IOTA/IOTA-ES occultation update for (461) Saskia / UCAC2 23411001 event on 2008 Jul 06, 15:34 UT Visible from Taiwan, China, India Summary ------- On 2008 Jul 06 UT, the 45 km diameter asteroid (461) Saskia will occult a 11.6 mag star in the constellation Ophiuchus for observers along a path across Taiwan, China, India. In the case of an occultation, the combined light of the asteroid and the star will drop by 4.4 mag to 15.9 mag (the magnitude of the asteroid) for at most 3.8 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: 14 * date and approx. time of event: 2008 Jul 06, 15:28 - 2008 Jul 06, 15:40 UT * magnitude of target star: 11.6 * magnitude drop [mag]: 4.4 * estimated maximum duration [s]: 3.8 * Moon: 16 % sunlit, 106° distance * Sun: 154° distance * rough path description: Taiwan, China, India The occultation path -------------------- * approximate projected width [km]: 63 * 1 sigma uncertainty interval [path widths]: +/- 4.83 * 1 sigma uncertainty interval [seconds]: +/- 17.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .118 +/- .116) * 1 sigma uncertainty ellipse (major, minor, PA): ( .118", .116", 90° ) * approx speed of asteroid's shadow [km/s]: 11.7195 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 23411001 by 461 Saskia on 2008 Jul 6 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 53 0 0 33 38 44 15 40 18 21 135 -1 33 57 34 33 20 0 37 5 48 30 24 20 54 0 0 33 17 21 15 40 13 22 136 -2 33 36 8 32 58 40 36 43 48 30 3 28 55 0 0 32 56 15 15 40 9 22 137 -2 33 14 59 32 37 38 36 22 5 29 42 52 56 0 0 32 35 26 15 40 4 23 137 -3 32 54 7 32 16 52 36 0 40 29 22 34 57 0 0 32 14 56 15 40 0 24 138 -4 32 33 33 31 56 24 35 39 33 29 2 33 58 0 0 31 54 43 15 39 55 25 139 -5 32 13 18 31 36 15 35 18 45 28 42 51 59 0 0 31 34 50 15 39 50 26 139 -6 31 53 21 31 16 24 34 58 15 28 23 27 60 0 0 31 15 15 15 39 44 26 140 -7 31 33 44 30 56 53 34 38 6 28 4 22 61 0 0 30 56 1 15 39 39 27 141 -8 31 14 26 30 37 42 34 18 16 27 45 37 62 0 0 30 37 6 15 39 34 28 142 -9 30 55 29 30 18 50 33 58 47 27 27 12 63 0 0 30 18 32 15 39 28 29 142 -10 30 36 52 30 0 19 33 39 39 27 9 6 64 0 0 30 0 19 15 39 22 29 143 -10 30 18 36 29 42 9 33 20 52 26 51 22 65 0 0 29 42 28 15 39 16 30 144 -11 30 0 42 29 24 20 33 2 27 26 33 58 66 0 0 29 24 58 15 39 10 31 145 -12 29 43 9 29 6 53 32 44 24 26 16 55 67 0 0 29 7 49 15 39 4 32 145 -13 29 25 58 28 49 47 32 26 43 26 0 14 68 0 0 28 51 4 15 38 58 32 146 -14 29 9 9 28 33 4 32 9 25 25 43 55 69 0 0 28 34 40 15 38 51 33 147 -15 28 52 43 28 16 43 31 52 31 25 27 58 70 0 0 28 18 40 15 38 45 34 148 -16 28 36 40 28 0 46 31 36 0 25 12 23 71 0 0 28 3 3 15 38 38 34 149 -16 28 21 1 27 45 11 31 19 53 24 57 11 72 0 0 27 47 49 15 38 31 35 150 -17 28 5 44 27 30 0 31 4 10 24 42 22 73 0 0 27 33 0 15 38 24 36 151 -18 27 50 52 27 15 13 30 48 52 24 27 56 74 0 0 27 18 34 15 38 17 36 152 -19 27 36 24 27 0 49 30 33 58 24 13 54 75 0 0 27 4 32 15 38 10 37 152 -20 27 22 20 26 46 50 30 19 29 24 0 15 76 0 0 26 50 55 15 38 3 37 153 -20 27 8 40 26 33 15 30 5 26 23 47 0 77 0 0 26 37 42 15 37 56 38 154 -21 26 55 26 26 20 4 29 51 47 23 34 9 78 0 0 26 24 55 15 37 48 39 155 -22 26 42 36 26 7 19 29 38 35 23 21 43 79 0 0 26 12 32 15 37 41 39 156 -23 26 30 11 25 54 58 29 25 48 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21 8 237 -23 35 42 14 35 4 6 38 53 31 .. .. .. 165 0 0 35 46 6 15 28 19 7 238 -23 36 5 17 35 27 3 39 17 7 .. .. .. 166 0 0 36 9 19 15 28 18 6 238 -22 36 28 32 35 50 12 39 40 56 .. .. .. 167 0 0 36 32 44 15 28 17 5 239 -21 36 52 0 36 13 34 40 4 57 .. .. .. 168 0 0 36 56 21 15 28 16 4 240 -20 37 15 41 36 37 8 40 29 10 .. .. .. 169 0 0 37 20 9 15 28 15 3 240 -19 37 39 32 37 0 53 40 53 33 .. .. .. 170 0 0 37 44 8 15 28 15 2 241 -19 38 3 34 37 24 49 41 18 7 .. .. .. 171 0 0 38 8 17 15 28 14 2 241 -18 38 27 45 37 48 55 .. .. .. .. .. .. 172 0 0 38 32 35 15 28 14 1 242 -17 38 52 6 38 13 10 .. .. .. .. .. .. Uncertainty in time = +/- 19 secs [Prediction of 2008 Jul 2.0] Data for the target star ------------------------ * name: UCAC2 23411001 * constellation : Ophiuchus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 17 10 58.6063 DE: -21 05 44.560 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .114, .114 ) * V mag [mag]: 11.6 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (461) Saskia approx. diameter [km]: 45 approx. diameter ["]: .024 distance from Earth [AU]: 2.62400 * orbital information: orbit source: Preston date of fit: 2008 Jul 02 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1000 number of rejected observations: 62 time covered by the observations: 1900 Oct 22 - 2008 May 18 1 sigma uncertainty ellipse (major, minor, PA): 0.029, 0.020, 95° remarks: * orbital elements for (461) Saskia : Mean anomaly = 162.30759989 deg Arg. of pericenter = 301.78215154 deg Long. of node = 157.37973461 deg Inclination = 1.44319338 deg Eccentricity = 0.14681290 Semimajor axis = 3.12270967 AU Perihelion dist = 2.66425562 AU Mag: H = 10.42, G = 0.15 Epoch of elements : MJD 54653.64900000 TDT (2008 Jul 06.649) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Jul 6 461 Saskia 15h 34.7m UT 11.6 17 10 58.606-21 5 44.56UCAC2 23411001 0.0 15.9 45 3.8 2.624 -1.581 0.96 99.0829 -21.095 -52.46 22.60 15.5782 0.02976 0.70008 -6.60860 0.28663 0.00253 -0.00038 2000 161.6558512008 7 3.00000301.782152157.379735 1.4431930.14681290 3.1227097 2.664255610.5 5.00.15 RATE 1.7861030 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.118 0.116 90 5.83 0.114 0 54649.5020080706_411001 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Jul 02, 19:05 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org