). It represents the cumulative collecting area over a given period of time for photons of a given energy coming from a given direction. 29/04/2013
New feature: creation of movies displaying the time evolution of a variable source or a transient event
The command :
allows the creation of an animation where
- the photon arrival time is included between time_min and time_max, expressed en MET (thses times must lie within the
limits of the considered week) Note : entering time_min=0 and time_max=0 allows one to selec all photons in the file. Delta_t is the time interval spanned by each image.
(in secondes).
Other, optional selections can be performed:
- in position, within a cicular sky region with radius r and centered at the point (RA,DEC);
- in energy included between emin and emax, expressed en MeV.
The resulting file, in "animated gif" format, is stored under the name movie/mov_#week.gif. It can be visualized, e.g, with firefox:
Installing create_movie.py is done by:
The file create_movie.csh can then be deleted:
Some examples of movies have been posted showing a gamma-ray burst, a solar flare, or the blazar 3C C454.3 (using 3 years of data),
07/03/2013 A tool creating an exposure map has been developed in order to better quantify variations of counting rate of a source (which depends on both flux and exposure).
The exposure has dimension area x time (and unit ). It represents the cumulative collecting area over a given period of time for photons of a given energy coming from a given direction.
To install the tool :
Usage :
This tool creates an exposure map for photons of energy 1 GeV for the considered week. It allows the user to see how exposure varies as a function of the source sky location and with time by comparing maps established for different weeks. The exposure map is located in the file figures/expo_aitoff_#semaine.gif.
06/03/2013 The Crab Nebula, long considered as the Standard Candle of Gamma-ray Astronomy is currently flaring, with a gamma-ray flux exceeding the usual flux by a factor of 3. This feature can be seen on the sky map in week 248, where the Crab now clearly outshines Geminga, in contrast to the usual situation. As an exceptional move, the NASA
mission management decided to alter the observation mode, switching form a sky-survey mode to a mode where the instrument points close to the Crab Nebulae most of the time.For more information, see the press release about a former flare.
06/03/2013creation of COSMAX News