IOTA/IOTA-ES occultation update for (849) Ara / HIP 41751 event on 2012 Sep 27, 01:52 UT Visible from Africa Summary ------- On 2012 Sep 27 UT, the 98 km diameter asteroid (849) Ara will occult a 9.4 mag star in the constellation Hydra for observers along a path across Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 5.5 mag to 14.9 mag (the magnitude of the asteroid) for at most 3.1 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: 69 * date and approx. time of event: 2012 Sep 27, 01:49 - 2012 Sep 27, 01:51 UT * geocentric midpoint of event [JD]: 2456197.57835417 * magnitude of target star: 9.4 * magnitude drop [mag]: 5.5 * estimated maximum duration [s]: 3.1 * Moon: 90 % sunlit, 159° distance * Sun: 56° distance * rough path description: Africa The occultation path -------------------- * approximate projected width [km]: 103 * 1 sigma uncertainty interval [path widths]: +/- 0.85 * 1 sigma uncertainty interval [seconds]: +/- 2.7 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .028 +/- .027) * 1 sigma uncertainty ellipse (major, minor, PA): ( .028", .027", 92° ) * approx speed of asteroid's shadow [km/s]: 31.1888 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of HIP 41751 by 849 Ara on 2012 Sep 27 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 4 0 0 11 9 0 1 49 36 0 88 -55 10 41 2 11 36 53 9 53 20 12 24 7 5 0 0 11 10 58 1 49 36 1 88 -54 10 43 1 11 38 50 9 55 19 12 26 4 6 0 0 11 12 24 1 49 36 2 88 -53 10 44 28 11 40 17 9 56 47 12 27 30 7 0 0 11 13 19 1 49 36 3 88 -52 10 45 23 11 41 12 9 57 42 12 28 25 8 0 0 11 13 43 1 49 36 4 89 -51 10 45 46 11 41 35 9 58 6 12 28 48 9 0 0 11 13 35 1 49 37 5 89 -50 10 45 38 11 41 27 9 57 57 12 28 40 10 0 0 11 12 55 1 49 37 6 89 -50 10 44 58 11 40 47 9 57 17 12 28 1 11 0 0 11 11 43 1 49 37 7 89 -49 10 43 46 11 39 36 9 56 4 12 26 50 12 0 0 11 10 0 1 49 38 8 89 -48 10 42 3 11 37 54 9 54 20 12 25 8 13 0 0 11 7 45 1 49 39 9 89 -47 10 39 47 11 35 39 9 52 3 12 22 55 14 0 0 11 4 59 1 49 39 10 90 -46 10 37 0 11 32 53 9 49 14 12 20 11 15 0 0 11 1 40 1 49 40 11 90 -45 10 33 40 11 29 36 9 45 54 12 16 55 16 0 0 10 57 50 1 49 41 12 90 -44 10 29 49 11 25 47 9 42 1 12 13 7 17 0 0 10 53 28 1 49 41 13 90 -43 10 25 26 11 21 26 9 37 35 12 8 48 18 0 0 10 48 34 1 49 42 14 90 -42 10 20 31 11 16 33 9 32 38 12 3 58 19 0 0 10 43 9 1 49 43 15 91 -41 10 15 4 11 11 9 9 27 8 11 58 36 20 0 0 10 37 11 1 49 44 16 91 -40 10 9 4 11 5 13 9 21 6 11 52 43 21 0 0 10 30 41 1 49 45 17 91 -39 10 2 33 10 58 45 9 14 32 11 46 18 22 0 0 10 23 40 1 49 46 18 91 -38 9 55 29 10 51 45 9 7 25 11 39 21 23 0 0 10 16 6 1 49 47 19 91 -37 9 47 54 10 44 14 8 59 46 11 31 53 24 0 0 10 8 0 1 49 49 20 91 -36 9 39 46 10 36 10 8 51 35 11 23 53 25 0 0 9 59 23 1 49 50 21 91 -35 9 31 6 10 27 35 8 42 51 11 15 21 26 0 0 9 50 13 1 49 51 22 92 -34 9 21 54 10 18 27 8 33 35 11 6 17 27 0 0 9 40 31 1 49 53 23 92 -33 9 12 10 10 8 48 8 23 47 10 56 42 28 0 0 9 30 17 1 49 54 24 92 -32 9 1 53 9 58 37 8 13 25 10 46 35 29 0 0 9 19 31 1 49 56 25 92 -31 8 51 5 9 47 53 8 2 32 10 35 56 30 0 0 9 8 13 1 49 58 26 92 -30 8 39 43 9 36 38 7 51 6 10 24 46 31 0 0 8 56 23 1 49 59 27 92 -29 8 27 50 9 24 51 7 39 8 10 13 3 32 0 0 8 44 0 1 50 1 28 92 -28 8 15 25 9 12 31 7 26 37 10 0 49 33 0 0 8 31 6 1 50 3 29 92 -27 8 2 27 8 59 40 7 13 33 9 48 3 34 0 0 8 17 39 1 50 5 30 92 -26 7 48 57 8 46 16 6 59 58 9 34 45 35 0 0 8 3 40 1 50 7 31 92 -25 7 34 55 8 32 21 6 45 49 9 20 56 36 0 0 7 49 9 1 50 9 32 92 -24 7 20 20 8 17 54 6 31 9 9 6 34 37 0 0 7 34 7 1 50 11 33 92 -23 7 5 14 8 2 54 6 15 56 8 51 41 38 0 0 7 18 32 1 50 13 34 92 -22 6 49 35 7 47 23 6 0 11 8 36 16 39 0 0 7 2 25 1 50 15 35 92 -21 6 33 24 7 31 20 5 43 54 8 20 20 40 0 0 6 45 46 1 50 17 36 92 -20 6 16 42 7 14 46 5 27 4 8 3 52 41 0 0 6 28 36 1 50 20 37 92 -19 5 59 27 6 57 39 5 9 43 7 46 52 42 0 0 6 10 53 1 50 22 38 92 -18 5 41 41 6 40 1 4 51 49 7 29 21 43 0 0 5 52 40 1 50 24 39 92 -17 5 23 23 6 21 52 4 33 24 7 11 19 44 0 0 5 33 54 1 50 27 40 92 -16 5 4 33 6 3 11 4 14 27 6 52 45 45 0 0 5 14 38 1 50 30 41 92 -15 4 45 12 5 43 58 3 54 58 6 33 40 46 0 0 4 54 50 1 50 32 42 91 -14 4 25 20 5 24 15 3 34 58 6 14 4 47 0 0 4 34 31 1 50 35 43 91 -13 4 4 56 5 4 0 3 14 26 5 53 57 48 0 0 4 13 41 1 50 38 44 91 -12 3 44 1 4 43 15 2 53 24 5 33 19 49 0 0 3 52 20 1 50 40 45 91 -11 3 22 36 4 21 59 2 31 50 5 12 11 50 0 0 3 30 29 1 50 43 46 90 -10 3 0 40 4 0 13 2 9 46 4 50 33 51 0 0 3 8 8 1 50 46 47 90 -9 2 38 14 3 37 56 1 47 12 4 28 24 52 0 0 2 45 16 1 50 49 48 90 -8 2 15 18 3 15 10 1 24 7 4 5 46 53 0 0 2 21 55 1 50 52 49 89 -7 1 51 52 2 51 53 1 0 33 3 42 38 54 0 0 1 58 5 1 50 55 50 89 -6 1 27 56 2 28 8 0 36 28 3 19 1 55 0 0 1 33 45 1 50 59 51 88 -5 1 3 32 2 3 53 0 11 55 2 54 54 56 0 0 1 8 57 1 51 2 52 88 -4 0 38 38 1 39 9 - 0 13 7 2 30 19 57 0 0 0 43 40 1 51 5 53 87 -3 0 13 16 1 13 58 - 0 38 37 2 5 16 58 0 0 0 17 55 1 51 8 54 87 -2 - 0 12 34 0 48 18 - 1 4 36 1 39 44 59 0 0 - 0 8 18 1 51 12 55 86 -1 - 0 38 51 0 22 10 - 1 31 2 1 13 45 Uncertainty in time = +/- 3 secs Prediction of 2012 Aug 7.0 Data for the target star ------------------------ * name: HIP 41751 * constellation : Hydra * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 08 30 49.2658 DE: +02 16 26.699 * position source: mpos:UCAC2 pm:UCAC2 plx:HIP2 * standard error: RA,DE ["]: ( .026, .026 ) * V mag [mag]: 9.4 * B mag [mag]: 10.1 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (849) Ara approx. diameter [km]: 98 approx. diameter ["]: .032 distance from Earth [AU]: 4.23200 * orbital information: orbit source: Preston date of fit: 2012 Aug 06 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1152 number of rejected observations: 94 time covered by the observations: 1919 Jul 03 - 2012 Mar 22 1 sigma uncertainty ellipse (major, minor, PA): 0.010, 0.008, 106° remarks: * orbital elements for (849) Ara : Mean anomaly = 188.14973203 deg Arg. of pericenter = 63.51657302 deg Long. of node = 228.38356444 deg Inclination = 19.52891972 deg Eccentricity = 0.19871867 Semimajor axis = 3.14700398 AU Perihelion dist = 2.52163553 AU Mag: H = 8.06, G = 0.15 Epoch of elements : MJD 56197.07800000 TDT (2012 Sep 27.078) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Sep 27 849 Ara 1h 52.8m UT 9.4 8 30 49.266 2 16 26.70HIP 41751 10.1 14.9 98 3.1 4.232 2.137 -17.68 93.2320 2.279 149.54 -1.74 1.8805 -0.15082 -0.26611 15.41309 -8.50477 -0.00487 0.00030 2000 186.9001392012 920.00000 63.516573228.383564 19.5289200.19871867 3.1470040 2.5216355 8.1 5.00.15 RATE 1.7654610 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.028 0.027 92 1.85 0.027 0 0-2-1 456146.0020120927__41751 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Aug 06, 21:05 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org