IOTA/IOTA-ES occultation update for (7) Iris / UCAC4 339-069785 event on 2023 Mar 06, 20:41 UT Visible from SE Asia, China Summary ------- On 2023 Mar 06 UT, the 222.3 km diameter asteroid (7) Iris will occult a 11.7 mag star in the constellation Libra for observers along a path across SE Asia, China. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.35 mag to 10.68 mag (the magnitude of the asteroid) for at most 179.850 seconds. This update is based on, astrometry for the asteroid kindly provided by the IAU Minor Planet Center. This work has made use of data from the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The event at a glimpse ---------------------- * Rank: 99 * date and approx. time of event: 2023 Mar 06, 19:15 - 2023 Mar 06, 22:11 * geocentric midpoint of event [JD]: 2460010.36332287 * magnitude of target star: 11.74 * magnitude drop [mag]: 0.35 * estimated maximum duration [s]: 179.850 * Moon: 99 % sunlit, 70° distance * Sun: 118° distance * rough path description: SE Asia, China Additional comments ------------------- low mag drop The occultation path -------------------- * approximate projected width [km]: 223 * 1 sigma uncertainty interval [path widths]: +/- 0.11 * 1 sigma uncertainty interval [seconds]: +/- 17.3 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- 0.015, +/- 0.012) * 1 sigma uncertainty ellipse (major, minor, PA): (0.015", 0.012", 98°) * approx speed of asteroid's shadow [km/s]: 1.2361 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC4 339-069785 by 7 Iris on 2023 Mar 6 Centre Star Star Sun Path Limits Error Limits Alt E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4 Crn o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " Latitude Latitude Latitude Latitude 102 0 0 .. .. .... .. .. .. .. .. .. -23 52 55 .. .. .. -22 10 32 .. .. .. .... 103 0 0 -24 40 40 20 44 30.7 84 68 -32 -16 50 38 .. .. .. -15 10 59 .. .. .. .... 104 0 0 -17 18 21 20 33 14.5 81 127 -36 - 9 28 22 -25 33 57 - 7 38 37 -27 40 13 -0.13 105 0 0 - 9 46 56 20 21 55.7 75 146 -40 - 0 32 48 -17 46 40 2 7 33 -19 34 22 -0.18 106 0 0 - 0 54 25 20 9 5.5 66 153 -44 .. .. .. -10 4 24 .. .. .. -11 53 3 -0.25 107 0 0 .. .. .... .. .. .. .. .. .. .. .. .. - 1 12 54 .. .. .. - 3 26 4 .... 108 0 0 .. .. .... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 10 10 0 .... Uncertainty in time = +/- 20 secs Prediction of 2023 Feb 15.9 Data for the target star ------------------------ * name: UCAC4 339-069785 * constellation : Libra * BCRS position with proper motion to date of event [h,m,s ; °,',"] RA: 14 55 07.4605 DE: -22 12 16.387 * GCRS Astrometric position with proper motion and parallax to date of event [h,m,s ; °,',"] RA: 14 55 07.4606 DE: -22 12 16.387 * position source: Gaia DR3 * standard error: RA,DE [mas]: (0.200,0.200) * V mag [mag]: 11.7 * Diameter [mas]: 0.00 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (7) Iris asteroid class: ShapeModel approx. diameter [km]: 222 approx. diameter ["]: 0.133 distance from Earth [AU]: 2.30880 asteroid position offset in RA [mas]: 0 asteroid position offset in DE [mas]: 0 * orbital information: orbit source: JPL#125 date of fit: 2023 Feb 07 source of used astrometry: MPC, JPL number of used observations: 0 number of rejected observations: 0 time covered by the observations: 1800 Jan 01 - 1800 Jan 01 1 sigma uncertainty ellipse (major, minor, PA): 0.015", 0.012", 97.746° remarks: * orbital elements for (7)Iris : Mean anomaly = 157.1140833889 deg Arg. of pericenter = 145.4145603496 deg Long. of node = 259.5038959657 deg Inclination = 5.5178415088 deg Eccentricity = 0.2296629294 Semimajor axis = 2.3869490737 AU Perihelion dist = 1.8387553571 AU Mag: H = 5.63, G = 0.15 Epoch of elements : MJD 60009.86208333 TDT (2023 Mar 06.8621) ------ occelmnt file for Occult BEGIN ----------------------------------- JPL#1252023Feb07,179.85,2023,3,6,20.719749,-0.093805,-0.025749,0.184266,-0.672894,-0.004880,0.001721,0.000001,0.000000 108.9966,-22.2985,-127.99,-5.52,False UCAC4 339-069785,14.91873902,-22.2045519,0.00,11.74,0.00,0.0,0,,14.94094908,-22.2985453,0.35,0.00,0,0,0 7,Iris,10.68,222.3,2.3088,0,0,0.050,-2.56,,15.2,0 0,156.8837,2023,3,6,145.4146,259.5039,5.5178,0.22966,2.38695,1.83876,5.62,5.0,0.15 1.110,0.0150,0.0123,98,0.0146,Known errors,-1.00,-1,-1,-1 20230306_069785,59990.86 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2023 Feb 15, 20:45 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 stevepr@acm.org