IOTA/IOTA-ES occultation update for (894) Erda / TYC 5164-01450-1 event on 2012 Aug 18, 08:51 UT Visible from W Canada, W USA, NE Australia Summary ------- On 2012 Aug 18 UT, the 38 km diameter asteroid (894) Erda will occult a 11.6 mag star in the constellation Aquila for observers along a path across W Canada, W USA, NE Australia. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.2 mag to 13.6 mag (the magnitude of the asteroid) for at most 4.0 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: 2012 Aug 18, 08:40 - 2012 Aug 18, 09:01 UT * geocentric midpoint of event [JD]: 2456157.86912917 * magnitude of target star: 11.6 * magnitude drop [mag]: 2.2 * estimated maximum duration [s]: 4.0 * Moon: 1 % sunlit, 146° distance * Sun: 151° distance * rough path description: W Canada, W USA, NE Australia The occultation path -------------------- * approximate projected width [km]: 39 * 1 sigma uncertainty interval [path widths]: +/- 1.18 * 1 sigma uncertainty interval [seconds]: +/- 5.3 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .042 +/- .029) * 1 sigma uncertainty ellipse (major, minor, PA): ( .042", .029", 85° ) * approx speed of asteroid's shadow [km/s]: 9.3809 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 5164-01450-1 by 894 Erda on 2012 Aug 18 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 - 77 43 35 55 0 0 8 40 33 3 259 -10 - 79 24 3 - 75 50 9 - 82 48 18 ... .. .. - 85 27 10 54 0 0 8 40 39 8 253 -14 - 86 34 7 - 84 16 52 - 89 1 21 - 81 13 54 Latitude Latitude Latitude Latitude - 87 0 0 53 44 40 8 40 40 9 252 -14 53 55 38 53 33 43 54 21 31 53 7 54 - 88 0 0 53 34 8 8 40 41 10 251 -15 53 45 8 53 23 9 54 11 8 52 57 15 - 89 0 0 53 23 8 8 40 43 10 250 -15 53 34 10 53 12 6 54 0 15 52 46 6 - 90 0 0 53 11 37 8 40 44 11 249 -16 53 22 42 53 0 33 53 48 53 52 34 27 - 91 0 0 52 59 37 8 40 46 11 249 -17 53 10 44 52 48 30 53 37 1 52 22 18 - 92 0 0 52 47 6 8 40 47 12 248 -17 52 58 16 52 35 56 53 24 39 52 9 39 - 93 0 0 52 34 4 8 40 49 13 247 -18 52 45 17 52 22 52 53 11 46 51 56 28 - 94 0 0 52 20 31 8 40 51 13 246 -18 52 31 46 52 9 16 52 58 22 51 42 45 - 95 0 0 52 6 26 8 40 52 14 245 -19 52 17 44 51 55 8 52 44 27 51 28 30 - 96 0 0 51 51 48 8 40 54 15 245 -19 52 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0 7 11 17 8 51 14 77 145 -50 7 25 22 6 57 13 7 58 41 6 24 5 -168 0 0 6 18 40 8 51 29 77 139 -49 6 32 43 6 4 39 7 5 56 5 31 36 -169 0 0 5 26 19 8 51 44 77 133 -49 5 40 19 5 12 19 6 13 26 4 39 23 -170 0 0 4 34 14 8 51 59 77 127 -48 4 48 11 4 20 17 5 21 12 3 47 27 -171 0 0 3 42 27 8 52 14 77 122 -48 3 56 22 3 28 33 4 29 16 2 55 49 -172 0 0 2 51 1 8 52 29 76 117 -47 3 4 53 2 37 10 3 37 40 2 4 33 -173 0 0 1 59 58 8 52 44 76 112 -47 2 13 47 1 46 10 2 46 27 1 13 40 -174 0 0 1 9 18 8 52 59 75 108 -46 1 23 4 0 55 34 1 55 37 0 23 11 -175 0 0 0 19 5 8 53 13 75 104 -46 0 32 48 0 5 23 1 5 13 - 0 26 52 -176 0 0 - 0 30 41 8 53 28 74 100 -45 - 0 17 2 - 0 44 19 0 15 16 - 1 16 27 -177 0 0 - 1 19 58 8 53 42 73 97 -44 - 1 6 22 - 1 33 33 - 0 34 12 - 2 5 33 -178 0 0 - 2 8 44 8 53 57 72 94 -44 - 1 55 11 - 2 22 16 - 1 23 10 - 2 54 8 -179 0 0 - 2 56 58 8 54 11 71 92 -43 - 2 43 29 - 3 10 26 - 2 11 36 - 3 42 10 -180 0 0 - 3 44 39 8 54 25 70 89 -42 - 3 31 14 - 3 58 4 - 2 59 29 - 4 29 39 179 0 0 - 4 31 45 8 54 39 70 87 -42 - 4 18 24 - 4 45 6 - 3 46 48 - 5 16 34 178 0 0 - 5 18 16 8 54 53 69 86 -41 - 5 4 58 - 5 31 33 - 4 33 31 - 6 2 52 177 0 0 - 6 4 10 8 55 7 68 84 -40 - 5 50 55 - 6 17 23 - 5 19 37 - 6 48 33 176 0 0 - 6 49 26 8 55 20 67 83 -39 - 6 36 15 - 7 2 36 - 6 5 6 - 7 33 37 175 0 0 - 7 34 3 8 55 33 65 81 -39 - 7 20 56 - 7 47 9 - 6 49 55 - 8 18 1 174 0 0 - 8 18 0 8 55 46 64 80 -38 - 8 4 57 - 8 31 2 - 7 34 5 - 9 1 46 173 0 0 - 9 1 17 8 55 59 63 79 -37 - 8 48 17 - 9 14 15 - 8 17 35 - 9 44 49 172 0 0 - 9 43 52 8 56 12 62 79 -36 - 9 30 57 - 9 56 47 - 9 0 23 -10 27 12 171 0 0 -10 25 45 8 56 24 61 78 -35 -10 12 54 -10 38 36 - 9 42 30 -11 8 53 170 0 0 -11 6 56 8 56 37 60 77 -35 -10 54 9 -11 19 43 -10 23 54 -11 49 51 169 0 0 -11 47 24 8 56 49 59 77 -34 -11 34 40 -12 0 7 -11 4 35 -12 30 5 168 0 0 -12 27 8 8 57 0 58 76 -33 -12 14 28 -12 39 48 -11 44 32 -13 9 37 167 0 0 -13 6 8 8 57 12 57 76 -32 -12 53 32 -13 18 44 -12 23 45 -13 48 24 166 0 0 -13 44 24 8 57 23 56 75 -31 -13 31 52 -13 56 56 -13 2 14 -14 26 27 165 0 0 -14 21 55 8 57 35 55 75 -30 -14 9 27 -14 34 23 -13 39 58 -15 3 45 164 0 0 -14 58 42 8 57 45 54 75 -29 -14 46 17 -15 11 6 -14 16 57 -15 40 19 163 0 0 -15 34 43 8 57 56 53 75 -29 -15 22 22 -15 47 3 -14 53 11 -16 16 7 162 0 0 -16 9 59 8 58 7 52 74 -28 -15 57 42 -16 22 15 -15 28 39 -16 51 11 161 0 0 -16 44 29 8 58 17 51 74 -27 -16 32 16 -16 56 42 -16 3 22 -17 25 29 160 0 0 -17 18 14 8 58 27 50 74 -26 -17 6 4 -17 30 23 -16 37 20 -17 59 1 159 0 0 -17 51 14 8 58 37 49 74 -25 -17 39 8 -18 3 19 -17 10 32 -18 31 49 158 0 0 -18 23 28 8 58 46 48 74 -24 -18 11 25 -18 35 29 -17 42 58 -19 3 51 157 0 0 -18 54 56 8 58 56 47 74 -24 -18 42 57 -19 6 54 -18 14 38 -19 35 7 156 0 0 -19 25 39 8 59 5 46 74 -23 -19 13 44 -19 37 34 -18 45 33 -20 5 39 155 0 0 -19 55 37 8 59 14 45 74 -22 -19 43 45 -20 7 28 -19 15 43 -20 35 25 154 0 0 -20 24 50 8 59 22 44 74 -21 -20 13 1 -20 36 38 -19 45 7 -21 4 26 153 0 0 -20 53 17 8 59 31 43 75 -20 -20 41 32 -21 5 2 -20 13 46 -21 32 43 152 0 0 -21 21 0 8 59 39 42 75 -19 -21 9 18 -21 32 41 -20 41 40 -22 0 14 151 0 0 -21 47 58 8 59 47 41 75 -18 -21 36 20 -21 59 36 -21 8 49 -22 27 2 150 0 0 -22 14 12 8 59 55 40 75 -18 -22 2 36 -22 25 47 -21 35 13 -22 53 5 149 0 0 -22 39 41 9 0 3 39 75 -17 -22 28 9 -22 51 13 -22 0 53 -23 18 24 148 0 0 -23 4 27 9 0 10 38 76 -16 -22 52 57 -23 15 55 -22 25 48 -23 42 59 147 0 0 -23 28 28 9 0 17 37 76 -15 -23 17 2 -23 39 54 -22 50 0 -24 6 50 146 0 0 -23 51 46 9 0 24 36 76 -14 -23 40 23 -24 3 9 -23 13 28 -24 29 59 145 0 0 -24 14 21 9 0 31 35 76 -13 -24 3 0 -24 25 41 -23 36 12 -24 52 24 144 0 0 -24 36 13 9 0 37 34 77 -13 -24 24 55 -24 47 30 -23 58 13 -25 14 6 143 0 0 -24 57 22 9 0 44 33 77 -12 -24 46 7 -25 8 36 -24 19 32 -25 35 6 142 0 0 -25 17 48 9 0 50 32 77 -11 -25 6 36 -25 29 0 -24 40 7 -25 55 24 141 0 0 -25 37 33 9 0 56 31 78 -10 -25 26 23 -25 48 42 -25 0 0 -26 15 0 140 0 0 -25 56 35 9 1 2 30 78 -9 -25 45 28 -26 7 42 -25 19 11 -26 33 55 139 0 0 -26 14 56 9 1 7 29 78 -9 -26 3 51 -26 26 1 -25 37 40 -26 52 7 138 0 0 -26 32 36 9 1 13 28 79 -8 -26 21 33 -26 43 38 -25 55 27 -27 9 39 137 0 0 -26 49 34 9 1 18 27 79 -7 -26 38 34 -27 0 34 -26 12 33 -27 26 30 136 0 0 -27 5 52 9 1 23 26 80 -6 -26 54 54 -27 16 50 -26 28 58 -27 42 41 135 0 0 -27 21 29 9 1 28 26 80 -5 -27 10 33 -27 32 25 -26 44 42 -27 58 11 134 0 0 -27 36 26 9 1 32 25 80 -5 -27 25 32 -27 47 20 -26 59 46 -28 13 1 133 0 0 -27 50 43 9 1 37 24 81 -4 -27 39 51 -28 1 35 -27 14 9 -28 27 11 132 0 0 -28 4 20 9 1 41 23 81 -3 -27 53 29 -28 15 10 -27 27 52 -28 40 42 131 0 0 -28 17 17 9 1 45 22 82 -2 -28 6 29 -28 28 6 -27 40 56 -28 53 34 130 0 0 -28 29 35 9 1 49 21 82 -1 -28 18 48 -28 40 22 -27 53 19 -29 5 46 129 0 0 -28 41 14 9 1 53 20 82 -1 -28 30 29 -28 51 59 -28 5 3 -29 17 20 Uncertainty in time = +/- 6 secs Prediction of 2012 Aug 7.0 Data for the target star ------------------------ * name: TYC 5164-01450-1 * constellation : Aquila * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 20 00 28.4630 DE: -03 20 30.336 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .028, .024 ) * V mag [mag]: 11.6 * B mag [mag]: 13.3 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (894) Erda approx. diameter [km]: 38 approx. diameter ["]: .029 distance from Earth [AU]: 1.83200 * orbital information: orbit source: Preston date of fit: 2012 Aug 06 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 919 number of rejected observations: 60 time covered by the observations: 1907 May 14 - 2012 Aug 03 1 sigma uncertainty ellipse (major, minor, PA): 0.031, 0.016, 81° remarks: * orbital elements for (894) Erda : Mean anomaly = 4.00260591 deg Arg. of pericenter = 113.80941025 deg Long. of node = 190.85103307 deg Inclination = 12.69781703 deg Eccentricity = 0.11423762 Semimajor axis = 3.11611464 AU Perihelion dist = 2.76013711 AU Mag: H = 9.54, G = 0.15 Epoch of elements : MJD 56157.36900000 TDT (2012 Aug 18.369) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 18 894 Erda 8h 51.5m UT 11.6 20 0 28.463- 3 20 30.34TYC 5164-01450-1 13.3 13.6 38 4.0 1.832 -1.245 -17.25 -159.8956 -3.337 48.06 12.91 8.8591 -0.14789 0.16155 -3.88778 -3.59453 0.00256 -0.00097 2000 2.6822462012 811.00000113.809410190.851033 12.6978170.11423762 3.1161146 2.7601371 9.4 5.00.15 RATE 1.7917770 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.042 0.029 85 2.18 0.034 0 0 0 4 056146.0020120818_1450-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Aug 06, 19:45 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org