A Titan IV rocket is scheduled to lift-off from Cape Canaveral on 2005 Apr
30 at 00:50 UTC (Apr 29 at 20:50 EDT). The duration of the launch window has
not been announced.

This will be the final Titan IV launch from Cape Canaveral, and its
trajectory will head north east, along the east coast of North America.

The rocket's trajectory is secret, but their is a good chance that it will
be readily visible to the unaided eye. I have cooked up some trajectory data
to aid in spotting it.

Rocket scientists likely would have a good laugh at my estimates, but I hope
that they will be sufficient to provide a rough idea of when and where to
look. However, if I guessed wrong, it may be far from the predicted path, or
not seen at all.

The following Excel spreadsheet computes the vehicle's azimuth and elevation
during the ascent to orbit:

http://satobs.org/seesat_ref/B-30/Ti...ook_angles.xls

All you need do is enter the lift-off time, and your latitude and longitude.
As downloaded, the file contains the latitude and longitude of Washington,
D.C., which you should replace with your latitude and longitude.

The spreadsheet computes azimuth and elevation at 10 s time intervals.
Azimuth is in degrees, clockwise from due north. Elevation is in degrees
above the horizon. Negative values of elevation indicate that the vehicle is
below the horizon.

The trajectory data begins at T+2:30, about the time that the solid rocket
motors burn out.

Observers who have seen Shuttle night-time ascents along the east coast,
should not expect the Titan IV's exhaust to be as bright.

For about 3 min after SRB burnout, the T-IVB's 1st stage will produce about
550,000 pounds of thrust - about one third the total output of a shuttle's
main engines.

The T-IVB's 2nd stage ignites for nearly 4 min; however, it produces a
little over 100,000 pounds of thrust - about 7 percent the total output of a
shuttle's main engines.

Assuming lift-off occurs near the scheduled time, the vehicle may be
illuminated by sunlight for some portion of its ascent, which should make it
easy to spot with the unaided eye. It could reach magnitude 1 or brighter.

I estimate that it will climb out of Earth's shadow at about T+3:30. How
long it remains in sunlight depends on how high it climbs. Since its
trajectory and planned orbit are secret, I can only guess.

I based the ascent trajectory on one of several possible target orbits,
specifically, that of a Lacrosse radar imaging satellite, inclined 57 deg,
and 425 X 671 km. An ascent trajectory bound for that orbit, would remain
illuminated throughout the powered ascent, after exiting the shadow at about
T+3:30.

In the event that the target orbit is much lower, then the vehicle may
re-enter the shadow before the end of the powered ascent, in which case the
vehicle would be illuminated only by its exhaust, which may not be visible
with the unaided eye.

Happy hunting!
Ted Molczan