IOTA/IOTA-ES occultation update for (128) Nemesis / UCAC2 23766657 event on 2008 May 03, 12:13 UT Visible from Mexico in twilight Summary ------- On 2008 May 03 UT, the 188 km diameter asteroid (128) Nemesis will occult a 11.5 mag star in the constellation Capricornus for observers along a path across Mexico in twilight. In the case of an occultation, the combined light of the asteroid and the star will drop by 1.5 mag to 12.7 mag (the magnitude of the asteroid) for at most 10.2 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 May 03, 12:09 - 2008 May 03, 12:12 UT * midpoint of event [JD]: 2454590.0095125 * magnitude of target star: 11.5 * magnitude drop [mag]: 1.5 * estimated maximum duration [s]: 10.2 * Moon: 6 % sunlit, 62° distance * Sun: 90° distance * rough path description: Mexico in twilight The occultation path -------------------- * approximate projected width [km]: 264 * 1 sigma uncertainty interval [path widths]: +/- 0.26 * 1 sigma uncertainty interval [seconds]: +/- 3.3 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .035 +/- .027) * 1 sigma uncertainty ellipse (major, minor, PA): ( .035", .027", 88° ) * approx speed of asteroid's shadow [km/s]: 18.3730 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 23766657 by 128 Nemesis on 2008 May 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 ' " Latitude Latitude Latitude Latitude -162 0 0 35 1 14 12 9 35 0 115 -35 33 43 25 .. .. .. 33 3 40 .. .. .. -161 0 0 34 37 59 12 9 35 1 116 -35 33 20 22 35 57 33 32 40 42 36 39 45 -160 0 0 34 14 58 12 9 35 2 116 -35 32 57 32 35 34 19 32 17 59 36 16 25 -159 0 0 33 52 12 12 9 35 3 117 -35 32 34 58 35 11 21 31 55 30 35 53 19 -158 0 0 33 29 41 12 9 36 4 118 -35 32 12 38 34 48 37 31 33 16 35 30 29 -157 0 0 33 7 26 12 9 36 5 118 -35 31 50 35 34 26 9 31 11 18 35 7 54 -156 0 0 32 45 27 12 9 37 6 119 -35 31 28 48 34 3 58 30 49 37 34 45 36 -155 0 0 32 23 46 12 9 38 6 119 -35 31 7 18 33 42 4 30 28 13 34 23 35 -154 0 0 32 2 22 12 9 39 7 120 -35 30 46 6 33 20 28 30 7 7 34 1 52 -153 0 0 31 41 17 12 9 40 8 120 -34 30 25 12 32 59 11 29 46 19 33 40 28 -152 0 0 31 20 31 12 9 41 9 121 -34 30 4 37 32 38 12 29 25 50 33 19 23 -151 0 0 31 0 4 12 9 42 10 121 -34 29 44 22 32 17 33 29 5 40 32 58 37 -150 0 0 30 39 58 12 9 44 11 122 -34 29 24 27 31 57 15 28 45 50 32 38 12 -149 0 0 30 20 12 12 9 45 12 122 -33 29 4 52 31 37 17 28 26 21 32 18 8 -148 0 0 30 0 47 12 9 47 13 123 -33 28 45 39 31 17 41 28 7 13 31 58 25 -147 0 0 29 41 44 12 9 49 14 124 -33 28 26 47 30 58 26 27 48 27 31 39 4 -146 0 0 29 23 4 12 9 51 15 124 -32 28 8 17 30 39 34 27 30 2 31 20 5 -145 0 0 29 4 46 12 9 53 16 125 -32 27 50 10 30 21 5 27 12 0 31 1 30 -144 0 0 28 46 51 12 9 55 16 125 -31 27 32 26 30 2 59 26 54 22 30 43 18 -143 0 0 28 29 20 12 9 57 17 126 -31 27 15 5 29 45 17 26 37 6 30 25 29 -142 0 0 28 12 14 12 10 0 18 126 -31 26 58 9 29 27 59 26 20 14 30 8 6 -141 0 0 27 55 31 12 10 2 19 127 -30 26 41 36 29 11 6 26 3 47 29 51 7 -140 0 0 27 39 14 12 10 5 20 128 -30 26 25 29 28 54 38 25 47 44 29 34 34 -139 0 0 27 23 22 12 10 8 21 128 -29 26 9 46 28 38 36 25 32 6 29 18 26 -138 0 0 27 7 56 12 10 10 22 129 -29 25 54 29 28 23 0 25 16 54 29 2 44 -137 0 0 26 52 55 12 10 13 23 129 -28 25 39 38 28 7 50 25 2 7 28 47 29 -136 0 0 26 38 22 12 10 17 23 130 -27 25 25 13 27 53 7 24 47 47 28 32 40 -135 0 0 26 24 15 12 10 20 24 131 -27 25 11 15 27 38 51 24 33 53 28 18 19 -134 0 0 26 10 35 12 10 23 25 131 -26 24 57 44 27 25 2 24 20 26 28 4 26 -133 0 0 25 57 23 12 10 27 26 132 -26 24 44 39 27 11 41 24 7 25 27 51 0 -132 0 0 25 44 38 12 10 30 27 133 -25 24 32 3 26 58 48 23 54 52 27 38 2 -131 0 0 25 32 21 12 10 34 28 133 -24 24 19 53 26 46 23 23 42 47 27 25 33 -130 0 0 25 20 33 12 10 37 28 134 -24 24 8 13 26 34 27 23 31 10 27 13 33 -129 0 0 25 9 13 12 10 41 29 135 -23 23 57 0 26 23 0 23 20 1 27 2 2 -128 0 0 24 58 22 12 10 45 30 135 -22 23 46 16 26 12 2 23 9 20 26 51 0 -127 0 0 24 48 1 12 10 49 31 136 -22 23 36 0 26 1 33 22 59 8 26 40 27 -126 0 0 24 38 8 12 10 53 31 137 -21 23 26 14 25 51 34 22 49 24 26 30 24 -125 0 0 24 28 45 12 10 58 32 138 -20 23 16 57 25 42 5 22 40 10 26 20 52 -124 0 0 24 19 52 12 11 2 33 138 -19 23 8 9 25 33 6 22 31 25 26 11 49 -123 0 0 24 11 28 12 11 6 34 139 -19 22 59 50 25 24 37 22 23 9 26 3 17 -122 0 0 24 3 35 12 11 11 34 140 -18 22 52 2 25 16 38 22 15 23 25 55 16 -121 0 0 23 56 11 12 11 15 35 141 -17 22 44 43 25 9 10 22 8 7 25 47 45 -120 0 0 23 49 19 12 11 20 36 142 -16 22 37 55 25 2 12 22 1 20 25 40 45 -119 0 0 23 42 56 12 11 25 36 143 -16 22 31 36 24 55 46 21 55 4 25 34 16 -118 0 0 23 37 5 12 11 29 37 144 -15 22 25 48 24 49 50 21 49 18 25 28 19 -117 0 0 23 31 44 12 11 34 38 145 -14 22 20 31 24 44 26 21 44 2 25 22 52 -116 0 0 23 26 54 12 11 39 38 146 -13 22 15 44 24 39 33 21 39 16 25 17 58 -115 0 0 23 22 35 12 11 44 39 147 -12 22 11 28 24 35 11 21 35 1 25 13 34 -114 0 0 23 18 47 12 11 49 39 148 -11 22 7 42 24 31 21 21 31 17 25 9 43 -113 0 0 23 15 31 12 11 54 40 149 -11 22 4 27 24 28 2 21 28 3 25 6 23 -112 0 0 23 12 45 12 11 59 40 150 -10 22 1 44 24 25 15 21 25 20 25 3 35 -111 0 0 23 10 31 12 12 5 41 151 -9 21 59 31 24 23 0 21 23 8 25 1 19 -110 0 0 23 8 49 12 12 10 41 152 -8 21 57 49 24 21 17 21 21 27 24 59 35 -109 0 0 23 7 38 12 12 15 42 153 -7 21 56 39 24 20 5 21 20 17 24 58 23 -108 0 0 23 6 58 12 12 21 42 154 -6 21 55 59 24 19 25 21 19 37 24 57 43 -107 0 0 23 6 50 12 12 26 43 155 -5 21 55 51 24 19 17 21 19 29 24 57 35 -106 0 0 23 7 13 12 12 31 43 156 -5 21 56 14 24 19 41 21 19 52 24 57 59 -105 0 0 23 8 8 12 12 37 43 158 -4 21 57 8 24 20 37 21 20 46 24 58 55 -104 0 0 23 9 35 12 12 42 44 159 -3 21 58 33 24 22 4 21 22 10 25 0 24 -103 0 0 23 11 33 12 12 48 44 160 -2 22 0 30 24 24 4 21 24 6 25 2 24 -102 0 0 23 14 2 12 12 54 44 161 -1 22 2 58 24 26 35 21 26 33 25 4 56 Uncertainty in time = +/- 3 secs [Prediction of 2008 Feb 17.0] Data for the target star ------------------------ * name: UCAC2 23766657 * constellation : Capricornus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 21 07 36.2046 DE: -20 31 59.527 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .033, .025 ) * V mag [mag]: 11.5 * B mag [mag]: 0.0 * Apparent position with proper motion RA(deg): 317.0223195275 DE(deg): -20.4996733724 * Equation of equinoxes (radians) : 0.000038062465301 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (128) Nemesis approx. diameter [km]: 188 approx. diameter ["]: .104 distance from Earth [AU]: 2.49700 * orbital information: orbit source: Preston date of fit: 2008 Feb 16 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 673 number of rejected observations: 155 time covered by the observations: 1904 Nov 17 - 2007 Sep 21 1 sigma uncertainty ellipse (major, minor, PA): 0.014, 0.010, 77° remarks: * orbital elements for (128) Nemesis : Mean anomaly = 286.92573772 deg Arg. of pericenter = 302.26620367 deg Long. of node = 76.45046864 deg Inclination = 6.25031266 deg Eccentricity = 0.12535412 Semimajor axis = 2.75213559 AU Perihelion dist = 2.40714405 AU Mag: H = 7.49, G = 0.15 Epoch of elements : MJD 54589.50900000 TDT (2008 May 03.509) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 May 3 128 Nemesis 12h 13.7m UT 11.5 21 7 36.205-20 31 59.53UCAC2 23766657 0.0 12.7 188 10.2 2.497 2.580 4.47 -88.2925 -20.534 -4.21 15.87 12.2283 -0.08480 0.69661 10.29233 1.26878 -0.00540 -0.00165 2000 284.8729972008 424.00000302.266204 76.450469 6.2503130.12535412 2.7521356 2.4071441 7.5 5.00.15 RATE 2.1587350 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.035 0.027 88 1.26 0.027 0 54513.5020080503_766657 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 31, 03:46 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org