IOTA/IOTA-ES occultation update for (879) Ricarda / HIP 75592 event on 2009 May 12, 07:50 UT Visible from Summary ------- On 2009 May 12 UT, the 22 km diameter asteroid (879) Ricarda will occult a 9.8 mag star in the constellation Lupus for observers along a path across . In the case of an occultation, the combined light of the asteroid and the star will drop by 5.0 mag to 14.8 mag (the magnitude of the asteroid) for at most 1.7 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC. The event at a glimpse ---------------------- * Rank: 24 * date and approx. time of event: 2009 May 12, 07:50 - 2009 May 12, 07:50 UT * magnitude of target star: 9.8 * magnitude drop [mag]: 5.0 * estimated maximum duration [s]: 1.7 * Moon: 91 % sunlit, 30° distance * Sun: 166° distance * rough path description: The occultation path -------------------- * approximate projected width [km]: 22 * 1 sigma uncertainty interval [path widths]: +/- 2.76 * 1 sigma uncertainty interval [seconds]: +/- 9.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .118 +/- .036) * 1 sigma uncertainty ellipse (major, minor, PA): ( .118", .034", 96° ) * approx speed of asteroid's shadow [km/s]: 12.8290 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Path does not land on Earth. Data for the target star ------------------------ * name: HIP 75592 * constellation : Lupus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 15 26 36.9793 DE: -31 38 39.016 * position source: mpos:UCAC2 pm:UCAC2 plx:HIP2 * standard error: RA,DE ["]: ( .018, .024 ) * V mag [mag]: 9.8 * B mag [mag]: 10.6 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (879) Ricarda approx. diameter [km]: 22 approx. diameter ["]: .017 distance from Earth [AU]: 1.76500 * orbital information: orbit source: Preston date of fit: 2008 Nov 16 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 709 number of rejected observations: 17 time covered by the observations: 1917 Jul 22 - 2008 Jun 26 1 sigma uncertainty ellipse (major, minor, PA): 0.117, 0.024, 96° remarks: * orbital elements for (879) Ricarda : Mean anomaly = 242.18101376 deg Arg. of pericenter = 96.38798164 deg Long. of node = 270.10594537 deg Inclination = 13.68198641 deg Eccentricity = 0.15536841 Semimajor axis = 2.53036054 AU Perihelion dist = 2.13722246 AU Mag: H = 10.87, G = 0.15 Epoch of elements : MJD 54963.32700000 TDT (2009 May 12.327) ------ occelmnt file for Occult BEGIN ----------------------------------- 2009 May 12 879 Ricarda 7h 50.6m UT 9.8 15 26 36.979-31 38 39.02HIP 75592 10.6 14.8 22 1.7 1.765 -2.540 15.84 -116.2146 -31.647 61.44 18.20 7.8431 0.44676 0.91542 -6.50738 3.17593 -0.00025 0.00131 2000 241.3663412009 5 9.00000 96.387982270.105945 13.6819860.15536841 2.5303605 2.137222410.9 5.00.15 RATE 2.4486710 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.118 0.034 96 3.76 0.047 0 54786.5020090512__75592 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Nov 16, 16:49 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org