- (Q) Why is Solar longitude is not 0.00 deg at 24.00 hrs MTC ?
- (A) Sub solar longitude depends upon MTC as well as on EoT[1]. Therefore at MTC 0.00 solar longitude is not 0.00. EoT can have maximum values of +/- 0.7 hrs i.e. 10.5 degrees [2 - (page 38/40)]. Hence user may not see Sun at prime meridian (0.00 deg) at MTC 0.00 hrs. In the presented website, it is noted that sub-solar longitude goes from a positive value (say 349.5 ) to a negative value (-10.5 or so), and moves normally to zero and after zero move with positive values. Following web links are to be referred.
[1] http://www.giss.nasa.gov/tools/mars24/help/algorithm.html
[2] http://www-mars.lmd.jussieu.fr/mars/info_web/MCD4.3_ddd.pdf
- (Q) Why does the radius of circle around satellite change?
- (A) It has been provided to give user an indication of the distance of satellite from ground. Smaller the circle indicates that satellite is close to ground, and larger circle indicate farness to ground. Roughly it can be said that satellite attains radio visibility (say altitude higher than 30 deg) from the ground under the circle.