RASNZ Occultation Section - Hispania Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (804) HISPANIA - 2002 JANUARY 22

The prediction given by Goffin passes between Adelaide and Melbourne before covering much of Tasmania. The path given by Occult is indistinguishable.

UPDATE: 18 JANUARY 2002

THE UPDATED PATH

Hispania Update

This updated path lies a fraction of a pathwidth to the east of that given by Goffin with a time difference only around five seconds. The path crosses central South Australia passing just to the east of Adelaide at 16:09:25 UT. Much of western and central Victoria lie within the path with Melbourne within the eastern boundary around 16:09:30 UT. Across Bass Strait, virtually all of Tasmania lies within the path including Hobart around 16:09:45 UT.

The uncertainties are such that Adelaide stands a very good chance of seeing an occultation with Canberra and Sydney rather less like (but still well worth observing) around the same time - 16:09:25 UT.

While the star is reasonably bright (magnitude = 9.7) , the main obstacle to observing this event is the relatively low altitude of the target star at the time. Adelaide observers will see the star at only 15 degrees while Melbourne observers will see it at 22 degrees. Hobart observers will see the star at 25 degrees.

Calculation Source

This prediction update has been computed by Steve Preston of Medina, Washington (state) in the United States based on astrometry from Ron Stone of the US Naval Observatory - Flagstaff Station, Bill Owen of Table Mountain Observatory (JPL) and Gordon Garradd supplemented with data from the AstDys database. The Hipparcos position of the target star has been used.

Additional details of this and other events are available at Steve Preston's website at http://www.oz.net/~stevepr/Asteroids/asteroid.htm

EVENT DETAILS SUMMARY:

Date and approx. UT time of event: 2002 January 22 - 16:09 UT
Magnitude of target star: 9.73
Magnitude drop [mag]: 3.9
Estimated maximum duration [s]: 4.5
Angular distance to moon, phase of moon [deg,%]: 158, 59%
Goffin's original chart reference: A02_0148

The Occultation Path:

Approximate width [km]: 261
Uncertainty [path widths]: +/- 0.46 (1 sigma)
Remarks: Uncertainities are given on the basis of the nominal star position errors and the expected asteroid positional accuracy.

Data for the target star:

Name: HIP 76232 = PPM 294006 = SAO 206778
Constellation: Lupus
J2000 position [h,m,s; ^o,',"]: 15h 34m 20.3880s; -30^o 46' 51.512"
Position source: Hipparcos
Estimated accuracy ["]: 0.023" (0.017", 0.015")
V mag [mag]: 9.73
B-V [mag]: +0.98
Remarks:
The target star is in northern Lupus near the border with Libra. It lies 1.4 degrees southwest of tau Librae (magnitude = 3.7).

Data for the minor planet:

Number, name: (804) Hispania
Approx. diameter [km]: 140.6
Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), TMO (Bill Owen), Gordon Garradd, AstDys
Number of used observations: 370
Number of rejected observations: 34
Time covered by the observations: 1903 11 26 - 2002 01 17
Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit).

IMPORTANT NOTE!

Astrometric updates such as these should not be taken as definitive, but rather only as an indication of where the true track may lie relative to the original predicted track. Observers must bear in mind that later astrometry, in which the target star is measured in the same field as the asteroid, may still reveal substantial changes to the predicted track and time of the event. For this reason it is most important that observers far from the predicted track still monitor the event.

Use these links for further information:
[Planetary Occultations] [Using the Predictions]
[Observing Details] [Timing Details] [Reporting Details] [Report Form]
[Asteroid Occultation Results]

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