[amsat-bb] AO-73 - Reminder for Northern Hemisphere Evening Passes

Paul Stoetzer n8hm at arrl.net
Wed Mar 11 23:58:55 UTC 2015

Good evening,

Just a reminder that we are starting to lose transponder time here in
the Northern Hemisphere on evening passes when the satellite is in
it's normal auto eclipse mode. For example, during the second pass
over Washington, DC this evening, I have AOS at 02:17 UTC and LOS at
02:30 UTC. However, the satellite will enter sunlight at 02:28:40 UTC,
one minute and 20 seconds before LOS and the transponder will shut

As we move towards the summer solstice in the Northern Hemisphere,
transponder time will continue to decrease on the evening passes. At
my latitude, by May 15th, for example, the satellite will be in
eclipse during evening passes for only 4-5 minutes. On June 21st, the
summer solstice, I show about 3 minutes of transponder time on evening
passes before the satellite enters sunlight.

Keep this in mind if you suddenly hear the transponder shut off during
a weekday evening pass. Tune down to the beacon frequency, and you'll
find it's suddenly 10 dB louder.


Paul Stoetzer, N8HM

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