IOTA/IOTA-ES occultation update for (85) Io / TYC 0620-00778-1 event on 2012 Sep 09, 00:56 UT Visible from Brazil Summary ------- On 2012 Sep 09 UT, the 208 km diameter asteroid (85) Io will occult a 11.6 mag star in the constellation Pisces for observers along a path across Brazil. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.5 mag to 10.9 mag (the magnitude of the asteroid) for at most 38.7 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: 99 * date and approx. time of event: 2012 Sep 09, 00:43 - 2012 Sep 09, 01:09 UT * geocentric midpoint of event [JD]: 2456179.53927083 * magnitude of target star: 11.6 * magnitude drop [mag]: 0.5 * estimated maximum duration [s]: 38.7 * Moon: 46 % sunlit, 57° distance * Sun: 142° distance * rough path description: Brazil The occultation path -------------------- * approximate projected width [km]: 304 * 1 sigma uncertainty interval [path widths]: +/- 0.17 * 1 sigma uncertainty interval [seconds]: +/- 5.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .037 +/- .030) * 1 sigma uncertainty ellipse (major, minor, PA): ( .037", .030", 87° ) * approx speed of asteroid's shadow [km/s]: 5.3762 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 0620-00778-1 by 85 Io on 2012 Sep 9 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 - 76 42 25 72 52 21 0 43 37 11 78 -2 - 66 10 59 73 52 51 - 89 35 56 70 52 41 - 62 53 19 74 6 4 - 95 40 46 69 34 25 - 66 23 50 72 30 16 0 43 58 14 88 -5 - 57 33 9 73 2 13 - 76 27 47 71 29 20 - 54 45 6 73 8 31 - 80 19 57 70 57 59 - 58 32 36 71 40 59 0 44 19 17 95 -7 - 50 57 40 71 56 19 - 66 59 55 71 7 16 - 48 32 54 71 58 23 - 70 8 2 70 49 59 - 52 27 42 70 37 45 0 44 40 19 100 -10 - 45 51 55 70 42 36 - 59 44 43 70 19 59 - 43 45 28 70 41 56 - 62 24 37 70 10 7 - 47 41 19 69 27 4 0 45 1 21 105 -12 - 41 52 16 69 24 59 - 54 4 0 69 19 32 - 40 0 22 69 22 30 - 56 23 0 69 14 13 - 43 53 37 68 12 29 0 45 22 22 108 -13 - 38 41 56 68 5 40 - 49 33 18 68 11 51 - 37 1 39 68 1 56 - 51 36 3 68 9 32 - 40 50 24 66 56 1 0 45 43 24 111 -15 - 36 8 56 66 45 53 - 45 55 31 67 0 11 - 34 38 4 66 41 18 - 47 45 19 66 59 57 - 38 21 24 65 38 52 0 46 4 25 113 -17 - 34 4 40 65 26 22 - 42 58 22 65 46 26 - 32 41 32 65 21 10 - 44 37 40 65 47 41 - 36 19 9 64 21 43 0 46 25 27 114 -18 - 32 22 55 64 7 31 - 40 32 52 64 31 47 - 31 6 13 64 1 53 - 42 3 33 64 34 6 - 34 38 6 63 5 0 0 46 46 28 115 -20 - 30 59 4 62 49 34 - 38 32 25 63 16 54 - 29 47 46 62 43 38 - 39 55 55 63 20 0 - 33 14 6 61 48 58 0 47 7 29 116 -21 - 29 49 39 61 32 38 - 36 52 2 62 2 14 - 28 42 57 61 26 29 - 38 9 30 62 5 56 - 32 4 1 60 33 46 0 47 28 30 117 -23 - 28 52 3 60 16 47 - 35 27 58 60 48 3 - 27 49 17 60 10 28 - 36 40 19 60 52 12 - 31 5 24 59 19 28 0 47 49 31 117 -24 - 28 4 13 59 2 0 - 34 17 20 59 34 30 - 27 4 52 58 55 35 - 35 25 15 59 39 0 - 30 16 21 58 6 5 0 48 10 32 117 -25 - 27 24 34 57 48 17 - 33 17 50 58 21 42 - 26 28 12 57 41 48 - 34 21 57 58 26 27 - 29 35 22 56 53 38 0 48 31 33 117 -26 - 26 51 50 56 35 37 - 32 27 44 57 9 41 - 25 58 5 56 29 5 - 33 28 32 57 14 38 - 29 1 16 55 42 6 0 48 51 34 117 -28 - 26 25 1 55 23 56 - 31 45 36 55 58 27 - 25 33 35 55 17 23 - 32 43 28 56 3 33 - 28 33 4 54 31 28 0 49 12 35 117 -29 - 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Uncertainty in time = +/- 7 secs Prediction of 2012 Aug 26.0 Data for the target star ------------------------ * name: TYC 0620-00778-1 * constellation : Pisces * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 01 23 18.2449 DE: +14 17 30.915 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .031, .028 ) * V mag [mag]: 11.6 * B mag [mag]: 12.0 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (85) Io approx. diameter [km]: 208 approx. diameter ["]: .211 distance from Earth [AU]: 1.36100 * orbital information: orbit source: Preston date of fit: 2012 Aug 25 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1182 number of rejected observations: 163 time covered by the observations: 1904 Oct 09 - 2012 Aug 13 1 sigma uncertainty ellipse (major, minor, PA): 0.021, 0.010, 82° remarks: * orbital elements for (85) Io : Mean anomaly = 29.02876210 deg Arg. of pericenter = 122.49126248 deg Long. of node = 203.37566234 deg Inclination = 11.95978634 deg Eccentricity = 0.19116079 Semimajor axis = 2.65371587 AU Perihelion dist = 2.14642944 AU Mag: H = 7.65, G = 0.15 Epoch of elements : MJD 56179.03900000 TDT (2012 Sep 09.039) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Sep 9 85 Io 0h 56.5m UT 11.6 1 23 18.245 14 17 30.92TYC 0620-00778-1 12.0 10.9 208 38.7 1.361 -0.694 -16.84 18.2028 14.297 165.20 5.23 0.9425 -0.62807 0.37168 -1.55803 -2.60394 -0.00297 -0.00160 2000 26.9679292012 831.00000122.491262203.375662 11.9597860.19116079 2.6537159 2.1464294 7.6 5.00.15 RATE 2.2799350 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.037 0.030 87 1.17 0.035 0 0-1-5 056165.0020120909_0778-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Aug 25, 22:36 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org