IOTA/IOTA-ES occultation update for (1813) Imhotep / TYC 7423-00712-1 event on 2012 Sep 26, 23:34 UT Visible from Africa, Brazil, Argentina Summary ------- On 2012 Sep 26 UT, the 24 km diameter asteroid (1813) Imhotep will occult a 10.2 mag star in the constellation Sagittarius for observers along a path across Africa, Brazil, Argentina. In the case of an occultation, the combined light of the asteroid and the star will drop by 6.7 mag to 16.9 mag (the magnitude of the asteroid) for at most 2.0 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: 24 * date and approx. time of event: 2012 Sep 26, 23:32 - 2012 Sep 26, 23:42 UT * geocentric midpoint of event [JD]: 2456197.4820875 * magnitude of target star: 10.2 * magnitude drop [mag]: 6.7 * estimated maximum duration [s]: 2.0 * Moon: 89 % sunlit, 42° distance * Sun: 102° distance * rough path description: Africa, Brazil, Argentina The occultation path -------------------- * approximate projected width [km]: 24 * 1 sigma uncertainty interval [path widths]: +/- 2.83 * 1 sigma uncertainty interval [seconds]: +/- 7.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .060 +/- .036) * 1 sigma uncertainty ellipse (major, minor, PA): ( .060", .036", 88° ) * approx speed of asteroid's shadow [km/s]: 12.1153 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 7423-00712-1 by 1813 Imhotep on 2012 Sep 26 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 - 83 0 0 -41 15 12 23 32 14 76 52 -1 -41 22 6 -41 8 19 -42 1 9 -40 29 19 - 82 0 0 -40 59 0 23 32 22 77 50 -1 -41 5 56 -40 52 5 -41 45 7 -40 12 56 - 81 0 0 -40 42 10 23 32 29 77 48 -2 -40 49 7 -40 35 13 -41 28 29 -39 55 54 - 80 0 0 -40 24 42 23 32 37 78 46 -3 -40 31 40 -40 17 43 -41 11 12 -39 38 14 - 79 0 0 -40 6 34 23 32 44 79 43 -4 -40 13 35 -39 59 34 -40 53 16 -39 19 55 - 78 0 0 -39 47 47 23 32 52 80 40 -5 -39 54 50 -39 40 45 -40 34 42 -39 0 55 - 77 0 0 -39 28 20 23 33 0 80 37 -5 -39 35 25 -39 21 16 -40 15 28 -38 41 16 - 76 0 0 -39 8 13 23 33 8 81 33 -6 -39 15 20 -39 1 7 -39 55 34 -38 20 56 - 75 0 0 -38 47 25 23 33 16 82 29 -7 -38 54 33 -38 40 17 -39 34 59 -37 59 54 - 74 0 0 -38 25 55 23 33 24 82 24 -8 -38 33 6 -38 18 45 -39 13 43 -37 38 11 - 73 0 0 -38 3 44 23 33 32 83 18 -9 -38 10 56 -37 56 32 -38 51 45 -37 15 45 - 72 0 0 -37 40 50 23 33 40 84 11 -10 -37 48 5 -37 33 35 -38 29 6 -36 52 37 - 71 0 0 -37 17 13 23 33 49 84 2 -11 -37 24 30 -37 9 56 -38 5 43 -36 28 46 - 70 0 0 -36 52 52 23 33 57 84 352 -11 -37 0 11 -36 45 34 -37 41 38 -36 4 10 - 69 0 0 -36 27 48 23 34 6 85 341 -12 -36 35 9 -36 20 27 -37 16 48 -35 38 51 - 68 0 0 -36 1 59 23 34 14 85 329 -13 -36 9 23 -35 54 36 -36 51 15 -35 12 47 - 67 0 0 -35 35 25 23 34 23 84 317 -14 -35 42 51 -35 28 0 -36 24 57 -34 45 57 - 66 0 0 -35 8 6 23 34 32 84 306 -15 -35 15 35 -35 0 38 -35 57 54 -34 18 22 - 65 0 0 -34 40 1 23 34 41 84 297 -16 -34 47 32 -34 32 31 -35 30 5 -33 50 1 - 64 0 0 -34 11 10 23 34 50 83 289 -17 -34 18 43 -34 3 37 -35 1 30 -33 20 54 - 63 0 0 -33 41 32 23 34 59 83 282 -18 -33 49 8 -33 33 57 -34 32 8 -32 51 0 - 62 0 0 -33 11 8 23 35 8 82 276 -19 -33 18 46 -33 3 30 -34 2 0 -32 20 19 - 61 0 0 -32 39 56 23 35 17 81 272 -20 -32 47 37 -32 32 15 -33 31 5 -31 48 50 - 60 0 0 -32 7 56 23 35 27 80 268 -21 -32 15 40 -32 0 13 -32 59 23 -31 16 34 - 59 0 0 -31 35 9 23 35 36 79 265 -22 -31 42 55 -31 27 24 -32 26 52 -30 43 30 - 58 0 0 -31 1 34 23 35 45 78 262 -23 -31 9 22 -30 53 46 -31 53 34 -30 9 38 - 57 0 0 -30 27 11 23 35 55 77 259 -24 -30 35 2 -30 19 20 -31 19 28 -29 34 58 - 56 0 0 -29 52 0 23 36 5 76 257 -25 -29 59 53 -29 44 6 -30 44 33 -28 59 30 - 55 0 0 -29 16 0 23 36 14 75 255 -26 -29 23 56 -29 8 4 -30 8 51 -28 23 14 - 54 0 0 -28 39 13 23 36 24 74 253 -27 -28 47 11 -28 31 14 -29 32 20 -27 46 9 - 53 0 0 -28 1 37 23 36 34 73 252 -28 -28 9 38 -27 53 36 -28 55 1 -27 8 17 - 52 0 0 -27 23 14 23 36 44 72 250 -29 -27 31 17 -27 15 10 -28 16 55 -26 29 37 - 51 0 0 -26 44 3 23 36 54 71 249 -30 -26 52 9 -26 35 57 -27 38 0 -25 50 10 - 50 0 0 -26 4 5 23 37 4 70 248 -31 -26 12 13 -25 55 57 -26 58 19 -25 9 56 - 49 0 0 -25 23 20 23 37 14 69 246 -33 -25 31 31 -25 15 10 -26 17 50 -24 28 56 - 48 0 0 -24 41 50 23 37 24 68 245 -34 -24 50 3 -24 33 37 -25 36 35 -23 47 9 - 47 0 0 -23 59 34 23 37 34 67 244 -35 -24 7 49 -23 51 19 -24 54 34 -23 4 38 - 46 0 0 -23 16 33 23 37 44 66 244 -36 -23 24 51 -23 8 16 -24 11 49 -22 21 23 - 45 0 0 -22 32 49 23 37 54 64 243 -37 -22 41 8 -22 24 29 -23 28 19 -21 37 24 - 44 0 0 -21 48 21 23 38 4 63 242 -38 -21 56 43 -21 40 0 -22 44 6 -20 52 42 - 43 0 0 -21 3 12 23 38 14 62 241 -39 -21 11 36 -20 54 49 -21 59 10 -20 7 20 - 42 0 0 -20 17 23 23 38 24 61 240 -41 -20 25 49 -20 8 57 -21 13 34 -19 21 18 - 41 0 0 -19 30 54 23 38 34 60 240 -42 -19 39 22 -19 22 27 -20 27 18 -18 34 37 - 40 0 0 -18 43 48 23 38 44 58 239 -43 -18 52 18 -18 35 19 -19 40 23 -17 47 19 - 39 0 0 -17 56 6 23 38 54 57 239 -44 -18 4 37 -17 47 35 -18 52 52 -16 59 25 - 38 0 0 -17 7 49 23 39 4 56 238 -45 -17 16 21 -16 59 16 -18 4 46 -16 10 58 - 37 0 0 -16 18 59 23 39 13 55 237 -47 -16 27 33 -16 10 25 -17 16 6 -15 21 59 - 36 0 0 -15 29 39 23 39 23 53 237 -48 -15 38 14 -15 21 4 -16 26 55 -14 32 29 - 35 0 0 -14 39 50 23 39 33 52 237 -49 -14 48 26 -14 31 13 -15 37 14 -13 42 32 - 34 0 0 -13 49 34 23 39 42 51 236 -50 -13 58 11 -13 40 56 -14 47 5 -12 52 9 - 33 0 0 -12 58 53 23 39 51 49 236 -52 -13 7 32 -12 50 15 -13 56 31 -12 1 22 - 32 0 0 -12 7 50 23 40 0 48 235 -53 -12 16 30 -11 59 11 -13 5 34 -11 10 14 - 31 0 0 -11 16 28 23 40 9 47 235 -54 -11 25 8 -11 7 47 -12 14 16 -10 18 46 - 30 0 0 -10 24 47 23 40 18 45 235 -55 -10 33 28 -10 16 7 -11 22 40 - 9 27 2 - 29 0 0 - 9 32 52 23 40 27 44 234 -57 - 9 41 33 - 9 24 11 -10 30 47 - 8 35 4 - 28 0 0 - 8 40 44 23 40 35 43 234 -58 - 8 49 26 - 8 32 3 - 9 38 42 - 7 42 54 - 27 0 0 - 7 48 26 23 40 44 41 234 -59 - 7 57 8 - 7 39 45 - 8 46 25 - 6 50 35 - 26 0 0 - 6 56 1 23 40 52 40 234 -60 - 7 4 43 - 6 47 20 - 7 54 0 - 5 58 10 - 25 0 0 - 6 3 31 23 41 0 39 233 -61 - 6 12 13 - 5 54 50 - 7 1 29 - 5 5 41 - 24 0 0 - 5 10 59 23 41 7 37 233 -63 - 5 19 41 - 5 2 18 - 6 8 55 - 4 13 10 - 23 0 0 - 4 18 27 23 41 15 36 233 -64 - 4 27 8 - 4 9 47 - 5 16 21 - 3 20 41 - 22 0 0 - 3 25 59 23 41 22 35 233 -65 - 3 34 39 - 3 17 18 - 4 23 49 - 2 28 16 - 21 0 0 - 2 33 36 23 41 29 33 233 -66 - 2 42 16 - 2 24 56 - 3 31 22 - 1 35 58 - 20 0 0 - 1 41 21 23 41 36 32 233 -67 - 1 50 0 - 1 32 42 - 2 39 2 - 0 43 48 - 19 0 0 - 0 49 17 23 41 42 31 233 -69 - 0 57 55 - 0 40 39 - 1 46 52 0 8 10 - 18 0 0 0 2 34 23 41 48 29 233 -70 - 0 6 3 0 11 11 - 0 54 54 0 59 54 - 17 0 0 0 54 9 23 41 54 28 233 -71 0 45 33 1 2 45 - 0 3 11 1 51 22 - 16 0 0 1 45 27 23 42 0 27 233 -72 1 36 52 1 54 2 0 48 15 2 42 31 - 15 0 0 2 36 25 23 42 5 25 233 -73 2 27 51 2 44 58 1 39 22 3 33 20 - 14 0 0 3 27 0 23 42 10 24 233 -74 3 18 28 3 35 32 2 30 7 4 23 45 - 13 0 0 4 17 11 23 42 15 23 233 -75 4 8 41 4 25 41 3 20 28 5 13 46 - 12 0 0 5 6 56 23 42 20 21 233 -75 4 58 27 5 15 24 4 10 24 6 3 20 - 11 0 0 5 56 12 23 42 24 20 233 -76 5 47 45 6 4 39 4 59 52 6 52 25 - 10 0 0 6 44 59 23 42 28 19 233 -77 6 36 34 6 53 24 5 48 51 7 41 0 - 9 0 0 7 33 14 23 42 31 18 233 -77 7 24 51 7 41 38 6 37 19 8 29 2 - 8 0 0 8 20 56 23 42 35 16 233 -78 8 12 35 8 29 18 7 25 14 9 16 31 - 7 0 0 9 8 4 23 42 38 15 233 -78 8 59 44 9 16 23 8 12 35 10 3 25 - 6 0 0 9 54 35 23 42 41 14 234 -79 9 46 18 10 2 52 8 59 20 10 49 43 - 5 0 0 10 40 29 23 42 43 12 234 -79 10 32 14 10 48 44 9 45 28 11 35 23 - 4 0 0 11 25 45 23 42 46 11 234 -79 11 17 32 11 33 58 10 30 59 12 20 24 - 3 0 0 12 10 21 23 42 48 10 234 -78 12 2 11 12 18 32 11 15 50 13 4 46 - 2 0 0 12 54 17 23 42 50 9 234 -78 12 46 9 13 2 25 12 0 0 13 48 27 - 1 0 0 13 37 32 23 42 51 8 235 -78 13 29 25 13 45 38 12 43 30 14 31 26 0 0 0 14 20 4 23 42 53 6 235 -77 14 12 0 14 28 8 13 26 18 15 13 44 1 0 0 15 1 54 23 42 54 5 235 -77 14 53 52 15 9 55 14 8 23 15 55 18 2 0 0 15 43 0 23 42 55 4 235 -76 15 35 1 15 50 59 14 49 45 16 36 9 3 0 0 16 23 23 23 42 55 3 236 -75 16 15 26 16 31 19 15 30 23 17 16 16 4 0 0 17 3 1 23 42 56 2 236 -75 16 55 6 17 10 55 16 10 17 17 55 38 5 0 0 17 41 54 23 42 56 1 236 -74 17 34 2 17 49 46 16 49 27 18 34 16 Uncertainty in time = +/- 8 secs Prediction of 2012 Aug 7.0 Data for the target star ------------------------ * name: TYC 7423-00712-1 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 19 14 42.6600 DE: -31 50 11.614 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .042, .027 ) * V mag [mag]: 10.2 * B mag [mag]: 11.6 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1813) Imhotep approx. diameter [km]: 24 approx. diameter ["]: .014 distance from Earth [AU]: 2.33800 * orbital information: orbit source: Preston date of fit: 2012 Aug 06 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1001 number of rejected observations: 10 time covered by the observations: 1960 Oct 17 - 2012 Jun 13 1 sigma uncertainty ellipse (major, minor, PA): 0.043, 0.024, 86° remarks: * orbital elements for (1813) Imhotep : Mean anomaly = 96.68985402 deg Arg. of pericenter = 166.37137786 deg Long. of node = 35.21933713 deg Inclination = 8.08685394 deg Eccentricity = 0.08054941 Semimajor axis = 2.68322089 AU Perihelion dist = 2.46708902 AU Mag: H = 11.82, G = 0.15 Epoch of elements : MJD 56196.98200000 TDT (2012 Sep 26.982) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Sep 26 1813 Imhotep 23h 34.2m UT 10.2 19 14 42.660-31 50 11.61TYC 7423-00712-1 11.6 16.9 24 2.0 2.338 1.817 11.21 -71.0443 -31.840 -175.79 -1.70 23.5701 0.03705 -0.07234 6.15495 2.97950 0.00548 0.00090 2000 95.1241872012 920.00000166.371378 35.219337 8.0868540.08054941 2.6832209 2.467089011.8 5.00.15 RATE 2.2424330 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.060 0.036 88 3.83 0.040 0 0 0-4 056146.0020120926_0712-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Aug 06, 21:04 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org