IOTA/IOTA-ES occultation update for (20) Massalia / 2UCAC 22751688 event on 2008 Apr 02, 06:17 UT Visible from Venezuela, Mexico Summary ------- On 2008 Apr 02 UT, the 146 km diameter asteroid (20) Massalia will occult a 11.6 mag star in the constellation Sagittarius for observers along a path across Venezuela, Mexico. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.6 mag to 11.3 mag (the magnitude of the asteroid) for at most 18.5 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: 93 * date and approx. time of event: 2008 Apr 02, 06:04 - 2008 Apr 02, 06:20 UT * magnitude of target star: 11.6 * magnitude drop [mag]: 0.6 * estimated maximum duration [s]: 18.5 * Moon: 19 % sunlit, 54° distance * Sun: 106° distance * rough path description: Venezuela, Mexico Additional comments ------------------- low mag drop The occultation path -------------------- * approximate projected width [km]: 162 * 1 sigma uncertainty interval [path widths]: +/- 0.48 * 1 sigma uncertainty interval [seconds]: +/- 7.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .040 +/- .044) * 1 sigma uncertainty ellipse (major, minor, PA): ( .044", .040", 0° ) * approx speed of asteroid's shadow [km/s]: 7.8637 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 22751688 by 20 Massalia on 2008 Apr 2 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 - 95 0 0 22 5 15 6 4 55 0 115 -63 21 17 32 22 53 19 20 32 1 .. .. .. - 94 0 0 21 39 26 6 4 55 1 115 -63 20 51 44 22 27 27 20 6 15 23 13 53 - 93 0 0 21 13 39 6 4 56 2 116 -64 20 26 0 22 1 38 19 40 33 22 48 2 - 92 0 0 20 47 55 6 4 57 3 116 -64 20 0 18 21 35 52 19 14 53 22 22 13 - 91 0 0 20 22 14 6 4 58 4 116 -65 19 34 40 21 10 9 18 49 18 21 56 28 - 90 0 0 19 56 39 6 4 59 5 117 -65 19 9 7 20 44 30 18 23 47 21 30 47 - 89 0 0 19 31 8 6 5 1 7 117 -65 18 43 39 20 18 57 17 58 21 21 5 10 - 88 0 0 19 5 43 6 5 3 8 117 -66 18 18 17 19 53 29 17 33 2 20 39 40 - 87 0 0 18 40 24 6 5 5 9 118 -66 17 53 1 19 28 7 17 7 49 20 14 15 - 86 0 0 18 15 13 6 5 8 10 118 -66 17 27 53 19 2 53 16 42 44 19 48 57 - 85 0 0 17 50 10 6 5 11 11 118 -67 17 2 53 18 37 46 16 17 48 19 23 47 - 84 0 0 17 25 15 6 5 14 12 119 -67 16 38 2 18 12 48 15 53 0 18 58 46 - 83 0 0 17 0 30 6 5 17 13 119 -67 16 13 20 17 47 59 15 28 21 18 33 54 - 82 0 0 16 35 55 6 5 21 14 119 -67 15 48 49 17 23 20 15 3 53 18 9 11 - 81 0 0 16 11 30 6 5 25 15 120 -67 15 24 28 16 58 52 14 39 36 17 44 39 - 80 0 0 15 47 17 6 5 30 16 120 -67 15 0 19 16 34 35 14 15 30 17 20 18 - 79 0 0 15 23 16 6 5 34 17 120 -67 14 36 22 16 10 30 13 51 37 16 56 9 - 78 0 0 14 59 28 6 5 39 18 121 -66 14 12 38 15 46 38 13 27 57 16 32 13 - 77 0 0 14 35 54 6 5 45 19 121 -66 13 49 7 15 22 59 13 4 30 16 8 30 - 76 0 0 14 12 33 6 5 50 20 121 -66 13 25 51 14 59 34 12 41 17 15 45 1 - 75 0 0 13 49 27 6 5 56 21 122 -66 13 2 49 14 36 24 12 18 20 15 21 46 - 74 0 0 13 26 36 6 6 2 22 122 -65 12 40 3 14 13 29 11 55 37 14 58 47 - 73 0 0 13 4 2 6 6 9 23 122 -65 12 17 32 13 50 50 11 33 11 14 36 4 - 72 0 0 12 41 44 6 6 16 24 123 -64 11 55 19 13 28 27 11 11 2 14 13 37 - 71 0 0 12 19 43 6 6 23 25 123 -64 11 33 23 13 6 22 10 49 10 13 51 27 - 70 0 0 11 58 0 6 6 30 26 123 -63 11 11 44 12 44 34 10 27 36 13 29 35 - 69 0 0 11 36 35 6 6 37 27 124 -63 10 50 24 12 23 5 10 6 20 13 8 1 - 68 0 0 11 15 30 6 6 45 28 124 -62 10 29 23 12 1 55 9 45 23 12 46 46 - 67 0 0 10 54 43 6 6 53 30 124 -61 10 8 41 11 41 4 9 24 46 12 25 51 - 66 0 0 10 34 17 6 7 2 31 125 -61 9 48 20 11 20 33 9 4 29 12 5 15 - 65 0 0 10 14 12 6 7 11 32 125 -60 9 28 19 11 0 22 8 44 32 11 45 0 - 64 0 0 9 54 27 6 7 20 33 125 -59 9 8 39 10 40 33 8 24 57 11 25 6 - 63 0 0 9 35 4 6 7 29 34 126 -59 8 49 20 10 21 5 8 5 42 11 5 34 - 62 0 0 9 16 3 6 7 38 35 126 -58 8 30 24 10 2 0 7 46 50 10 46 24 - 61 0 0 8 57 25 6 7 48 36 127 -57 8 11 50 9 43 17 7 28 21 10 27 36 - 60 0 0 8 39 9 6 7 58 37 127 -56 7 53 39 9 24 56 7 10 14 10 9 11 - 59 0 0 8 21 17 6 8 8 38 127 -55 7 35 52 9 7 0 6 52 31 9 51 10 - 58 0 0 8 3 49 6 8 18 39 128 -54 7 18 28 8 49 27 6 35 11 9 33 33 - 57 0 0 7 46 45 6 8 29 40 128 -54 7 1 28 8 32 18 6 18 16 9 16 20 - 56 0 0 7 30 5 6 8 40 41 129 -53 6 44 53 8 15 34 6 1 45 8 59 32 - 55 0 0 7 13 51 6 8 51 42 129 -52 6 28 43 7 59 16 5 45 39 8 43 9 - 54 0 0 6 58 2 6 9 2 43 130 -51 6 12 58 7 43 22 5 29 58 8 27 11 - 53 0 0 6 42 38 6 9 14 44 131 -50 5 57 39 7 27 55 5 14 43 8 11 39 - 52 0 0 6 27 41 6 9 25 44 131 -49 5 42 46 7 12 53 4 59 54 7 56 34 - 51 0 0 6 13 10 6 9 37 45 132 -48 5 28 19 6 58 18 4 45 31 7 41 54 - 50 0 0 5 59 6 6 9 49 46 132 -47 5 14 19 6 44 10 4 31 34 7 27 42 - 49 0 0 5 45 29 6 10 1 47 133 -46 5 0 45 6 30 29 4 18 5 7 13 57 - 48 0 0 5 32 19 6 10 14 48 134 -45 4 47 39 6 17 15 4 5 2 7 0 40 - 47 0 0 5 19 36 6 10 26 49 135 -44 4 35 1 6 4 29 3 52 27 6 47 50 - 46 0 0 5 7 22 6 10 39 50 135 -43 4 22 50 5 52 11 3 40 19 6 35 28 - 45 0 0 4 55 35 6 10 52 51 136 -42 4 11 7 5 40 21 3 28 40 6 23 35 - 44 0 0 4 44 17 6 11 5 52 137 -41 3 59 52 5 28 59 3 17 28 6 12 10 - 43 0 0 4 33 27 6 11 18 53 138 -40 3 49 5 5 18 6 3 6 45 6 1 14 - 42 0 0 4 23 6 6 11 32 53 139 -39 3 38 47 5 7 42 2 56 30 5 50 47 - 41 0 0 4 13 14 6 11 45 54 140 -38 3 28 58 4 57 47 2 46 43 5 40 49 - 40 0 0 4 3 51 6 11 59 55 141 -37 3 19 38 4 48 21 2 37 26 5 31 20 - 39 0 0 3 54 58 6 12 12 56 142 -36 3 10 47 4 39 24 2 28 38 5 22 21 - 38 0 0 3 46 33 6 12 26 56 143 -35 3 2 25 4 30 57 2 20 18 5 13 51 - 37 0 0 3 38 39 6 12 40 57 145 -34 2 54 33 4 23 0 2 12 28 5 5 52 - 36 0 0 3 31 14 6 12 54 58 146 -33 2 47 11 4 15 33 2 5 8 4 58 22 - 35 0 0 3 24 19 6 13 8 59 147 -32 2 40 18 4 8 36 1 58 17 4 51 23 - 34 0 0 3 17 54 6 13 23 59 149 -31 2 33 55 4 2 9 1 51 56 4 44 54 - 33 0 0 3 11 59 6 13 37 60 150 -30 2 28 2 3 56 12 1 46 5 4 38 55 - 32 0 0 3 6 34 6 13 52 60 152 -29 2 22 39 3 50 46 1 40 43 4 33 27 - 31 0 0 3 1 40 6 14 6 61 154 -28 2 17 46 3 45 50 1 35 52 4 28 29 - 30 0 0 2 57 16 6 14 21 61 155 -27 2 13 23 3 41 24 1 31 30 4 24 3 - 29 0 0 2 53 22 6 14 35 62 157 -26 2 9 31 3 37 29 1 27 39 4 20 7 - 28 0 0 2 49 59 6 14 50 62 159 -25 2 6 9 3 34 5 1 24 18 4 16 42 - 27 0 0 2 47 7 6 15 5 63 161 -24 2 3 17 3 31 12 1 21 28 4 13 48 - 26 0 0 2 44 45 6 15 20 63 163 -23 2 0 56 3 28 50 1 19 8 4 11 24 - 25 0 0 2 42 54 6 15 35 64 165 -22 1 59 6 3 26 58 1 17 18 4 9 32 - 24 0 0 2 41 34 6 15 50 64 167 -21 1 57 46 3 25 37 1 15 58 4 8 11 - 23 0 0 2 40 44 6 16 5 64 169 -20 1 56 57 3 24 48 1 15 9 4 7 21 - 22 0 0 2 40 26 6 16 20 64 172 -18 1 56 38 3 24 29 1 14 51 4 7 3 - 21 0 0 2 40 38 6 16 35 64 174 -17 1 56 50 3 24 41 1 15 3 4 7 15 - 20 0 0 2 41 21 6 16 50 64 176 -16 1 57 33 3 25 25 1 15 45 4 7 58 - 19 0 0 2 42 35 6 17 5 64 178 -15 1 58 46 3 26 39 1 16 58 4 9 13 - 18 0 0 2 44 19 6 17 20 64 181 -14 2 0 30 3 28 24 1 18 41 4 10 59 - 17 0 0 2 46 35 6 17 35 64 183 -13 2 2 45 3 30 40 1 20 55 4 13 16 - 16 0 0 2 49 21 6 17 50 64 185 -12 2 5 30 3 33 27 1 23 40 4 16 4 - 15 0 0 2 52 37 6 18 5 64 187 -11 2 8 46 3 36 45 1 26 54 4 19 23 - 14 0 0 2 56 25 6 18 20 64 190 -10 2 12 32 3 40 34 1 30 39 4 23 13 - 13 0 0 3 0 43 6 18 35 64 192 -9 2 16 49 3 44 53 1 34 55 4 27 34 - 12 0 0 3 5 32 6 18 50 63 194 -8 2 21 36 3 49 44 1 39 40 4 32 26 - 11 0 0 3 10 51 6 19 4 63 196 -7 2 26 53 3 55 5 1 44 56 4 37 48 - 10 0 0 3 16 40 6 19 19 62 198 -6 2 32 41 4 0 56 1 50 42 4 43 41 - 9 0 0 3 23 0 6 19 34 62 200 -5 2 38 59 4 7 18 1 56 58 4 50 5 - 8 0 0 3 29 50 6 19 49 62 202 -4 2 45 47 4 14 10 2 3 43 4 57 0 - 7 0 0 3 37 10 6 20 4 61 203 -3 2 53 4 4 21 33 2 10 59 5 4 25 - 6 0 0 3 45 0 6 20 18 61 205 -1 3 0 52 4 29 25 2 18 44 5 12 20 - 5 0 0 3 53 20 6 20 33 60 207 0 3 9 9 4 37 48 2 26 59 5 20 45 Uncertainty in time = +/- 9 secs [Prediction of 2008 Mar 28.0] Data for the target star ------------------------ * name: 2UCAC 22751688 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 17 47 26.6453 DE: -22 52 05.484 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .039, .043 ) * V mag [mag]: 11.6 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (20) Massalia approx. diameter [km]: 146 approx. diameter ["]: .091 distance from Earth [AU]: 2.21800 * orbital information: orbit source: Preston date of fit: 2008 Mar 27 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1377 number of rejected observations: 252 time covered by the observations: 1900 Jul 17 - 2008 Feb 09 1 sigma uncertainty ellipse (major, minor, PA): 0.009, 0.007, 91° remarks: * orbital elements for (20) Massalia : Mean anomaly = 133.33674661 deg Arg. of pericenter = 255.60270940 deg Long. of node = 206.50180752 deg Inclination = 0.70683156 deg Eccentricity = 0.14246069 Semimajor axis = 2.40947693 AU Perihelion dist = 2.06622117 AU Mag: H = 6.45, G = 0.25 Epoch of elements : MJD 54558.26200000 TDT (2008 Apr 02.262) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Apr 2 20 Massalia 6h 17.1m UT 11.6 17 47 26.645-22 52 5.482UCAC 22751688 0.0 11.3 146 18.5 2.218 1.272 0.46 -18.3873 -22.868 86.61 5.09 6.2853 -0.01007 0.43157 4.43700 0.11542 -0.00553 0.00011 2000 131.1595132008 325.00000255.602709206.501808 0.7068320.14246069 2.4094769 2.0662212 6.5 5.00.25 RATE 2.6352380 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.044 0.040 0 1.48 0.044 0 54553.5020080402_751688 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 28, 06:25 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org