IOTA/IOTA-ES occultation update for (2911) Miahelena / TYC 0297-00418-1 event on 2008 Apr 01, 01:31 UT Visible from Brazil, Bolivia, Peru Summary ------- On 2008 Apr 01 UT, the 18 km diameter asteroid (2911) Miahelena will occult a 10.2 mag star in the constellation Virgo for observers along a path across Brazil, Bolivia, Peru. In the case of an occultation, the combined light of the asteroid and the star will drop by 4.5 mag to 14.7 mag (the magnitude of the asteroid) for at most 1.7 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: 17 * date and approx. time of event: 2008 Apr 01, 01:24 - 2008 Apr 01, 01:38 UT * midpoint of event [JD]: 2454557.56338333 * magnitude of target star: 10.2 * magnitude drop [mag]: 4.5 * estimated maximum duration [s]: 1.7 * Moon: 29 % sunlit, 118° distance * Sun: 169° distance * rough path description: Brazil, Bolivia, Peru The occultation path -------------------- * approximate projected width [km]: 25 * 1 sigma uncertainty interval [path widths]: +/- 3.86 * 1 sigma uncertainty interval [seconds]: +/- 9.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .087 +/- .060) * 1 sigma uncertainty ellipse (major, minor, PA): ( .089", .057", 105° ) * approx speed of asteroid's shadow [km/s]: 10.8281 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 0297-00418-1 by 2911 Miahelena on 2008 Apr 1 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 39 37 46 -78 0 0 1 24 11 1 303 -11 40 39 12 38 37 35 ... .. .. 31 27 6 32 54 42 -77 0 0 1 24 12 2 309 -12 33 44 44 32 5 21 ... .. .. 26 3 15 Latitude Latitude Latitude Latitude 31 0 0 -76 39 53 1 24 12 3 311 -13 -76 31 21 -76 48 27 .. .. .. -77 55 27 30 0 0 -76 28 46 1 24 12 3 312 -13 -76 20 9 -76 37 25 .. .. .. -77 45 5 29 0 0 -76 17 13 1 24 13 4 313 -13 -76 8 31 -76 25 57 .. .. .. -77 34 18 28 0 0 -76 5 13 1 24 13 4 314 -14 -75 56 26 -76 14 2 .. .. .. -77 23 6 27 0 0 -75 52 46 1 24 13 4 315 -14 -75 43 53 -76 1 40 -74 36 14 -77 11 27 26 0 0 -75 39 49 1 24 14 5 316 -14 -75 30 51 -75 48 49 -74 22 33 -76 59 20 25 0 0 -75 26 23 1 24 14 5 317 -15 -75 17 19 -75 35 28 -74 8 20 -76 46 44 24 0 0 -75 12 25 1 24 15 5 318 -15 -75 3 16 -75 21 37 -73 53 36 -76 33 38 23 0 0 -74 57 56 1 24 15 6 319 -15 -74 48 41 -75 7 13 -73 38 18 -76 20 1 22 0 0 -74 42 53 1 24 15 6 320 -16 -74 33 32 -74 52 16 -73 22 27 -76 5 51 21 0 0 -74 27 16 1 24 16 6 321 -16 -74 17 49 -74 36 45 -73 6 1 -75 51 8 20 0 0 -74 11 3 1 24 17 7 322 -17 -74 1 30 -74 20 38 -72 48 58 -75 35 50 19 0 0 -73 54 13 1 24 17 7 323 -17 -73 44 34 -74 3 54 -72 31 18 -75 19 55 18 0 0 -73 36 44 1 24 18 7 324 -17 -73 27 0 -73 46 31 -72 12 59 -75 3 23 17 0 0 -73 18 36 1 24 19 8 325 -18 -73 8 45 -73 28 29 -71 54 0 -74 46 11 16 0 0 -72 59 47 1 24 20 8 326 -18 -72 49 50 -73 9 46 -71 34 20 -74 28 19 15 0 0 -72 40 15 1 24 21 9 326 -19 -72 30 12 -72 50 21 -71 13 57 -74 9 44 14 0 0 -72 20 0 1 24 22 9 327 -19 -72 9 51 -72 30 12 -70 52 51 -73 50 26 13 0 0 -71 58 59 1 24 23 10 328 -20 -71 48 44 -72 9 17 -70 31 0 -73 30 22 12 0 0 -71 37 12 1 24 24 10 329 -20 -71 26 51 -71 47 36 -70 8 22 -73 9 32 11 0 0 -71 14 37 1 24 25 11 330 -21 -71 4 9 -71 25 7 -69 44 56 -72 47 53 10 0 0 -70 51 12 1 24 26 11 331 -21 -70 40 39 -71 1 48 -69 20 42 -72 25 25 9 0 0 -70 26 57 1 24 28 12 332 -22 -70 16 17 -70 37 39 -68 55 38 -72 2 4 8 0 0 -70 1 49 1 24 29 12 333 -22 -69 51 4 -70 12 37 -68 29 42 -71 37 51 7 0 0 -69 35 48 1 24 31 13 334 -23 -69 24 57 -69 46 42 -68 2 55 -71 12 44 6 0 0 -69 8 52 1 24 33 13 335 -23 -68 57 56 -69 19 52 -67 35 14 -70 46 40 5 0 0 -68 41 1 1 24 35 14 336 -24 -68 29 59 -68 52 6 -67 6 39 -70 19 39 4 0 0 -68 12 13 1 24 37 14 337 -24 -68 1 6 -68 23 23 -66 37 8 -69 51 39 3 0 0 -67 42 27 1 24 39 15 338 -25 -67 31 15 -67 53 42 -66 6 42 -69 22 39 2 0 0 -67 11 42 1 24 42 16 339 -26 -67 0 25 -67 23 2 -65 35 19 -68 52 38 1 0 0 -66 39 57 1 24 44 16 340 -26 -66 28 37 -66 51 22 -65 2 59 -68 21 35 0 0 0 -66 7 13 1 24 47 17 341 -27 -65 55 48 -66 18 41 -64 29 41 -67 49 30 - 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8 12 55 - 98 0 0 - 7 8 19 1 38 4 13 82 -16 - 7 1 36 - 7 15 4 - 6 10 3 - 8 7 33 - 99 0 0 - 7 3 51 1 38 7 12 83 -15 - 6 57 7 - 7 10 35 - 6 5 36 - 8 3 3 -100 0 0 - 7 0 13 1 38 9 11 83 -14 - 6 53 29 - 7 6 57 - 6 2 0 - 7 59 23 -101 0 0 - 6 57 25 1 38 12 10 83 -13 - 6 50 42 - 7 4 9 - 5 59 13 - 7 56 34 -102 0 0 - 6 55 28 1 38 14 9 83 -12 - 6 48 44 - 7 2 12 - 5 57 16 - 7 54 36 -103 0 0 - 6 54 21 1 38 16 8 83 -11 - 6 47 37 - 7 1 5 - 5 56 8 - 7 53 30 -104 0 0 - 6 54 5 1 38 18 7 83 -10 - 6 47 21 - 7 0 49 - 5 55 51 - 7 53 15 -105 0 0 - 6 54 39 1 38 20 6 83 -9 - 6 47 56 - 7 1 24 .. .. .. - 7 53 52 -106 0 0 - 6 56 5 1 38 21 5 84 -8 - 6 49 21 - 7 2 50 .. .. .. - 7 55 20 -107 0 0 - 6 58 22 1 38 22 4 84 -7 - 6 51 38 - 7 5 7 .. .. .. - 7 57 41 -108 0 0 - 7 1 31 1 38 23 3 84 -6 - 6 54 46 - 7 8 16 .. .. .. - 8 0 54 -109 0 0 - 7 5 31 1 38 23 2 84 -5 - 6 58 45 - 7 12 17 .. .. .. - 8 4 59 -110 0 0 - 7 10 22 1 38 24 1 84 -4 - 7 3 36 - 7 17 9 .. .. .. - 8 9 56 Uncertainty in time = +/- 9 secs [Prediction of 2008 Mar 7.0] Data for the target star ------------------------ * name: TYC 0297-00418-1 * constellation : Virgo * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 12 50 13.3768 DE: +05 51 35.163 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .020, .021 ) * V mag [mag]: 10.2 * B mag [mag]: 11.5 * Apparent position with proper motion RA(deg): 192.6682429679 DE(deg): 5.8112309890 * Equation of equinoxes (radians) : 0.000041586606374 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (2911) Miahelena approx. diameter [km]: 18 approx. diameter ["]: .016 distance from Earth [AU]: 1.56400 * orbital information: orbit source: Preston date of fit: 2008 Feb 27 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 677 number of rejected observations: 17 time covered by the observations: 1938 Apr 07 - 2008 Feb 09 1 sigma uncertainty ellipse (major, minor, PA): 0.087, 0.053, 106° remarks: * orbital elements for (2911) Miahelena : Mean anomaly = 340.75124115 deg Arg. of pericenter = 64.37843263 deg Long. of node = 149.36601642 deg Inclination = 9.61979284 deg Eccentricity = 0.09280863 Semimajor axis = 2.79426496 AU Perihelion dist = 2.53493307 AU Mag: H = 11.44, G = 0.15 Epoch of elements : MJD 54557.06400000 TDT (2008 Apr 01.064) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Apr 1 2911 Miahelena 1h 31.3m UT 10.2 12 50 13.377 5 51 35.16TYC 0297-00418-1 11.5 14.7 18 1.7 1.564 -1.859 20.29 -20.0500 5.853 158.16 4.63 1.5212 -0.40602 -0.55487 -4.93285 3.60827 -0.00022 -0.00102 2000 339.2606682008 325.00000 64.378433149.366016 9.6197930.09280863 2.7942650 2.534933111.3 5.00.15 RATE 2.1100980 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.089 0.057 105 4.86 0.062 0 54532.5020080401_0418-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 07, 13:13 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org