is an old saying, "Chance favors the prepared
mind." Well, I do not know how prepared
Vance Bagwell and I were to contemplate what we saw
on one beautiful, November night, but at least our equipment
was ready to capture it in pictures.
and I are veterans at astronomy outreach events, so
when a couple of Fort Worth visitors to the Comanche
Springs Astronomy Campus near Crowell, Texas, came to
us at 2:40am on November 11th to ask why nobody told
them about that comet up in Orion, we immediate rolled
our eyes. After all, we've heard something like
that a million times when visitors come to our dark
skies for the first time. However, when I loaned
my green laser pointer to Danny Townsend and Kevin Ulrich
of Fort Worth to
show us what it is that had them so excited, our eyes
stopped rolling. Mouths agape at the naked
eye object that was both larger and brighter than the
Orion Nebula, which rested only a couple of fingers
away, Vance and I immediately shifted into our "serious"
astronomer persona and grabbed any optics available
to catch a closer view.
when we detected movement of the mysterious object from
west to east, heading on a collision course with the
Orion Nebula, both Vance and I scrambled to halt our
imaging sessions and acquire the event. Since
my scope was already on the nearby M78, it was a quick
jog, thankfully. Upon acquision of the object
just west of the Orion nebula, I managed 211 one second
focus frames while tracking on the slowly moving "comet."
Of course, knowing that this wasn't likely
to be a new comet due to its brightness and speed,
our spectulation at the time was some kind of rocket
shot or reentry vehicle.
wasn't until the next day that the mystery was solved
in our minds. Spaceweather.com reported that the
event was a Delta IV Centaur fuel dump, which happened
at an altitude of approximately 22,000 miles. More
on this from Ed Cannon of Austin, TX:
"Early Sunday morning a couple of transient naked-eye "nebulae"
or "comets" are expected to be observable, weather permitting, from all of the
western hemisphere at the end of the launch sequence of DSP 23.
launch window is 8:39 - 10:41 PM EST Saturday night (1:39 - 3:41 Sunday UTC)
from Cape Canaveral, Florida.
Just about six hours after launch (i.e.,
2:39-4:41 AM EST, 7:39-9:41 UTC), when the payload and Centaur upper stage have
reached very near to geostationary height, there will be a three-minute burn to
change the orbital inclincation and circularize the orbit. This will occur at
about longitude 90 west, plus or minus some degrees, close to the celestial
equator. This will be the first nebula/comet. (I believe but am not certain that
this will be the fainter of the two.)
Spacecraft separation will occur
just about 6.5 minutes after the end of the burn. Not long after spacecraft
separation excess fuel and oxidizer will be vented from the Centaur. This will
be the second nebula/comet -- the brighter one, I think (but am not
The burn itself (i.e., the flame) may be visible with a telescope.
At least one of the nebulae/comets may be as bright as first
As these events will occur very near geostationary height,
they will not move very much in the sky. The burn cloud may move at nearly
sidereal rate. The venting cloud may be nearly stationary as the stars move by.
But both of them may move to the north or south, as the nominal final orbital
inclination is four, not zero.
DSP satellites themselves are very faint
unless specular reflections off their four solar panels are observed. They are
spin-stabilized at 6 RPM.".