IOTA/IOTA-ES occultation update for (177) Irma / TYC 0273-00410-1 event on 2012 Dec 01, 02:06 UT Visible from Russia Summary ------- On 2012 Dec 01 UT, the 73 km diameter asteroid (177) Irma will occult a 9.7 mag star in the constellation Virgo for observers along a path across Russia. In the case of an occultation, the combined light of the asteroid and the star will drop by 5.9 mag to 15.5 mag (the magnitude of the asteroid) for at most 3.0 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: 69 * date and approx. time of event: 2012 Dec 01, 02:04 - 2012 Dec 01, 02:05 UT * geocentric midpoint of event [JD]: 2456262.58810833 * magnitude of target star: 9.7 * magnitude drop [mag]: 5.9 * estimated maximum duration [s]: 3.0 * Moon: 94 % sunlit, 83° distance * Sun: 69° distance * rough path description: Russia The occultation path -------------------- * approximate projected width [km]: 135 * 1 sigma uncertainty interval [path widths]: +/- 0.85 * 1 sigma uncertainty interval [seconds]: +/- 2.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .029 +/- .025) * 1 sigma uncertainty ellipse (major, minor, PA): ( .029", .025", 94° ) * approx speed of asteroid's shadow [km/s]: 24.1113 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 0273-00410-1 by 177 Irma on 2012 Dec 1 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 27 6 36 80 14 58 2 4 34 6 128 -26 6 0 31 82 9 37 35 22 39 78 38 27 ... .. .. .. .. .. 42 37 46 76 19 20 41 29 7 78 31 23 2 4 38 9 142 -24 35 19 3 80 6 54 45 16 57 77 7 17 ... .. .. .. .. .. 49 17 42 75 1 46 49 58 57 77 0 55 2 4 41 12 151 -23 47 1 21 78 24 18 52 2 49 75 45 26 36 55 28 81 14 41 54 25 39 73 50 8 55 59 58 75 39 37 2 4 45 13 157 -21 54 24 32 76 54 35 57 10 43 74 30 31 49 52 39 79 21 17 58 36 15 72 43 15 60 39 22 74 25 8 2 4 49 15 161 -20 59 47 26 75 33 49 61 19 2 73 21 1 57 31 14 77 44 42 62 7 55 71 40 16 64 27 41 73 15 57 2 4 52 16 165 -18 64 1 41 74 19 45 64 47 32 72 15 51 62 55 18 76 19 5 65 11 32 70 40 32 67 41 15 72 11 4 2 4 56 18 169 -17 67 31 56 73 10 54 67 47 44 71 14 18 67 6 18 75 1 22 67 54 6 69 43 36 70 29 49 71 9 46 2 5 0 19 172 -16 70 31 48 72 6 18 70 26 52 70 15 48 70 31 56 73 49 39 70 20 18 68 49 5 72 59 35 70 11 28 2 5 3 20 174 -15 73 9 34 71 5 14 72 49 47 69 19 56 73 26 55 72 42 42 72 33 29 67 56 41 75 14 48 69 15 46 2 5 7 21 177 -14 75 30 36 70 7 8 74 59 52 68 26 20 75 59 54 71 39 40 74 36 6 67 6 10 77 18 25 68 22 20 2 5 10 22 179 -13 77 38 33 69 11 36 76 59 34 67 34 46 78 16 26 70 39 55 76 29 58 66 17 20 79 12 37 67 30 53 2 5 14 23 181 -12 79 36 2 68 18 20 78 50 44 66 44 59 80 20 15 69 42 57 78 16 29 65 30 1 80 59 2 66 41 14 2 5 18 23 183 -11 81 25 0 67 27 1 80 34 46 65 56 48 82 13 56 68 48 25 79 56 47 64 44 4 82 38 55 65 53 10 2 5 21 24 185 -10 83 6 53 66 37 29 82 12 45 65 10 4 83 59 25 67 56 1 81 31 45 63 59 22 84 13 17 65 6 32 2 5 25 25 186 -9 84 42 50 65 49 32 83 45 35 64 24 40 85 38 7 67 5 29 83 2 6 63 15 49 85 42 54 64 21 14 2 5 29 26 188 -8 86 13 43 65 3 0 85 13 57 63 40 28 87 11 9 66 16 38 84 28 25 62 33 19 87 8 25 63 37 7 2 5 32 26 190 -7 87 40 15 64 17 47 86 38 27 62 57 23 88 39 23 65 29 18 85 51 12 61 51 48 88 30 22 62 54 6 2 5 36 27 191 -6 89 3 2 63 33 45 87 59 33 62 15 19 90 3 30 64 43 21 87 10 52 61 11 12 89 49 11 62 12 6 2 5 40 27 193 -5 90 22 32 62 50 49 89 17 41 61 34 11 91 24 4 63 58 39 88 27 47 60 31 26 91 5 15 61 31 2 2 5 43 28 195 -4 91 39 10 62 8 53 90 33 9 60 53 56 92 41 33 63 15 5 89 42 13 59 52 27 92 18 53 60 50 51 2 5 47 28 196 -3 92 53 15 61 27 54 91 46 17 60 14 31 93 56 19 62 32 36 90 54 28 59 14 13 93 30 20 60 11 29 2 5 51 29 198 -2 94 5 6 60 47 47 92 57 19 59 35 51 95 8 44 61 51 4 92 4 44 58 36 40 94 39 51 59 32 53 2 5 54 29 199 -1 95 14 57 60 8 28 94 6 29 58 57 55 96 19 2 61 10 27 93 13 13 57 59 46 95 47 39 58 55 0 2 5 58 30 200 0 96 23 1 59 29 55 95 13 57 58 20 39 97 27 29 60 30 41 94 20 7 57 23 30 Uncertainty in time = +/- 3 secs Prediction of 2012 Nov 16.0 Data for the target star ------------------------ * name: TYC 0273-00410-1 * constellation : Virgo * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 11 59 33.3845 DE: +00 09 51.582 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .026, .023 ) * V mag [mag]: 9.7 * B mag [mag]: 10.1 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (177) Irma approx. diameter [km]: 73 approx. diameter ["]: .030 distance from Earth [AU]: 3.37400 * orbital information: orbit source: Preston date of fit: 2012 Jul 10 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1190 number of rejected observations: 94 time covered by the observations: 1900 Oct 23 - 2012 Apr 21 1 sigma uncertainty ellipse (major, minor, PA): 0.012, 0.009, 115° remarks: * orbital elements for (177) Irma : Mean anomaly = 115.79719377 deg Arg. of pericenter = 38.21986375 deg Long. of node = 347.57811039 deg Inclination = 1.39021749 deg Eccentricity = 0.23852794 Semimajor axis = 2.76731815 AU Perihelion dist = 2.10723545 AU Mag: H = 9.59, G = 0.15 Epoch of elements : MJD 56262.08800000 TDT (2012 Dec 01.088) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Dec 1 177 Irma 2h 6.9m UT 9.7 11 59 33.385 0 9 51.58TYC 0273-00410-1 10.1 15.5 73 3.0 3.374 2.156 -14.54 77.8283 0.169 145.55 -21.84 2.1146 0.34481 0.76721 12.41237 -5.58037 -0.00513 0.00223 2000 115.35015420121129.00000 38.219864347.578110 1.3902170.23852794 2.7673182 2.1072355 9.5 5.00.15 RATE 2.1409940 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.029 0.025 94 1.85 0.025 0 0-5 2 056247.0020121201_0410-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Jul 10, 03:58 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org