C2A 2.0.53

A solar system simulation software.
C2A (Computer Aided Astronomy) is a Planetarium software that allows you to build detailed views of multiple stellar fields. An important objective of this software is to take into account the main catalogues available to professional and amateur astronomers in order to prepare observations on small fields as well as astrometry and photometry works.

C2A is also an easy to use general purpose Planetarium software with many functions. C2A is able to display the following catalogues: SAO, GCVS, WDS and Hipparcos (all four provided with the standard program distribution), Guide Star, Tycho-2, USNO-SA1.0, USNO-A2.0, USNO-B1.0, UCAC1, UCAC2, UCAC3, NOMAD and PPMXL.

For photometry purpose, C2A natively integrates the Loneos catalogue. C2A is able to access directly over the Internet the catalogues ArasBeAM and Exoplanet Transit Database. Finally, C2A integrates an asterism catalogue.

Main features:

  • Milky Way display:
  • C2A displays the Milky Way whatever is the zoom level. Bézier curve computing is performed in order to render curved shapes
  • Nebulae display:
  • When the RNGCIC (Revised New General Catalogue and Index Catalogue) catalogue is the currently displayed catalogue, a certain number of diffuse nebulae are displayed with their real shape. The display of nebulae's shapes depends on both the zoom level and the filters in place for the deep sky objects. Some shapes are directly associated to NGC and IC objects (in which case they are displayed in light green) while others are not related to any specific NGC or IC objects (they can typically include several NGC and IC objects, in which case they are displayed in dark green)
  • Solar System:
  • Regarding the Solar System, positions computing of the Sun, Moon and planets are performed using some special algorithms from the Institut de Mécanique Céleste (Bureau des Longitudes) in Paris. Polynomial coefficients used in these algorithms provide a very high accuracy on object positions (1/100 arc second over the period 1987/2020, which can be extended to 2100 using the polynomial coefficient file available in the Downloads page of this site). The screenshot shows Venus path with a retrogradation at the top of a synthetic sky background
  • Ecliptic View:
  • C2A integrates a tool to view planet, asteroid and comet positions according to an ecliptic view (accessible from the Tools menu). It is possible to easily change the angle of view as well as the zoom level using the mouse. Furthermore, an animation mode is available
  • Ephemeris Production:
  • C2A includes a full Ephemeris production system (Moon, Sun, planets as well as comets and asteroids known through their orbital elements). The output step can be adjusted and the produced ephemeris can be saved under the form of a text file or directly printed
  • Moon Phases:
  • C2A includes a module to compute and display Moon phases for a given month. Furthermore, dates of Full Moon, New Moon, First Quarter and Second Quarter are specifically provided
  • Asteroids and comets:
  • C2A includes a powerful system to compute asteroid and comet position calculation from their orbital elements. A Graphical User Interface allows the user to import and handle orbital elements. It is possible to import orbital elements directly from the Internet, for instance from the Minor Planet Center site. Several different orbital elements formats are supported. Once the orbital elements are loaded, it is then possible to plot the positions or trajectories of the objects
  • Planetary Positions:
  • C2A gives the possibility to display planetary positions at 3 different dates for a given month. This display is performed either at the beginning, middle or end of the night. It is done on a map with constant azimut and altitude. This is a useful tool to see at a glance what are going to be the observing conditions for a given object during a given month. It is possible to parameterize the display through numerous options
  • Proper Motions:
  • C2A is able to take into account proper motions for the stars in the catalogues UCAC1, UCAC2, UCAC3, Hipparcos and Tycho-2. The associated image shows the successive positions of the Barnard's star between 1959 and 2030. This animated image has been created with the UCAC2 catalogue
  • Image Processing:
  • C2A integrates an image processing tool where the most common tasks around astronomical images can be performed: contrast display, visualization threshold setting, color palette changes, zoom, printing, ... Several different formats are taken into account, either formats with visualization dynamics (FITS, CR2, PPM, PGM and PIC the format of the Iris software), or formats without visualization dynamics (JPG, GIF, BMP). Beside these basics features, C2A has several advanced features: automatic astrometry on a field using the PinPoint engine, image acquisition through the Maxim DL software and a camera focus tool
  • User Images:
  • The user has the possibility to add its own images in the C2A environment. Once one or several images are associated to a given object (for instance a Messier or an NGC object), access to those images is performed through the button Image... in the information window displayed for that object. The command Image... in the contextual menu can also be used (this menu is displayed with the mouse right button when an object with an associated image is pointed). Object types to which images can be associated to are the following: deep sky objects from the standard deep sky, PGC and RNGCIC catalogues, SAO stars, user objects, Tycho2 star, UCAC1, UCAC2 and UCAC3 stars, ArasBeAM stars, Hipparcos, GCVS, WDS or Loneos stars, planets, Moon, Sun and satellites. User can also associate a text of his/her choice to a given image (for example some comments about how the image was acquired). This text is then automatically displayed in an information box associated to the image. All the images must be stored in a directory declared in the Path tab of the Options dialog box. The first image associated to an object must be named according to the pattern [object name]_1.[extension] where [object name] is the name of the object displayed in the information window and [extension] is the file extension associated to one of the supported image formats (fit, fts, fits, pic, jpg, gif and bmp ). For example, the first JPEG image associated to the object NGC 1972 must be named NGC 1972_1.jpg. The second one must be named NGC 1972_2.jpg, etc
  • Printing:
  • Maps, ephemeris and pictures can be printed on all the printers supported by the Windows Operating System. Several options are possible to improve printing results as shown in the associated image. To see a printing result in the PDF format, click here
  • Prepoint Track:
  • C2A includes a simple tool to position a telescope on the sky in such a way that at a given time, a pre-defined object is at the center of the field pointed by the telescope. This function, called prepointing, is especially useful in the scope of occultations of stars by asteroids where, several minutes or hours before the event, the telescope is put in position with the RA tracking stopped. The star will drift in the field of view until it reaches the center at the target time

last updated on:
August 15th, 2014, 7:20 GMT
file size:
38.9 MB
developed by:
Philippe Deverchère
license type:
operating system(s):
Windows XP / Vista / 7 / 7 64 bit
C: \ Others \ Home & Education


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17 Screenshots
C2A - This is the main user interface of C2A where you can search for a specific solar body and the map will center to it, displaying detailed info at the same time.C2A - The File menu is where you can save your map, create a restore point, access user catalogs or export objects.C2A - By accessing the Edit menu you are able to use the zooming tool, go to next or previous field and launch the Find tool.C2A - You can enable the grid, meridian, constelations, ecliptic, Milky Way or synthetic sky views.C2AC2AC2AC2AC2AC2AC2AC2AC2AC2AC2AC2AC2A
What's New in This Release:
  • New features:
  • Support of the catalogue CMC15, an astrometric and photometric catalogue of more than 122.7 million stars in the red magnitude range 9 to 17.
  • Support of the catalogues Guide Star 1.2 and Guide Star ACT in their native formats. This provides more information on the catalogue objects than the compressed version of the 1.1 catalogue used until now by C2A. It is also posible to perform searches on the 1.2 and ACT catalogue objects.
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