IOTA/IOTA-ES occultation update for (1287) Lorcia / TYC 1312-02300-1 event on 2008 May 12, 20:46 UT Visible from UK in twilight , low altitude Summary ------- On 2008 May 12 UT, the 22 km diameter asteroid (1287) Lorcia will occult a 10.5 mag star in the constellation Orion for observers along a path across UK in twilight , low altitude. In the case of an occultation, the combined light of the asteroid and the star will drop by 6.3 mag to 16.8 mag (the magnitude of the asteroid) for at most 0.5 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: 22 * date and approx. time of event: 2008 May 12, 20:47 - 2008 May 12, 20:47 UT * midpoint of event [JD]: 2454599.36527917 * magnitude of target star: 10.5 * magnitude drop [mag]: 6.3 * estimated maximum duration [s]: 0.5 * Moon: 57 % sunlit, 62° distance * Sun: 37° distance * rough path description: UK in twilight , low altitude The occultation path -------------------- * approximate projected width [km]: 37 * 1 sigma uncertainty interval [path widths]: +/- 3.07 * 1 sigma uncertainty interval [seconds]: +/- 1.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .032 +/- .028) * 1 sigma uncertainty ellipse (major, minor, PA): ( .032", .028", 91° ) * approx speed of asteroid's shadow [km/s]: 41.2951 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 1312-02300-1 by 1287 Lorcia on 2008 May 12 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 - 7 0 0 60 2 3 20 47 22 15 276 0 59 50 47 60 13 22 58 42 49 61 24 10 - 6 0 0 59 46 31 20 47 23 15 276 -1 59 35 14 59 57 50 58 27 12 61 8 42 - 5 0 0 59 30 47 20 47 24 14 277 -1 59 19 30 59 42 7 58 11 25 60 53 3 - 4 0 0 59 14 53 20 47 24 13 278 -2 59 3 35 59 26 14 57 55 27 60 37 13 - 3 0 0 58 58 48 20 47 25 13 279 -3 58 47 30 59 10 10 57 39 19 60 21 12 - 2 0 0 58 42 33 20 47 25 12 280 -3 58 31 15 58 53 55 57 23 2 60 5 0 - 1 0 0 58 26 9 20 47 26 12 281 -4 58 14 50 58 37 31 57 6 35 59 48 38 0 0 0 58 9 34 20 47 27 11 282 -4 57 58 15 58 20 57 56 49 58 59 32 6 1 0 0 57 52 51 20 47 27 11 283 -5 57 41 32 58 4 13 56 33 13 59 15 24 2 0 0 57 35 58 20 47 28 10 284 -5 57 24 39 57 47 21 56 16 20 58 58 32 3 0 0 57 18 57 20 47 28 9 284 -6 57 7 38 57 30 20 55 59 18 58 41 32 4 0 0 57 1 48 20 47 28 9 285 -7 56 50 28 57 13 10 55 42 8 58 24 23 5 0 0 56 44 30 20 47 29 8 286 -7 56 33 11 56 55 53 55 24 50 58 7 6 6 0 0 56 27 5 20 47 29 8 287 -8 56 15 46 56 38 28 55 7 26 57 49 40 7 0 0 56 9 33 20 47 30 7 288 -8 55 58 14 56 20 56 54 49 55 57 32 7 8 0 0 55 51 54 20 47 30 6 289 -9 55 40 35 56 3 17 .. .. .. 57 14 27 9 0 0 55 34 9 20 47 30 6 290 -9 55 22 51 55 45 32 .. .. .. 56 56 40 10 0 0 55 16 18 20 47 31 5 290 -10 55 5 0 55 27 41 .. .. .. 56 38 47 11 0 0 54 58 22 20 47 31 5 291 -11 54 47 4 55 9 44 .. .. .. 56 20 48 12 0 0 54 40 21 20 47 31 4 292 -11 54 29 3 54 51 42 .. .. .. 56 2 44 13 0 0 54 22 15 20 47 31 3 293 -12 54 10 57 54 33 36 .. .. .. 55 44 34 14 0 0 54 4 5 20 47 31 3 294 -12 53 52 48 54 15 25 .. .. .. 55 26 21 15 0 0 53 45 51 20 47 32 2 294 -13 53 34 35 53 57 11 .. .. .. 55 8 3 16 0 0 53 27 35 20 47 32 1 295 -13 53 16 19 53 38 54 .. .. .. 54 49 41 17 0 0 53 9 15 20 47 32 1 296 -14 52 58 0 53 20 34 .. .. .. 54 31 17 Uncertainty in time = +/- 2 secs [Prediction of 2008 Mar 29.0] Data for the target star ------------------------ * name: TYC 1312-02300-1 * constellation : Orion * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 05 54 55.7768 DE: +15 48 44.534 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .019, .019 ) * V mag [mag]: 10.5 * B mag [mag]: 11.4 * Apparent position with proper motion RA(deg): 88.8507009395 DE(deg): 15.8149064558 * Equation of equinoxes (radians) : 0.000041131340732 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1287) Lorcia approx. diameter [km]: 22 approx. diameter ["]: .009 distance from Earth [AU]: 3.55800 * orbital information: orbit source: Preston date of fit: 2008 Mar 28 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 789 number of rejected observations: 29 time covered by the observations: 1933 Aug 25 - 2008 Feb 12 1 sigma uncertainty ellipse (major, minor, PA): 0.025, 0.020, 91° remarks: * orbital elements for (1287) Lorcia : Mean anomaly = 348.85842211 deg Arg. of pericenter = 271.40294312 deg Long. of node = 202.69974354 deg Inclination = 9.82937399 deg Eccentricity = 0.06506262 Semimajor axis = 3.01090827 AU Perihelion dist = 2.81501068 AU Mag: H = 10.97, G = 0.15 Epoch of elements : MJD 54598.86500000 TDT (2008 May 12.865) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 May 12 1287 Lorcia 20h 46.0m UT 10.5 5 54 55.777 15 48 44.53TYC 1312-02300-1 11.4 16.8 22 0.5 3.558 3.988 2.21 -93.7577 15.812 -132.41 18.39 20.7667 -0.03149 0.80237 23.29082 0.89762 0.00332 -0.00057 2000 347.1860362008 5 4.00000271.402943202.699744 9.8293740.06506262 3.0109083 2.815010711.1 5.00.15 RATE 1.8865040 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.032 0.028 91 4.07 0.026 0 54554.5020080512_2300-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 31, 04:47 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org