IOTA/IOTA-ES occultation update for (620) Drakonia / TYC 7423-01109-1 event on 2008 Mar 31, 01:18 UT Visible from Africa Summary ------- On 2008 Mar 31 UT, the 18 km diameter asteroid (620) Drakonia will occult a 8.8 mag star in the constellation Sagittarius 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 7.2 mag to 16.0 mag (the magnitude of the asteroid) for at most 0.8 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: 29 * date and approx. time of event: 2008 Mar 31, 01:13 - 2008 Mar 31, 01:17 UT * magnitude of target star: 8.8 * magnitude drop [mag]: 7.2 * estimated maximum duration [s]: 0.8 * Moon: 39 % sunlit, 8° distance * Sun: 84° distance * rough path description: Africa The occultation path -------------------- * approximate projected width [km]: 19 * 1 sigma uncertainty interval [path widths]: +/- 2.27 * 1 sigma uncertainty interval [seconds]: +/- 2.3 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .038 +/- .025) * 1 sigma uncertainty ellipse (major, minor, PA): ( .039", .025", 83° ) * approx speed of asteroid's shadow [km/s]: 23.0595 * website for maps: http://lunar-occultations.com/iota/asteroids/astrndx.htm http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 7423-01109-1 by 620 Drakonia on 2008 Mar 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 ' " Latitude Latitude Latitude Latitude 0 0 0 12 13 11 1 13 48 0 121 -66 12 7 20 12 19 2 .. .. .. 12 45 40 1 0 0 11 37 32 1 13 48 2 121 -66 11 31 41 11 43 24 11 5 9 12 10 1 2 0 0 11 1 55 1 13 48 3 122 -65 10 56 4 11 7 46 10 29 33 11 34 22 3 0 0 10 26 20 1 13 48 4 122 -65 10 20 29 10 32 10 9 53 59 10 58 45 4 0 0 9 50 48 1 13 49 5 122 -64 9 44 57 9 56 38 9 18 29 10 23 11 5 0 0 9 15 20 1 13 49 6 122 -64 9 9 30 9 21 10 8 43 3 9 47 41 6 0 0 8 39 58 1 13 50 7 122 -63 8 34 8 8 45 48 8 7 44 9 12 17 7 0 0 8 4 43 1 13 51 8 122 -63 7 58 53 8 10 32 7 32 31 8 36 59 8 0 0 7 29 35 1 13 51 10 123 -62 7 23 46 7 35 24 6 57 26 8 1 49 9 0 0 6 54 36 1 13 52 11 123 -61 6 48 48 7 0 25 6 22 30 7 26 48 10 0 0 6 19 48 1 13 54 12 123 -61 6 14 0 6 25 35 5 47 44 6 51 56 11 0 0 5 45 10 1 13 55 13 123 -60 5 39 23 5 50 57 5 13 10 6 17 15 12 0 0 5 10 45 1 13 56 14 123 -59 5 4 58 5 16 31 4 38 48 5 42 46 13 0 0 4 36 32 1 13 58 15 123 -58 4 30 47 4 42 18 4 4 39 5 8 31 14 0 0 4 2 34 1 13 59 16 123 -58 3 56 49 4 8 19 3 30 44 4 34 29 15 0 0 3 28 51 1 14 1 18 123 -57 3 23 7 3 34 36 2 57 5 4 0 42 16 0 0 2 55 24 1 14 3 19 123 -56 2 49 40 3 1 8 2 23 42 3 27 11 17 0 0 2 22 14 1 14 5 20 124 -55 2 16 31 2 27 58 1 50 36 2 53 57 18 0 0 1 49 23 1 14 7 21 124 -54 1 43 40 1 55 5 1 17 48 2 21 1 19 0 0 1 16 50 1 14 9 22 124 -53 1 11 8 1 22 31 0 45 20 1 48 24 20 0 0 0 44 36 1 14 11 23 124 -52 0 38 56 0 50 17 0 13 11 1 16 6 21 0 0 0 12 44 1 14 13 24 124 -51 0 7 4 0 18 24 - 0 18 37 0 44 9 22 0 0 - 0 18 47 1 14 15 26 124 -50 - 0 24 26 - 0 13 8 - 0 50 4 0 12 34 23 0 0 - 0 49 56 1 14 18 27 124 -49 - 0 55 35 - 0 44 18 - 1 21 8 - 0 18 40 24 0 0 - 1 20 43 1 14 21 28 124 -48 - 1 26 20 - 1 15 5 - 1 51 50 - 0 49 31 25 0 0 - 1 51 5 1 14 23 29 124 -47 - 1 56 42 - 1 45 29 - 2 22 7 - 1 19 58 26 0 0 - 2 21 3 1 14 26 30 124 -46 - 2 26 39 - 2 15 28 - 2 52 1 - 1 50 2 27 0 0 - 2 50 37 1 14 29 31 124 -45 - 2 56 11 - 2 45 2 - 3 21 29 - 2 19 40 28 0 0 - 3 19 44 1 14 32 32 124 -45 - 3 25 18 - 3 14 10 - 3 50 32 - 2 48 52 29 0 0 - 3 48 26 1 14 35 33 124 -44 - 3 53 58 - 3 42 53 - 4 19 8 - 3 17 39 30 0 0 - 4 16 40 1 14 38 34 124 -43 - 4 22 12 - 4 11 8 - 4 47 18 - 3 45 59 31 0 0 - 4 44 28 1 14 41 36 124 -42 - 4 49 59 - 4 38 56 - 5 15 0 - 4 13 51 32 0 0 - 5 11 47 1 14 44 37 124 -41 - 5 17 17 - 5 6 17 - 5 42 14 - 4 41 16 33 0 0 - 5 38 39 1 14 48 38 124 -40 - 5 44 8 - 5 33 9 - 6 9 1 - 5 8 12 34 0 0 - 6 5 1 1 14 51 39 125 -39 - 6 10 30 - 5 59 33 - 6 35 18 - 5 34 40 35 0 0 - 6 30 55 1 14 54 40 125 -38 - 6 36 22 - 6 25 27 - 7 1 7 - 6 0 39 36 0 0 - 6 56 19 1 14 58 41 125 -37 - 7 1 45 - 6 50 52 - 7 26 26 - 6 26 8 37 0 0 - 7 21 13 1 15 1 42 125 -36 - 7 26 39 - 7 15 47 - 7 51 15 - 6 51 7 38 0 0 - 7 45 37 1 15 5 43 125 -35 - 7 51 2 - 7 40 12 - 8 15 34 - 7 15 36 39 0 0 - 8 9 30 1 15 9 44 125 -33 - 8 14 54 - 8 4 6 - 8 39 22 - 7 39 34 40 0 0 - 8 32 53 1 15 13 45 125 -32 - 8 38 16 - 8 27 30 - 9 2 40 - 8 3 2 41 0 0 - 8 55 44 1 15 16 46 125 -31 - 9 1 6 - 8 50 22 - 9 25 26 - 8 25 58 42 0 0 - 9 18 5 1 15 20 47 125 -30 - 9 23 26 - 9 12 43 - 9 47 42 - 8 48 24 43 0 0 - 9 39 53 1 15 24 48 125 -29 - 9 45 13 - 9 34 33 -10 9 25 - 9 10 17 44 0 0 -10 1 10 1 15 28 49 126 -28 -10 6 29 - 9 55 51 -10 30 37 - 9 31 39 45 0 0 -10 21 55 1 15 32 50 126 -27 -10 27 13 -10 16 36 -10 51 18 - 9 52 28 46 0 0 -10 42 8 1 15 36 51 126 -26 -10 47 25 -10 36 50 -11 11 26 -10 12 46 47 0 0 -11 1 48 1 15 40 52 126 -25 -11 7 5 -10 56 31 -11 31 2 -10 32 31 48 0 0 -11 20 56 1 15 44 53 126 -24 -11 26 12 -11 15 40 -11 50 6 -10 51 43 49 0 0 -11 39 32 1 15 49 54 127 -23 -11 44 47 -11 34 17 -12 8 37 -11 10 24 50 0 0 -11 57 35 1 15 53 55 127 -22 -12 2 50 -11 52 21 -12 26 36 -11 28 31 51 0 0 -12 15 5 1 15 57 56 127 -21 -12 20 19 -12 9 52 -12 44 2 -11 46 5 52 0 0 -12 32 3 1 16 1 57 128 -20 -12 37 16 -12 26 50 -13 0 55 -12 3 7 53 0 0 -12 48 28 1 16 6 58 128 -19 -12 53 40 -12 43 15 -13 17 16 -12 19 36 54 0 0 -13 4 20 1 16 10 59 129 -18 -13 9 31 -12 59 8 -13 33 4 -12 35 32 55 0 0 -13 19 39 1 16 15 60 129 -17 -13 24 49 -13 14 28 -13 48 19 -12 50 54 56 0 0 -13 34 24 1 16 19 61 130 -17 -13 39 35 -13 29 14 -14 3 1 -13 5 44 57 0 0 -13 48 37 1 16 23 62 130 -16 -13 53 47 -13 43 28 -14 17 11 -13 20 1 58 0 0 -14 2 17 1 16 28 63 131 -15 -14 7 26 -13 57 8 -14 30 47 -13 33 44 59 0 0 -14 15 24 1 16 32 64 132 -14 -14 20 33 -14 10 16 -14 43 51 -13 46 54 60 0 0 -14 27 58 1 16 37 64 132 -13 -14 33 6 -14 22 50 -14 56 21 -13 59 31 61 0 0 -14 39 59 1 16 41 65 133 -12 -14 45 6 -14 34 52 -15 8 19 -14 11 35 62 0 0 -14 51 27 1 16 46 66 134 -11 -14 56 33 -14 46 20 -15 19 44 -14 23 6 63 0 0 -15 2 22 1 16 50 67 135 -10 -15 7 28 -14 57 15 -15 30 36 -14 34 4 64 0 0 -15 12 43 1 16 55 68 136 -9 -15 17 49 -15 7 38 -15 40 55 -14 44 28 65 0 0 -15 22 32 1 17 0 69 138 -8 -15 27 37 -15 17 27 -15 50 41 -14 54 19 66 0 0 -15 31 48 1 17 4 69 139 -7 -15 36 53 -15 26 43 -15 59 55 -15 3 38 67 0 0 -15 40 31 1 17 9 70 141 -6 -15 45 35 -15 35 26 -16 8 35 -15 12 23 68 0 0 -15 48 41 1 17 14 71 142 -5 -15 53 44 -15 43 36 -16 16 43 -15 20 35 69 0 0 -15 56 17 1 17 18 72 144 -4 -16 1 21 -15 51 14 -16 24 18 -15 28 14 70 0 0 -16 3 21 1 17 23 72 146 -3 -16 8 25 -15 58 18 -16 31 20 -15 35 20 71 0 0 -16 9 53 1 17 28 73 148 -2 -16 14 56 -16 4 50 -16 37 49 -15 41 53 72 0 0 -16 15 51 1 17 32 73 150 -1 -16 20 54 -16 10 48 -16 43 46 -15 47 53 Uncertainty in time = +/- 3 secs [Prediction of 2008 Feb 15.0] Data for the target star ------------------------ * name: TYC 7423-01109-1 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 19 17 42.7763 DE: -30 21 25.935 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .020, .020 ) * V mag [mag]: 8.8 * B mag [mag]: 10.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (620) Drakonia approx. diameter [km]: 18 approx. diameter ["]: .011 distance from Earth [AU]: 2.19400 * orbital information: orbit source: Preston date of fit: 2008 Feb 13 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 770 number of rejected observations: 42 time covered by the observations: 1931 Mar 27 - 2007 Aug 07 1 sigma uncertainty ellipse (major, minor, PA): 0.033, 0.014, 80° remarks: * orbital elements for (620) Drakonia : Mean anomaly = 299.70366314 deg Arg. of pericenter = 335.79463887 deg Long. of node = 0.18464033 deg Inclination = 7.73317817 deg Eccentricity = 0.13456009 Semimajor axis = 2.43628336 AU Perihelion dist = 2.10845684 AU Mag: H = 10.81, G = 0.15 Epoch of elements : MJD 54556.05500000 TDT (2008 Mar 31.055) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Mar 31 620 Drakonia 1h 18.3m UT 8.8 19 17 42.776-30 21 25.94TYC 7423-01109-1 10.0 16.0 18 0.8 2.194 4.030 -0.58 81.0658 -30.357 161.48 4.24 1.3046 0.00382 0.23667 13.01465 -0.14414 -0.00546 -0.00082 2000 298.1342892008 325.00000335.794639 0.184640 7.7331780.13456009 2.4362834 2.108456911.3 5.00.15 RATE 2.5918650 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.039 0.025 83 3.27 0.026 0 54511.5020080331_1109-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Feb 15, 05:22 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org