An observation of the Atlas 5 launch (with the Cygnus cargo craft)

From: Skywayinc--- via Seesat-l <>
Date: Wed, 9 Dec 2015 01:19:40 -0500
The following was posted on the Astronomical  Society of Long Island (ASLI) 
list-bot, by ASLI member Tom Penino of his  observation of last Sunday's 
Atlas5 launch as it traveled northeast along the US  Eastern Seaboard.  I 
thought it might be of interest to those here at  SeeSat-L.  -- joe rao 

Hi all,

Following is "my observation  report" of the Atlas 5 launch from Cape 
Canaveral, which took place on Sunday  afternoon.   This launch is carrying the 
Cygnus cargo craft to deliver  supplies & experiments up to the International 
Space Station  (ISS).

Launch occurred on time, 4:44 PM.  I went outside around 4:51  PM.   First 
sighting of the Centaur upper stage must have occurred  around 4:53 PM in 
the SSE.  Then, for the next three minutes, i observed  this tandem of lights 
moving eastward, eventually disappearing over the eastern  horizon.

Upon the advice of fellow member Joe Rao, who informs us on how  to best 
view any US launches, I first watched the Atlas 5 liftoff on NASA  TV.  A 
little over 4 minutes into the flight, the 1st stage of the Atlas  had separated 
& the 2nd stage Centaur engine ignited. Shortly after 2nd  stage ignition, 
the twin fairings jettisoned from around the Cygnus cargo craft,  and could 
be seen falling away from the centaur engine from a camera mounted on  this 
2nd stage.  It was shortly after this, about 6 minutes into the  flight, 
that I went outside & viewed to the very clear southern sky,  hopefully to get 
a glimpse of the Centaur engine, along with Cygnus, riding up  & out along 
the east coast.

It took about 2 minutes, then all of a  sudden, a bright light appeared in 
the SSE sky.  I would estimate its  magnitude to be about 0, and appeared 
approx 25 in altitude, moving smoothly  & quite rapidly towards the east.  I 
was sure that this was the 2nd  stage Centaur, illuminated by sunlight, just 
as Joe Rao had predicted. As it was  moving, two much dimmer (and tightly 
grouped lights) could be seen about 2 in  front (and slightly above) the 
Centaur. These two dim lights would fade in &  out, as the entire system of 
lights flew in tandem towards the east.  I was  confused to what I was actually 
viewing, as I could not account for the two,  tightly packed dim lights.  I 
had considered the two payload fairing  halves, however I would think that 
they would be "trailing" the 2nd stage  Centaur. The pass was observed for 
at least two minutes, eventually fading from  view along the eastern horizon. 
  At first, I did not post this  report  

Then upon watching the post launch news conference, it was  mentioned that 
there were sightings of "multiple objects" viewed along the  coast. One 
thought was that it could have been the ISS, but no ISS pass was  viewable at 
that time.  I wrote to our expert Joe Rao, and he informed me  that a Father & 
Son team observed the exact same tandem of lights, while  viewing from up 
in Massachusetts. What they indicated was that the two dim  lights were 
actually the "two fairing halves", tumbling, thus fading in &  out of sunlight.  
The 0 magnitude light that was trailing them was indeed  the 2nd stage 
Centaur rocket.

I must tell you that it was a "magnificent  sight", one of the best & 
clearest viewings of rocket launches that I have  ever observed.   However my one 
confusion is this - how could the two  fairing halves, that separated & 
fell away from the 2nd stage Centaur  minutes earlier, appear to me as "in 
front of" the 2nd stage centaur rocket,  from my prospective viewing location ???

The only rationale that I can  come up with is that these fairing halves 
were actually "much lower" than the  2nd stage Centaur as I viewed them. The 
Centaur engine continued to burn for  another 14 minutes after fairing sep, 
thereby speeding up & raising the  Centaur 2nd stage.  Also, perhaps the 2nd 
stage was steered more towards  the NE as it was firing, while the fairing 
halves continued their falling  trajectory along the coast. Anyway, somehow 
the fairing halves "appeared to be  in front of the 2nd stage Centaur", from 
my prospective observing  location.

Any of our physicists out there, who could possibly explain  this "optical 
dilemma", please do so.  I will close in reiterating that  this launch was a 
"magnificent sight. One of my best" !!!

Tom P.  

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Received on Wed Dec 09 2015 - 00:20:35 UTC

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