IOTA/IOTA-ES occultation update for (895) Helio / UCAC2 22022322 event on 2009 Sep 10, 14:38 UT Visible from Summary ------- On 2009 Sep 10 UT, the 142 km diameter asteroid (895) Helio will occult a 11.5 mag star in the constellation Scorpius for observers along a path across . In the case of an occultation, the combined light of the asteroid and the star will drop by 3.5 mag to 14.9 mag (the magnitude of the asteroid) for at most 6.0 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: 79 * date and approx. time of event: 2009 Sep 10, 14:40 - 2009 Sep 10, 14:42 UT * magnitude of target star: 11.5 * magnitude drop [mag]: 3.5 * estimated maximum duration [s]: 6.0 * Moon: 67 % sunlit, 178° distance * Sun: 72° distance * rough path description: The occultation path -------------------- * approximate projected width [km]: 166 * 1 sigma uncertainty interval [path widths]: +/- 0.70 * 1 sigma uncertainty interval [seconds]: +/- 4.3 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .040 +/- .036) * 1 sigma uncertainty ellipse (major, minor, PA): ( .040", .036", 87° ) * approx speed of asteroid's shadow [km/s]: 23.6150 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 22022322 by 895 Helio on 2009 Sep 10 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 51 0 0 13 20 39 14 40 58 46 212 -1 12 32 56 14 8 47 11 26 49 15 16 57 52 0 0 13 42 8 14 41 2 45 213 -2 12 54 18 14 30 24 11 48 1 15 38 44 53 0 0 14 4 3 14 41 6 44 214 -3 13 16 6 14 52 26 12 9 40 16 0 57 54 0 0 14 26 24 14 41 10 43 214 -4 13 38 20 15 14 55 12 31 44 16 23 37 55 0 0 14 49 11 14 41 14 42 215 -5 14 0 59 15 37 49 12 54 13 16 46 41 56 0 0 15 12 22 14 41 18 41 216 -6 14 24 3 16 1 8 13 17 7 17 10 11 57 0 0 15 35 57 14 41 21 40 217 -7 14 47 31 16 24 50 13 40 25 17 34 5 58 0 0 15 59 56 14 41 25 40 217 -7 15 11 23 16 48 57 14 4 7 17 58 22 59 0 0 16 24 18 14 41 29 39 218 -8 15 35 37 17 13 26 14 28 11 18 23 3 60 0 0 16 49 3 14 41 32 38 219 -9 16 0 14 17 38 19 14 52 38 18 48 6 61 0 0 17 14 9 14 41 36 37 220 -10 16 25 13 18 3 32 15 17 28 19 13 30 62 0 0 17 39 37 14 41 39 36 220 -11 16 50 34 18 29 8 15 42 38 19 39 16 63 0 0 18 5 25 14 41 43 35 221 -12 17 16 15 18 55 3 16 8 9 20 5 23 64 0 0 18 31 33 14 41 46 34 221 -13 17 42 15 19 21 19 16 34 0 20 31 49 65 0 0 18 58 0 14 41 49 33 222 -14 18 8 35 19 47 53 17 0 10 20 58 35 66 0 0 19 24 46 14 41 52 32 223 -15 18 35 14 20 14 46 17 26 39 21 25 38 67 0 0 19 51 49 14 41 55 31 223 -15 19 2 10 20 41 57 17 53 26 21 53 0 68 0 0 20 19 10 14 41 58 30 224 -16 19 29 24 21 9 25 18 20 30 22 20 38 69 0 0 20 46 46 14 42 1 29 224 -17 19 56 54 21 37 8 18 47 50 22 48 31 70 0 0 21 14 38 14 42 4 28 225 -18 20 24 39 22 5 7 19 15 26 23 16 41 71 0 0 21 42 45 14 42 7 27 225 -19 20 52 39 22 33 21 19 43 17 23 45 4 72 0 0 22 11 5 14 42 9 26 226 -20 21 20 53 23 1 48 20 11 22 24 13 41 73 0 0 22 39 38 14 42 12 25 226 -20 21 49 19 23 30 28 20 39 41 24 42 30 74 0 0 23 8 24 14 42 14 24 227 -21 22 17 59 23 59 19 21 8 11 25 11 31 75 0 0 23 37 20 14 42 16 23 228 -22 22 46 49 24 28 22 21 36 53 25 40 43 76 0 0 24 6 27 14 42 19 22 228 -23 23 15 50 24 57 35 22 5 46 26 10 5 77 0 0 24 35 43 14 42 21 21 229 -23 23 45 0 25 26 57 22 34 49 26 39 35 78 0 0 25 5 8 14 42 23 20 229 -24 24 14 20 25 56 27 23 4 1 27 9 14 79 0 0 25 34 40 14 42 25 19 230 -25 24 43 47 26 26 5 23 33 21 27 39 0 80 0 0 26 4 19 14 42 26 18 230 -26 25 13 20 26 55 49 24 2 48 28 8 52 81 0 0 26 34 4 14 42 28 17 231 -26 25 43 0 27 25 39 24 32 21 28 38 49 82 0 0 27 3 53 14 42 30 16 231 -27 26 12 45 27 55 33 25 1 59 29 8 50 83 0 0 27 33 47 14 42 31 15 232 -27 26 42 34 28 25 31 25 31 42 29 38 54 84 0 0 28 3 43 14 42 33 14 232 -28 27 12 26 28 55 32 26 1 29 30 9 1 85 0 0 28 33 41 14 42 34 13 233 -29 27 42 21 29 25 34 26 31 18 30 39 10 86 0 0 29 3 41 14 42 35 12 233 -29 28 12 16 29 55 37 27 1 9 31 9 18 87 0 0 29 33 40 14 42 36 11 234 -30 28 42 13 30 25 40 27 31 1 31 39 26 88 0 0 30 3 39 14 42 37 10 234 -30 29 12 8 30 55 42 28 0 52 32 9 33 89 0 0 30 33 36 14 42 38 9 235 -31 29 42 2 31 25 42 28 30 43 32 39 37 90 0 0 31 3 31 14 42 39 8 235 -32 30 11 54 31 55 39 29 0 31 33 9 38 91 0 0 31 33 22 14 42 40 7 236 -32 30 41 43 32 25 33 29 30 17 33 39 35 92 0 0 32 3 8 14 42 40 6 236 -33 31 11 28 32 55 21 29 59 59 34 9 26 93 0 0 32 32 49 14 42 41 5 237 -33 31 41 7 33 25 4 30 29 36 34 39 12 94 0 0 33 2 24 14 42 41 4 237 -33 32 10 41 33 54 41 30 59 8 35 8 50 95 0 0 33 31 53 14 42 41 3 238 -34 32 40 8 34 24 10 31 28 34 35 38 21 96 0 0 34 1 13 14 42 42 2 238 -34 33 9 28 34 53 31 31 57 53 36 7 43 97 0 0 34 30 25 14 42 42 1 239 -35 33 38 39 35 22 43 .. .. .. 36 36 56 98 0 0 34 59 27 14 42 42 0 240 -35 34 7 41 .. .. .. .. .. .. .. .. .. Uncertainty in time = +/- 5 secs [Prediction of 2008 Mar 20.0] Data for the target star ------------------------ * name: UCAC2 22022322 * constellation : Scorpius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 15 47 50.3824 DE: -24 26 27.462 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .036, .034 ) * V mag [mag]: 11.5 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (895) Helio approx. diameter [km]: 142 approx. diameter ["]: .051 distance from Earth [AU]: 3.83900 * orbital information: orbit source: Preston date of fit: 2008 Mar 20 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 819 number of rejected observations: 57 time covered by the observations: 1906 Jun 21 - 2008 Feb 17 1 sigma uncertainty ellipse (major, minor, PA): 0.018, 0.011, 77° remarks: * orbital elements for (895) Helio : Mean anomaly = 167.29204852 deg Arg. of pericenter = 179.11012941 deg Long. of node = 264.78745666 deg Inclination = 26.06478141 deg Eccentricity = 0.14739109 Semimajor axis = 3.19917952 AU Perihelion dist = 2.72764896 AU Mag: H = 8.34, G = 0.15 Epoch of elements : MJD 55084.61000000 TDT (2009 Sep 10.610) ------ occelmnt file for Occult BEGIN ----------------------------------- 2009 Sep 10 895 Helio 14h 38.9m UT 11.5 15 47 50.382-24 26 27.46UCAC2 22022322 0.0 14.9 142 6.0 3.839 2.217 3.99 27.4811 -24.442 -40.49 4.73 14.6476 -0.06925 0.51615 13.21455 1.74256 0.00538 -0.00134 2000 166.4980002009 9 6.00000179.110129264.787457 26.0647810.14739109 3.1991795 2.7276490 8.3 5.00.15 RATE 1.7224490 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.040 0.036 87 1.70 0.036 0 54545.5020090910_022322 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 20, 13:09 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org