IOTA/IOTA-ES occultation update for (618) Elfriede / TYC 6394-01090-1 event on 2008 May 20, 19:51 UT Visible from China Summary ------- On 2008 May 20 UT, the 120 km diameter asteroid (618) Elfriede will occult a 12.2 mag star in the constellation Aquarius for observers along a path across China. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.0 mag to 14.0 mag (the magnitude of the asteroid) for at most 5.2 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: 75 * date and approx. time of event: 2008 May 20, 19:48 - 2008 May 20, 19:49 UT * midpoint of event [JD]: 2454607.327325 * magnitude of target star: 12.2 * magnitude drop [mag]: 2.0 * estimated maximum duration [s]: 5.2 * Moon: 99 % sunlit, 91° distance * Sun: 81° distance * rough path description: China The occultation path -------------------- * approximate projected width [km]: 195 * 1 sigma uncertainty interval [path widths]: +/- 0.75 * 1 sigma uncertainty interval [seconds]: +/- 3.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .041 +/- .042) * 1 sigma uncertainty ellipse (major, minor, PA): ( .042", .041", 359° ) * approx speed of asteroid's shadow [km/s]: 23.2167 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6394-01090-1 by 618 Elfriede 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 96 0 0 47 7 57 19 48 32 0 113 -16 46 11 9 .. .. .. .. .. .. .. .. .. 97 0 0 46 50 16 19 48 32 1 114 -16 45 53 34 47 48 19 .. .. .. .. .. .. 98 0 0 46 32 42 19 48 33 2 115 -16 45 36 5 47 30 39 .. .. .. 49 0 20 99 0 0 46 15 14 19 48 33 2 116 -16 45 18 43 47 13 5 .. .. .. 48 42 36 100 0 0 45 57 53 19 48 33 3 116 -16 45 1 27 46 55 38 .. .. .. 48 24 58 101 0 0 45 40 39 19 48 33 4 117 -15 44 44 19 46 38 17 .. .. .. 48 7 28 102 0 0 45 23 33 19 48 34 5 118 -15 44 27 19 46 21 5 .. .. .. 47 50 5 103 0 0 45 6 35 19 48 34 5 118 -15 44 10 27 46 4 1 .. .. .. 47 32 51 104 0 0 44 49 46 19 48 35 6 119 -15 43 53 44 45 47 6 42 31 52 47 15 45 105 0 0 44 33 6 19 48 36 7 120 -14 43 37 10 45 30 20 42 15 27 46 58 48 106 0 0 44 16 36 19 48 36 8 121 -14 43 20 46 45 13 43 41 59 11 46 42 1 107 0 0 44 0 17 19 48 37 8 121 -14 43 4 32 44 57 17 41 43 6 46 25 25 108 0 0 43 44 8 19 48 38 9 122 -14 42 48 30 44 41 2 41 27 12 46 8 59 109 0 0 43 28 10 19 48 39 10 123 -13 42 32 38 44 24 58 41 11 28 45 52 44 110 0 0 43 12 24 19 48 40 11 123 -13 42 16 58 44 9 5 40 55 57 45 36 41 111 0 0 42 56 51 19 48 41 11 124 -13 42 1 30 43 53 25 40 40 37 45 20 50 112 0 0 42 41 29 19 48 42 12 125 -12 41 46 15 43 37 57 40 25 30 45 5 12 113 0 0 42 26 21 19 48 44 13 126 -12 41 31 13 43 22 43 40 10 37 44 49 47 114 0 0 42 11 27 19 48 45 14 126 -11 41 16 24 43 7 42 39 55 56 44 34 35 115 0 0 41 56 46 19 48 47 14 127 -11 41 1 49 42 52 55 39 41 30 44 19 38 116 0 0 41 42 19 19 48 48 15 128 -11 40 47 29 42 38 22 39 27 17 44 4 55 117 0 0 41 28 8 19 48 50 16 129 -10 40 33 23 42 24 4 39 13 19 43 50 26 118 0 0 41 14 11 19 48 52 17 129 -10 40 19 32 42 10 1 38 59 37 43 36 14 119 0 0 41 0 30 19 48 53 17 130 -9 40 5 57 41 56 14 38 46 9 43 22 17 120 0 0 40 47 5 19 48 55 18 131 -9 39 52 38 41 42 43 38 32 58 43 8 36 121 0 0 40 33 57 19 48 57 19 132 -8 39 39 35 41 29 29 38 20 2 42 55 11 122 0 0 40 21 4 19 48 59 19 132 -8 39 26 48 41 16 31 38 7 23 42 42 4 123 0 0 40 8 30 19 49 1 20 133 -7 39 14 18 41 3 50 37 55 1 42 29 14 124 0 0 39 56 12 19 49 4 21 134 -7 39 2 6 40 51 27 37 42 56 42 16 41 125 0 0 39 44 12 19 49 6 22 135 -6 38 50 11 40 39 21 37 31 9 42 4 27 126 0 0 39 32 30 19 49 8 22 136 -6 38 38 35 40 27 34 37 19 39 41 52 31 127 0 0 39 21 7 19 49 11 23 136 -5 38 27 16 40 16 6 37 8 28 41 40 53 128 0 0 39 10 2 19 49 13 24 137 -4 38 16 17 40 4 56 36 57 35 41 29 35 129 0 0 38 59 17 19 49 16 24 138 -4 38 5 36 39 54 5 36 47 1 41 18 36 130 0 0 38 48 50 19 49 18 25 139 -3 37 55 14 39 43 34 36 36 45 41 7 57 131 0 0 38 38 43 19 49 21 26 140 -3 37 45 12 39 33 22 36 26 49 40 57 37 132 0 0 38 28 56 19 49 24 26 141 -2 37 35 29 39 23 30 36 17 13 40 47 38 133 0 0 38 19 30 19 49 27 27 141 -1 37 26 6 39 13 59 36 7 56 40 37 59 134 0 0 38 10 23 19 49 29 27 142 -1 37 17 4 39 4 48 35 58 59 40 28 41 135 0 0 38 1 37 19 49 32 28 143 0 37 8 22 38 55 58 35 50 23 40 19 44 Uncertainty in time = +/- 4 secs [Prediction of 2008 Apr 13.0] Data for the target star ------------------------ * name: TYC 6394-01090-1 * constellation : Aquarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 22 57 10.1865 DE: -15 42 57.507 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .036, .041 ) * V mag [mag]: 12.2 * B mag [mag]: 13.6 * Apparent position with proper motion RA(deg): 344.4050292871 DE(deg): -15.6702310864 * Equation of equinoxes (radians) : 0.000040029970552 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (618) Elfriede approx. diameter [km]: 120 approx. diameter ["]: .056 distance from Earth [AU]: 2.94800 * orbital information: orbit source: Preston date of fit: 2008 Apr 08 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 680 number of rejected observations: 73 time covered by the observations: 1906 Oct 18 - 2007 Aug 25 1 sigma uncertainty ellipse (major, minor, PA): 0.019, 0.010, 80° remarks: * orbital elements for (618) Elfriede : Mean anomaly = 344.38719025 deg Arg. of pericenter = 227.70217105 deg Long. of node = 111.10675672 deg Inclination = 17.04311287 deg Eccentricity = 0.07594776 Semimajor axis = 3.18841551 AU Perihelion dist = 2.94626250 AU Mag: H = 8.18, G = 0.15 Epoch of elements : MJD 54606.82700000 TDT (2008 May 20.827) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 May 20 618 Elfriede 19h 51.4m UT 12.2 22 57 10.187-15 42 57.51TYC 6394-01090-1 13.6 14.0 120 5.2 2.948 2.704 1.86 167.6170 -15.716 -118.69 20.18 19.8558 -0.03714 0.78707 13.08920 0.62563 -0.00506 -0.00226 2000 343.2053152008 514.00000227.702171111.106757 17.0431130.07594776 3.1884155 2.9462625 8.3 5.00.15 RATE 1.7311780 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.042 0.041 359 1.75 0.042 0 54569.5020080520_1090-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Apr 13, 03:35 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org