Lydia
Site Admin
Posted:
Tue Jan 17, 2006 1:57 pm
Joined: 03 Feb 2004
Posts: 610
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http://news.bbc.co.uk/2/hi/science/nature/4599634.stm
"Another historic endeavor of planetary exploration" by N.A.S.A.
The following is an updated message from David Dunham,
President of I.O.T.A.
LL
*****
This is an update to the message that I distributed to most of
you last night. You can now see New Horizon's ground track on a
New Horizons Web page at
http://pluto.jhuapl.edu/groundtrack/index.php .
The red curve that extends farthest to the southeast is for the
opening of the two-hour launch window, and is the most likely path
that the spacecraft will have, and is the one on which the
predictions both on my Web site at http://iota.jhuapl.edu/nh116.htm
and on the New Horizons Web site above are based. The New Horizons
Web site has the latest predictions, for dozens of cities in Asia
and Australia, and especially for many in Japan, and it should be
used first. But if your station is not on that site, you can find
many more observatories and more cities and locations at my Web
site. Comparison of my data with the New Horizons Web site is good,
within 0.1 deg. for most of the ephemerides. The New Horizons Web
site has data at integral minutes, from 19:08 to 21:14 (almost the
same interval as my data here, which has information also at 1-min.
intervals but at each half-minute). Also, only the last 10 minutes
uses a 10-minute interval on the New Horizons site, the rest being
1-minute, while the data on my site are at 10-minute intervals for
the last 50 minutes.
The yellow and lavender ground tracks shown on the New Horizons
Web site, successively farther northwest, are for the middle and end
of the launch window, in case there is a delay in the launch for any
reason. The observation information posted on the New Horizons Web
site will be updated in real time if the launch time changes; I will
also try to change it on my Web site but am not sure that will be
possible.
2ND AND 3RD-STAGE BURNS WILL BE BRIGHT OVER THE INDIAN OCEAN
When the 2nd and third stages of the rocket ignite to propel
the spacecraft from the circular parking orbit, it should be quite
bright, possible to see with binoculars and, from some islands in
the Indian Ocean, maybe without any optical aid. The burns will be
visible very low in the eastern sky as seen from Mauritius and
Reunion islands, and will be higher as seen from Rodriguez and a few
other islands farther east in the Indian Ocean. The third-stage
burn is planned to occur at 19:06 UT over the Indian Ocean if the
spacecraft is launched at the beginning of its planned launch
window; the 2nd-stage burn will be 5 to 2 minutes earlier, so
observers in the Indian Ocean region should start observing by 19:00
UT. The three islands named above are shown as three small dots on
the groundtrack map just east and a little north of the "I" mark on
the lavendar track (for the end of the launch window). Topocentric
predictions for six Indian Ocean islands are on my Web site
at http://iota.jhuapl.edu/nhindoc.txt , but for them, you should
just use the 1st minute to see where the 3rd-stage burn will be.
The 2nd-stage burn will be earlier than the data, as indicated above
may be as early as 19:00, and the ground track will be farther
northwest, so that the spacecraft and rocket combination will be
higher in the sky, and farther west, for Reunion, Mauritius, and
Rodriguez, but lower, probably below the horizon, for Cocos and
Christmas Islands.
OBSERVING NEW HORIZONS AFTER EMERGING FROM EARTH'S SHADOW
New Horizons will rapidly rise, moving out of the Earth's
shadow a few minutes after the 3rd-stage burn to become visible as
it is lit by the Sun. At about this time, the spacecraft will
separate from the 3rd stage, so both may be visible close to each
other; following well behind them may be the larger and brighter 2nd
stage rocket. The best place to see this will be the eastern Indian
Ocean, and western and central Australia. As the spacecraft rises
further, it will become visible in the night sky across south-
central and eastern Asia, from India to Japan to Indonesia.
Unfortunately, when the spacecraft rises for populous parts of
southeastern Australia, the Sun will be rising so New Horizons won't
be visible there, but observers in central and northern Australia
will have some good visibility before morning twilight becomes too
bright (it will be early Wednesday morning, January 18, at those
longitudes). The ground track passes right over Alice Springs, NT,
Australia just after astronomical twilight begins.
Posted on my Web site are predictions of the path of the
spacecraft in the sky for observers on the Earth's surface for the
first two hours after the nominal third-stage injection maneuver,
specifically, at 1-minute intervals from 19:06.5 to 20:24.5 UT and
then at 10-minute intervals from then to 21:14.5 UT of 2006 January
17, UT. As noted above, it is best to use the data on
the New Horizons Web site. We estimate that the spacecraft will be
between 10th and 14th magnitude during this time, depending on your
location and the time, the spacecraft of course becoming fainter as
it is higher. If your location is not near one of the cities in the
New Horizons Web site database above, you might find it on my Web
site. Predictions for all Minor Planet Center observatories within the
region of visibility described above up to 21:14.5 UT are at
http://iota.jhuapl.edu/nhjan17.txt (an almost 1-megabyte file). In
these predictions, the first 3 characters of the location name are
the MPC Observatory code, followed by a blank and then just the
first 14 characters of the observatory name from the MPC Observatory
list. Predictions for several other cities and towns, especially
those with IOTA observers, are at http://iota.jhuapl.edu/nhiota.txt
including locations especially in western and central Australia, but
also places like Pune and Ahmedabad, India, and Kuala Lumpur,
Malaysia. These will be most useful for observers in the parts of
Asia and Australia mentioned above before other predictions noted
below become available. Note that since the actual spacecraft will
deviate a little from its planned trajectory, our predictions can be
in error by a degree or so, and of course the error will be larger
if the launch is delayed beyond the start of the daily launch
window. If the launch is delayed, we'll put updated data on our Web
sites as soon as possible. I can generate predictions for locations
other than those already available upon request to
dunham@starpower.net and david.dunham@jhuapl.edu , but only for the
area described above from which the spacecraft will be visible
(Indian Ocean, central & east Asia, western and central Australia).
VISIBILITY MORE THAN 2 HOURS AFTER LAUNCH, FOR AFRICA, EUROPE, AND
THE AMERICAS
Some time an hour or two after launch, the trajectory will be
placed on Jet Propulsion Laboratory's Ephemeris Generator Web site
at http://ssd.jpl.nasa.gov/cgi-bin/eph where observers can then
obtain better predictions for their location. This will be
especially the case for observers in Europe and Africa, then the
Americas, who will be able to observe the departing spacecraft after
about 22h UT. Of course, as the spacecraft moves even farther from
the Earth, it will become fainter, to 15th to 19th magnitude for
those areas probable. The predictions on my Web site and the New
Horizons site linked to above are only valid to 21:14 UT when the
spacecraft will not be visible from Europe, Africa, or the Americas.
David Dunham, IOTA and Johns Hopkins Applied Physics Lab. (APL)
with much help from
Yanping Guo, APL New Horizons Trajectory Design lead
(she set up the New Horizons Web site using my program for the
topocentric ephemeris calculations there)
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