IOTA/IOTA-ES occultation update for (7) Iris / TYC 1325-00234-1 event on 2007 Apr 21, 10:24 UT Visible from Australia Summary ------- On 2007 Apr 21 UT, the 200 km diameter asteroid (7) Iris will occult a 9.6 mag star in the constellation Orion for observers along a path across Australia. In the case of an occultation, the combined light of the asteroid and the star will drop by 1.1 mag to 10.2 mag (the magnitude of the asteroid) for at most 5.6 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Ron Stone, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC. The event at a glimpse ---------------------- * Rank: 99 * date and approx. time of event: 2007 Apr 21, 10:22 - 2007 Apr 21, 10:26 UT * magnitude of target star: 9.6 * magnitude drop [mag]: 1.1 * estimated maximum duration [s]: 5.6 * Moon: 21 % sunlit, 10° distance * Sun: 59° distance * rough path description: Australia The occultation path -------------------- * approximate projected width [km]: 260 * 1 sigma uncertainty interval [path widths]: +/- 0.18 * 1 sigma uncertainty interval [seconds]: +/- 0.7 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .016 +/- .021) * 1 sigma uncertainty ellipse (major, minor, PA): ( .021", .016", 0° ) * approx speed of asteroid's shadow [km/s]: 35.9074 * website for maps: http://lunar-occultations.com/iota/asteroids/astrndx.htm http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 1325-00234-1 by 7 Iris on 2007 Apr 21 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 12 0 0 -35 9 4 10 22 24 1 64 42 -36 27 50 .. .. .. -36 56 36 .. .. .. 13 0 0 -34 45 31 10 22 24 2 63 42 -36 4 10 .. .. .. -36 32 54 .. .. .. 14 0 0 -34 22 3 10 22 24 3 63 43 -35 40 34 -33 5 8 -36 9 16 .. .. .. 15 0 0 -33 58 41 10 22 24 4 62 44 -35 17 5 -32 41 53 -35 45 43 .. .. .. 16 0 0 -33 35 25 10 22 24 4 62 44 -34 53 41 -32 18 44 -35 22 17 .. .. .. 17 0 0 -33 12 16 10 22 25 5 61 45 -34 30 24 -31 55 43 -34 58 57 -31 28 31 18 0 0 -32 49 15 10 22 25 6 60 45 -34 7 15 -31 32 49 -34 35 45 -31 5 40 19 0 0 -32 26 22 10 22 26 7 60 46 -33 44 14 -31 10 5 -34 12 40 -30 42 58 20 0 0 -32 3 39 10 22 26 8 59 46 -33 21 22 -30 47 29 -33 49 45 -30 20 25 21 0 0 -31 41 5 10 22 27 9 59 47 -32 58 39 -30 25 3 -33 26 59 -29 58 2 22 0 0 -31 18 41 10 22 27 10 58 47 -32 36 7 -30 2 47 -33 4 23 -29 35 49 23 0 0 -30 56 28 10 22 28 11 58 47 -32 13 45 -29 40 43 -32 41 59 -29 13 48 24 0 0 -30 34 27 10 22 29 12 57 48 -31 51 35 -29 18 50 -32 19 45 -28 51 58 25 0 0 -30 12 38 10 22 29 13 57 48 -31 29 37 -28 57 10 -31 57 44 -28 30 21 26 0 0 -29 51 2 10 22 30 14 56 48 -31 7 52 -28 35 43 -31 35 55 -28 8 56 27 0 0 -29 29 39 10 22 31 15 56 49 -30 46 20 -28 14 29 -31 14 19 -27 47 45 28 0 0 -29 8 31 10 22 32 16 55 49 -30 25 2 -27 53 29 -30 52 58 -27 26 48 29 0 0 -28 47 37 10 22 33 16 54 49 -30 3 58 -27 32 43 -30 31 51 -27 6 6 30 0 0 -28 26 58 10 22 34 17 54 49 -29 43 10 -27 12 13 -30 10 59 -26 45 39 31 0 0 -28 6 34 10 22 36 18 53 50 -29 22 37 -26 51 59 -29 50 23 -26 25 28 32 0 0 -27 46 27 10 22 37 19 53 50 -29 2 21 -26 32 1 -29 30 3 -26 5 33 33 0 0 -27 26 37 10 22 38 20 52 50 -28 42 21 -26 12 19 -29 10 0 -25 45 54 34 0 0 -27 7 4 10 22 39 21 52 50 -28 22 39 -25 52 55 -28 50 14 -25 26 33 35 0 0 -26 47 49 10 22 41 22 51 50 -28 3 14 -25 33 49 -28 30 46 -25 7 30 36 0 0 -26 28 52 10 22 42 23 51 50 -27 44 8 -25 15 1 -28 11 36 -24 48 45 37 0 0 -26 10 14 10 22 44 24 50 50 -27 25 21 -24 56 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Data for the target star ------------------------ * name: TYC 1325-00234-1 * constellation : Orion * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 06 00 45.5545 DE: +20 41 42.950 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .013, .020 ) * V mag [mag]: 9.6 * B mag [mag]: 10.2 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (7) Iris approx. diameter [km]: 200 approx. diameter ["]: .114 distance from Earth [AU]: 2.41400 * orbital information: orbit source: Preston date of fit: 2007 Apr 06 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 4096 number of rejected observations: 309 time covered by the observations: 1901 Mar 27 - 2007 Feb 22 1 sigma uncertainty ellipse (major, minor, PA): 0.008, 0.005, 96° remarks: * orbital elements for (7) Iris : Mean anomaly = 46.40242824 deg Arg. of pericenter = 145.39414476 deg Long. of node = 259.72223059 deg Inclination = 5.52744828 deg Eccentricity = 0.23142890 Semimajor axis = 2.38544397 AU Perihelion dist = 1.83338330 AU Mag: H = 5.46, G = 0.15 Epoch of elements : MJD 54211.43400000 TDT (2007 Apr 21.434) ------ occelmnt file for Occult BEGIN ----------------------------------- 2007 Apr 21 7 Iris 10h 24.7m UT 9.6 6 0 45.555 20 41 42.95TYC 1325-00234-1 10.2 10.2 200 5.6 2.414 5.259 -2.02 84.906 20.695 23.54 11.80 10.4111 -.01856 -.63828 20.25955 -0.55354 0.00456 -0.00014 2000 46.01880962007 420.00000145.394145259.722231 5.5274480.231428902.385443971.833383305.515 0.15 RATE 2.6751629 .0000000 .0000000 .0000000 .00000000 .00000000 .00000000 Meas 0.021 0.016 0.3 1.180 0.021 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2007 Apr 06, 20:51 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org