IOTA/IOTA-ES occultation update for (2241) Alcathous / UCAC2 23982965 event on 2010 Mar 11, 03:54 UT Visible from N Africa Summary ------- On 2010 Mar 11 UT, the 115 km diameter asteroid (2241) Alcathous will occult a 11.4 mag star in the constellation Sagittarius for observers along a path across N Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 5.1 mag to 16.5 mag (the magnitude of the asteroid) for at most 4.4 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: 25 * date and approx. time of event: 2010 Mar 11, 03:52 - 2010 Mar 11, 03:54 UT * magnitude of target star: 11.4 * magnitude drop [mag]: 5.1 * estimated maximum duration [s]: 4.4 * Moon: 19 % sunlit, 13° distance * Sun: 64° distance * rough path description: N Africa The occultation path -------------------- * approximate projected width [km]: 217 * 1 sigma uncertainty interval [path widths]: +/- 2.64 * 1 sigma uncertainty interval [seconds]: +/- 10.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .075 +/- .077) * 1 sigma uncertainty ellipse (major, minor, PA): ( .077", .075", 356° ) * approx speed of asteroid's shadow [km/s]: 26.2874 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 23982965 by 2241 Alcathous on 2010 Mar 11 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 Latitude Latitude Latitude Latitude 36 0 0 34 0 9 3 54 21 31 154 0 32 59 40 35 2 28 28 4 44 41 11 54 35 0 0 33 47 12 3 54 17 31 152 -1 32 46 57 34 49 17 27 52 57 40 56 51 34 0 0 33 35 1 3 54 14 31 151 -2 32 34 58 34 36 52 27 41 51 40 42 43 33 0 0 33 23 36 3 54 10 31 150 -3 32 23 45 34 25 14 27 31 27 40 29 29 32 0 0 33 12 57 3 54 6 30 149 -4 32 13 17 34 14 23 27 21 45 40 17 9 31 0 0 33 3 5 3 54 3 30 148 -5 32 3 35 34 4 19 27 12 45 40 5 43 30 0 0 32 53 58 3 53 59 30 147 -5 31 54 37 33 55 3 27 4 28 39 55 10 29 0 0 32 45 38 3 53 56 29 146 -6 31 46 26 33 46 33 26 56 52 39 45 31 28 0 0 32 38 4 3 53 53 29 145 -7 31 39 0 33 38 51 26 49 59 39 36 45 27 0 0 32 31 16 3 53 49 29 144 -8 31 32 19 33 31 55 26 43 48 39 28 53 26 0 0 32 25 15 3 53 46 28 143 -9 31 26 24 33 25 47 26 38 20 39 21 55 25 0 0 32 20 0 3 53 43 28 142 -10 31 21 14 33 20 26 26 33 34 39 15 50 24 0 0 32 15 31 3 53 40 27 142 -11 31 16 50 33 15 52 26 29 30 39 10 38 23 0 0 32 11 49 3 53 36 27 141 -11 31 13 12 33 12 5 26 26 8 39 6 19 22 0 0 32 8 52 3 53 33 26 140 -12 31 10 19 33 9 5 26 23 29 39 2 53 21 0 0 32 6 43 3 53 30 26 139 -13 31 8 12 33 6 53 26 21 33 39 0 21 20 0 0 32 5 19 3 53 27 25 138 -14 31 6 50 33 5 27 26 20 18 38 58 41 19 0 0 32 4 41 3 53 25 25 137 -15 31 6 13 33 4 48 26 19 46 38 57 55 18 0 0 32 4 50 3 53 22 24 136 -16 31 6 22 33 4 57 26 19 56 38 58 1 17 0 0 32 5 45 3 53 19 23 136 -17 31 7 16 33 5 52 26 20 48 38 59 0 16 0 0 32 7 26 3 53 16 23 135 -17 31 8 56 33 7 34 26 22 23 39 0 53 15 0 0 32 9 53 3 53 14 22 134 -18 31 11 21 33 10 4 26 24 40 39 3 38 14 0 0 32 13 6 3 53 11 21 133 -19 31 14 31 33 13 19 26 27 39 39 7 15 13 0 0 32 17 4 3 53 9 21 133 -20 31 18 27 33 17 22 26 31 20 39 11 46 12 0 0 32 21 49 3 53 6 20 132 -21 31 23 7 33 22 11 26 35 42 39 17 9 11 0 0 32 27 20 3 53 4 19 131 -22 31 28 33 33 27 47 26 40 47 39 23 25 10 0 0 32 33 36 3 53 2 19 130 -22 31 34 43 33 34 10 26 46 34 39 30 33 9 0 0 32 40 38 3 52 59 18 130 -23 31 41 39 33 41 19 26 53 2 39 38 35 8 0 0 32 48 25 3 52 57 17 129 -24 31 49 19 33 49 14 27 0 12 39 47 29 7 0 0 32 56 58 3 52 55 16 128 -25 31 57 44 33 57 56 27 8 4 39 57 15 6 0 0 33 6 17 3 52 53 16 128 -26 32 6 54 34 7 24 27 16 36 40 7 54 5 0 0 33 16 21 3 52 52 15 127 -26 32 16 48 34 17 38 27 25 51 40 19 26 4 0 0 33 27 9 3 52 50 14 126 -27 32 27 27 34 28 38 27 35 46 40 31 50 3 0 0 33 38 43 3 52 48 13 126 -28 32 38 49 34 40 24 27 46 23 40 45 8 2 0 0 33 51 2 3 52 47 13 125 -29 32 50 56 34 52 56 27 57 40 40 59 17 1 0 0 34 4 6 3 52 45 12 124 -29 33 3 47 35 6 13 .. .. .. 41 14 20 0 0 0 34 17 54 3 52 44 11 124 -30 33 17 22 35 20 16 .. .. .. 41 30 14 - 1 0 0 34 32 27 3 52 43 10 123 -31 33 31 40 35 35 5 .. .. .. 41 47 2 - 2 0 0 34 47 44 3 52 41 9 123 -32 33 46 42 35 50 38 .. .. .. 42 4 42 - 3 0 0 35 3 45 3 52 40 8 122 -32 34 2 28 36 6 57 .. .. .. 42 23 15 - 4 0 0 35 20 30 3 52 39 8 121 -33 34 18 56 36 24 0 .. .. .. 42 42 41 - 5 0 0 35 37 59 3 52 39 7 121 -34 34 36 7 36 41 49 .. .. .. 43 2 59 - 6 0 0 35 56 11 3 52 38 6 120 -34 34 54 1 37 0 21 .. .. .. 43 24 11 - 7 0 0 36 15 7 3 52 37 5 120 -35 35 12 37 37 19 38 .. .. .. 43 46 15 - 8 0 0 36 34 45 3 52 37 4 119 -35 35 31 56 37 39 39 .. .. .. 44 9 11 - 9 0 0 36 55 7 3 52 36 3 118 -36 35 51 56 38 0 24 .. .. .. .. .. .. - 10 0 0 37 16 11 3 52 36 2 118 -37 36 12 38 38 21 52 .. .. .. .. .. .. - 11 0 0 37 37 56 3 52 36 2 117 -37 36 34 1 38 44 3 .. .. .. .. .. .. - 12 0 0 38 0 24 3 52 35 1 117 -38 36 56 5 39 6 57 .. .. .. .. .. .. Uncertainty in time = +/- 12 secs Prediction of 2010 Jan 26.0 Data for the target star ------------------------ * name: UCAC2 23982965 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 19 08 25.0584 DE: -20 17 25.650 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .025, .070 ) * V mag [mag]: 11.4 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (2241) Alcathous approx. diameter [km]: 115 approx. diameter ["]: .029 distance from Earth [AU]: 5.44900 * orbital information: orbit source: Preston date of fit: 2010 Jan 25 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 626 number of rejected observations: 13 time covered by the observations: 1950 Jun 19 - 2009 Jul 10 1 sigma uncertainty ellipse (major, minor, PA): 0.071, 0.032, 68° remarks: * orbital elements for (2241) Alcathous : Mean anomaly = 68.84898709 deg Arg. of pericenter = 292.18762125 deg Long. of node = 267.98060109 deg Inclination = 16.60847894 deg Eccentricity = 0.06581913 Semimajor axis = 5.20084292 AU Perihelion dist = 4.85852798 AU Mag: H = 8.62, G = 0.15 Epoch of elements : MJD 55266.16300000 TDT (2010 Mar 11.163) ------ occelmnt file for Occult BEGIN ----------------------------------- 2010 Mar 11 2241 Alcathous 3h 54.7m UT 11.4 19 8 25.058-20 17 25.65UCAC2 23982965 0.0 16.5 115 4.4 5.449 1.627 7.02 59.7159 -20.292 123.86 -3.78 3.9117 -0.25286 0.81021 14.18528 4.35025 -0.00544 -0.00054 2000 68.3368512010 3 5.00000292.187621267.980601 16.6084790.06581913 5.2008429 4.8585280 8.6 5.00.15 RATE 0.8309850 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.077 0.075 356 3.64 0.077 0 055222.0020100311_982965 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2010 Jan 25, 20:15 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org