IOTA/IOTA-ES occultation update for (140) Siwa / TYC 0283-00347-1 event on 2008 Mar 03, 11:55 UT Visible from NE Canada in twilight Summary ------- On 2008 Mar 03 UT, the 110 km diameter asteroid (140) Siwa will occult a 9.3 mag star in the constellation Virgo for observers along a path across NE Canada in twilight. In the case of an occultation, the combined light of the asteroid and the star will drop by 3.6 mag to 12.8 mag (the magnitude of the asteroid) for at most 8.5 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: . The event at a glimpse ---------------------- * Rank: 95 * date and approx. time of event: 2008 Mar 03, 11:54 - 2008 Mar 03, 11:57 UT * magnitude of target star: 9.3 * magnitude drop [mag]: 3.6 * estimated maximum duration [s]: 8.5 * Moon: 19 % sunlit, 113° distance * Sun: 164° distance * rough path description: NE Canada in twilight The occultation path -------------------- * approximate projected width [km]: 532 * 1 sigma uncertainty interval [path widths]: +/- 0.44 * 1 sigma uncertainty interval [seconds]: +/- 3.5 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .030 +/- .032) * 1 sigma uncertainty ellipse (major, minor, PA): ( .032", .030", 2° ) * approx speed of asteroid's shadow [km/s]: 12.9151 * website for maps: http://lunar-occultations.com/iota/asteroids/astrndx.htm http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 0283-00347-1 by 140 Siwa on 2008 Mar 3 Centre Star Star Sun Path Limit1 Path Limit2 Error Limit1 Error Limit2 E. Longitude Latitude U.T. Alt Az Alt o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' " Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude - 77 7 18 54 22 11 11 54 37 8 267 0 - 82 14 54 54 1 54 - 67 30 53 54 21 9 - 85 44 2 53 39 31 ... .. .. .. .. .. - 77 45 40 54 41 49 11 54 40 8 266 -1 - 82 46 3 54 20 37 - 69 12 22 54 46 16 - 86 12 36 53 57 45 ... .. .. .. .. .. - 78 21 42 55 1 23 11 54 43 8 266 -1 - 83 16 0 54 39 21 - 70 27 1 55 9 19 - 86 40 20 54 16 1 ... .. .. .. .. .. - 78 55 42 55 20 53 11 54 46 9 265 -2 - 83 44 51 54 58 5 - 71 28 11 55 31 23 - 87 7 16 54 34 18 ... .. .. .. .. .. - 79 27 51 55 40 20 11 54 49 9 265 -2 - 84 12 38 55 16 50 - 72 20 42 55 52 53 - 87 33 27 54 52 38 ... .. .. .. .. .. - 79 58 20 55 59 47 11 54 52 9 264 -2 - 84 39 26 55 35 38 - 73 7 1 56 14 0 - 87 58 54 55 11 1 ... .. .. .. .. .. - 80 27 15 56 19 14 11 54 55 9 264 -3 - 85 5 18 55 54 27 - 73 48 32 56 34 52 - 88 23 40 55 29 27 ... .. .. .. .. .. - 80 54 45 56 38 41 11 54 59 10 264 -3 - 85 30 15 56 13 19 - 74 26 9 56 55 32 - 88 47 44 55 47 56 ... .. .. .. .. .. - 81 20 54 56 58 10 11 55 2 10 263 -3 - 85 54 21 56 32 15 - 75 0 29 57 16 6 - 89 11 10 56 6 29 ... .. .. .. .. .. - 81 45 46 57 17 40 11 55 5 10 263 -3 - 86 17 36 56 51 13 - 75 31 59 57 36 33 - 89 33 58 56 25 5 ... .. .. .. .. .. - 82 9 26 57 37 12 11 55 8 10 262 -4 - 86 40 3 57 10 15 - 76 0 57 57 56 58 - 89 56 8 56 43 46 ... .. .. .. .. .. - 82 31 55 57 56 48 11 55 11 10 262 -4 - 87 1 42 57 29 21 - 76 27 38 58 17 20 - 90 17 42 57 2 31 - 65 17 23 58 7 33 - 82 53 18 58 16 26 11 55 14 11 262 -4 - 87 22 34 57 48 32 - 76 52 13 58 37 41 - 90 38 40 57 21 20 - 66 45 46 58 33 31 - 83 13 34 58 36 8 11 55 17 11 261 -4 - 87 42 41 58 7 47 - 77 14 50 58 58 3 - 90 59 2 57 40 15 - 67 43 42 58 57 11 - 83 32 46 58 55 54 11 55 20 11 261 -4 - 88 2 3 58 27 7 - 77 35 37 59 18 26 - 91 18 49 57 59 14 - 68 27 43 59 19 53 - 83 50 54 59 15 45 11 55 23 11 261 -5 - 88 20 39 58 46 32 - 77 54 37 59 38 50 - 91 38 1 58 18 19 - 69 2 50 59 42 4 - 84 8 0 59 35 40 11 55 26 11 260 -5 - 88 38 31 59 6 2 - 78 11 53 59 59 16 - 91 56 39 58 37 30 - 69 31 22 60 3 54 - 84 24 3 59 55 40 11 55 29 11 260 -5 - 88 55 38 59 25 38 - 78 27 29 60 19 46 - 92 14 41 58 56 46 - 69 54 35 60 25 29 - 84 39 3 60 15 46 11 55 32 11 260 -5 - 89 12 0 59 45 20 - 78 41 26 60 40 18 - 92 32 9 59 16 8 - 70 13 15 60 46 55 - 84 53 0 60 35 57 11 55 35 11 260 -5 - 89 27 37 60 5 8 - 78 53 43 61 0 55 - 92 49 1 59 35 37 - 70 27 47 61 8 14 - 85 5 53 60 56 14 11 55 38 11 259 -5 - 89 42 28 60 25 3 - 79 4 21 61 21 36 - 93 5 18 59 55 12 - 70 38 29 61 29 26 - 85 17 41 61 16 38 11 55 41 11 259 -5 - 89 56 32 60 45 5 - 79 13 18 61 42 21 - 93 20 58 60 14 54 - 70 45 28 61 50 35 - 85 28 22 61 37 8 11 55 44 11 259 -6 - 90 9 49 61 5 13 - 79 20 32 62 3 11 - 93 36 2 60 34 44 - 70 48 49 62 11 40 - 85 37 56 61 57 45 11 55 47 11 259 -6 - 90 22 16 61 25 29 - 79 26 1 62 24 6 - 93 50 28 60 54 40 - 70 48 27 62 32 41 - 85 46 18 62 18 29 11 55 50 11 259 -6 - 90 33 54 61 45 53 - 79 29 41 62 45 6 - 94 4 16 61 14 44 - 70 44 15 62 53 40 - 85 53 28 62 39 21 11 55 53 11 258 -6 - 90 44 40 62 6 24 - 79 31 27 63 6 12 - 94 17 24 61 34 57 - 70 36 2 63 14 34 - 85 59 22 63 0 21 11 55 56 11 258 -6 - 90 54 32 62 27 4 - 79 31 15 63 27 23 - 94 29 51 61 55 17 - 70 23 27 63 35 24 - 86 3 57 63 21 28 11 55 59 11 258 -6 - 91 3 28 62 47 53 - 79 28 56 63 48 41 - 94 41 36 62 15 46 - 70 6 4 63 56 8 - 86 7 8 63 42 44 11 56 2 11 258 -6 - 91 11 27 63 8 50 - 79 24 25 64 10 4 - 94 52 37 62 36 24 - 69 43 19 64 16 43 - 86 8 52 64 4 8 11 56 5 11 258 -6 - 91 18 25 63 29 56 - 79 17 32 64 31 32 - 95 2 52 62 57 11 - 69 14 19 64 37 7 - 86 9 3 64 25 41 11 56 8 11 258 -6 - 91 24 19 63 51 12 - 79 8 6 64 53 7 - 95 12 20 63 18 8 - 68 37 51 64 57 13 - 86 7 36 64 47 22 11 56 11 11 258 -6 - 91 29 6 64 12 37 - 78 55 56 65 14 47 - 95 20 58 63 39 14 - 67 52 2 65 16 55 - 86 4 23 65 9 13 11 56 14 11 258 -6 - 91 32 42 64 34 13 - 78 40 45 65 36 32 - 95 28 44 64 0 30 - 66 53 40 65 35 56 - 85 59 18 65 31 14 11 56 17 11 258 -6 - 91 35 3 64 55 59 - 78 22 18 65 58 21 - 95 35 35 64 21 57 - 65 36 22 65 53 47 - 85 52 11 65 53 23 11 56 20 10 258 -6 - 91 36 3 65 17 56 - 78 0 13 66 20 15 - 95 41 27 64 43 35 - 63 42 0 66 8 59 - 85 42 53 66 15 43 11 56 23 10 258 -6 - 91 35 38 65 40 3 - 77 34 5 66 42 11 - 95 46 18 65 5 24 ... .. .. .. .. .. - 85 31 13 66 38 12 11 56 26 10 258 -6 - 91 33 41 66 2 23 - 77 3 25 67 4 10 - 95 50 2 65 27 25 ... .. .. .. .. .. - 85 16 58 67 0 51 11 56 29 10 258 -6 - 91 30 6 66 24 54 - 76 27 35 67 26 7 - 95 52 36 65 49 37 ... .. .. .. .. .. - 84 59 53 67 23 39 11 56 32 10 258 -6 - 91 24 44 66 47 37 - 75 45 47 67 48 2 - 95 53 55 66 12 2 ... .. .. .. .. .. - 84 39 41 67 46 37 11 56 35 10 259 -5 - 91 17 27 67 10 32 - 74 57 2 68 9 51 - 95 53 54 66 34 40 ... .. .. .. .. .. - 84 16 1 68 9 44 11 56 38 9 259 -5 - 91 8 4 67 33 40 - 73 59 58 68 31 28 - 95 52 25 66 57 32 ... .. .. .. .. .. - 83 48 30 68 33 0 11 56 41 9 259 -5 - 90 56 24 67 57 1 - 72 52 42 68 52 47 - 95 49 21 67 20 37 ... .. .. .. .. .. - 83 16 39 68 56 23 11 56 44 9 260 -5 - 90 42 13 68 20 35 - 71 32 31 69 13 34 - 95 44 36 67 43 56 ... .. .. .. .. .. - 82 39 55 69 19 54 11 56 47 9 260 -5 - 90 25 17 68 44 22 - 69 54 57 69 33 30 - 95 37 59 68 7 30 ... .. .. .. .. .. - 81 57 36 69 43 30 11 56 50 8 261 -5 - 90 5 17 69 8 23 - 67 51 46 69 51 56 - 95 29 20 68 31 18 ... .. .. .. .. .. - 81 8 53 70 7 9 11 56 53 8 262 -4 - 89 41 53 69 32 37 - 65 2 53 70 7 13 - 95 18 28 68 55 23 ... .. .. .. .. .. - 80 12 42 70 30 48 11 56 56 7 263 -4 - 89 14 42 69 57 5 - 59 0 41 70 7 15 - 95 5 8 69 19 43 ... .. .. .. .. .. - 79 7 43 70 54 24 11 57 0 7 264 -4 - 88 43 13 70 21 45 ... .. .. .. .. .. - 94 49 6 69 44 20 ... .. .. .. .. .. - 77 52 8 71 17 49 11 57 3 7 265 -4 - 88 6 55 70 46 38 ... .. .. .. .. .. - 94 30 1 70 9 13 ... .. .. .. .. .. - 76 23 32 71 40 55 11 57 6 6 266 -3 - 87 25 6 71 11 43 ... .. .. .. .. .. - 94 7 34 70 34 24 ... .. .. .. .. .. - 74 38 26 72 3 28 11 57 9 6 268 -3 - 86 36 56 71 36 59 ... .. .. .. .. .. - 93 41 20 70 59 51 ... .. .. .. .. .. - 72 31 21 72 25 3 11 57 12 5 270 -2 - 85 41 27 72 2 23 ... .. .. .. .. .. - 93 10 48 71 25 36 ... .. .. .. .. .. - 69 52 40 72 44 56 11 57 15 4 272 -1 - 84 37 21 72 27 52 ... .. .. .. .. .. - 92 35 25 71 51 38 ... .. .. .. .. .. - 66 20 58 73 1 23 11 57 18 3 276 -1 - 83 23 4 72 53 24 ... .. .. .. .. .. - 91 54 27 72 17 58 ... .. .. .. .. .. Uncertainty in time = +/- 4 secs [Prediction of 2008 Feb 27.0] Data for the target star ------------------------ * name: TYC 0283-00347-1 * constellation : Virgo * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 12 00 14.9496 DE: +04 37 59.835 * position source: mpos:TYC pm:TYC * standard error: RA,DE ["]: ( .025, .031 ) * V mag [mag]: 9.3 * B mag [mag]: 10.2 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (140) Siwa approx. diameter [km]: 110 approx. diameter ["]: .073 distance from Earth [AU]: 2.07100 * orbital information: orbit source: Preston date of fit: 2008 Feb 27 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1214 number of rejected observations: 178 time covered by the observations: 1900 Apr 26 - 2008 Feb 18 1 sigma uncertainty ellipse (major, minor, PA): 0.018, 0.011, 112° remarks: * orbital elements for (140) Siwa : Mean anomaly = 249.61484963 deg Arg. of pericenter = 197.27885304 deg Long. of node = 107.29457991 deg Inclination = 3.18754032 deg Eccentricity = 0.21673432 Semimajor axis = 2.73183361 AU Perihelion dist = 2.13975150 AU Mag: H = 8.47, G = 0.15 Epoch of elements : MJD 54528.49700000 TDT (2008 Mar 03.497) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Mar 3 140 Siwa 11h 55.8m UT 9.3 12 0 14.950 4 37 59.84TYC 0283-00347-1 10.2 12.8 110 8.5 2.071 -1.835 14.39 -160.5157 4.630 4.02 -6.57 11.9297 0.45473 0.86632 -6.45498 3.38705 -0.00160 0.00023 2000 247.7600872008 224.00000197.278853107.294580 3.1875400.21673432 2.7318336 2.1397515 8.3 5.00.15 RATE 2.1828440 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.032 0.030 2 1.44 0.032 0 54523.5020080303_0347-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Feb 27, 19:25 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org