RE:Rocket Burn Visibility

Bud Smith (
Fri, 9 Jul 1999 22:17:40 -0400

My recent posts on the Delta/Globalstar burn visibilities raises
issues about what such an event would look like.  Since I have
never seen one, I have to rely on previous sightings as a guide.

I believe someone in the NE USA saw a Delta burn a year or two ago
and Mike McCants saw a Centaur burn in the recent past.  Both are
liquid propellants.

This seems to eliminate the concern about liquid versus solid.  My
initial thought was that solids would eject more particulates
making them easier to see (if sunlit).

Then there is the issue about when the cloud will appear relative
to the firing time.  Will the cloud expand slowly becoming more
visible perhaps a minute or two after the firing?   I will leave this
to others to provide answers so we can know what to expect when this
launch occurs.

As far as saying one or more of the burns is visible in the central
USA region, each observer will have to assess his twilight/darkness
conditions.  Two days ago I went out and was able to find suitable
guide stars even though it seemed too light.  My suggestion is to
try to observe this event if you are interested even if it might
appear questionable at first glance.  Of course each launch delay
improves the sky conditions for us east of the Rockies.

Ron Lee

Last year I was lucky enough to observe a SECO burn of the Delta 
/Globalstar launch on 04/24/98. Using elsets posted here by dedicated 
individuals, I  was attempting to observe the "train"  of sats shortly 
after release from the booster. I was not expecting or did I know about the 
SECO burn . As I remember  it was at very late twilight and the burn was 
well back lit from the setting sun. I was using the 10x50s looking for 
faint objects when  I saw the plume .  The plume was visible immediately 
behind the booster. The booster was faintly visible during the burn. The 
plume fanned out to the rear and took on a mushroom shape . The " mushroom" 
 grew to about 15 deg then dissipated over the next 30 seconds. This was by 
far the most spectacular event I have observed in my short time training my 
attention toward the sky . I don't have the elsets for the launch handy for 
this post but from my log:

Launch    22:38:34 UTC  04/24/98

Observed 00:34:00 UTC  04/25/98

Lat 41.4248  N

Lon 73.3610 W

Thanks to all in this group that make this space enjoyable  to the casual 
observer and avid reader .

 Now I just need to grt out and observe more

Bud Smith