IOTA/IOTA-ES occultation update for (1585) Union / TYC 5783-00181-1 event on 2012 Sep 13, 01:43 UT Visible from W Africa Summary ------- On 2012 Sep 13 UT, the 51 km diameter asteroid (1585) Union will occult a 10.0 mag star in the constellation Capricornus for observers along a path across W Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 4.7 mag to 14.7 mag (the magnitude of the asteroid) for at most 4.2 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: 72 * date and approx. time of event: 2012 Sep 13, 01:36 - 2012 Sep 13, 01:51 UT * geocentric midpoint of event [JD]: 2456183.57199167 * magnitude of target star: 10.0 * magnitude drop [mag]: 4.7 * estimated maximum duration [s]: 4.2 * Moon: 11 % sunlit, 177° distance * Sun: 144° distance * rough path description: W Africa The occultation path -------------------- * approximate projected width [km]: 57 * 1 sigma uncertainty interval [path widths]: +/- 0.80 * 1 sigma uncertainty interval [seconds]: +/- 2.8 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .033 +/- .026) * 1 sigma uncertainty ellipse (major, minor, PA): ( .033", .026", 96° ) * approx speed of asteroid's shadow [km/s]: 12.1950 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 5783-00181-1 by 1585 Union on 2012 Sep 13 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 9 25 58 29 46 34 1 36 3 10 247 -43 10 12 47 29 50 23 8 42 3 29 43 32 11 35 36 29 58 40 7 36 37 29 40 1 4 6 16 27 1 35 1 36 14 15 245 -48 4 37 39 27 1 19 3 35 44 27 2 5 5 29 47 27 1 27 2 48 27 27 3 21 0 27 43 24 45 36 1 36 26 19 243 -52 0 53 47 24 43 57 0 2 6 24 47 23 1 36 30 24 41 37 - 0 38 1 24 50 31 - 2 24 25 22 43 40 1 36 38 22 242 -56 - 2 1 11 22 41 18 - 2 47 20 22 46 9 - 1 23 22 22 37 43 - 3 23 25 22 50 18 - 4 48 26 20 50 41 1 36 50 25 242 -58 - 4 27 2 20 47 51 - 5 9 38 20 53 35 - 3 52 17 20 43 29 - 5 43 4 20 58 23 - 6 53 14 19 4 4 1 37 1 27 241 -61 - 6 33 6 19 0 56 - 7 13 11 19 7 16 - 6 0 29 18 56 2 - 7 44 46 19 12 32 - 8 43 51 17 22 21 1 37 13 30 241 -63 - 8 24 40 17 18 59 - 9 2 54 17 25 46 - 7 53 38 17 13 43 - 9 33 4 17 31 21 - 10 23 33 15 44 32 1 37 25 32 241 -66 - 10 5 5 15 41 0 - 10 41 52 15 48 7 - 9 35 16 15 35 26 - 11 10 57 15 53 58 - 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63 22 6 -85 46 46 1 50 54 19 359 -7 - 60 21 10 -86 6 55 - 65 56 15 -85 26 30 - 54 15 45 -86 38 31 - 69 20 55 -84 54 3 -124 16 54 -89 20 50 1 51 6 15 60 -4 -169 23 54 -89 37 13 -110 17 22 -88 56 17 119 9 23 -89 11 11 -102 36 33 -88 15 18 Uncertainty in time = +/- 3 secs Prediction of 2012 Sep 8.0 Data for the target star ------------------------ * name: TYC 5783-00181-1 * constellation : Capricornus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 21 04 07.4297 DE: -14 36 20.583 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .022, .021 ) * V mag [mag]: 10.0 * B mag [mag]: 10.2 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1585) Union approx. diameter [km]: 51 approx. diameter ["]: .040 distance from Earth [AU]: 1.74000 * orbital information: orbit source: Preston date of fit: 2012 Sep 07 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 1008 number of rejected observations: 61 time covered by the observations: 1939 Feb 13 - 2012 Sep 01 1 sigma uncertainty ellipse (major, minor, PA): 0.025, 0.015, 101° remarks: * orbital elements for (1585) Union : Mean anomaly = 306.61511124 deg Arg. of pericenter = 264.79577645 deg Long. of node = 150.11655850 deg Inclination = 26.17433970 deg Eccentricity = 0.30885739 Semimajor axis = 2.92849144 AU Perihelion dist = 2.02400522 AU Mag: H = 10.21, G = 0.15 Epoch of elements : MJD 56183.07200000 TDT (2012 Sep 13.072) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Sep 13 1585 Union 1h 43.7m UT 10.0 21 4 7.430-14 36 20.58TYC 5783-00181-1 10.2 14.7 51 4.2 1.740 -1.143 -30.55 -62.3466 -14.598 153.06 3.69 1.7278 0.39696 -0.21464 -3.28747 -6.04737 0.00323 0.00080 2000 306.0109412012 910.00000264.795776150.116558 26.1743400.30885739 2.9284914 2.024005210.7 5.00.15 RATE 1.9667000 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.033 0.026 96 1.80 0.032 0 0-3-3 056178.0020120913_0181-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Sep 07, 22:47 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org