Is there a "easy" way of figuring out where/when a given apogee will at a given lat.long? I want to try to predetermine when the apogee will be on AO-7 to favor the northern hemisphere. To "maybe" help in dx contacts. The difference is only bout 17km in altitude, it just might streeeetch the footprint enough. Also just how much does the 17km add to the footprint?
73 Bob W7LRD
Is there a "easy" way of figuring out where/when a given apogee will at a given lat.long?
73 Bob W7LRD
Hi Bob, W7LRD
Using InstantTrack it is easy but the procedure is a little bit long.
When you are in the Map Screen push F until you get a phs (phase) of 128 for AO7
At phs 128 you are at the Apogee and you can read down the map the Lat/long of the satellite subpoint at the Apogee
If you now push E you will read the keplerian elements on the map screen and if you push D you can read the derived velues at time.
To day Feb 26 we have:
Perigee Height : 1440.2 km Apogee Height : 1459.0 km Latitude of Apogee : -48.9° (South) Rate of change of Apogee: -1.866 ° / day Rate of change Argument of Perigee : - 1.957° / day
Now if you want to know the numbar of days that the apogee need to go from the actual Latitude of - 48.9° South to a wanted Latitude North you must consider that since the AO7 inclination is greater then 90° the line of the apsides that join the apogee with the perigee moves in the opposite direction of the satellite.
As an example:
If you want to know how many days the Apogee needs to go from the actual Lat of - 48.9° South to a wanted Lat of + 55.0° North the Apogee must move by 180 + (55.0 - 48.9 ) = 186.1° in the South direction so that the numbar of days needed are:
186.1° / 1.957° day = 95.09 days from February 26 i.e day 1 june 2010
If you check on any tracking program you will see that AO7 on day 1 june 2010 at 10:17 UTC will be about at phs 128 at Apogee with latitude of about + 55° North and longitude 38.0° West with the satellite subpoint at Apogee just in the middle of the Atlantic ocean.
InstantTrack is a great program if one know how to talk with him !