IOTA/IOTA-ES occultation update for (856) Backlunda / TYC 6954-00751-1 event on 2012 Sep 17, 06:16 UT Visible from SE USA, Mexico Summary ------- On 2012 Sep 17 UT, the 60 km diameter asteroid (856) Backlunda will occult a 10.4 mag star in the constellation Aquarius for observers along a path across SE USA, Mexico. In the case of an occultation, the combined light of the asteroid and the star will drop by 4.3 mag to 14.7 mag (the magnitude of the asteroid) for at most 6.9 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: 2012 Sep 17, 06:05 - 2012 Sep 17, 06:26 UT * geocentric midpoint of event [JD]: 2456187.76184167 * magnitude of target star: 10.4 * magnitude drop [mag]: 4.3 * estimated maximum duration [s]: 6.9 * Moon: 2 % sunlit, 132° distance * Sun: 149° distance * rough path description: SE USA, Mexico The occultation path -------------------- * approximate projected width [km]: 65 * 1 sigma uncertainty interval [path widths]: +/- 0.69 * 1 sigma uncertainty interval [seconds]: +/- 4.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .035 +/- .033) * 1 sigma uncertainty ellipse (major, minor, PA): ( .035", .033", 88° ) * approx speed of asteroid's shadow [km/s]: 8.6512 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6954-00751-1 by 856 Backlunda on 2012 Sep 17 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 172 0 0 -14 37 47 6 26 58 27 109 -1 -14 20 3 -14 55 29 -13 55 31 -15 19 50 173 0 0 -14 44 56 6 26 52 28 109 -2 -14 27 14 -15 2 36 -14 2 44 -15 26 56 174 0 0 -14 51 27 6 26 45 29 109 -3 -14 33 46 -15 9 5 -14 9 18 -15 33 23 175 0 0 -14 57 19 6 26 39 30 109 -3 -14 39 40 -15 14 56 -14 15 14 -15 39 12 176 0 0 -15 2 33 6 26 32 31 109 -4 -14 44 55 -15 20 9 -14 20 31 -15 44 23 177 0 0 -15 7 9 6 26 25 32 109 -5 -14 49 32 -15 24 44 -14 25 9 -15 48 56 178 0 0 -15 11 7 6 26 18 33 109 -6 -14 53 31 -15 28 41 -14 29 10 -15 52 52 179 0 0 -15 14 27 6 26 11 34 109 -7 -14 56 52 -15 32 0 -14 32 32 -15 56 10 180 0 0 -15 17 10 6 26 4 35 109 -8 -14 59 35 -15 34 42 -14 35 16 -15 58 51 -179 0 0 -15 19 15 6 25 56 35 109 -9 -15 1 41 -15 36 47 -14 37 23 -16 0 55 -178 0 0 -15 20 43 6 25 49 36 108 -10 -15 3 9 -15 38 14 -14 38 52 -16 2 22 -177 0 0 -15 21 33 6 25 41 37 108 -11 -15 4 0 -15 39 4 -14 39 43 -16 3 11 -176 0 0 -15 21 46 6 25 33 38 108 -12 -15 4 13 -15 39 17 -14 39 57 -16 3 24 -175 0 0 -15 21 22 6 25 25 39 108 -13 -15 3 49 -15 38 53 -14 39 33 -16 3 0 -174 0 0 -15 20 21 6 25 17 40 108 -14 -15 2 48 -15 37 52 -14 38 31 -16 1 58 -173 0 0 -15 18 43 6 25 9 41 108 -15 -15 1 10 -15 36 14 -14 36 53 -16 0 21 -172 0 0 -15 16 28 6 25 0 42 108 -16 -14 58 54 -15 33 59 -14 34 37 -15 58 6 -171 0 0 -15 13 36 6 24 51 42 108 -17 -14 56 2 -15 31 7 -14 31 44 -15 55 15 -170 0 0 -15 10 7 6 24 43 43 109 -17 -14 52 32 -15 27 39 -14 28 14 -15 51 47 -169 0 0 -15 6 1 6 24 34 44 109 -18 -14 48 26 -15 23 33 -14 24 6 -15 47 43 -168 0 0 -15 1 18 6 24 25 45 109 -19 -14 43 42 -15 18 51 -14 19 21 -15 43 2 -167 0 0 -14 55 58 6 24 15 46 109 -20 -14 38 21 -15 13 33 -14 13 59 -15 37 44 -166 0 0 -14 50 1 6 24 6 47 109 -21 -14 32 24 -15 7 37 -14 8 0 -15 31 50 -165 0 0 -14 43 28 6 23 56 48 109 -22 -14 25 49 -15 1 5 -14 1 24 -15 25 19 -164 0 0 -14 36 17 6 23 47 48 110 -23 -14 18 37 -14 53 55 -13 54 11 -15 18 12 -163 0 0 -14 28 30 6 23 37 49 110 -24 -14 10 49 -14 46 9 -13 46 20 -15 10 28 -162 0 0 -14 20 6 6 23 27 50 110 -25 -14 2 23 -14 37 47 -13 37 52 -15 2 7 -161 0 0 -14 11 4 6 23 17 51 110 -26 -13 53 20 -14 28 47 -13 28 47 -14 53 10 -160 0 0 -14 1 26 6 23 7 52 111 -27 -13 43 40 -14 19 10 -13 19 4 -14 43 35 -159 0 0 -13 51 11 6 22 56 53 111 -28 -13 33 22 -14 8 57 -13 8 44 -14 33 24 -158 0 0 -13 40 18 6 22 46 53 112 -29 -13 22 28 -13 58 6 -12 57 47 -14 22 36 -157 0 0 -13 28 48 6 22 35 54 112 -30 -13 10 56 -13 46 38 -12 46 12 -14 11 11 -156 0 0 -13 16 41 6 22 25 55 113 -31 -12 58 46 -13 34 33 -12 34 0 -13 59 9 -155 0 0 -13 3 56 6 22 14 56 113 -32 -12 46 0 -13 21 51 -12 21 10 -13 46 30 -154 0 0 -12 50 35 6 22 3 56 114 -33 -12 32 35 -13 8 32 -12 7 42 -13 33 14 -153 0 0 -12 36 35 6 21 52 57 115 -33 -12 18 33 -12 54 35 -11 53 36 -13 19 21 -152 0 0 -12 21 58 6 21 40 58 115 -34 -12 3 54 -12 40 0 -11 38 53 -13 4 50 -151 0 0 -12 6 44 6 21 29 59 116 -35 -11 48 36 -12 24 49 -11 23 32 -12 49 42 -150 0 0 -11 50 51 6 21 17 59 117 -36 -11 32 41 -12 8 59 -11 7 33 -12 33 57 -149 0 0 -11 34 21 6 21 6 60 118 -37 -11 16 8 -11 52 32 -10 50 55 -12 17 34 -148 0 0 -11 17 13 6 20 54 61 119 -38 -10 58 57 -11 35 27 -10 33 40 -12 0 33 -147 0 0 -10 59 27 6 20 42 61 120 -39 -10 41 8 -11 17 45 -10 15 46 -11 42 55 -146 0 0 -10 41 4 6 20 30 62 121 -40 -10 22 41 -10 59 24 - 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54 0 0 45 46 50 6 5 41 1 234 -31 46 8 33 45 25 12 46 38 38 44 55 26 Uncertainty in time = +/- 5 secs Prediction of 2012 Sep 8.0 Data for the target star ------------------------ * name: TYC 6954-00751-1 * constellation : Aquarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 22 05 37.7861 DE: -23 46 00.467 * position source: mpos:UCAC4 pm:UCAC4 * standard error: RA,DE ["]: ( .028, .030 ) * V mag [mag]: 10.4 * B mag [mag]: 11.1 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (856) Backlunda approx. diameter [km]: 60 approx. diameter ["]: .048 distance from Earth [AU]: 1.72400 * orbital information: orbit source: Preston date of fit: 2012 Sep 07 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 985 number of rejected observations: 54 time covered by the observations: 1931 Feb 28 - 2012 Sep 01 1 sigma uncertainty ellipse (major, minor, PA): 0.020, 0.013, 85° remarks: * orbital elements for (856) Backlunda : Mean anomaly = 128.20267206 deg Arg. of pericenter = 73.14783962 deg Long. of node = 125.59621967 deg Inclination = 14.31727951 deg Eccentricity = 0.11971229 Semimajor axis = 2.43463809 AU Perihelion dist = 2.14318199 AU Mag: H = 10.62, G = 0.15 Epoch of elements : MJD 56187.26200000 TDT (2012 Sep 17.262) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Sep 17 856 Backlunda 6h 17.1m UT 10.4 22 5 37.786-23 46 0.47TYC 6954-00751-1 11.1 14.7 60 6.9 1.724 -1.576 -12.30 -119.4462 -23.763 84.35 2.08 6.2842 -0.18495 0.32557 -4.24433 -2.41439 0.00228 0.00190 2000 126.3185512012 910.00000 73.147840125.596220 14.3172800.11971229 2.4346381 2.143182010.7 5.00.15 RATE 2.5944930 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.035 0.033 88 1.69 0.033 0 0 1 3 056178.0020120917_0751-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Sep 07, 22:58 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org