See NEAR during its Thurs. night Earth swingby
Joan and David Dunham (dunham@erols.com)
Wed, 21 Jan 1998 02:59:42 -0500
You might be able to see the Near Earth Asteroid Rendezvous (NEAR)
interplanetary spacecraft as it swings by the Earth Thursday night
and Friday morning. You can generate your own topocentric ephemeris
of NEAR at the "topocentric ephemeris for NEAR flyby" item that is
available at the I.A.U. Minor Planet Center's Web site:
http://cfa-www.harvard.edu/cfa/ps/mpc.html
Topocentric ephemerides for NEAR for 32 locations around the world
will also be posted on the following Web sites from which they can
be downloaded:
http://sd-www.jhuapl.edu/NEAR/ (NEAR site)
http://www.sky.net/~robinson/iotandx.htm (IOTA lunar site)
http://www.anomalies.com/iota/splash.htm (IOTA asteroidal site)
These have an improved format, with the time in hours and minutes,
and with the Sun altitude given (with no lines when the Sun is above
the horizon), that supersedes the ephemerides distributed to some
of you yesterday. In addition, data for January 23rd U.T. are now
included, including the closest approach with the sunglint phase for
the U.S.A. and after the closest approach for the Southern
Hemisphere. Later today, a more detailed "groundtrack" ephemeris
(long., lat., and altitude) will be placed on the NEAR Web site
covering the Sunglint times (Jan. 23, 6:24 - 6:50 U.T.) at one-
minute intervals. The Sunglints, when NEAR will shine briefly about
as bright as Capella for many regions of the U.S.A., are described
in items on the IOTA and NEAR Web sites; timed observations of them
are sought to measure solar panel misalignments. This evening, CNN
plans to broadcast a short clip about NEAR's Earth swingby and the
Sunglints, including an interview with me. An improved local-time
map of the U.S.A. showing the predicted track of the Sunglint is now
on the NEAR Web site (although it has a few small errors in the city
and timezone locations that we'll try to fix by late this afternoon).
Skyviews locating the Sunglint for nine different regions are on the
NEAR Web site, with one for Hawaii on the IOTA asteroidal site.
There is a chart of Perseus, with north up, showing in more detail
the location of NEAR during the Sunglint maneuvers for almost 40
cities; it will help those using large binoculars or telescopes
which, however, are not necessary; the glint should be easily
visible with the naked eye. Note that the Sunglint maneuvers are
performed only by rotating the spacecraft slightly using momentum
wheels, powered by the ample electricity available from the solar
panels; there are no thrusting maneuvers using the spacecraft's fuel
to accomplish these pointings. They are a byproduct of a navigation
test of the satellite.
Most of the time, NEAR will not be reflecting Sunlight from its
solar panels and will then be quite dim; see the geocentric
ephemeris below. The list of locations for which topocentric
ephemerides have been computed are as follows:
Location Latitude E. Longitude
AUCKLAND, N.Z. -36.908 174.777
TOKYO, Japan 35.6605 139.7702
BRISBANE, Queens. -27.516 153.070
MELBOURNE, Vict. -37.75 145.0
NANKING, China 32.0666 118.8210
PERTH, W. Austrl. -31.95 115.83
NAINI TAL, India 29.3608 79.4567
KODAIKANAL, India 10.2306 77.4686
MOSCOW, Russia 55.755 37.570
MITZPE RAMON,Isrl. 30.597 34.763
CAPE, S. Africa -33.933 18.475
TIRGO Obs., Switz. 45.98447 7.79167
HERSTMONCEUX, UK 50.871 0.338
SAN FERNANDO, Spn. 36.462 -6.200
LA PALMA, CanaryIs 28.75833 -17.8800
RIO DE JANEIRO,Br. -22.8975 -43.18625
ST. JOHN'S, Nfld. 47.537 -52.753
CARACAS, Venezuela 10.5068 -66.928
SANTIAGO, Chile -33.41833 -70.630
Boston, MA 42.3567 -71.0569
Chelmsford, MA 42.62 -71.39
Charlotte Hall, MD 38.51 -76.76
Miami FL 25.77667 -80.19167
near Chicago, IL 42.317 -88.00
Houston, Texas 29.6049 -95.1086
Coal Creek Can.,CO 39.877 -105.391
Mt. Hopkins, Ariz. 31.5647 -110.8846
Casa Grande, Ariz. 32.9583 -111.6542
Los Angeles CA 34.05500 -118.24167
Seattle WA 47.60833 -122.33667
ANCHORAGE, Alaska 61.21 -149.87
Honolulu HI 21.30667 -157.86000
An abbreviated geocentric ephemeris of NEAR is given below. The
magnitude could be wrong by a few units; we hope to receive some
observations soon so that it might be calibrated and updated. A
more detailed version of the geocentric ephemeris is on the IOTA
lunar Web site. Due to the relatively unfavorable phase angle after
the closest approach (which occurs on 1998 Jan. 23, 7:23 U.T. over
the Middle East, in daylight), NEAR will likely be much fainter than
during its approach. Also, after the swingby, you can see from the
table below that NEAR will be visible only from southern-hemisphere
observatories.
Geocentric ephemeris for NEAR from JPL ephemeris file p_tcm11_n0a
generated 1998 Jan. 19
Calendar Solar J2000 min.topo.
Date UTC Elong. R.A. Dec. Distance NEAR
Year Mo Day h m deg. deg. deg. km Mag.
1998 JAN 21 12:00 140.31 81.01973 21.19753 1097657 17.3
1998 JAN 22 0:00 139.74 80.92815 21.42858 798920 16.7
1998 JAN 22 12:00 139.10 80.73434 21.93338 499065 15.6
1998 JAN 22 18:00 138.69 80.51496 22.50639 348217 14.9
1998 JAN 22 20:00 138.52 80.39282 22.82385 297669 14.5
1998 JAN 23 0:00 138.02 79.96055 23.93556 195848 13.6
1998 JAN 23 2:00 137.59 79.51691 25.05603 144317 12.9
1998 JAN 23 3:00 137.24 79.15099 25.96415 118277 12.5
1998 JAN 23 4:00 136.70 78.57920 27.35372 91951 12.0
1998 JAN 23 5:00 135.71 77.54841 29.76695 65184 11.2
1998 JAN 23 5:30 134.80 76.63340 31.80984 51545 10.7
1998 JAN 23 6:00 133.20 75.05630 35.11400 37647 10.0
1998 JAN 23 6:10 132.35 74.23407 36.73016 32938 9.8
1998 JAN 23 6:20 131.22 73.13511 38.78023 28182 9.4
1998 JAN 23 6:30 129.65 71.58201 41.47221 23373 9.0
1998 JAN 23 6:40 127.33 69.19788 45.17163 18509 8.5
1998 JAN 23 6:50 123.60 65.01014 50.57217 13597 7.9
1998 JAN 23 7:00 116.91 55.51731 59.04067 8687 6.9
1998 JAN 23 7:40 46.40 255.52222 -34.21045 5871 6.9
1998 JAN 23 7:50 54.21 247.58190 -47.43933 10697 8.1
1998 JAN 23 8:00 59.34 241.27041 -54.45557 15620 8.8
1998 JAN 23 8:30 67.14 227.87440 -63.41631 30142 10.1
1998 JAN 23 9:00 70.69 219.29026 -66.74216 44221 10.9
1998 JAN 23 10:00 74.10 209.08617 -69.31563 71530 11.9
1998 JAN 23 12:00 76.79 199.60940 -70.80685 124420 13.1
1998 JAN 23 15:00 78.35 193.72607 -71.40726 201865 14.1
1998 JAN 23 18:00 79.11 190.90908 -71.61942 278269 14.8
1998 JAN 24 0:00 79.89 188.16638 -71.78267 429611 15.7
David Dunham, NEAR Mission Design, 1998 Jan. 21, 8h U.T.