Unknown (?) short period flasher....

Thought I'd post this observation as I can't figure out what it was I
saw; Bart suggested it might be a Zenith rocket but I could only match
it to an old Cosmos ....

I was actually out looking for Lacrosse 1, but the sky was quite cloudy
(in fact broken cloud covering 3/4 of the sky) and but seeing conditions
about mag +5.5. I noticed a flashing satellite heading across the sky
from south to north. It was tumbling with a period of ~3 sec. (sorry
couldn't count n flashes and divide by total time as it jumped in and
out of cloud). It went from a maximum brightness of mag. +3 down to
around mag +7 - estimated with binoculars which I used to check for
navigation lights in order to rule out a plane. Around 1938 UTC it
passed Castor (Gemini) and reached the bottom right hand corner star of
the 'Dipper pan' of the Plough/Big Dipper/Ursa Major at about 1941 UTC
(sorry for the approx. times - it *was* cold and I was trying to still
spot Lacrosse too). Other details :

date: Sunday March 5th,
location:central England; 52.675 deg N, 1.896 deg W, 135m above sea
level.

The pulsation seemed quite regular except for two glitches/stutters.
 
I checked 4000 odd elements and the best match was for Cosmos 252 (3530)
which I have found to be an anti-satellite weapon launched in November
1968. Currently in an orbit of 560 km x 2080 km at 62.3 deg. Don't
know what state it is in as these Chelomei ASAT's were supposed to
explode generating a lethal cloud of debris to destroy the target. I'm
surprised that there is anything large enough to be that bright given
this - and the fact it was near apogee during the pass.

Apologies for the lack of accurate information,

-- 
Neil Clifford                Mail for PGP key           *MIME spoken here*
<n.clifford@eleceng.ucl.ac.uk> http://www.ee.ucl.ac.uk/~ncliffor/home.html