Intelsat 4-7r / 73058B / 6797

Jason Hatton (
Sun, 22 Mar 1998 11:35:29 +0000

Following Ed Cannon's post (10th March 1998) on a naked eye observation
of Intelsat 4-7r (73058B) I decided to look for it. After a couple of
weeks of grey skies we were treated to a crystal clear sky last night. I
picked up Intelsat 4-7r at 20:06 UT, 21/Mar/98 quite easily in 10x50
binoculars  At a range of approximately 3500km it showed nice sharp
flashes at around Mag +5, with a flash period of 3.2s. I followed for a
few minutes & made a flash timing, but lost track of it after I stopped
to record the timing. The last reported flash measurements in the PPAS
database are from 1983 when its flash period was 2.9s, so it hasn't
slowed much in 15 years. It's a nice easy object to find when it's
relatively close & well worth a look. I think it's a Centaur rocket,
like 71116B / 6779 which I spotted serendiptously when I was observing
Gorizont 23 last month. There are many other Centaur rockets (eg all the
Intelsat series 4 rockets) up there, some of which are reported as
flashing in PPAS database, so these might be worth looking for when
the're favourably placed.

Best Wishes,
Jason P Hatton
ETS Strasbourg
67065 Strasbourg Cedex

48.538N / 7.731E / 143m