IOTA/IOTA-ES occultation update for (171) Ophelia / HIP 91993 event on 2012 Oct 29, 14:51 UT Visible from SW Asia Summary ------- On 2012 Oct 29 UT, the 105 km diameter asteroid (171) Ophelia will occult a 9.1 mag star in the constellation Sagittarius for observers along a path across SW Asia. In the case of an occultation, the combined light of the asteroid and the star will drop by 5.6 mag to 14.7 mag (the magnitude of the asteroid) for at most 3.6 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: . The event at a glimpse ---------------------- * Rank: 88 * date and approx. time of event: 2012 Oct 29, 14:52 - 2012 Oct 29, 14:53 UT * geocentric midpoint of event [JD]: 2456230.11928333 * magnitude of target star: 9.1 * magnitude drop [mag]: 5.6 * estimated maximum duration [s]: 3.6 * Moon: 100 % sunlit, 113° distance * Sun: 64° distance * rough path description: SW Asia The occultation path -------------------- * approximate projected width [km]: 183 * 1 sigma uncertainty interval [path widths]: +/- 0.56 * 1 sigma uncertainty interval [seconds]: +/- 2.8 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .032 +/- .022) * 1 sigma uncertainty ellipse (major, minor, PA): ( .032", .022", 90° ) * approx speed of asteroid's shadow [km/s]: 28.7763 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of HIP 91993 by 171 Ophelia on 2012 Oct 29 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 74 50 46 51 0 0 14 53 52 1 229 -31 76 52 14 72 47 12 ... .. .. 70 25 58 72 56 5 50 0 0 14 53 51 3 227 -30 74 56 55 70 53 0 ... .. .. 68 32 6 71 0 32 49 0 0 14 53 51 4 226 -29 73 0 59 68 57 39 ... .. .. 66 36 43 69 3 46 48 0 0 14 53 50 6 224 -28 71 4 8 67 0 46 ... .. .. 64 39 26 67 5 28 47 0 0 14 53 48 8 223 -27 69 6 3 65 2 1 71 18 7 62 39 51 65 5 14 46 0 0 14 53 47 9 221 -25 67 6 21 63 0 58 69 18 46 60 37 32 Latitude Latitude Latitude Latitude 64 0 0 45 27 55 14 53 46 10 221 -25 44 28 34 46 29 6 43 24 4 47 40 5 63 0 0 44 58 43 14 53 45 11 220 -24 43 59 43 45 59 31 42 55 34 47 10 1 62 0 0 44 29 50 14 53 43 12 219 -23 43 31 11 45 30 16 42 27 23 46 40 17 61 0 0 44 1 18 14 53 42 13 218 -23 43 2 59 45 1 21 41 59 32 46 10 54 60 0 0 43 33 6 14 53 41 13 218 -22 42 35 8 44 32 47 41 32 2 45 41 53 59 0 0 43 5 17 14 53 39 14 217 -21 42 7 39 44 4 36 41 4 54 45 13 15 58 0 0 42 37 51 14 53 38 15 216 -21 41 40 32 43 36 48 40 38 8 44 45 0 57 0 0 42 10 49 14 53 36 16 215 -20 41 13 50 43 9 25 40 11 45 44 17 11 56 0 0 41 44 11 14 53 35 17 215 -19 40 47 32 42 42 27 39 45 47 43 49 46 55 0 0 41 18 0 14 53 33 17 214 -18 40 21 39 42 15 54 39 20 14 43 22 49 54 0 0 40 52 14 14 53 31 18 213 -17 39 56 12 41 49 49 38 55 6 42 56 18 53 0 0 40 26 56 14 53 29 19 212 -17 39 31 12 41 24 11 38 30 25 42 30 16 52 0 0 40 2 6 14 53 27 20 211 -16 39 6 40 40 59 1 38 6 11 42 4 42 51 0 0 39 37 45 14 53 25 20 211 -15 38 42 36 40 34 21 37 42 26 41 39 39 50 0 0 39 13 52 14 53 23 21 210 -14 38 19 1 40 10 10 37 19 8 41 15 5 49 0 0 38 50 30 14 53 21 22 209 -13 37 55 55 39 46 29 36 56 20 40 51 2 48 0 0 38 27 38 14 53 19 23 208 -13 37 33 20 39 23 20 36 34 2 40 27 31 47 0 0 38 5 18 14 53 17 23 207 -12 37 11 16 39 0 42 36 12 14 40 4 32 46 0 0 37 43 29 14 53 14 24 206 -11 36 49 42 38 38 36 35 50 57 39 42 6 45 0 0 37 22 12 14 53 12 25 205 -10 36 28 41 38 17 3 35 30 11 39 20 13 44 0 0 37 1 28 14 53 9 25 205 -9 36 8 12 37 56 3 35 9 58 38 58 54 43 0 0 36 41 18 14 53 7 26 204 -8 35 48 15 37 35 37 34 50 16 38 38 9 42 0 0 36 21 41 14 53 4 27 203 -8 35 28 52 37 15 45 34 31 8 38 17 59 41 0 0 36 2 38 14 53 1 27 202 -7 35 10 3 36 56 28 34 12 32 37 58 24 40 0 0 35 44 9 14 52 59 28 201 -6 34 51 48 36 37 46 33 54 31 37 39 24 39 0 0 35 26 16 14 52 56 28 200 -5 34 34 7 36 19 39 33 37 3 37 21 1 38 0 0 35 8 58 14 52 53 29 199 -4 34 17 1 36 2 7 33 20 10 37 3 14 37 0 0 34 52 15 14 52 50 29 198 -3 34 0 30 35 45 12 33 3 52 36 46 3 36 0 0 34 36 9 14 52 47 30 197 -2 33 44 35 35 28 54 32 48 8 36 29 30 35 0 0 34 20 38 14 52 44 30 196 -1 33 29 16 35 13 12 32 33 0 36 13 34 34 0 0 34 5 45 14 52 41 31 195 -1 33 14 32 34 58 7 32 18 28 35 58 15 Uncertainty in time = +/- 3 secs Prediction of 2012 Oct 8.0 Data for the target star ------------------------ * name: HIP 91993 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 18 45 00.4409 DE: -23 38 17.934 * position source: mpos:HIP2 pm:HIP2 plx:HIP2 * standard error: RA,DE ["]: ( .030, .020 ) * V mag [mag]: 9.1 * B mag [mag]: 10.0 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (171) Ophelia approx. diameter [km]: 105 approx. diameter ["]: .039 distance from Earth [AU]: 3.72700 * orbital information: orbit source: Preston date of fit: 2012 Oct 07 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 1193 number of rejected observations: 91 time covered by the observations: 1903 Nov 14 - 2012 Sep 30 1 sigma uncertainty ellipse (major, minor, PA): 0.012, 0.008, 88° remarks: * orbital elements for (171) Ophelia : Mean anomaly = 127.13835288 deg Arg. of pericenter = 56.99557152 deg Long. of node = 100.53939298 deg Inclination = 2.54670182 deg Eccentricity = 0.13075518 Semimajor axis = 3.13171116 AU Perihelion dist = 2.72222369 AU Mag: H = 8.44, G = 0.15 Epoch of elements : MJD 56229.61900000 TDT (2012 Oct 29.619) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 29 171 Ophelia 14h 51.8m UT 9.1 18 45 0.441-23 38 17.93HIP 91993 10.0 14.7 105 3.6 3.727 2.783 2.41 19.9710 -23.638 -47.01 -13.72 14.8628 -0.04718 0.81724 16.20990 1.02284 0.00531 0.00038 2000 125.42770220121020.00000 56.995572100.539393 2.5467020.13075518 3.1317112 2.7222237 8.3 5.00.15 RATE 1.7784080 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.032 0.022 90 1.56 0.022 0 0-1-4 056208.0020121029__91993 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Oct 07, 19:38 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org