IOTA/IOTA-ES occultation update for (185) Eunike / 2UCAC 31802515 event on 2012 Aug 03, 10:43 UT Visible from NW USA Summary ------- On 2012 Aug 03 UT, the 168 km diameter asteroid (185) Eunike will occult a 13.2 mag star in the constellation Eridanus for observers along a path across NW USA. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.5 mag to 12.6 mag (the magnitude of the asteroid) for at most 6.1 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: 95 * date and approx. time of event: 2012 Aug 03, 10:39 - 2012 Aug 03, 10:40 UT * geocentric midpoint of event [JD]: 2456142.94640417 * magnitude of target star: 13.2 * magnitude drop [mag]: 0.5 * estimated maximum duration [s]: 6.1 * Moon: 98 % sunlit, 89° distance * Sun: 77° distance * rough path description: NW USA The occultation path -------------------- * approximate projected width [km]: 202 * 1 sigma uncertainty interval [path widths]: +/- 0.44 * 1 sigma uncertainty interval [seconds]: +/- 3.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .047 +/- .042) * 1 sigma uncertainty ellipse (major, minor, PA): ( .047", .042", 90° ) * approx speed of asteroid's shadow [km/s]: 27.3925 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 31802515 by 185 Eunike on 2012 Aug 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 -145 0 0 44 57 18 10 39 37 0 90 -27 44 2 46 45 52 25 43 15 14 46 41 25 -144 0 0 44 57 27 10 39 37 1 91 -26 44 2 55 45 52 34 43 15 23 46 41 34 -143 0 0 44 57 26 10 39 37 2 91 -26 44 2 54 45 52 33 43 15 23 46 41 33 -142 0 0 44 57 15 10 39 37 2 92 -26 44 2 43 45 52 22 43 15 12 46 41 22 -141 0 0 44 56 54 10 39 38 3 93 -26 44 2 22 45 52 0 43 14 51 46 41 1 -140 0 0 44 56 22 10 39 38 4 93 -26 44 1 51 45 51 29 43 14 19 46 40 30 -139 0 0 44 55 41 10 39 38 4 94 -25 44 1 9 45 50 48 43 13 38 46 39 49 -138 0 0 44 54 50 10 39 38 5 95 -25 44 0 18 45 49 57 43 12 46 46 38 58 -137 0 0 44 53 48 10 39 39 6 95 -25 43 59 16 45 48 55 43 11 44 46 37 56 -136 0 0 44 52 36 10 39 39 7 96 -25 43 58 4 45 47 44 43 10 31 46 36 45 -135 0 0 44 51 14 10 39 39 7 97 -24 43 56 42 45 46 22 43 9 9 46 35 24 -134 0 0 44 49 43 10 39 40 8 98 -24 43 55 9 45 44 51 43 7 36 46 33 53 -133 0 0 44 48 1 10 39 40 9 98 -24 43 53 27 45 43 9 43 5 54 46 32 12 -132 0 0 44 46 8 10 39 41 9 99 -24 43 51 34 45 41 18 43 4 1 46 30 21 -131 0 0 44 44 6 10 39 42 10 100 -23 43 49 32 45 39 16 43 1 57 46 28 20 -130 0 0 44 41 54 10 39 42 11 100 -23 43 47 19 45 37 5 42 59 44 46 26 9 -129 0 0 44 39 32 10 39 43 12 101 -23 43 44 56 45 34 43 42 57 21 46 23 47 -128 0 0 44 36 59 10 39 44 12 102 -22 43 42 23 45 32 11 42 54 47 46 21 16 -127 0 0 44 34 17 10 39 44 13 103 -22 43 39 40 45 29 30 42 52 3 46 18 35 -126 0 0 44 31 25 10 39 45 14 103 -22 43 36 46 45 26 38 42 49 9 46 15 45 -125 0 0 44 28 22 10 39 46 14 104 -21 43 33 43 45 23 36 42 46 5 46 12 44 -124 0 0 44 25 10 10 39 47 15 105 -21 43 30 30 45 20 25 42 42 51 46 9 33 -123 0 0 44 21 47 10 39 48 16 106 -20 43 27 7 45 17 3 42 39 27 46 6 12 -122 0 0 44 18 15 10 39 49 17 106 -20 43 23 33 45 13 32 42 35 53 46 2 42 -121 0 0 44 14 33 10 39 50 17 107 -20 43 19 50 45 9 51 42 32 9 45 59 2 -120 0 0 44 10 40 10 39 51 18 108 -19 43 15 57 45 6 0 42 28 15 45 55 11 -119 0 0 44 6 38 10 39 52 19 109 -19 43 11 54 45 1 59 42 24 11 45 51 11 -118 0 0 44 2 26 10 39 53 19 109 -18 43 7 41 44 57 48 42 19 57 45 47 2 -117 0 0 43 58 5 10 39 54 20 110 -18 43 3 18 44 53 27 42 15 33 45 42 42 -116 0 0 43 53 33 10 39 56 21 111 -18 42 58 45 44 48 57 42 10 59 45 38 13 -115 0 0 43 48 52 10 39 57 21 112 -17 42 54 2 44 44 17 42 6 16 45 33 34 -114 0 0 43 44 1 10 39 58 22 112 -17 42 49 10 44 39 27 42 1 22 45 28 46 -113 0 0 43 39 0 10 40 0 23 113 -16 42 44 8 44 34 28 41 56 19 45 23 47 -112 0 0 43 33 50 10 40 1 24 114 -16 42 38 56 44 29 19 41 51 6 45 18 40 -111 0 0 43 28 30 10 40 3 24 115 -15 42 33 35 44 24 0 41 45 44 45 13 22 -110 0 0 43 23 0 10 40 4 25 115 -15 42 28 4 44 18 32 41 40 12 45 7 55 -109 0 0 43 17 21 10 40 6 26 116 -14 42 22 23 44 12 54 41 34 30 45 2 19 -108 0 0 43 11 32 10 40 7 26 117 -14 42 16 34 44 7 7 41 28 39 44 56 33 -107 0 0 43 5 34 10 40 9 27 118 -13 42 10 34 44 1 11 41 22 38 44 50 38 -106 0 0 42 59 27 10 40 11 28 119 -13 42 4 25 43 55 5 41 16 28 44 44 34 -105 0 0 42 53 10 10 40 12 28 120 -12 41 58 7 43 48 50 41 10 8 44 38 20 -104 0 0 42 46 45 10 40 14 29 120 -12 41 51 40 43 42 26 41 3 40 44 31 57 -103 0 0 42 40 9 10 40 16 30 121 -11 41 45 3 43 35 52 40 57 2 44 25 25 -102 0 0 42 33 25 10 40 18 31 122 -11 41 38 17 43 29 9 40 50 15 44 18 44 -101 0 0 42 26 32 10 40 20 31 123 -10 41 31 23 43 22 18 40 43 19 44 11 54 -100 0 0 42 19 30 10 40 22 32 124 -10 41 24 19 43 15 17 40 36 13 44 4 55 - 99 0 0 42 12 19 10 40 23 33 125 -9 41 17 6 43 8 8 40 28 59 43 57 47 - 98 0 0 42 4 59 10 40 26 33 126 -9 41 9 44 43 0 49 40 21 36 43 50 30 - 97 0 0 41 57 30 10 40 28 34 126 -8 41 2 14 42 53 22 40 14 5 43 43 4 - 96 0 0 41 49 52 10 40 30 35 127 -7 40 54 35 42 45 46 40 6 24 43 35 30 - 95 0 0 41 42 6 10 40 32 35 128 -7 40 46 47 42 38 2 39 58 35 43 27 47 - 94 0 0 41 34 12 10 40 34 36 129 -6 40 38 51 42 30 9 39 50 38 43 19 56 - 93 0 0 41 26 9 10 40 36 37 130 -6 40 30 47 42 22 8 39 42 32 43 11 56 - 92 0 0 41 17 58 10 40 39 37 131 -5 40 22 34 42 13 58 39 34 17 43 3 48 - 91 0 0 41 9 38 10 40 41 38 132 -5 40 14 13 42 5 40 39 25 55 42 55 31 - 90 0 0 41 1 10 10 40 43 39 133 -4 40 5 43 41 57 14 39 17 24 42 47 7 - 89 0 0 40 52 35 10 40 46 39 134 -3 39 57 6 41 48 40 39 8 46 42 38 34 - 88 0 0 40 43 51 10 40 48 40 135 -3 39 48 21 41 39 58 39 0 0 42 29 54 - 87 0 0 40 35 0 10 40 51 41 136 -2 39 39 28 41 31 9 38 51 5 42 21 6 - 86 0 0 40 26 1 10 40 53 41 137 -1 39 30 28 41 22 11 38 42 4 42 12 10 - 85 0 0 40 16 55 10 40 56 42 138 -1 39 21 20 41 13 6 38 32 54 42 3 6 - 84 0 0 40 7 41 10 40 58 42 139 0 39 12 4 41 3 54 38 23 38 41 53 55 Uncertainty in time = +/- 3 secs Prediction of 2012 Jun 6.0 Data for the target star ------------------------ * name: 2UCAC 31802515 * constellation : Eridanus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 03 48 34.1579 DE: +00 13 53.391 * position source: Pos: UCAC4, pm: UCAC4, pi: * standard error: RA,DE ["]: ( .045, .042 ) * V mag [mag]: 13.2 * B mag [mag]: 0.0 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (185) Eunike approx. diameter [km]: 168 approx. diameter ["]: .096 distance from Earth [AU]: 2.40500 * orbital information: orbit source: Preston date of fit: 2012 Jun 06 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1656 number of rejected observations: 142 time covered by the observations: 1905 Mar 13 - 2011 Nov 23 1 sigma uncertainty ellipse (major, minor, PA): 0.011, 0.006, 81° remarks: * orbital elements for (185) Eunike : Mean anomaly = 9.76146749 deg Arg. of pericenter = 224.61239565 deg Long. of node = 153.91131153 deg Inclination = 23.22155141 deg Eccentricity = 0.12865791 Semimajor axis = 2.73898399 AU Perihelion dist = 2.38659203 AU Mag: H = 7.64, G = 0.15 Epoch of elements : MJD 56142.44700000 TDT (2012 Aug 03.447) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 3 185 Eunike 10h 42.8m UT 13.2 3 48 34.158 0 13 53.392UCAC 31802515 0.0 12.6 168 6.1 2.405 3.703 -10.59 -55.9821 0.235 20.84 17.33 10.7137 0.10183 0.54858 15.18802 -2.89294 -0.00499 -0.00161 2000 9.2294152012 8 1.00000224.612396153.911312 23.2215510.12865791 2.7389840 2.3865920 7.6 5.00.15 RATE 2.1743020 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.047 0.042 90 1.44 0.043 0 0-1 1 056084.0020120803_802515 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Jun 06, 04:33 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org