IOTA/IOTA-ES occultation update for (1254) Erfordia / HIP 29840 event on 2008 May 20, 10:25 UT Visible from W Australia Summary ------- On 2008 May 20 UT, the 48 km diameter asteroid (1254) Erfordia will occult a 6.2 mag star in the constellation Gemini for observers along a path across W Australia. In the case of an occultation, the combined light of the asteroid and the star will drop by 10.7 mag to 16.9 mag (the magnitude of the asteroid) for at most 1.2 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: . The event at a glimpse ---------------------- * Rank: 62 * date and approx. time of event: 2008 May 20, 10:27 - 2008 May 20, 10:27 UT * midpoint of event [JD]: 2454606.9344875 * magnitude of target star: 6.2 * magnitude drop [mag]: 10.7 * estimated maximum duration [s]: 1.2 * Moon: 100 % sunlit, 149° distance * Sun: 34° distance * rough path description: W Australia The occultation path -------------------- * approximate projected width [km]: 56 * 1 sigma uncertainty interval [path widths]: +/- 0.99 * 1 sigma uncertainty interval [seconds]: +/- 1.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .025 +/- .017) * 1 sigma uncertainty ellipse (major, minor, PA): ( .025", .017", 95° ) * approx speed of asteroid's shadow [km/s]: 40.7351 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of HIP 29840 by 1254 Erfordia 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 105 0 0 -19 34 24 10 27 33 28 312 0 -19 50 57 -19 17 53 -20 23 54 -18 45 21 106 0 0 -19 59 44 10 27 34 27 311 -1 -20 16 19 -19 43 11 -20 49 20 -19 10 34 107 0 0 -20 25 19 10 27 36 26 311 -2 -20 41 56 -20 8 44 -21 15 1 -19 36 3 108 0 0 -20 51 8 10 27 37 25 310 -3 -21 7 48 -20 34 31 -21 40 57 -20 1 47 109 0 0 -21 17 11 10 27 39 24 310 -4 -21 33 53 -21 0 32 -22 7 6 -20 27 44 110 0 0 -21 43 27 10 27 40 23 309 -5 -22 0 11 -21 26 47 -22 33 28 -20 53 55 111 0 0 -22 9 56 10 27 41 22 309 -6 -22 26 41 -21 53 13 -23 0 2 -21 20 18 112 0 0 -22 36 35 10 27 42 21 309 -7 -22 53 23 -22 19 51 -23 26 47 -21 46 52 113 0 0 -23 3 26 10 27 44 20 308 -8 -23 20 15 -22 46 40 -23 53 43 -22 13 38 114 0 0 -23 30 27 10 27 45 19 308 -9 -23 47 18 -23 13 39 -24 20 49 -22 40 33 115 0 0 -23 57 37 10 27 46 18 307 -10 -24 14 29 -23 40 47 -24 48 4 -23 7 38 116 0 0 -24 24 55 10 27 47 17 307 -11 -24 41 49 -24 8 4 -25 15 28 -23 34 52 117 0 0 -24 52 21 10 27 47 16 306 -12 -25 9 17 -24 35 28 -25 42 58 -24 2 13 118 0 0 -25 19 54 10 27 48 15 306 -13 -25 36 51 -25 3 0 -26 10 36 -24 29 41 119 0 0 -25 47 33 10 27 49 14 305 -14 -26 4 32 -25 30 37 -26 38 19 -24 57 16 120 0 0 -26 15 17 10 27 50 13 305 -15 -26 32 17 -25 58 20 -27 6 7 -25 24 56 121 0 0 -26 43 5 10 27 51 12 304 -16 -27 0 7 -26 26 7 -27 34 0 -25 52 40 122 0 0 -27 10 57 10 27 51 11 304 -17 -27 28 0 -26 53 58 -28 1 55 -26 20 29 123 0 0 -27 38 52 10 27 52 10 303 -18 -27 55 56 -27 21 51 -28 29 54 -26 48 20 124 0 0 -28 6 49 10 27 52 9 303 -19 -28 23 54 -27 49 47 -28 57 54 -27 16 13 125 0 0 -28 34 46 10 27 53 8 302 -20 -28 51 53 -28 17 44 -29 25 55 -27 44 8 126 0 0 -29 2 45 10 27 53 7 302 -21 -29 19 52 -28 45 41 -29 53 56 -28 12 3 127 0 0 -29 30 42 10 27 53 6 301 -22 -29 47 50 -29 13 37 -30 21 56 -28 39 58 128 0 0 -29 58 38 10 27 54 5 301 -23 -30 15 47 -29 41 33 -30 49 54 -29 7 52 129 0 0 -30 26 32 10 27 54 4 300 -24 -30 43 42 -30 9 26 -31 17 51 -29 35 44 130 0 0 -30 54 24 10 27 54 3 300 -25 -31 11 34 -30 37 17 -31 45 44 -30 3 34 131 0 0 -31 22 11 10 27 54 2 299 -26 -31 39 22 -31 5 4 -32 13 33 .. .. .. 132 0 0 -31 49 54 10 27 54 1 299 -27 -32 7 5 -31 32 46 -32 41 17 .. .. .. Uncertainty in time = +/- 2 secs [Prediction of 2008 Apr 13.0] Data for the target star ------------------------ * name: HIP 29840 * constellation : Gemini * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 06 16 58.7054 DE: +23 44 27.252 * position source: mpos:HIP pm:HIP plx:HIP * standard error: RA,DE ["]: ( .016, .011 ) * V mag [mag]: 6.2 * B mag [mag]: 6.7 * Apparent position with proper motion RA(deg): 94.3702331489 DE(deg): 23.7394128819 * Equation of equinoxes (radians) : 0.000039878525520 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1254) Erfordia approx. diameter [km]: 48 approx. diameter ["]: .017 distance from Earth [AU]: 3.87000 * orbital information: orbit source: Preston date of fit: 2008 Apr 08 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 881 number of rejected observations: 62 time covered by the observations: 1931 Jan 13 - 2008 Feb 13 1 sigma uncertainty ellipse (major, minor, PA): 0.019, 0.013, 99° remarks: * orbital elements for (1254) Erfordia : Mean anomaly = 295.93242701 deg Arg. of pericenter = 244.38874515 deg Long. of node = 288.14446823 deg Inclination = 7.06627203 deg Eccentricity = 0.03782747 Semimajor axis = 3.13449989 AU Perihelion dist = 3.01592970 AU Mag: H = 10.53, G = 0.15 Epoch of elements : MJD 54606.43400000 TDT (2008 May 20.434) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 May 20 1254 Erfordia 10h 25.7m UT 6.2 6 16 58.705 23 44 27.25HIP 29840 6.7 16.9 48 1.2 3.870 3.792 -4.34 59.3782 23.742 22.72 20.10 10.4277 -0.04311 -0.50846 22.91275 -1.90750 0.00318 -0.00006 2000 294.7897262008 514.00000244.388745288.144468 7.0662720.03782747 3.1344999 3.015929710.8 5.00.15 RATE 1.7760350 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.025 0.017 95 1.99 0.017 0 54569.5020080520__29840 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Apr 13, 03:33 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org