IOTA/IOTA-ES occultation update for (20) Massalia / 2UCAC 22752001 event on 2008 May 08, 19:35 UT Visible from N Australia, Africa Summary ------- On 2008 May 08 UT, the 146 km diameter asteroid (20) Massalia will occult a 12.5 mag star in the constellation Sagittarius for observers along a path across N Australia, Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.2 mag to 10.7 mag (the magnitude of the asteroid) for at most 22.0 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: 58 * date and approx. time of event: 2008 May 08, 19:23 - 2008 May 08, 19:51 UT * magnitude of target star: 12.5 * magnitude drop [mag]: 0.2 * estimated maximum duration [s]: 22.0 * Moon: 16 % sunlit, 171° distance * Sun: 141° distance * rough path description: N Australia, Africa The occultation path -------------------- * approximate projected width [km]: 148 * 1 sigma uncertainty interval [path widths]: +/- 1.07 * 1 sigma uncertainty interval [seconds]: +/- 22.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .118 +/- .118) * 1 sigma uncertainty ellipse (major, minor, PA): ( .118", .118", 90° ) * approx speed of asteroid's shadow [km/s]: 6.6039 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 22752001 by 20 Massalia on 2008 May 8 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 18 0 0 11 40 22 19 51 24 1 113 -38 12 24 13 10 56 37 .. .. .. 9 23 20 19 0 0 11 15 0 19 51 23 2 114 -39 11 58 52 10 31 15 13 33 7 8 57 58 20 0 0 10 49 37 19 51 23 3 114 -40 11 33 28 10 5 52 13 7 43 8 32 35 21 0 0 10 24 11 19 51 22 4 114 -42 11 8 3 9 40 27 12 42 17 8 7 10 22 0 0 9 58 45 19 51 20 5 114 -43 10 42 36 9 15 1 12 16 50 7 41 45 23 0 0 9 33 19 19 51 18 6 114 -44 10 17 9 8 49 35 11 51 22 7 16 20 24 0 0 9 7 53 19 51 16 7 114 -45 9 51 42 8 24 10 11 25 54 6 50 56 25 0 0 8 42 28 19 51 14 8 115 -46 9 26 17 7 58 46 11 0 26 6 25 34 26 0 0 8 17 4 19 51 11 9 115 -47 9 0 52 7 33 23 10 35 0 6 0 13 27 0 0 7 51 43 19 51 8 10 115 -48 8 35 30 7 8 3 10 9 35 5 34 56 28 0 0 7 26 25 19 51 5 11 115 -49 8 10 10 6 42 46 9 44 13 5 9 41 29 0 0 7 1 10 19 51 1 12 115 -50 7 44 54 6 17 32 9 18 53 4 44 31 30 0 0 6 35 59 19 50 57 14 115 -51 7 19 41 5 52 23 8 53 37 4 19 24 31 0 0 6 10 53 19 50 52 15 115 -52 6 54 33 5 27 18 8 28 26 3 54 23 32 0 0 5 45 51 19 50 48 16 115 -53 6 29 30 5 2 19 8 3 19 3 29 27 33 0 0 5 20 56 19 50 43 17 116 -54 6 4 33 4 37 25 7 38 17 3 4 38 34 0 0 4 56 7 19 50 37 18 116 -55 5 39 42 4 12 38 7 13 22 2 39 55 35 0 0 4 31 25 19 50 32 19 116 -56 5 14 58 3 47 58 6 48 33 2 15 20 36 0 0 4 6 50 19 50 26 20 116 -57 4 50 20 3 23 25 6 23 51 1 50 52 37 0 0 3 42 23 19 50 19 21 116 -58 4 25 51 2 59 1 5 59 16 1 26 32 38 0 0 3 18 4 19 50 13 22 116 -59 4 1 30 2 34 45 5 34 50 1 2 21 39 0 0 2 53 55 19 50 6 23 116 -60 3 37 18 2 10 38 5 10 32 0 38 20 40 0 0 2 29 55 19 49 59 24 116 -61 3 13 15 1 46 40 4 46 24 0 14 28 41 0 0 2 6 5 19 49 51 25 116 -62 2 49 22 1 22 53 4 22 25 - 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9 53 32 -14 8 53 146 0 0 -11 51 37 19 26 4 53 248 -14 -11 10 53 -12 32 16 - 9 43 25 -13 59 2 147 0 0 -11 41 17 19 25 52 52 248 -13 -11 0 30 -12 21 58 - 9 32 56 -13 48 49 148 0 0 -11 30 35 19 25 39 51 248 -13 -10 49 46 -12 11 19 - 9 22 6 -13 38 16 149 0 0 -11 19 32 19 25 26 50 248 -12 -10 38 40 -12 0 19 - 9 10 54 -13 27 22 150 0 0 -11 8 8 19 25 14 49 248 -11 -10 27 13 -11 48 58 - 8 59 21 -13 16 7 151 0 0 -10 56 23 19 25 2 48 248 -10 -10 15 25 -11 37 16 - 8 47 27 -13 4 30 152 0 0 -10 44 17 19 24 50 47 248 -9 -10 3 16 -11 25 13 - 8 35 11 -12 52 34 153 0 0 -10 31 50 19 24 38 46 248 -8 - 9 50 46 -11 12 49 - 8 22 34 -12 40 16 154 0 0 -10 19 1 19 24 26 45 248 -7 - 9 37 54 -11 0 4 - 8 9 36 -12 27 37 155 0 0 -10 5 52 19 24 15 44 248 -6 - 9 24 42 -10 46 58 - 7 56 16 -12 14 38 156 0 0 - 9 52 22 19 24 3 43 248 -5 - 9 11 9 -10 33 31 - 7 42 36 -12 1 18 157 0 0 - 9 38 32 19 23 52 42 248 -4 - 8 57 15 -10 19 43 - 7 28 35 -11 47 38 158 0 0 - 9 24 20 19 23 41 41 248 -3 - 8 43 0 -10 5 35 - 7 14 13 -11 33 37 159 0 0 - 9 9 48 19 23 30 40 248 -2 - 8 28 24 - 9 51 7 - 6 59 30 -11 19 15 160 0 0 - 8 54 55 19 23 19 40 248 -1 - 8 13 28 - 9 36 18 - 6 44 26 -11 4 33 161 0 0 - 8 39 42 19 23 9 39 248 0 - 7 58 12 - 9 21 8 - 6 29 2 -10 49 31 Uncertainty in time = +/- 24 secs [Prediction of 2008 Apr 23.0] Data for the target star ------------------------ * name: 2UCAC 22752001 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 17 47 45.2391 DE: -22 38 53.979 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .118, .118 ) * V mag [mag]: 12.5 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (20) Massalia approx. diameter [km]: 146 approx. diameter ["]: .110 distance from Earth [AU]: 1.83600 * orbital information: orbit source: Preston date of fit: 2008 Apr 22 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1385 number of rejected observations: 251 time covered by the observations: 1900 Jul 17 - 2008 Apr 15 1 sigma uncertainty ellipse (major, minor, PA): 0.011, 0.009, 91° remarks: * orbital elements for (20) Massalia : Mean anomaly = 142.93531744 deg Arg. of pericenter = 255.63819716 deg Long. of node = 206.49778376 deg Inclination = 0.70677936 deg Eccentricity = 0.14238060 Semimajor axis = 2.40972049 AU Perihelion dist = 2.06662304 AU Mag: H = 6.45, G = 0.25 Epoch of elements : MJD 54594.81600000 TDT (2008 May 08.816) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 May 8 20 Massalia 19h 35.5m UT 12.5 17 47 45.239-22 38 53.982UCAC 22752001 0.0 10.7 146 22.0 1.836 -1.288 1.28 106.0686 -22.648 -114.75 17.35 19.5914 0.01180 0.15276 -3.71784 0.26682 -0.00350 0.00001 2000 141.6663792008 5 4.00000255.638197206.497784 0.7067790.14238060 2.4097205 2.0666230 6.5 5.00.25 RATE 2.6348380 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.118 0.118 90 2.07 0.118 0 54579.5020080508_752001 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Apr 23, 04:13 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org