IOTA/IOTA-ES occultation update for (1108) Demeter / TYC 5012-00841-1 event on 2012 Aug 17, 18:40 UT Visible from Africa Summary ------- On 2012 Aug 17 UT, the 31 km diameter asteroid (1108) Demeter will occult a 9.5 mag star in the constellation Libra for observers along a path across Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 6.5 mag to 16.0 mag (the magnitude of the asteroid) for at most 1.5 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: 44 * date and approx. time of event: 2012 Aug 17, 18:41 - 2012 Aug 17, 18:45 UT * geocentric midpoint of event [JD]: 2456157.27829583 * magnitude of target star: 9.5 * magnitude drop [mag]: 6.5 * estimated maximum duration [s]: 1.5 * Moon: 0 % sunlit, 80° distance * Sun: 81° distance * rough path description: Africa The occultation path -------------------- * approximate projected width [km]: 32 * 1 sigma uncertainty interval [path widths]: +/- 1.48 * 1 sigma uncertainty interval [seconds]: +/- 2.3 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .036 +/- .034) * 1 sigma uncertainty ellipse (major, minor, PA): ( .036", .034", 76° ) * approx speed of asteroid's shadow [km/s]: 21.0101 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 5012-00841-1 by 1108 Demeter on 2012 Aug 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 - 13 0 0 -17 47 52 18 41 23 77 326 -1 -17 56 26 -17 39 18 -18 21 50 -17 13 58 - 12 0 0 -17 48 10 18 41 28 76 323 -2 -17 56 44 -17 39 36 -18 22 7 -17 14 16 - 11 0 0 -17 48 20 18 41 33 75 319 -2 -17 56 54 -17 39 46 -18 22 18 -17 14 26 - 10 0 0 -17 48 23 18 41 38 75 316 -3 -17 56 57 -17 39 49 -18 22 21 -17 14 29 - 9 0 0 -17 48 19 18 41 43 74 314 -4 -17 56 53 -17 39 45 -18 22 16 -17 14 25 - 8 0 0 -17 48 7 18 41 48 73 311 -5 -17 56 41 -17 39 33 -18 22 5 -17 14 13 - 7 0 0 -17 47 48 18 41 53 73 309 -6 -17 56 23 -17 39 14 -18 21 46 -17 13 54 - 6 0 0 -17 47 22 18 41 58 72 306 -7 -17 55 57 -17 38 48 -18 21 20 -17 13 28 - 5 0 0 -17 46 49 18 42 3 71 304 -8 -17 55 23 -17 38 15 -18 20 47 -17 12 55 - 4 0 0 -17 46 8 18 42 8 70 303 -9 -17 54 43 -17 37 34 -18 20 6 -17 12 14 - 3 0 0 -17 45 21 18 42 13 69 301 -10 -17 53 55 -17 36 47 -18 19 19 -17 11 26 - 2 0 0 -17 44 26 18 42 18 69 299 -11 -17 53 0 -17 35 51 -18 18 24 -17 10 31 - 1 0 0 -17 43 23 18 42 23 68 298 -12 -17 51 58 -17 34 49 -18 17 21 -17 9 29 0 0 0 -17 42 14 18 42 28 67 296 -13 -17 50 48 -17 33 40 -18 16 12 -17 8 19 1 0 0 -17 40 57 18 42 33 66 295 -14 -17 49 32 -17 32 23 -18 14 56 -17 7 3 2 0 0 -17 39 34 18 42 37 65 294 -15 -17 48 8 -17 30 59 -18 13 32 -17 5 39 3 0 0 -17 38 3 18 42 42 64 293 -16 -17 46 37 -17 29 29 -18 12 1 -17 4 8 4 0 0 -17 36 25 18 42 47 63 291 -17 -17 44 59 -17 27 51 -18 10 24 -17 2 30 5 0 0 -17 34 40 18 42 52 62 290 -18 -17 43 14 -17 26 6 -18 8 39 -17 0 45 6 0 0 -17 32 48 18 42 56 62 289 -19 -17 41 22 -17 24 14 -18 6 47 -16 58 53 7 0 0 -17 30 49 18 43 1 61 289 -20 -17 39 23 -17 22 15 -18 4 48 -16 56 54 8 0 0 -17 28 43 18 43 5 60 288 -21 -17 37 18 -17 20 9 -18 2 42 -16 54 48 9 0 0 -17 26 30 18 43 10 59 287 -22 -17 35 5 -17 17 56 -18 0 30 -16 52 35 10 0 0 -17 24 11 18 43 14 58 286 -23 -17 32 45 -17 15 36 -17 58 10 -16 50 15 11 0 0 -17 21 44 18 43 19 57 285 -23 -17 30 19 -17 13 9 -17 55 44 -16 47 48 12 0 0 -17 19 11 18 43 23 56 284 -24 -17 27 46 -17 10 36 -17 53 11 -16 45 14 13 0 0 -17 16 31 18 43 27 55 284 -25 -17 25 6 -17 7 56 -17 50 31 -16 42 34 14 0 0 -17 13 44 18 43 32 54 283 -26 -17 22 19 -17 5 9 -17 47 44 -16 39 47 15 0 0 -17 10 51 18 43 36 53 282 -27 -17 19 26 -17 2 16 -17 44 51 -16 36 54 16 0 0 -17 7 51 18 43 40 52 282 -28 -17 16 26 -16 59 16 -17 41 52 -16 33 54 17 0 0 -17 4 44 18 43 44 51 281 -29 -17 13 19 -16 56 9 -17 38 45 -16 30 47 18 0 0 -17 1 31 18 43 48 50 281 -30 -17 10 6 -16 52 56 -17 35 33 -16 27 34 19 0 0 -16 58 12 18 43 52 49 280 -31 -17 6 47 -16 49 37 -17 32 14 -16 24 14 20 0 0 -16 54 46 18 43 56 48 279 -32 -17 3 22 -16 46 11 -17 28 48 -16 20 48 21 0 0 -16 51 14 18 44 0 48 279 -33 -16 59 50 -16 42 39 -17 25 16 -16 17 16 22 0 0 -16 47 36 18 44 4 47 278 -34 -16 56 11 -16 39 1 -17 21 39 -16 13 38 23 0 0 -16 43 52 18 44 8 46 278 -35 -16 52 27 -16 35 17 -17 17 54 -16 9 53 24 0 0 -16 40 1 18 44 12 45 277 -36 -16 48 37 -16 31 26 -17 14 4 -16 6 2 25 0 0 -16 36 5 18 44 15 44 277 -37 -16 44 40 -16 27 30 -17 10 8 -16 2 6 26 0 0 -16 32 2 18 44 19 43 277 -38 -16 40 38 -16 23 27 -17 6 6 -15 58 3 27 0 0 -16 27 54 18 44 22 42 276 -39 -16 36 30 -16 19 19 -17 1 58 -15 53 54 28 0 0 -16 23 40 18 44 26 41 276 -40 -16 32 16 -16 15 5 -16 57 44 -15 49 40 29 0 0 -16 19 20 18 44 29 40 275 -41 -16 27 56 -16 10 45 -16 53 25 -15 45 20 30 0 0 -16 14 55 18 44 33 39 275 -42 -16 23 31 -16 6 19 -16 48 59 -15 40 54 31 0 0 -16 10 24 18 44 36 38 274 -43 -16 19 0 -16 1 48 -16 44 29 -15 36 23 32 0 0 -16 5 48 18 44 39 37 274 -44 -16 14 24 -15 57 12 -16 39 53 -15 31 46 33 0 0 -16 1 6 18 44 42 36 274 -45 -16 9 42 -15 52 30 -16 35 11 -15 27 4 34 0 0 -15 56 19 18 44 45 35 273 -46 -16 4 55 -15 47 43 -16 30 24 -15 22 17 35 0 0 -15 51 26 18 44 48 34 273 -47 -16 0 3 -15 42 50 -16 25 32 -15 17 24 36 0 0 -15 46 29 18 44 51 33 273 -48 -15 55 5 -15 37 53 -16 20 35 -15 12 27 37 0 0 -15 41 26 18 44 54 32 272 -49 -15 50 3 -15 32 50 -16 15 33 -15 7 24 38 0 0 -15 36 19 18 44 57 31 272 -50 -15 44 55 -15 27 43 -16 10 26 -15 2 16 39 0 0 -15 31 7 18 45 0 30 272 -51 -15 39 43 -15 22 30 -16 5 14 -14 57 4 40 0 0 -15 25 50 18 45 2 29 271 -51 -15 34 26 -15 17 13 -15 59 57 -14 51 46 41 0 0 -15 20 28 18 45 5 28 271 -52 -15 29 5 -15 11 52 -15 54 36 -14 46 24 42 0 0 -15 15 2 18 45 7 27 271 -53 -15 23 39 -15 6 25 -15 49 10 -14 40 58 43 0 0 -15 9 31 18 45 10 26 270 -54 -15 18 8 -15 0 55 -15 43 39 -14 35 27 44 0 0 -15 3 56 18 45 12 25 270 -55 -15 12 33 -14 55 20 -15 38 5 -14 29 52 45 0 0 -14 58 17 18 45 14 24 270 -56 -15 6 54 -14 49 40 -15 32 26 -14 24 12 46 0 0 -14 52 34 18 45 16 23 269 -57 -15 1 11 -14 43 57 -15 26 42 -14 18 29 47 0 0 -14 46 46 18 45 18 22 269 -58 -14 55 23 -14 38 9 -15 20 55 -14 12 41 48 0 0 -14 40 55 18 45 20 21 269 -59 -14 49 32 -14 32 18 -15 15 4 -14 6 50 49 0 0 -14 35 0 18 45 22 20 268 -60 -14 43 37 -14 26 23 -15 9 9 -14 0 54 50 0 0 -14 29 1 18 45 24 19 268 -61 -14 37 38 -14 20 24 -15 3 11 -13 54 55 51 0 0 -14 22 59 18 45 26 18 268 -62 -14 31 36 -14 14 22 -14 57 9 -13 48 53 52 0 0 -14 16 53 18 45 27 18 268 -63 -14 25 30 -14 8 16 -14 51 3 -13 42 47 53 0 0 -14 10 44 18 45 29 17 267 -64 -14 19 21 -14 2 6 -14 44 54 -13 36 37 54 0 0 -14 4 31 18 45 30 16 267 -65 -14 13 9 -13 55 54 -14 38 42 -13 30 24 55 0 0 -13 58 16 18 45 32 15 267 -66 -14 6 53 -13 49 38 -14 32 27 -13 24 9 56 0 0 -13 51 57 18 45 33 14 267 -67 -14 0 35 -13 43 20 -14 26 8 -13 17 50 57 0 0 -13 45 36 18 45 34 13 266 -68 -13 54 13 -13 36 58 -14 19 47 -13 11 28 58 0 0 -13 39 11 18 45 35 12 266 -69 -13 47 49 -13 30 34 -14 13 23 -13 5 4 59 0 0 -13 32 44 18 45 36 11 266 -70 -13 41 22 -13 24 7 -14 6 56 -12 58 37 60 0 0 -13 26 15 18 45 37 10 266 -71 -13 34 53 -13 17 38 -14 0 27 -12 52 7 61 0 0 -13 19 43 18 45 38 9 265 -72 -13 28 21 -13 11 6 -13 53 55 -12 45 35 62 0 0 -13 13 9 18 45 39 8 265 -73 -13 21 47 -13 4 31 -13 47 21 -12 39 1 63 0 0 -13 6 33 18 45 40 7 265 -74 -13 15 11 -12 57 55 -13 40 45 -12 32 25 64 0 0 -12 59 54 18 45 40 6 265 -75 -13 8 32 -12 51 17 -13 34 7 -12 25 46 65 0 0 -12 53 14 18 45 41 5 264 -76 -13 1 52 -12 44 37 -13 27 27 -12 19 6 66 0 0 -12 46 32 18 45 41 4 264 -77 -12 55 10 -12 37 55 -13 20 45 -12 12 24 67 0 0 -12 39 49 18 45 41 3 264 -78 -12 48 27 -12 31 11 -13 14 1 -12 5 40 68 0 0 -12 33 3 18 45 42 2 264 -79 -12 41 41 -12 24 26 -13 7 16 -11 58 55 69 0 0 -12 26 17 18 45 42 1 264 -80 -12 34 55 -12 17 39 -13 0 30 -11 52 8 Uncertainty in time = +/- 2 secs Prediction of 2012 Jun 21.0 Data for the target star ------------------------ * name: TYC 5012-00841-1 * constellation : Libra * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 15 04 57.0982 DE: -06 22 48.909 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .023, .030 ) * V mag [mag]: 9.5 * B mag [mag]: 10.6 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1108) Demeter approx. diameter [km]: 31 approx. diameter ["]: .023 distance from Earth [AU]: 1.85700 * orbital information: orbit source: Preston date of fit: 2012 Jun 21 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 679 number of rejected observations: 41 time covered by the observations: 1929 May 31 - 2012 May 21 1 sigma uncertainty ellipse (major, minor, PA): 0.028, 0.016, 67° remarks: * orbital elements for (1108) Demeter : Mean anomaly = 327.61561879 deg Arg. of pericenter = 77.64448186 deg Long. of node = 234.41845440 deg Inclination = 24.93314665 deg Eccentricity = 0.25649621 Semimajor axis = 2.42752481 AU Perihelion dist = 1.80487391 AU Mag: H = 11.89, G = 0.15 Epoch of elements : MJD 56156.77800000 TDT (2012 Aug 17.778) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 17 1108 Demeter 18h 40.7m UT 9.5 15 4 57.098- 6 22 48.91TYC 5012-00841-1 10.6 16.0 31 1.5 1.857 3.766 -1.16 -20.4934 -6.380 -99.21 13.10 18.6791 -0.00161 -0.19348 11.85614 -0.24501 0.00489 -0.00126 2000 325.8493372012 811.00000 77.644482234.418454 24.9331470.25649621 2.4275248 1.804873911.9 5.00.15 RATE 2.6059050 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.036 0.034 76 2.48 0.034 0 0 2 1 056099.0020120817_0841-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Jun 21, 01:31 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org