IOTA/IOTA-ES occultation update for (1200) Imperatrix / UCAC2 37835986 event on 2012 Oct 20, 18:17 UT Visible from SE Asia Summary ------- On 2012 Oct 20 UT, the 44 km diameter asteroid (1200) Imperatrix will occult a 11.9 mag star in the constellation Taurus for observers along a path across SE Asia. In the case of an occultation, the combined light of the asteroid and the star will drop by 3.9 mag to 15.7 mag (the magnitude of the asteroid) for at most 4.0 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: 43 * date and approx. time of event: 2012 Oct 20, 18:09 - 2012 Oct 20, 18:26 UT * geocentric midpoint of event [JD]: 2456221.26201667 * magnitude of target star: 11.9 * magnitude drop [mag]: 3.9 * estimated maximum duration [s]: 4.0 * Moon: 35 % sunlit, 139° distance * Sun: 149° distance * rough path description: SE Asia The occultation path -------------------- * approximate projected width [km]: 48 * 1 sigma uncertainty interval [path widths]: +/- 1.52 * 1 sigma uncertainty interval [seconds]: +/- 6.8 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .043 +/- .038) * 1 sigma uncertainty ellipse (major, minor, PA): ( .043", .037", 85° ) * approx speed of asteroid's shadow [km/s]: 10.8323 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 37835986 by 1200 Imperatrix on 2012 Oct 20 Centre Star Star Sun Path Limits Error Limits E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4 o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " Latitude Latitude Latitude Latitude 39 0 0 -43 16 41 18 26 13 0 65 -25 -43 2 16 -43 31 8 .. .. .. .. .. .. 40 0 0 -42 56 34 18 26 13 1 65 -25 -42 42 7 -43 11 3 .. .. .. -43 55 17 41 0 0 -42 36 4 18 26 13 2 64 -26 -42 21 34 -42 50 35 -41 37 42 -43 34 56 42 0 0 -42 15 10 18 26 12 3 63 -27 -42 0 38 -42 29 44 -41 16 40 -43 14 11 43 0 0 -41 53 53 18 26 12 4 63 -28 -41 39 19 -42 8 29 -40 55 14 -42 53 3 44 0 0 -41 32 13 18 26 11 4 62 -28 -41 17 37 -41 46 51 -40 33 25 -42 31 31 45 0 0 -41 10 10 18 26 11 5 61 -29 -40 55 32 -41 24 50 -40 11 14 -42 9 37 46 0 0 -40 47 44 18 26 10 6 61 -30 -40 33 4 -41 2 26 -39 48 40 -41 47 19 47 0 0 -40 24 55 18 26 8 7 60 -31 -40 10 13 -40 39 39 -39 25 43 -41 24 39 48 0 0 -40 1 44 18 26 7 8 59 -32 -39 47 0 -40 16 30 -39 2 24 -41 1 36 49 0 0 -39 38 11 18 26 6 9 59 -32 -39 23 25 -39 52 59 -38 38 44 -40 38 10 50 0 0 -39 14 16 18 26 4 10 58 -33 -38 59 28 -39 29 6 -38 14 41 -40 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time = +/- 7 secs Prediction of 2012 Oct 8.0 Data for the target star ------------------------ * name: UCAC2 37835986 * constellation : Taurus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 03 49 16.7565 DE: +17 21 27.478 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .027, .030 ) * V mag [mag]: 11.9 * B mag [mag]: 0.0 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1200) Imperatrix approx. diameter [km]: 44 approx. diameter ["]: .025 distance from Earth [AU]: 2.47100 * orbital information: orbit source: Preston date of fit: 2012 Oct 07 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1099 number of rejected observations: 58 time covered by the observations: 1913 Mar 08 - 2012 Sep 26 1 sigma uncertainty ellipse (major, minor, PA): 0.034, 0.022, 82° remarks: * orbital elements for (1200) Imperatrix : Mean anomaly = 151.72628199 deg Arg. of pericenter = 47.96187678 deg Long. of node = 205.31362851 deg Inclination = 4.60608684 deg Eccentricity = 0.10590460 Semimajor axis = 3.06726069 AU Perihelion dist = 2.74242368 AU Mag: H = 10.82, G = 0.15 Epoch of elements : MJD 56220.76200000 TDT (2012 Oct 20.762) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 20 1200 Imperatrix 18h 17.3m UT 11.9 3 49 16.756 17 21 27.48UCAC2 37835986 0.0 15.7 44 4.0 2.471 -1.416 -7.96 113.3840 17.359 -98.15 -10.68 18.2884 0.15088 -0.38466 -5.69050 -2.23609 -0.00304 -0.00043 2000 151.58647420121020.00000 47.961877205.313629 4.6060870.10590460 3.0672607 2.742423710.5 5.00.15 RATE 1.8347550 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.043 0.037 85 2.52 0.037 0 0 5-2 056208.0020121020_835986 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Oct 07, 19:05 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org