IOTA/IOTA-ES occultation update for
(928) Hildrun / HIP 83770 event on 1999, June 18
visible from space
Summary
On the night June 18, 1999 was predicted occultation of 7.8 mag star by a 70 km asteroid (928) Hildrun. This update is based on USNO/Flagstaff and TMO astrometry for asteroid and HIPPARCOS star position.
This update gives ~0.5" north shift and time ~1.2 minutes earlier compared to Goffin's nominal prediction.
Because Edwin's prediction itself gave a miss just north of the globe, this means there be surely no occultation visible from Earth surface because the expected star and asteroid position uncertainity are well below the miss distance. This independent calculation confirms Martin Federspiel's result issued about one hour earlier. Only limited data are given below.
Data for the target star:
* name: HIP 83770 = SAO 141524 = PPM 200357 = TYC 5068 00801 1
* constellation: Ophiuchus
* J2000 position [h,m,s; o,',"]: 17h 07m 14.420s; -02o 52' 00.99"
* position source: HIPPARCOS
* estimated accuracy ["]: 0.01" (0.01", 0.01")
* Johnson V mag [mag]: 7.83
* B-V [mag]: +0.74
* remarks:
Data for the minor planet:
* general information:
number, name: (928) Hildrun
approx. diameter [km]: 70
* orbital information
orbit source: calculation Manek
source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
number of used observations: 30 USNO, 2 TMO
number of rejected observations: 3 USNO (1998 03 25.239667,
1999 05 02.434563, 1999 05 03.431543)
time covered by the observations: 1998 02 24 - 1999 06 10
rms residuals ["] (RA,DE): 0.09", 0.09"
estimated positional accuracy at epoch of event ["]: 0.09"
remarks:
Calculator(s): Jan Manek
----------------------------------------------------------------------------
Jan Manek
Stefanik Observatory Private :
Petrin 205 Werichova 950
118 46 Praha 1 152 00 Praha 5 - Barrandov |_|_|
Czech Republic Czech Republic / \
Internet : jmanek@mbox.vol.cz |-O-O-|
--------------------------------------------------------------------U---U---
IOTA/IOTA-ES occultation update for
(928) Hildrun/HIP 83770 event on 1999 June 18
Summary
There will be *no* occultation of HIP 83770 by (928) Hildrun on 1999 June 18. According to very accurate USNO/ACT astrometry for the minor planet and the Hipparcos position of the star the shadow of the minor planet will miss the Earth by more than 0.5". Given the quality of the astrometry this excludes the possibility an occultation for any place on Earth. Edwin Goffin's first nominal prediction suggested a possible event in Central Europe.
------------------------------------------------------------------------- Martin Federspiel ******** E-mail: martin@astro.unibas.ch Astronomisches Institut ******** oder: federspi@astro.unibas.ch der Universitaet Basel **** oder: federspielm@ubaclu.unibas.ch Venusstr. 7 Telefon: (CH)-61/2055413 CH-4102 Binningen (Schweiz) Fax: (CH)-61/2055455 -------------------------------------------------------------------------