IOTA/IOTA-ES occultation update for (20) Massalia / 2UCAC 22752235 event on 2008 Apr 03, 09:17 UT Visible from N Canada (low altitude) Summary ------- On 2008 Apr 03 UT, the 146 km diameter asteroid (20) Massalia will occult a 11.9 mag star in the constellation Sagittarius for observers along a path across N Canada (low altitude). In the case of an occultation, the combined light of the asteroid and the star will drop by 0.5 mag to 11.3 mag (the magnitude of the asteroid) for at most 19.7 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: 99 * date and approx. time of event: 2008 Apr 03, 09:14 - 2008 Apr 03, 09:18 UT * magnitude of target star: 11.9 * magnitude drop [mag]: 0.5 * estimated maximum duration [s]: 19.7 * Moon: 11 % sunlit, 69° distance * Sun: 107° distance * rough path description: N Canada (low altitude) The occultation path -------------------- * approximate projected width [km]: 739 * 1 sigma uncertainty interval [path widths]: +/- 0.29 * 1 sigma uncertainty interval [seconds]: +/- 4.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .025 +/- .027) * 1 sigma uncertainty ellipse (major, minor, PA): ( .027", .025", 0° ) * approx speed of asteroid's shadow [km/s]: 7.3839 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 22752235 by 20 Massalia on 2008 Apr 3 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 - 58 0 0 57 48 57 9 18 34 9 186 0 54 28 0 63 16 28 52 52 2 .. .. .. - 59 0 0 57 34 56 9 18 26 10 185 -1 54 16 31 62 50 19 52 41 21 .. .. .. - 60 0 0 57 22 24 9 18 18 10 184 -1 54 6 11 62 28 5 52 31 44 .. .. .. - 61 0 0 57 11 19 9 18 10 10 183 -2 53 57 1 62 9 10 52 23 12 .. .. .. - 62 0 0 57 1 39 9 18 1 10 182 -3 53 49 0 61 53 9 52 15 43 .. .. .. - 63 0 0 56 53 23 9 17 53 10 181 -3 53 42 7 61 39 45 52 9 17 .. .. .. - 64 0 0 56 46 30 9 17 44 11 180 -4 53 36 22 61 28 46 52 3 55 .. .. .. - 65 0 0 56 40 57 9 17 36 11 179 -4 53 31 44 61 20 3 51 59 36 .. .. .. - 66 0 0 56 36 46 9 17 27 11 178 -5 53 28 14 61 13 31 51 56 19 .. .. .. - 67 0 0 56 33 54 9 17 18 11 177 -5 53 25 50 61 9 5 51 54 6 .. .. .. - 68 0 0 56 32 23 9 17 10 11 176 -6 53 24 34 61 6 42 51 52 55 .. .. .. - 69 0 0 56 32 11 9 17 1 11 175 -7 53 24 25 61 6 21 51 52 46 .. .. .. - 70 0 0 56 33 18 9 16 52 11 175 -7 53 25 22 61 8 2 51 53 41 .. .. .. - 71 0 0 56 35 45 9 16 44 10 174 -8 53 27 27 61 11 44 51 55 38 .. .. .. - 72 0 0 56 39 31 9 16 36 10 173 -8 53 30 38 61 17 32 51 58 37 .. .. .. - 73 0 0 56 44 38 9 16 27 10 172 -9 53 34 57 61 25 27 52 2 39 .. .. .. - 74 0 0 56 51 6 9 16 19 10 171 -9 53 40 22 61 35 36 52 7 44 .. .. .. - 75 0 0 56 58 55 9 16 11 10 170 -9 53 46 55 61 48 6 52 13 52 .. .. .. - 76 0 0 57 8 8 9 16 3 10 169 -10 53 54 37 62 3 7 52 21 3 .. .. .. - 77 0 0 57 18 44 9 15 55 9 168 -10 54 3 26 62 20 54 52 29 17 .. .. .. - 78 0 0 57 30 47 9 15 48 9 167 -11 54 13 24 62 41 48 52 38 35 .. .. .. - 79 0 0 57 44 17 9 15 40 9 166 -11 54 24 31 63 6 19 52 48 56 .. .. .. - 80 0 0 57 59 17 9 15 33 8 165 -11 54 36 48 63 35 15 53 0 22 .. .. .. - 81 0 0 58 15 50 9 15 26 8 164 -12 54 50 16 64 10 0 53 12 52 .. .. .. - 82 0 0 58 33 59 9 15 20 7 163 -12 55 4 55 64 53 22 53 26 27 .. .. .. - 83 0 0 58 53 49 9 15 13 7 162 -12 55 20 46 65 53 16 53 41 7 .. .. .. - 84 0 0 59 15 25 9 15 8 6 161 -13 55 37 52 .. .. .. 53 56 54 .. .. .. - 85 0 0 59 38 52 9 15 2 6 160 -13 55 56 12 .. .. .. 54 13 47 .. .. .. - 86 0 0 60 4 19 9 14 57 5 159 -13 56 15 49 .. .. .. 54 31 48 .. .. .. - 87 0 0 60 31 56 9 14 52 5 158 -13 56 36 44 .. .. .. 54 50 57 .. .. .. - 88 0 0 61 1 56 9 14 48 4 158 -13 56 59 0 .. .. .. 55 11 15 .. .. .. - 89 0 0 61 34 36 9 14 44 3 157 -13 57 22 39 .. .. .. 55 32 44 .. .. .. - 90 0 0 62 10 20 9 14 41 3 156 -13 57 47 44 .. .. .. 55 55 25 .. .. .. - 91 0 0 62 49 43 9 14 39 2 155 -13 58 14 18 .. .. .. 56 19 19 .. .. .. - 92 0 0 63 33 36 9 14 38 1 154 -13 58 42 27 .. .. .. 56 44 29 .. .. .. Uncertainty in time = +/- 6 secs [Prediction of 2008 Mar 28.0] Data for the target star ------------------------ * name: 2UCAC 22752235 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 17 48 00.0755 DE: -22 51 54.714 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .023, .026 ) * V mag [mag]: 11.9 * 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]: 2.20500 * 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 = 133.63228943 deg Arg. of pericenter = 255.60367083 deg Long. of node = 206.50173523 deg Inclination = 0.70683048 deg Eccentricity = 0.14245845 Semimajor axis = 2.40948385 AU Perihelion dist = 2.06623252 AU Mag: H = 6.45, G = 0.25 Epoch of elements : MJD 54559.38700000 TDT (2008 Apr 03.387) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Apr 3 20 Massalia 9h 17.3m UT 11.9 17 48 0.076-22 51 54.712UCAC 22752235 0.0 11.3 146 19.7 2.205 1.201 0.50 -64.3972 -22.864 41.49 5.52 9.2879 -0.02841 0.97988 4.16578 0.12564 -0.00550 0.00010 2000 131.1586012008 325.00000255.603671206.501735 0.7068300.14245845 2.4094839 2.0662325 6.5 5.00.25 RATE 2.6352270 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.027 0.025 0 1.29 0.027 0 54553.5020080403_752235 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 28, 06:34 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org