IOTA/IOTA-ES occultation update for (351) Yrsa / TYC 1866-00249-1 event on 2008 Mar 25, 19:04 UT Visible from Africa Summary ------- On 2008 Mar 25 UT, the 40 km diameter asteroid (351) Yrsa will occult a 10.1 mag star in the constellation Taurus for observers along a path across Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 3.7 mag to 13.8 mag (the magnitude of the asteroid) for at most 1.8 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: 52 * date and approx. time of event: 2008 Mar 25, 19:04 - 2008 Mar 25, 19:07 UT * magnitude of target star: 10.1 * magnitude drop [mag]: 3.7 * estimated maximum duration [s]: 1.8 * Moon: 85 % sunlit, 143° distance * Sun: 82° distance * rough path description: Africa The occultation path -------------------- * approximate projected width [km]: 65 * 1 sigma uncertainty interval [path widths]: +/- 1.22 * 1 sigma uncertainty interval [seconds]: +/- 1.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .023 +/- .029) * 1 sigma uncertainty ellipse (major, minor, PA): ( .029", .023", 359° ) * approx speed of asteroid's shadow [km/s]: 22.0435 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 1866-00249-1 by 351 Yrsa on 2008 Mar 25 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 Latitude Latitude Latitude Latitude - 15 0 0 -26 23 54 19 4 22 38 351 -1 -26 41 52 -26 6 4 -27 26 15 -25 23 0 - 14 0 0 -26 17 26 19 4 27 38 350 -2 -26 35 23 -25 59 37 -27 19 41 -25 16 38 - 13 0 0 -26 11 41 19 4 32 38 349 -2 -26 29 36 -25 53 53 -27 13 50 -25 10 57 - 12 0 0 -26 6 39 19 4 36 37 348 -3 -26 24 33 -25 48 53 -27 8 44 -25 6 0 - 11 0 0 -26 2 21 19 4 41 37 347 -4 -26 20 13 -25 44 35 -27 4 21 -25 1 45 - 10 0 0 -25 58 45 19 4 45 37 346 -5 -26 16 37 -25 41 1 -27 0 43 -24 58 13 - 9 0 0 -25 55 53 19 4 50 37 345 -6 -26 13 44 -25 38 10 -26 57 48 -24 55 23 - 8 0 0 -25 53 44 19 4 55 37 343 -7 -26 11 35 -25 36 1 -26 55 37 -24 53 16 - 7 0 0 -25 52 19 19 4 59 37 342 -8 -26 10 9 -25 34 36 -26 54 10 -24 51 52 - 6 0 0 -25 51 37 19 5 4 36 341 -9 -26 9 26 -25 33 54 -26 53 27 -24 51 11 - 5 0 0 -25 51 38 19 5 8 36 340 -10 -26 9 27 -25 33 56 -26 53 28 -24 51 12 - 4 0 0 -25 52 22 19 5 12 36 339 -11 -26 10 12 -25 34 40 -26 54 13 -24 51 56 - 3 0 0 -25 53 50 19 5 17 35 338 -12 -26 11 40 -25 36 7 -26 55 42 -24 53 23 - 2 0 0 -25 56 1 19 5 21 35 337 -13 -26 13 51 -25 38 18 -26 57 54 -24 55 32 - 1 0 0 -25 58 55 19 5 26 34 336 -13 -26 16 46 -25 41 11 -27 0 50 -24 58 24 0 0 0 -26 2 32 19 5 30 34 335 -14 -26 20 24 -25 44 47 -27 4 31 -25 1 58 1 0 0 -26 6 52 19 5 34 34 334 -15 -26 24 45 -25 49 6 -27 8 54 -25 6 15 2 0 0 -26 11 55 19 5 38 33 333 -16 -26 29 50 -25 54 8 -27 14 2 -25 11 14 3 0 0 -26 17 42 19 5 42 33 332 -17 -26 35 37 -25 59 53 -27 19 53 -25 16 56 4 0 0 -26 24 11 19 5 46 32 331 -18 -26 42 8 -26 6 21 -27 26 27 -25 23 20 5 0 0 -26 31 23 19 5 50 32 330 -19 -26 49 21 -26 13 31 -27 33 45 -25 30 26 6 0 0 -26 39 17 19 5 54 31 329 -20 -26 57 18 -26 21 24 -27 41 47 -25 38 14 7 0 0 -26 47 54 19 5 58 30 329 -21 -27 5 57 -26 29 59 -27 50 31 -25 46 45 8 0 0 -26 57 14 19 6 2 30 328 -21 -27 15 19 -26 39 16 -27 59 59 -25 55 57 9 0 0 -27 7 16 19 6 6 29 327 -22 -27 25 23 -26 49 16 -28 10 10 -26 5 51 10 0 0 -27 18 0 19 6 9 28 326 -23 -27 36 10 -26 59 58 -28 21 3 -26 16 26 11 0 0 -27 29 27 19 6 13 28 325 -24 -27 47 40 -27 11 21 -28 32 40 -26 27 43 12 0 0 -27 41 35 19 6 16 27 324 -25 -27 59 51 -27 23 27 -28 44 59 -26 39 42 13 0 0 -27 54 25 19 6 20 26 324 -26 -28 12 44 -27 36 14 -28 58 0 -26 52 22 14 0 0 -28 7 57 19 6 23 26 323 -27 -28 26 19 -27 49 42 -29 11 44 -27 5 42 15 0 0 -28 22 10 19 6 26 25 322 -27 -28 40 36 -28 3 52 -29 26 9 -27 19 44 16 0 0 -28 37 4 19 6 30 24 321 -28 -28 55 34 -28 18 42 -29 41 17 -27 34 26 17 0 0 -28 52 40 19 6 33 23 321 -29 -29 11 13 -28 34 14 -29 57 6 -27 49 48 18 0 0 -29 8 56 19 6 36 23 320 -30 -29 27 34 -28 50 26 -30 13 37 -28 5 51 19 0 0 -29 25 52 19 6 39 22 319 -31 -29 44 34 -29 7 18 -30 30 48 -28 22 34 20 0 0 -29 43 29 19 6 41 21 319 -31 -30 2 16 -29 24 51 -30 48 41 -28 39 56 21 0 0 -30 1 46 19 6 44 20 318 -32 -30 20 37 -29 43 3 -31 7 14 -28 57 58 22 0 0 -30 20 43 19 6 47 19 317 -33 -30 39 39 -30 1 55 -31 26 28 -29 16 38 23 0 0 -30 40 18 19 6 49 19 317 -34 -30 59 19 -30 21 26 -31 46 21 -29 35 58 24 0 0 -31 0 33 19 6 52 18 316 -34 -31 19 39 -30 41 36 -32 6 54 -29 55 56 25 0 0 -31 21 26 19 6 54 17 315 -35 -31 40 38 -31 2 24 -32 28 7 -30 16 31 26 0 0 -31 42 58 19 6 56 16 315 -36 -32 2 15 -31 23 50 -32 49 58 -30 37 45 27 0 0 -32 5 7 19 6 58 15 314 -36 -32 24 30 -31 45 54 -33 12 28 -30 59 36 28 0 0 -32 27 54 19 7 0 14 313 -37 -32 47 23 -32 8 35 -33 35 35 -31 22 3 29 0 0 -32 51 18 19 7 2 13 313 -37 -33 10 52 -32 31 52 -33 59 20 -31 45 7 30 0 0 -33 15 18 19 7 4 13 312 -38 -33 34 59 -32 55 46 -34 23 42 -32 8 46 31 0 0 -33 39 53 19 7 5 12 312 -39 -33 59 41 -33 20 16 -34 48 41 -32 33 1 32 0 0 -34 5 5 19 7 7 11 311 -39 -34 24 59 -33 45 20 -35 14 16 -32 57 51 33 0 0 -34 30 50 19 7 8 10 310 -40 -34 50 51 -34 11 0 -35 40 26 -33 23 15 34 0 0 -34 57 10 19 7 9 9 310 -40 -35 17 18 -34 37 13 -36 7 10 -33 49 12 35 0 0 -35 24 4 19 7 11 8 309 -41 -35 44 19 -35 3 59 -36 34 29 -34 15 42 36 0 0 -35 51 30 19 7 12 7 309 -41 -36 11 52 -35 31 18 -37 2 21 -34 42 45 37 0 0 -36 19 28 19 7 13 6 308 -41 -36 39 58 -35 59 9 -37 30 46 -35 10 19 38 0 0 -36 47 58 19 7 13 5 307 -42 -37 8 35 -36 27 31 -37 59 42 -35 38 24 39 0 0 -37 16 58 19 7 14 4 307 -42 -37 37 43 -36 56 24 -38 29 10 .. .. .. 40 0 0 -37 46 27 19 7 14 3 306 -42 -38 7 20 -37 25 46 -38 59 8 .. .. .. 41 0 0 -38 16 26 19 7 15 2 306 -43 -38 37 27 -37 55 37 -39 29 35 .. .. .. 42 0 0 -38 46 53 19 7 15 2 305 -43 -39 8 2 -38 25 55 -40 0 31 .. .. .. 43 0 0 -39 17 46 19 7 15 1 304 -43 -39 39 3 -38 56 41 .. .. .. .. .. .. Uncertainty in time = +/- 2 secs [Prediction of 2008 Mar 12.0] Data for the target star ------------------------ * name: TYC 1866-00249-1 * constellation : Taurus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 05 48 17.9863 DE: +25 32 17.475 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .019, .028 ) * V mag [mag]: 10.1 * B mag [mag]: 10.5 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (351) Yrsa approx. diameter [km]: 40 approx. diameter ["]: .024 distance from Earth [AU]: 2.27000 * orbital information: orbit source: Preston date of fit: 2008 Mar 12 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 702 number of rejected observations: 88 time covered by the observations: 1905 Sep 23 - 2008 Mar 03 1 sigma uncertainty ellipse (major, minor, PA): 0.013, 0.009, 77° remarks: * orbital elements for (351) Yrsa : Mean anomaly = 346.54739983 deg Arg. of pericenter = 31.54798626 deg Long. of node = 99.44015463 deg Inclination = 9.19414682 deg Eccentricity = 0.15637550 Semimajor axis = 2.76472445 AU Perihelion dist = 2.33238928 AU Mag: H = 8.86, G = 0.15 Epoch of elements : MJD 54550.79500000 TDT (2008 Mar 25.795) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Mar 25 351 Yrsa 19h 4.3m UT 10.1 5 48 17.986 25 32 17.48TYC 1866-00249-1 10.5 13.8 40 1.8 2.270 3.530 6.35 -22.6108 25.536 -104.63 2.19 19.0718 0.10381 -0.78366 12.33320 1.64138 0.00552 0.00014 2000 346.3769512008 325.00000 31.547986 99.440155 9.1941470.15637550 2.7647245 2.3323893 9.0 5.00.15 RATE 2.1440080 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.029 0.023 359 2.22 0.030 0 54537.5020080325_0249-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 12, 23:51 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org