IOTA/IOTA-ES occultation update for (1381) Danubia / TYC 6840-00716-1 event on 2012 Aug 31, 16:40 UT Visible from SW Asia Summary ------- On 2012 Aug 31 UT, the 24 km diameter asteroid (1381) Danubia will occult a 9.2 mag star in the constellation Sagittarius for observers along a path across SW Asia. In the case of an occultation, the combined light of the asteroid and the star will drop by 7.5 mag to 16.7 mag (the magnitude of the asteroid) for at most 3.2 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: UCAC. The event at a glimpse ---------------------- * Rank: 26 * date and approx. time of event: 2012 Aug 31, 16:43 - 2012 Aug 31, 16:49 UT * geocentric midpoint of event [JD]: 2456171.19587917 * magnitude of target star: 9.2 * magnitude drop [mag]: 7.5 * estimated maximum duration [s]: 3.2 * Moon: 100 % sunlit, 72° distance * Sun: 109° distance * rough path description: SW Asia The occultation path -------------------- * approximate projected width [km]: 47 * 1 sigma uncertainty interval [path widths]: +/- 2.55 * 1 sigma uncertainty interval [seconds]: +/- 11.8 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .075 +/- .041) * 1 sigma uncertainty ellipse (major, minor, PA): ( .075", .041", 92° ) * approx speed of asteroid's shadow [km/s]: 7.4688 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6840-00716-1 by 1381 Danubia on 2012 Aug 31 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 ' " Longitude Longitude Longitude Longitude 57 15 33 59 0 0 16 49 15 1 200 -12 57 41 8 56 49 52 ... .. .. 54 36 53 56 32 9 58 0 0 16 49 14 2 199 -12 56 57 11 56 7 1 ... .. .. 53 56 50 55 47 25 57 0 0 16 49 13 3 198 -12 56 11 57 55 22 46 ... .. .. 53 15 8 55 1 22 56 0 0 16 49 12 4 198 -13 55 25 27 54 37 9 ... .. .. 52 31 49 54 14 0 55 0 0 16 49 9 5 197 -13 54 37 41 53 50 12 ... .. .. 51 46 55 53 25 20 54 0 0 16 49 6 6 196 -13 53 48 40 53 1 54 ... .. .. 51 0 27 52 35 22 53 0 0 16 49 3 7 196 -13 52 58 22 52 12 14 54 54 0 50 12 25 51 44 3 52 0 0 16 48 58 8 195 -13 52 6 46 51 21 13 54 0 57 49 22 49 50 51 23 51 0 0 16 48 53 9 194 -13 51 13 52 50 28 47 53 6 46 48 31 36 49 57 19 50 0 0 16 48 48 10 193 -13 50 19 35 49 34 56 52 11 25 47 38 46 49 1 49 49 0 0 16 48 41 11 193 -13 49 23 54 48 39 35 51 14 49 46 44 15 48 4 48 48 0 0 16 48 34 13 192 -13 48 26 45 47 42 42 50 16 56 45 47 59 47 6 12 47 0 0 16 48 26 14 191 -13 47 28 4 46 44 13 49 17 41 44 49 55 46 5 57 46 0 0 16 48 17 15 190 -13 46 27 45 45 44 1 48 17 1 43 49 56 45 3 57 45 0 0 16 48 8 16 189 -13 45 25 44 44 42 1 47 14 48 42 47 56 44 0 4 44 0 0 16 47 57 17 188 -12 44 21 52 43 38 7 46 10 57 41 43 47 42 54 11 43 0 0 16 47 46 18 187 -12 43 16 3 42 32 10 45 5 22 40 37 21 41 46 8 42 0 0 16 47 33 19 186 -11 42 8 7 41 23 59 43 57 53 39 28 25 40 35 44 41 0 0 16 47 20 20 185 -11 40 57 53 40 13 25 42 48 20 38 16 47 39 22 46 40 0 0 16 47 6 21 184 -10 39 45 8 39 0 13 41 36 34 37 2 10 38 6 59 39 0 0 16 46 50 22 183 -10 38 29 39 37 44 8 40 22 21 35 44 17 36 48 4 38 0 0 16 46 33 23 181 -9 37 11 6 36 24 50 39 5 26 34 22 43 35 25 39 37 0 0 16 46 15 24 180 -8 35 49 8 35 1 57 37 45 31 32 57 1 33 59 17 36 0 0 16 45 56 25 178 -7 34 23 20 33 34 59 36 22 14 31 26 33 32 28 23 35 0 0 16 45 35 26 177 -6 32 53 8 32 3 21 34 55 9 29 50 34 30 52 14 34 0 0 16 45 12 27 175 -5 31 17 51 30 26 17 33 23 43 28 8 2 29 9 54 33 0 0 16 44 47 28 173 -4 29 36 36 28 42 48 31 47 15 26 17 35 27 20 6 32 0 0 16 44 21 29 171 -3 27 48 11 26 51 32 30 4 51 24 17 15 25 21 4 31 0 0 16 43 51 30 169 -1 25 50 58 24 50 35 28 15 22 22 4 5 Uncertainty in time = +/- 14 secs Prediction of 2012 Aug 26.0 Data for the target star ------------------------ * name: TYC 6840-00716-1 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 17 48 42.4722 DE: -28 40 17.946 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .025, .027 ) * V mag [mag]: 9.2 * B mag [mag]: 10.8 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1381) Danubia approx. diameter [km]: 24 approx. diameter ["]: .018 distance from Earth [AU]: 1.88600 * orbital information: orbit source: Preston date of fit: 2012 Aug 25 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1148 number of rejected observations: 62 time covered by the observations: 1928 Jan 29 - 2012 Aug 12 1 sigma uncertainty ellipse (major, minor, PA): 0.071, 0.031, 92° remarks: * orbital elements for (1381) Danubia : Mean anomaly = 290.11876158 deg Arg. of pericenter = 29.33570755 deg Long. of node = 351.95453714 deg Inclination = 4.69371423 deg Eccentricity = 0.18056683 Semimajor axis = 2.48865575 AU Perihelion dist = 2.03928708 AU Mag: H = 12.27, G = 0.15 Epoch of elements : MJD 56170.69500000 TDT (2012 Aug 31.695) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 31 1381 Danubia 16h 42.1m UT 9.2 17 48 42.472-28 40 17.95TYC 6840-00716-1 10.8 16.7 24 3.2 1.886 1.412 6.44 36.3973 -28.672 -70.48 8.32 16.7011 -0.27968 0.81238 3.98268 1.38180 0.00515 0.00006 2000 289.9442842012 831.00000 29.335708351.954537 4.6937140.18056683 2.4886558 2.039287112.3 5.00.15 RATE 2.5104800 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.075 0.041 92 3.55 0.045 0 0 2 4 056165.0020120831_0716-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Aug 25, 22:18 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org