IOTA/IOTA-ES occultation update for (305) Gordonia / TYC 5231-01580-1 event on 2008 May 20, 15:05 UT Visible from W Pacific Summary ------- On 2008 May 20 UT, the 49 km diameter asteroid (305) Gordonia will occult a 11.5 mag star in the constellation Aquarius for observers along a path across W Pacific. In the case of an occultation, the combined light of the asteroid and the star will drop by 3.7 mag to 15.1 mag (the magnitude of the asteroid) for at most 2.9 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: 54 * date and approx. time of event: 2008 May 20, 15:00 - 2008 May 20, 15:05 UT * midpoint of event [JD]: 2454607.12860833 * magnitude of target star: 11.5 * magnitude drop [mag]: 3.7 * estimated maximum duration [s]: 2.9 * Moon: 99 % sunlit, 88° distance * Sun: 86° distance * rough path description: W Pacific The occultation path -------------------- * approximate projected width [km]: 69 * 1 sigma uncertainty interval [path widths]: +/- 1.18 * 1 sigma uncertainty interval [seconds]: +/- 3.7 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .024 +/- .022) * 1 sigma uncertainty ellipse (major, minor, PA): ( .024", .022", 83° ) * approx speed of asteroid's shadow [km/s]: 16.7644 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 5231-01580-1 by 305 Gordonia on 2008 May 20 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 143 0 0 18 11 17 15 0 40 0 96 -51 17 52 38 18 30 2 .. .. .. 19 14 40 144 0 0 18 5 27 15 0 40 1 97 -51 17 46 49 18 24 10 .. .. .. 19 8 46 145 0 0 18 0 14 15 0 40 2 97 -50 17 41 37 18 18 57 .. .. .. 19 3 31 146 0 0 17 55 40 15 0 41 3 97 -50 17 37 4 18 14 22 .. .. .. 18 58 54 147 0 0 17 51 43 15 0 41 4 98 -50 17 33 8 18 10 24 .. .. .. 18 54 55 148 0 0 17 48 25 15 0 42 5 98 -50 17 29 50 18 7 6 .. .. .. 18 51 35 149 0 0 17 45 44 15 0 43 6 98 -49 17 27 10 18 4 25 16 43 42 18 48 54 150 0 0 17 43 42 15 0 44 7 99 -49 17 25 8 18 2 23 16 41 41 18 46 51 151 0 0 17 42 19 15 0 45 8 99 -49 17 23 45 18 0 59 16 40 17 18 45 27 152 0 0 17 41 34 15 0 46 9 99 -48 17 22 59 18 0 14 16 39 32 18 44 42 153 0 0 17 41 27 15 0 48 10 100 -48 17 22 52 18 0 8 16 39 25 18 44 36 154 0 0 17 41 59 15 0 49 11 100 -47 17 23 24 18 0 40 16 39 56 18 45 9 155 0 0 17 43 10 15 0 51 12 100 -47 17 24 34 18 1 51 16 41 5 18 46 21 156 0 0 17 44 59 15 0 53 13 101 -46 17 26 23 18 3 41 16 42 52 18 48 13 157 0 0 17 47 27 15 0 55 14 101 -46 17 28 50 18 6 10 16 45 18 18 50 44 158 0 0 17 50 34 15 0 57 15 101 -45 17 31 56 18 9 18 16 48 22 18 53 54 159 0 0 17 54 20 15 1 0 16 102 -45 17 35 41 18 13 4 16 52 4 18 57 43 160 0 0 17 58 44 15 1 2 16 102 -44 17 40 5 18 17 30 16 56 25 19 2 12 161 0 0 18 3 48 15 1 5 17 103 -44 17 45 7 18 22 35 17 1 24 19 7 20 162 0 0 18 9 31 15 1 7 18 103 -43 17 50 48 18 28 19 17 7 2 19 13 8 163 0 0 18 15 52 15 1 10 19 103 -42 17 57 8 18 34 43 17 13 19 19 19 35 164 0 0 18 22 53 15 1 13 20 104 -42 18 4 7 18 41 45 17 20 14 19 26 41 165 0 0 18 30 33 15 1 17 21 104 -41 18 11 45 18 49 27 17 27 47 19 34 28 166 0 0 18 38 51 15 1 20 22 105 -40 18 20 2 18 57 47 17 35 59 19 42 53 167 0 0 18 47 49 15 1 23 23 105 -39 18 28 57 19 6 47 17 44 50 19 51 58 168 0 0 18 57 26 15 1 27 24 106 -39 18 38 32 19 16 26 17 54 19 20 1 43 169 0 0 19 7 42 15 1 31 25 106 -38 18 48 45 19 26 44 18 4 27 20 12 7 170 0 0 19 18 36 15 1 34 25 107 -37 18 59 37 19 37 42 18 15 13 20 23 11 171 0 0 19 30 10 15 1 38 26 107 -36 19 11 8 19 49 18 18 26 38 20 34 53 172 0 0 19 42 22 15 1 42 27 108 -35 19 23 17 20 1 33 18 38 41 20 47 15 173 0 0 19 55 13 15 1 47 28 109 -35 19 36 6 20 14 27 18 51 22 21 0 17 174 0 0 20 8 43 15 1 51 29 109 -34 19 49 32 20 28 0 19 4 42 21 13 57 175 0 0 20 22 51 15 1 55 30 110 -33 20 3 37 20 42 11 19 18 39 21 28 17 176 0 0 20 37 38 15 2 0 30 110 -32 20 18 21 20 57 2 19 33 15 21 43 15 177 0 0 20 53 3 15 2 5 31 111 -31 20 33 42 21 12 30 19 48 29 21 58 53 178 0 0 21 9 6 15 2 10 32 112 -30 20 49 42 21 28 37 20 4 20 22 15 8 179 0 0 21 25 47 15 2 15 33 113 -29 21 6 19 21 45 22 20 20 49 22 32 3 180 0 0 21 43 6 15 2 20 34 113 -28 21 23 34 22 2 45 20 37 55 22 49 35 -179 0 0 22 1 3 15 2 25 34 114 -27 21 41 27 22 20 46 20 55 39 23 7 46 -178 0 0 22 19 37 15 2 30 35 115 -26 21 59 57 22 39 24 21 13 59 23 26 35 -177 0 0 22 38 48 15 2 35 36 116 -26 22 19 4 22 58 40 21 32 56 23 46 1 -176 0 0 22 58 37 15 2 41 36 117 -25 22 38 48 23 18 33 21 52 30 24 6 4 -175 0 0 23 19 1 15 2 46 37 118 -24 22 59 8 23 39 2 22 12 40 24 26 45 -174 0 0 23 40 2 15 2 52 38 119 -23 23 20 4 24 0 8 22 33 26 24 48 2 -173 0 0 24 1 39 15 2 58 38 120 -22 23 41 37 24 21 49 22 54 47 25 9 55 -172 0 0 24 23 52 15 3 4 39 121 -21 24 3 44 24 44 7 23 16 44 25 32 25 -171 0 0 24 46 39 15 3 10 40 122 -20 24 26 27 25 6 59 23 39 15 25 55 30 -170 0 0 25 10 2 15 3 16 40 123 -19 24 49 44 25 30 27 24 2 21 26 19 10 -169 0 0 25 33 58 15 3 22 41 124 -18 25 13 36 25 54 29 24 26 0 26 43 24 -168 0 0 25 58 29 15 3 28 41 125 -17 25 38 1 26 19 4 24 50 14 27 8 13 -167 0 0 26 23 32 15 3 34 42 127 -16 26 2 59 26 44 13 25 15 0 27 33 35 -166 0 0 26 49 9 15 3 40 42 128 -15 26 28 30 27 9 55 25 40 18 27 59 31 -165 0 0 27 15 17 15 3 47 43 129 -14 26 54 33 27 36 9 26 6 8 28 25 58 -164 0 0 27 41 57 15 3 53 43 131 -13 27 21 7 28 2 55 26 32 30 28 52 58 -163 0 0 28 9 7 15 4 0 43 132 -12 27 48 12 28 30 11 26 59 22 29 20 28 -162 0 0 28 36 48 15 4 6 44 133 -11 28 15 47 28 57 57 27 26 44 29 48 29 -161 0 0 29 4 58 15 4 13 44 135 -10 28 43 51 29 26 13 27 54 35 30 16 59 -160 0 0 29 33 36 15 4 19 44 136 -9 29 12 24 29 54 58 28 22 54 30 45 58 -159 0 0 30 2 42 15 4 26 45 138 -8 29 41 24 30 24 10 28 51 41 31 15 25 -158 0 0 30 32 15 15 4 33 45 139 -7 30 10 51 30 53 49 29 20 55 31 45 18 -157 0 0 31 2 14 15 4 39 45 141 -6 30 40 44 31 23 54 29 50 34 32 15 38 -156 0 0 31 32 38 15 4 46 45 142 -5 31 11 2 31 54 24 30 20 39 32 46 23 -155 0 0 32 3 26 15 4 53 45 144 -4 31 41 44 32 25 18 30 51 7 33 17 32 -154 0 0 32 34 37 15 5 0 45 145 -3 32 12 49 32 56 35 31 21 58 33 49 4 -153 0 0 33 6 10 15 5 6 45 147 -2 32 44 16 33 28 14 31 53 12 34 20 58 -152 0 0 33 38 4 15 5 13 46 149 -1 33 16 4 34 0 14 32 24 46 34 53 12 Uncertainty in time = +/- 4 secs [Prediction of 2008 Feb 17.0] Data for the target star ------------------------ * name: TYC 5231-01580-1 * constellation : Aquarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 22 17 18.3846 DE: -06 04 31.363 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .019, .019 ) * V mag [mag]: 11.5 * B mag [mag]: 11.7 * Apparent position with proper motion RA(deg): 334.4383867989 DE(deg): -6.0337889655 * Equation of equinoxes (radians) : 0.000039950873544 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (305) Gordonia approx. diameter [km]: 49 approx. diameter ["]: .019 distance from Earth [AU]: 3.50500 * orbital information: orbit source: Preston date of fit: 2008 Feb 16 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 797 number of rejected observations: 90 time covered by the observations: 1902 Mar 04 - 2007 Sep 02 1 sigma uncertainty ellipse (major, minor, PA): 0.015, 0.011, 72° remarks: * orbital elements for (305) Gordonia : Mean anomaly = 221.36350688 deg Arg. of pericenter = 260.65988090 deg Long. of node = 207.60424340 deg Inclination = 4.43837245 deg Eccentricity = 0.19029594 Semimajor axis = 3.09505775 AU Perihelion dist = 2.50608084 AU Mag: H = 8.68, G = 0.15 Epoch of elements : MJD 54606.62900000 TDT (2008 May 20.629) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 May 20 305 Gordonia 15h 5.2m UT 11.5 22 17 18.385- 6 4 31.36TYC 5231-01580-1 11.7 15.1 49 2.9 3.505 1.428 10.47 -130.6145 -6.078 -47.16 20.14 15.0866 -0.30809 0.62787 8.49176 4.17433 -0.00533 -0.00202 2000 220.1635962008 514.00000260.659881207.604243 4.4383720.19029594 3.0950578 2.5060808 8.8 5.00.15 RATE 1.8100930 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.024 0.022 83 2.18 0.023 0 54513.5020080520_1580-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Apr 13, 03:34 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org