The ASAS All Sky Automated Survey is an astronomical survey which goal is the photometric monitoring of 10^7 stars brighter than mag 14, all over the sky. Initiator of the project is Prof. Pzynski of Princeton University.

Each ASAS observation is characterised by a time stamp (Julian Date), one or more Aperture magnitudes with their corresponding error values, and a Grade:

  • Aperture magnitude: ASAS works with 5 apertures per exposure: 2, 3, 4, 5 and 6 pixels wide. Magnitudes obtained with the smallest aperture (2 pixels wide) are called MAG_0 magnitudes. MAG_4 magnitudes use the largest aperture (6 pixels wide). Peranso let's you select which aperture(s) to plot. Use small apertures for faint stars and larger ones for brighter stars. As a rule of thumb: use apertures in accordance with below table:




12 - 14


11 - 12


10 - 11


9 - 10




  • Grade: this is a quality indicator, going from A (best quality), B (medium quality), C (bad quality), to D (worst quality, probably useless). Peranso by default plots ASAS observations of grade A and B, but you can decide to plot other grades as well.


All ASAS observations are by default already heliocentric corrected.

Important note: Peranso uses a different color notation than ASAS for plotting light curves. The color of a Peranso ASAS observation is determined by the Grade of that observation. This allows to easily differentiate between high quality and low(er) quality ASAS observations. 

Peranso lets you plot ASAS light curves directly through the Internet by clicking on the Add Asas-3 light curve button in the ObsWin toolbar. But you can also import ASAS text files.

We acknowledge with thanks the services provided by the ASAS All Sky Automated Survey. For more information about ASAS, we refer to Pojmanski, G., 1997, Acta Astronomica, 47, 467. The All Sky Automated Survey