IOTA/IOTA-ES occultation update for (405) Thia / UCAC2 39293200 event on 2009 Nov 01, 06:00 UT Visible from Summary ------- On 2009 Nov 01 UT, the 125 km diameter asteroid (405) Thia will occult a 12.0 mag star in the constellation Gemini for observers along a path across . In the case of an occultation, the combined light of the asteroid and the star will drop by 1.6 mag to 13.3 mag (the magnitude of the asteroid) for at most 29.2 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: 98 * date and approx. time of event: 2009 Nov 01, 05:37 - 2009 Nov 01, 06:13 UT * magnitude of target star: 12.0 * magnitude drop [mag]: 1.6 * estimated maximum duration [s]: 29.2 * Moon: 97 % sunlit, 81° distance * Sun: 120° distance * rough path description: The occultation path -------------------- * approximate projected width [km]: 130 * 1 sigma uncertainty interval [path widths]: +/- 0.36 * 1 sigma uncertainty interval [seconds]: +/- 10.2 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .029 +/- .028) * 1 sigma uncertainty ellipse (major, minor, PA): ( .029", .028", 95° ) * approx speed of asteroid's shadow [km/s]: 4.2767 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 39293200 by 405 Thia on 2009 Nov 1 Centre Star Star Sun Path Limit1 Path Limit2 Error Limit1 Error Limit2 E. Longitude Latitude U.T. Alt Az Alt o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' " Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude 151 19 41 76 59 11 5 37 44 8 357 -8 149 26 47 75 45 5 153 36 43 78 1 37 148 20 54 74 41 19 155 30 28 78 41 0 144 17 38 83 24 20 5 38 21 15 350 -10 141 5 49 82 38 44 148 21 2 84 5 40 139 14 15 82 3 21 151 54 22 84 32 36 116 35 19 87 25 51 5 38 57 19 322 -12 114 47 17 86 41 20 120 18 42 88 8 45 114 5 35 86 8 22 125 44 9 88 38 16 25 9 57 87 27 24 5 39 33 23 232 -13 39 33 42 87 14 14 9 31 27 87 30 35 48 29 26 86 59 26 - 1 27 16 87 26 34 0 37 7 84 41 4 5 40 9 26 207 -14 7 52 30 84 45 56 - 6 15 23 84 32 11 13 15 6 84 46 45 - 10 54 38 84 23 35 - 5 57 53 81 55 21 5 40 45 29 201 -15 - 1 23 3 82 3 54 - 10 20 5 81 44 37 2 1 54 82 8 35 - 13 20 32 81 35 40 - 8 52 12 79 20 9 5 41 21 32 199 -16 - 5 29 21 79 29 39 - 12 7 34 79 9 12 - 2 58 51 79 35 32 - 14 23 29 79 0 29 - 10 28 18 76 54 30 5 41 57 34 198 -17 - 7 45 36 77 4 11 - 13 6 5 76 43 44 - 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10 34 21 - 5 3 17 Uncertainty in time = +/- 11 secs [Prediction of 2008 Mar 20.0] Data for the target star ------------------------ * name: UCAC2 39293200 * constellation : Gemini * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 06 39 37.5967 DE: +21 29 55.156 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .024, .025 ) * V mag [mag]: 12.0 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (405) Thia approx. diameter [km]: 125 approx. diameter ["]: .079 distance from Earth [AU]: 2.17600 * orbital information: orbit source: Preston date of fit: 2008 Mar 20 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 715 number of rejected observations: 83 time covered by the observations: 1903 Jun 27 - 2007 Nov 20 1 sigma uncertainty ellipse (major, minor, PA): 0.016, 0.013, 106° remarks: * orbital elements for (405) Thia : Mean anomaly = 262.98482126 deg Arg. of pericenter = 309.02765027 deg Long. of node = 255.29885648 deg Inclination = 11.95003724 deg Eccentricity = 0.24455221 Semimajor axis = 2.58372763 AU Perihelion dist = 1.95187133 AU Mag: H = 8.45, G = 0.15 Epoch of elements : MJD 55136.25100000 TDT (2009 Nov 01.251) ------ occelmnt file for Occult BEGIN ----------------------------------- 2009 Nov 1 405 Thia 6h 1.2m UT 12.0 6 39 37.597 21 29 55.16UCAC2 39293200 0.0 13.3 125 29.2 2.176 0.190 -9.39 -31.0616 21.501 85.60 -14.48 6.0203 0.27421 0.07760 0.66205 -2.32130 -0.00503 0.00042 2000 261.50133520091026.00000309.027650255.298856 11.9500370.24455221 2.5837276 1.9518713 8.5 5.00.15 RATE 2.3731980 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.029 0.028 95 1.36 0.029 0 54545.5020091101_293200 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 20, 15:59 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org