IOTA/IOTA-ES occultation update for (1838) Ursa / TYC 2434-00776-1 event on 2012 Oct 10, 02:23 UT Visible from Arabia, Africa Summary ------- On 2012 Oct 10 UT, the 40 km diameter asteroid (1838) Ursa will occult a 10.5 mag star in the constellation Auriga for observers along a path across Arabia, Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 5.8 mag to 16.3 mag (the magnitude of the asteroid) for at most 2.8 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC. The event at a glimpse ---------------------- * Rank: 36 * date and approx. time of event: 2012 Oct 10, 02:17 - 2012 Oct 10, 02:24 UT * geocentric midpoint of event [JD]: 2456210.60017917 * magnitude of target star: 10.5 * magnitude drop [mag]: 5.8 * estimated maximum duration [s]: 2.8 * Moon: 32 % sunlit, 37° distance * Sun: 101° distance * rough path description: Arabia, Africa Additional comments ------------------- 5" double star The occultation path -------------------- * approximate projected width [km]: 41 * 1 sigma uncertainty interval [path widths]: +/- 1.82 * 1 sigma uncertainty interval [seconds]: +/- 5.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .048 +/- .032) * 1 sigma uncertainty ellipse (major, minor, PA): ( .048", .031", 80° ) * approx speed of asteroid's shadow [km/s]: 14.4640 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 2434-00776-1 by 1838 Ursa on 2012 Oct 10 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 ' " Longitude Longitude Longitude Longitude - 0 21 30 -43 0 0 2 17 5 0 34 -30 - 0 3 29 - 0 39 33 1 1 55 ... .. .. 0 32 20 -42 0 0 2 17 5 2 33 -30 0 50 0 0 14 39 1 54 6 - 0 49 57 1 24 37 -41 0 0 2 17 6 3 33 -30 1 41 57 1 7 16 2 44 49 0 3 56 2 15 27 -40 0 0 2 17 6 4 32 -31 2 32 28 1 58 26 3 34 12 0 56 16 3 4 57 -39 0 0 2 17 7 5 31 -31 3 21 39 2 48 13 4 22 20 1 47 11 3 53 12 -38 0 0 2 17 8 6 31 -31 4 9 38 3 36 46 5 9 18 2 36 45 4 40 19 -37 0 0 2 17 9 8 31 -31 4 56 29 4 24 8 5 55 12 3 25 7 5 26 22 -36 0 0 2 17 10 9 30 -31 5 42 17 5 10 26 6 40 7 4 12 20 6 11 26 -35 0 0 2 17 12 10 30 -31 6 27 7 5 55 44 7 24 7 4 58 29 6 55 35 -34 0 0 2 17 13 11 29 -32 7 11 3 6 40 6 8 7 15 5 43 40 7 38 53 -33 0 0 2 17 15 12 29 -32 7 54 9 7 23 37 8 49 37 6 27 57 8 21 24 -32 0 0 2 17 17 13 28 -32 8 36 28 8 6 20 9 31 14 7 11 23 9 3 12 -31 0 0 2 17 19 15 28 -32 9 18 4 8 48 18 10 12 11 7 54 2 9 44 19 -30 0 0 2 17 22 16 28 -32 9 59 1 9 29 36 10 52 31 8 35 58 10 24 48 -29 0 0 2 17 24 17 27 -32 10 39 21 10 10 15 11 32 16 9 17 13 11 4 44 -28 0 0 2 17 27 18 27 -32 11 19 8 10 50 20 12 11 30 9 57 52 11 44 8 -27 0 0 2 17 30 19 27 -32 11 58 23 11 29 52 12 50 14 10 37 56 12 23 2 -26 0 0 2 17 33 20 26 -32 12 37 9 12 8 55 13 28 32 11 17 28 13 1 30 -25 0 0 2 17 36 22 26 -31 13 15 30 12 47 30 14 6 25 11 56 32 13 39 34 -24 0 0 2 17 40 23 26 -31 13 53 26 13 25 41 14 43 56 12 35 9 14 17 15 -23 0 0 2 17 43 24 25 -31 14 31 1 14 3 29 15 21 8 13 13 21 14 54 37 -22 0 0 2 17 47 25 25 -31 15 8 17 14 40 57 15 58 1 13 51 12 15 31 41 -21 0 0 2 17 51 26 25 -31 15 45 15 15 18 6 16 34 39 14 28 42 16 8 28 -20 0 0 2 17 55 27 24 -31 16 21 57 15 54 59 17 11 2 15 5 55 16 45 2 -19 0 0 2 17 59 28 24 -31 16 58 26 16 31 38 17 47 14 15 42 52 17 21 24 -18 0 0 2 18 4 30 24 -30 17 34 43 17 8 4 18 23 15 16 19 35 17 57 35 -17 0 0 2 18 8 31 24 -30 18 10 51 17 44 20 18 59 8 16 56 6 18 33 38 -16 0 0 2 18 13 32 23 -30 18 46 50 18 20 26 19 34 53 17 32 26 19 9 34 -15 0 0 2 18 18 33 23 -30 19 22 42 18 56 26 20 10 34 18 8 38 19 45 25 -14 0 0 2 18 23 34 23 -29 19 58 30 19 32 19 20 46 11 18 44 43 20 21 12 -13 0 0 2 18 28 35 23 -29 20 34 15 20 8 10 21 21 47 19 20 43 20 56 58 -12 0 0 2 18 33 36 22 -29 21 9 58 20 43 58 21 57 22 19 56 39 21 32 43 -11 0 0 2 18 39 38 22 -28 21 45 42 21 19 45 22 32 59 20 32 34 22 8 30 -10 0 0 2 18 45 39 22 -28 22 21 28 21 55 34 23 8 39 21 8 29 22 44 21 - 9 0 0 2 18 50 40 22 -28 22 57 17 22 31 25 23 44 24 21 44 25 23 20 16 - 8 0 0 2 18 56 41 21 -27 23 33 11 23 7 21 24 20 16 22 20 25 23 56 17 - 7 0 0 2 19 3 42 21 -27 24 9 12 23 43 23 24 56 15 22 56 30 24 32 27 - 6 0 0 2 19 9 43 21 -26 24 45 21 24 19 33 25 32 24 23 32 41 25 8 47 - 5 0 0 2 19 15 45 20 -26 25 21 41 24 55 53 26 8 45 24 9 0 25 45 18 - 4 0 0 2 19 22 46 20 -25 25 58 13 25 32 24 26 45 19 24 45 29 26 22 2 - 3 0 0 2 19 28 47 20 -25 26 34 58 26 9 7 27 22 7 25 22 10 26 59 2 - 2 0 0 2 19 35 48 19 -24 27 11 59 26 46 6 27 59 13 25 59 5 27 36 19 - 1 0 0 2 19 42 49 19 -24 27 49 17 27 23 21 28 36 37 26 36 14 28 13 54 0 0 0 2 19 49 50 19 -23 28 26 54 28 0 54 29 14 22 27 13 41 28 51 50 1 0 0 2 19 57 51 18 -23 29 4 53 28 38 48 29 52 29 27 51 27 Latitude Latitude Latitude Latitude 29 0 0 1 12 50 2 19 58 52 18 -23 0 52 19 1 33 19 - 0 22 46 2 47 29 30 0 0 2 46 18 2 20 10 53 18 -22 2 26 0 3 6 33 1 11 45 4 19 55 31 0 0 4 18 8 2 20 22 55 17 -21 3 58 5 4 38 9 2 44 41 5 50 40 32 0 0 5 48 14 2 20 34 57 16 -20 5 28 25 6 8 0 4 15 54 7 19 40 33 0 0 7 16 29 2 20 46 59 15 -19 6 56 54 7 36 1 5 45 18 8 46 47 34 0 0 8 42 49 2 20 58 60 14 -18 8 23 29 9 2 6 7 12 48 10 11 58 35 0 0 10 7 9 2 21 10 62 13 -17 9 48 5 10 26 11 8 38 20 11 35 9 36 0 0 11 29 26 2 21 22 63 12 -16 11 10 38 11 48 13 10 1 49 12 56 16 37 0 0 12 49 39 2 21 34 65 11 -15 12 31 5 13 8 10 11 23 13 14 15 19 38 0 0 14 7 44 2 21 45 66 9 -14 13 49 26 14 26 1 12 42 30 15 32 14 39 0 0 15 23 42 2 21 57 68 8 -14 15 5 39 15 41 43 13 59 39 16 47 2 40 0 0 16 37 31 2 22 9 69 6 -13 16 19 43 16 55 17 15 14 39 17 59 42 41 0 0 17 49 12 2 22 20 70 4 -12 17 31 39 18 6 43 16 27 30 19 10 14 42 0 0 18 58 45 2 22 31 72 1 -11 18 41 27 19 16 2 17 38 12 20 18 40 43 0 0 20 6 12 2 22 43 73 358 -10 19 49 8 20 23 14 18 46 47 21 25 0 44 0 0 21 11 34 2 22 54 74 355 -9 20 54 44 21 28 21 19 53 15 22 29 16 45 0 0 22 14 52 2 23 4 75 352 -8 21 58 16 22 31 25 20 57 39 23 31 30 46 0 0 23 16 8 2 23 15 75 348 -7 22 59 46 23 32 28 21 59 59 24 31 43 47 0 0 24 15 25 2 23 26 76 344 -6 23 59 17 24 31 32 23 0 19 25 29 59 48 0 0 25 12 45 2 23 36 77 339 -5 24 56 50 25 28 39 23 58 40 26 26 19 49 0 0 26 8 11 2 23 46 77 334 -5 25 52 28 26 23 52 24 55 5 27 20 46 50 0 0 27 1 44 2 23 56 78 329 -4 26 46 14 27 17 13 25 49 36 28 13 23 51 0 0 27 53 28 2 24 6 78 324 -3 27 38 10 28 8 45 26 42 17 29 4 11 52 0 0 28 43 26 2 24 15 78 319 -2 28 28 19 28 58 31 27 33 9 29 53 15 53 0 0 29 31 39 2 24 24 78 314 -1 29 16 44 29 46 33 28 22 16 30 40 36 54 0 0 30 18 11 2 24 34 78 309 0 30 3 27 30 32 54 29 9 39 31 26 18 Uncertainty in time = +/- 7 secs Prediction of 2012 Jul 10.0 Data for the target star ------------------------ * name: TYC 2434-00776-1 * constellation : Auriga * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 06 27 58.6024 DE: +37 14 44.162 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .017, .018 ) * V mag [mag]: 10.5 * B mag [mag]: 11.0 * Apparent position with proper motion RA(deg): 97.2175370215 DE(deg): 37.2340086105 * Equation of equinoxes (radians) : 0.000062306484957 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1838) Ursa approx. diameter [km]: 40 approx. diameter ["]: .020 distance from Earth [AU]: 2.82000 * orbital information: orbit source: Preston date of fit: 2012 Jul 09 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 908 number of rejected observations: 12 time covered by the observations: 1951 Apr 09 - 2012 Feb 02 1 sigma uncertainty ellipse (major, minor, PA): 0.045, 0.025, 79° remarks: * orbital elements for (1838) Ursa : Mean anomaly = 341.72657114 deg Arg. of pericenter = 53.94129631 deg Long. of node = 44.26603060 deg Inclination = 21.98189750 deg Eccentricity = 0.01809134 Semimajor axis = 3.22009463 AU Perihelion dist = 3.16183881 AU Mag: H = 10.69, G = 0.15 Epoch of elements : MJD 56210.10000000 TDT (2012 Oct 10.100) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 10 1838 Ursa 2h 24.3m UT 10.5 6 27 58.602 37 14 44.16TYC 2434-00776-1 11.0 16.3 40 2.8 2.820 1.448 18.69 41.8295 37.240 140.69 -6.75 2.4043 0.15220 -0.14201 5.54668 5.99027 -0.00576 0.00002 2000 340.0038202012 930.00000 53.941296 44.266031 21.9818970.01809134 3.2200946 3.161838810.6 5.00.15 RATE 1.7056940 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.048 0.031 80 2.82 0.036 0 0 4 2 056118.0020121010_0776-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Aug 26, 02:05 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org