3.3.1 ASTROVIEWER - Tool to aid Celestial Source Viewing

The tool gives the view periods of a selected celestial source for a prolonged period of one year maximum.  Also, the view periods that satisfy all the constraints are provided orbit-wise so that the PIs of proposals can plan their observations more accurately and also season-wise. For UVIT payload users, view duration timings during eclipse that satisfies all envisaged constraints are available in a separate file as UVIT is expected to observe only in eclipse.  The Tool has been designed to use the latest orbit information available on a daily basis and provides the various constraint angle characteristics in graphical plots so that GO can visualize the situation while planning for observations. The view period of the selected source is stored orbit wise and is made available in tabular form for the GO to use.  Since the ram angle constraint for certain sources are on and off due to the closeness to the orbit inclination, this output contains flags ‘0’ for satisfying the constraint and ‘1’ for violating the constraint in the table.  A Graphical User Interface program allows the user to interact remotely and obtain the required details. Additional information like Eclipse and occult Entry/Exit is also made available. 

Geometrical Constraints

  • RAM angle (+ROLL and velocity vector) > 12˚
  • Terminator (+ROLL and Bright Earth Limb)  > 12˚
  • Sun Angle (+ROLL and SUN)  > 65˚
  • Angle b/w +YAW and SUN > 90˚
  • Angle b/w Star Sensor and SUN > 50˚  Angle b/w +ROLL and Albedo > 12˚