IOTA/IOTA-ES occultation update for (791) Ani / TYC 6905-01988-1 event on 2008 Oct 18, 00:59 UT Visible from near North America Summary ------- On 2008 Oct 18 UT, the 104 km diameter asteroid (791) Ani will occult a 10.4 mag star in the constellation Sagittarius for observers along a path across near North America. In the case of an occultation, the combined light of the asteroid and the star will drop by 3.7 mag to 14.1 mag (the magnitude of the asteroid) for at most 6.1 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC. The event at a glimpse ---------------------- * Rank: 42 * date and approx. time of event: 2008 Oct 18, 00:59 - 2008 Oct 18, 00:59 UT * magnitude of target star: 10.4 * magnitude drop [mag]: 3.7 * estimated maximum duration [s]: 6.1 * Moon: 86 % sunlit, 131° distance * Sun: 94° distance * rough path description: near North America Additional comments ------------------- 0.6" double star m11.2/m11.2 The occultation path -------------------- * approximate projected width [km]: 104 * 1 sigma uncertainty interval [path widths]: +/- 1.57 * 1 sigma uncertainty interval [seconds]: +/- 8.8 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .101 +/- .100) * 1 sigma uncertainty ellipse (major, minor, PA): ( .101", .100", 90° ) * approx speed of asteroid's shadow [km/s]: 16.9294 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Path does not land on Earth. Data for the target star ------------------------ * name: TYC 6905-01988-1 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 20 05 55.6964 DE: -24 16 01.415 * position source: Pos: mpos:UCAC2 pm:UCAC2, pm: , pi: * standard error: RA,DE ["]: ( .100, .100 ) * V mag [mag]: 10.4 * B mag [mag]: 11.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (791) Ani approx. diameter [km]: 104 approx. diameter ["]: .064 distance from Earth [AU]: 2.23500 * orbital information: orbit source: Preston date of fit: 2008 Oct 15 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 801 number of rejected observations: 73 time covered by the observations: 1915 Dec 06 - 2008 Sep 25 1 sigma uncertainty ellipse (major, minor, PA): 0.012, 0.010, 107° remarks: * orbital elements for (791) Ani : Mean anomaly = 353.96936254 deg Arg. of pericenter = 201.58440056 deg Long. of node = 130.05154748 deg Inclination = 16.39513683 deg Eccentricity = 0.19886198 Semimajor axis = 3.11827526 AU Perihelion dist = 2.49816887 AU Mag: H = 9.19, G = 0.15 Epoch of elements : MJD 54757.04100000 TDT (2008 Oct 18.041) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Oct 18 791 Ani 0h 59.6m UT 10.4 20 5 55.696-24 16 1.42TYC 6905-01988-1 11.0 14.1 104 6.1 2.235 2.748 -1.52 -100.3103 -24.266 161.40 -9.69 0.9931 0.04192 1.03656 9.54753 -0.38802 0.00552 0.00120 2000 352.70908420081011.00000201.584401130.051547 16.3951370.19886198 3.1182753 2.4981689 9.3 5.00.15 RATE 1.7899150 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.101 0.100 90 2.57 0.101 0 54755.5020081018_1988-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Oct 16, 00:38 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org