellar fields. It has the ability to display various catalogs including SAO, GCVS, WDS, Gliese, and Hipparcos. C2A is able to access ArasBeAM, Exoplanet Transit Database, and IAU Meteor Showers over the Internet. C2A integrates numerous functions such as planetary position computing, asteroid and comet path display, ephemeris production, and telescope control.
You may want to check out more software, such as StatPlus, StarCalc or Water And Steam Properties for Windows, which might be similar to C2A.