IOTA/IOTA-ES occultation update for (20) Massalia / HIP 43412 event on 2007 Apr 24, 23:20 UT Visible from Brazil, Argentina, Chile Summary ------- On 2007 Apr 24 UT, the 146 km diameter asteroid (20) Massalia will occult a 8.1 mag star in the constellation Cancer for observers along a path across Brazil, Argentina, Chile. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.6 mag to 10.6 mag (the magnitude of the asteroid) for at most 9.1 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Ron Stone, 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: . The event at a glimpse ---------------------- * Rank: 99 * date and approx. time of event: 2007 Apr 24, 23:15 - 2007 Apr 24, 23:25 UT * magnitude of target star: 8.1 * magnitude drop [mag]: 2.6 * estimated maximum duration [s]: 9.1 * Moon: 57 % sunlit, 4° distance * Sun: 96° distance * rough path description: Brazil, Argentina, Chile The occultation path -------------------- * approximate projected width [km]: 190 * 1 sigma uncertainty interval [path widths]: +/- 0.16 * 1 sigma uncertainty interval [seconds]: +/- 2.2 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .028 +/- .017) * 1 sigma uncertainty ellipse (major, minor, PA): ( .028", .017", 92° ) * approx speed of asteroid's shadow [km/s]: 16.0958 * website for maps: http://lunar-occultations.com/iota/asteroids/astrndx.htm http://www.asteroidoccultation.com Path Coordinates: Occultation of HIP 43412 by 20 Massalia on 2007 Apr 24 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 -150 0 0 -24 6 26 23 15 29 1 71 48 -25 0 46 .. .. .. -25 18 19 .. .. .. -149 0 0 -23 48 16 23 15 29 2 71 48 -24 42 29 .. .. .. -24 59 59 .. .. .. -148 0 0 -23 30 28 23 15 29 3 70 48 -24 24 34 -22 37 6 -24 42 3 .. .. .. -147 0 0 -23 13 3 23 15 30 4 70 48 -24 7 2 -22 19 47 -24 24 28 .. .. .. -146 0 0 -22 56 1 23 15 30 5 69 48 -23 49 54 -22 2 52 -24 7 18 -21 46 0 -145 0 0 -22 39 23 23 15 31 6 69 47 -23 33 9 -21 46 20 -23 50 31 -21 29 30 -144 0 0 -22 23 9 23 15 32 7 69 47 -23 16 48 -21 30 11 -23 34 8 -21 13 23 -143 0 0 -22 7 19 23 15 33 8 68 46 -23 0 52 -21 14 27 -23 18 9 -20 57 41 -142 0 0 -21 51 53 23 15 34 8 68 46 -22 45 20 -20 59 8 -23 2 36 -20 42 23 -141 0 0 -21 36 53 23 15 35 9 67 46 -22 30 14 -20 44 13 -22 47 27 -20 27 31 -140 0 0 -21 22 18 23 15 37 10 67 45 -22 15 33 -20 29 44 -22 32 45 -20 13 3 -139 0 0 -21 8 8 23 15 39 11 67 45 -22 1 18 -20 15 40 -22 18 28 -19 59 1 -138 0 0 -20 54 25 23 15 40 12 66 44 -21 47 29 -20 2 2 -22 4 37 -19 45 25 -137 0 0 -20 41 8 23 15 42 13 66 44 -21 34 7 -19 48 50 -21 51 13 -19 32 14 -136 0 0 -20 28 18 23 15 44 14 65 43 -21 21 11 -19 36 5 -21 38 16 -19 19 31 -135 0 0 -20 15 54 23 15 47 15 65 43 -21 8 43 -19 23 46 -21 25 46 -19 7 14 -134 0 0 -20 3 58 23 15 49 16 65 42 -20 56 42 -19 11 55 -21 13 43 -18 55 23 -133 0 0 -19 52 29 23 15 51 17 64 41 -20 45 8 -19 0 30 -21 2 8 -18 44 0 -132 0 0 -19 41 28 23 15 54 18 64 41 -20 34 2 -18 49 33 -20 51 0 -18 33 5 -131 0 0 -19 30 55 23 15 57 19 63 40 -20 23 25 -18 39 4 -20 40 21 -18 22 37 -130 0 0 -19 20 49 23 16 0 20 63 40 -20 13 15 -18 29 3 -20 30 11 -18 12 37 -129 0 0 -19 11 12 23 16 3 21 62 39 -20 3 34 -18 19 30 -20 20 29 -18 3 5 -128 0 0 -19 2 4 23 16 6 22 62 38 -19 54 22 -18 10 25 -20 11 15 -17 54 1 -127 0 0 -18 53 24 23 16 9 23 62 37 -19 45 39 -18 1 49 -20 2 31 -17 45 26 -126 0 0 -18 45 14 23 16 13 23 61 37 -19 37 25 -17 53 41 -19 54 16 -17 37 20 -125 0 0 -18 37 32 23 16 16 24 61 36 -19 29 40 -17 46 3 -19 46 30 -17 29 42 -124 0 0 -18 30 20 23 16 20 25 60 35 -19 22 25 -17 38 53 -19 39 14 -17 22 33 -123 0 0 -18 23 37 23 16 24 26 60 34 -19 15 39 -17 32 13 -19 32 27 -17 15 54 -122 0 0 -18 17 23 23 16 27 27 59 34 -19 9 24 -17 26 2 -19 26 11 -17 9 44 -121 0 0 -18 11 40 23 16 31 28 59 33 -19 3 38 -17 20 20 -19 20 24 -17 4 3 -120 0 0 -18 6 26 23 16 36 29 58 32 -18 58 22 -17 15 9 -19 15 7 -16 58 52 -119 0 0 -18 1 42 23 16 40 30 57 31 -18 53 36 -17 10 26 -19 10 21 -16 54 10 -118 0 0 -17 57 28 23 16 44 31 57 30 -18 49 21 -17 6 14 -19 6 5 -16 49 58 -117 0 0 -17 53 45 23 16 49 31 56 30 -18 45 36 -17 2 32 -19 2 20 -16 46 16 -116 0 0 -17 50 31 23 16 53 32 56 29 -18 42 21 -16 59 20 -18 59 5 -16 43 4 -115 0 0 -17 47 48 23 16 58 33 55 28 -18 39 37 -16 56 37 -18 56 20 -16 40 23 -114 0 0 -17 45 36 23 17 3 34 54 27 -18 37 24 -16 54 25 -18 54 7 -16 38 11 -113 0 0 -17 43 53 23 17 8 35 54 26 -18 35 41 -16 52 44 -18 52 24 -16 36 29 -112 0 0 -17 42 42 23 17 13 35 53 25 -18 34 30 -16 51 33 -18 51 12 -16 35 18 -111 0 0 -17 42 1 23 17 18 36 52 24 -18 33 49 -16 50 52 -18 50 32 -16 34 37 -110 0 0 -17 41 51 23 17 23 37 51 24 -18 33 39 -16 50 41 -18 50 22 -16 34 27 -109 0 0 -17 42 11 23 17 28 38 51 23 -18 34 0 -16 51 1 -18 50 43 -16 34 47 -108 0 0 -17 43 3 23 17 34 38 50 22 -18 34 52 -16 51 52 -18 51 35 -16 35 37 -107 0 0 -17 44 25 23 17 39 39 49 21 -18 36 15 -16 53 13 -18 52 58 -16 36 58 -106 0 0 -17 46 17 23 17 45 40 48 20 -18 38 9 -16 55 5 -18 54 53 -16 38 49 -105 0 0 -17 48 41 23 17 51 41 47 19 -18 40 34 -16 57 27 -18 57 18 -16 41 11 -104 0 0 -17 51 35 23 17 56 41 46 18 -18 43 30 -17 0 20 -19 0 15 -16 44 3 -103 0 0 -17 55 1 23 18 2 42 45 17 -18 46 57 -17 3 43 -19 3 42 -16 47 26 -102 0 0 -17 58 56 23 18 8 43 44 16 -18 50 54 -17 7 37 -19 7 41 -16 51 19 -101 0 0 -18 3 23 23 18 14 43 43 15 -18 55 23 -17 12 1 -19 12 10 -16 55 43 -100 0 0 -18 8 20 23 18 20 44 42 14 -19 0 23 -17 16 56 -19 17 11 -17 0 37 - 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3 0 0 .. .. .. .. .. .. .. .. .. .. .. .. -49 56 42 .. .. .. .. .. .. Data for the target star ------------------------ * name: HIP 43412 * constellation : Cancer * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 08 50 33.2804 DE: +17 01 55.136 * position source: mpos:HIP pm:HIP plx:HIP * standard error: RA,DE ["]: ( .026, .015 ) * V mag [mag]: 8.1 * B mag [mag]: 8.2 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (20) Massalia approx. diameter [km]: 146 approx. diameter ["]: .110 distance from Earth [AU]: 1.83400 * orbital information: orbit source: Preston date of fit: 2007 Apr 20 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 1346 number of rejected observations: 252 time covered by the observations: 1900 Jul 17 - 2007 Apr 11 1 sigma uncertainty ellipse (major, minor, PA): 0.010, 0.008, 105° remarks: * orbital elements for (20) Massalia : Mean anomaly = 42.93296423 deg Arg. of pericenter = 255.49079962 deg Long. of node = 206.50740468 deg Inclination = 0.70693276 deg Eccentricity = 0.14275858 Semimajor axis = 2.40881439 AU Perihelion dist = 2.06493547 AU Mag: H = 6.44, G = 0.25 Epoch of elements : MJD 54214.97300000 TDT (2007 Apr 24.973) ------ occelmnt file for Occult BEGIN ----------------------------------- 2007 Apr 24 20 Massalia 23h 20.6m UT 8.1 8 50 33.280 17 1 55.14HIP 43412 8.2 10.6 146 9.1 1.834 2.943 -10.72 -70.104 17.034 -170.60 12.99 23.3425 -.15814 -.61779 8.80544 -2.23600 0.00515 -0.00144 2000 41.62191932007 420.00000255.490800206.507405 0.7069330.142758582.408814392.064935476.505 0.25 RATE 2.6363257 .0000000 .0000000 .0000000 .00000000 .00000000 .00000000 Meas 0.028 0.017 91.9 1.160 0.017 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2007 Apr 20, 23:25 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org