IOTA/IOTA-ES occultation update for (2154) Underhill / TYC 2420-00380-1 event on 2012 Sep 23, 07:40 UT Visible from SE USA, Mexico Summary ------- On 2012 Sep 23 UT, the 21 km diameter asteroid (2154) Underhill will occult a 9.7 mag star in the constellation Auriga for observers along a path across SE USA, Mexico. In the case of an occultation, the combined light of the asteroid and the star will drop by 7.8 mag to 17.5 mag (the magnitude of the asteroid) for at most 1.0 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: 16 * date and approx. time of event: 2012 Sep 23, 07:35 - 2012 Sep 23, 07:40 UT * geocentric midpoint of event [JD]: 2456193.81998333 * magnitude of target star: 9.7 * magnitude drop [mag]: 7.8 * estimated maximum duration [s]: 1.0 * Moon: 55 % sunlit, 169° distance * Sun: 87° distance * rough path description: SE USA, Mexico The occultation path -------------------- * approximate projected width [km]: 22 * 1 sigma uncertainty interval [path widths]: +/- 4.19 * 1 sigma uncertainty interval [seconds]: +/- 4.1 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .060 +/- .054) * 1 sigma uncertainty ellipse (major, minor, PA): ( .060", .054", 91° ) * approx speed of asteroid's shadow [km/s]: 20.3764 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 2420-00380-1 by 2154 Underhill on 2012 Sep 23 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 -117 0 0 8 28 22 7 35 51 0 59 -82 8 21 17 8 35 28 .. .. .. 9 35 11 -116 0 0 9 5 8 7 35 51 1 59 -81 8 58 1 9 12 15 .. .. .. 10 12 9 -115 0 0 9 42 12 7 35 52 2 59 -81 9 35 5 9 49 21 .. .. .. 10 49 24 -114 0 0 10 19 34 7 35 52 4 59 -80 10 12 25 10 26 44 .. .. .. 11 26 57 -113 0 0 10 57 12 7 35 53 5 59 -79 10 50 2 11 4 22 .. .. .. 12 4 45 -112 0 0 11 35 5 7 35 53 6 59 -78 11 27 54 11 42 16 10 27 55 12 42 48 -111 0 0 12 13 11 7 35 54 7 60 -77 12 5 59 12 20 24 11 5 52 13 21 4 -110 0 0 12 51 31 7 35 55 8 60 -76 12 44 17 12 58 44 11 44 2 13 59 33 -109 0 0 13 30 1 7 35 56 9 60 -75 13 22 47 13 37 15 12 22 24 14 38 12 -108 0 0 14 8 41 7 35 57 11 60 -74 14 1 26 14 15 56 13 0 56 15 17 0 -107 0 0 14 47 30 7 35 58 12 61 -73 14 40 14 14 54 46 13 39 37 15 55 57 -106 0 0 15 26 26 7 36 0 13 61 -72 15 19 9 15 33 43 14 18 26 16 35 0 -105 0 0 16 5 28 7 36 1 14 61 -71 15 58 11 16 12 46 14 57 21 17 14 9 -104 0 0 16 44 34 7 36 3 15 62 -70 16 37 16 16 51 53 15 36 22 17 53 21 -103 0 0 17 23 44 7 36 5 16 62 -69 17 16 25 17 31 3 16 15 26 18 32 36 -102 0 0 18 2 55 7 36 7 18 62 -68 17 55 36 18 10 14 16 54 32 19 11 53 -101 0 0 18 42 6 7 36 9 19 63 -66 18 34 46 18 49 26 17 33 38 19 51 8 -100 0 0 19 21 16 7 36 11 20 63 -65 19 13 56 19 28 36 18 12 45 20 30 22 - 99 0 0 20 0 23 7 36 14 21 63 -64 19 53 3 20 7 44 18 51 49 21 9 33 - 98 0 0 20 39 27 7 36 16 22 64 -63 20 32 6 20 46 47 19 30 50 21 48 38 - 97 0 0 21 18 24 7 36 19 23 64 -62 21 11 4 21 25 45 20 9 46 22 27 38 - 96 0 0 21 57 15 7 36 21 24 65 -61 21 49 54 22 4 37 20 48 35 23 6 30 - 95 0 0 22 35 58 7 36 24 26 65 -60 22 28 37 22 43 19 21 27 17 23 45 14 - 94 0 0 23 14 31 7 36 27 27 66 -59 23 7 10 23 21 52 22 5 50 24 23 47 - 93 0 0 23 52 53 7 36 30 28 66 -58 23 45 32 24 0 14 22 44 13 25 2 8 - 92 0 0 24 31 3 7 36 33 29 67 -56 24 23 42 24 38 24 23 22 24 25 40 16 - 91 0 0 25 8 59 7 36 36 30 67 -55 25 1 38 25 16 20 24 0 22 26 18 10 - 90 0 0 25 46 40 7 36 39 31 68 -54 25 39 20 25 54 1 24 38 6 26 55 49 - 89 0 0 26 24 5 7 36 43 32 68 -53 26 16 46 26 31 26 25 15 34 27 33 11 - 88 0 0 27 1 13 7 36 46 33 69 -52 26 53 54 27 8 33 25 52 46 28 10 15 - 87 0 0 27 38 3 7 36 50 34 70 -51 27 30 44 27 45 22 26 29 40 28 47 0 - 86 0 0 28 14 33 7 36 53 35 70 -50 28 7 15 28 21 52 27 6 15 29 23 25 - 85 0 0 28 50 42 7 36 57 36 71 -49 28 43 25 28 58 1 27 42 30 29 59 28 - 84 0 0 29 26 30 7 37 1 37 72 -48 29 19 13 29 33 48 28 18 24 30 35 10 - 83 0 0 30 1 56 7 37 4 38 72 -47 29 54 39 30 9 12 28 53 57 31 10 28 - 82 0 0 30 36 57 7 37 8 39 73 -46 30 29 42 30 44 13 29 29 6 31 45 22 - 81 0 0 31 11 35 7 37 12 40 74 -45 31 4 20 31 18 50 30 3 51 32 19 52 - 80 0 0 31 45 47 7 37 16 41 75 -44 31 38 33 31 53 1 30 38 12 32 53 55 - 79 0 0 32 19 33 7 37 20 42 75 -43 32 12 20 32 26 47 31 12 7 33 27 32 - 78 0 0 32 52 53 7 37 24 43 76 -41 32 45 41 33 0 5 31 45 36 34 0 42 - 77 0 0 33 25 45 7 37 28 44 77 -40 33 18 34 33 32 56 32 18 38 34 33 25 - 76 0 0 33 58 10 7 37 32 45 78 -39 33 51 0 34 5 20 32 51 12 35 5 38 - 75 0 0 34 30 5 7 37 36 46 79 -38 34 22 57 34 37 14 33 23 19 35 37 23 - 74 0 0 35 1 32 7 37 40 47 80 -37 34 54 25 35 8 40 33 54 57 36 8 39 - 73 0 0 35 32 29 7 37 45 48 81 -37 35 25 23 35 39 36 34 26 5 36 39 24 - 72 0 0 36 2 57 7 37 49 49 82 -36 35 55 52 36 10 2 34 56 44 37 9 40 - 71 0 0 36 32 53 7 37 53 50 83 -35 36 25 50 36 39 57 35 26 53 37 39 24 - 70 0 0 37 2 20 7 37 57 51 84 -34 36 55 17 37 9 22 35 56 31 38 8 38 - 69 0 0 37 31 15 7 38 1 51 85 -33 37 24 14 37 38 16 36 25 39 38 37 20 - 68 0 0 37 59 39 7 38 6 52 86 -32 37 52 39 38 6 39 36 54 16 39 5 32 - 67 0 0 38 27 32 7 38 10 53 87 -31 38 20 34 38 34 30 37 22 22 39 33 11 - 66 0 0 38 54 53 7 38 14 54 89 -30 38 47 56 39 1 50 37 49 56 40 0 19 - 65 0 0 39 21 42 7 38 18 55 90 -29 39 14 47 39 28 38 38 16 58 40 26 54 - 64 0 0 39 48 0 7 38 23 55 91 -28 39 41 6 39 54 54 38 43 29 40 52 58 - 63 0 0 40 13 45 7 38 27 56 93 -27 40 6 53 40 20 38 39 9 29 41 18 30 - 62 0 0 40 38 59 7 38 31 57 94 -26 40 32 8 40 45 51 39 34 56 41 43 30 - 61 0 0 41 3 41 7 38 36 58 95 -25 40 56 52 41 10 31 39 59 52 42 7 58 - 60 0 0 41 27 51 7 38 40 58 97 -25 41 21 3 41 34 39 40 24 15 42 31 54 - 59 0 0 41 51 29 7 38 44 59 98 -24 41 44 43 41 58 16 40 48 7 42 55 18 - 58 0 0 42 14 36 7 38 48 60 100 -23 42 7 51 42 21 21 41 11 27 43 18 10 - 57 0 0 42 37 10 7 38 52 60 101 -22 42 30 27 42 43 54 41 34 16 43 40 31 - 56 0 0 42 59 14 7 38 57 61 103 -21 42 52 32 43 5 56 41 56 33 44 2 20 - 55 0 0 43 20 45 7 39 1 62 105 -20 43 14 5 43 27 26 42 18 18 44 23 38 - 54 0 0 43 41 46 7 39 5 62 106 -20 43 35 7 43 48 26 42 39 32 44 44 25 - 53 0 0 44 2 16 7 39 9 63 108 -19 43 55 38 44 8 54 43 0 15 45 4 41 - 52 0 0 44 22 14 7 39 13 63 110 -18 44 15 38 44 28 51 43 20 27 45 24 26 - 51 0 0 44 41 42 7 39 17 64 112 -17 44 35 7 44 48 17 43 40 9 45 43 40 - 50 0 0 45 0 40 7 39 22 65 114 -16 44 54 6 45 7 13 43 59 19 46 2 24 - 49 0 0 45 19 7 7 39 26 65 116 -16 45 12 35 45 25 39 44 17 59 46 20 38 - 48 0 0 45 37 4 7 39 30 66 118 -15 45 30 33 45 43 35 44 36 9 46 38 22 - 47 0 0 45 54 31 7 39 34 66 120 -14 45 48 2 46 1 1 44 53 49 46 55 36 - 46 0 0 46 11 29 7 39 38 67 122 -13 46 5 1 46 17 57 45 11 0 47 12 21 - 45 0 0 46 27 57 7 39 42 67 124 -13 46 21 31 46 34 24 45 27 40 47 28 37 - 44 0 0 46 43 57 7 39 46 67 126 -12 46 37 31 46 50 22 45 43 52 47 44 24 - 43 0 0 46 59 27 7 39 50 68 129 -11 46 53 3 47 5 52 45 59 34 47 59 43 - 42 0 0 47 14 29 7 39 54 68 131 -10 47 8 6 47 20 52 46 14 48 48 14 33 - 41 0 0 47 29 3 7 39 58 68 133 -10 47 22 41 47 35 25 46 29 33 48 28 55 - 40 0 0 47 43 8 7 40 2 69 136 -9 47 36 48 47 49 29 46 43 49 48 42 50 - 39 0 0 47 56 46 7 40 6 69 138 -8 47 50 27 48 3 6 46 57 38 48 56 16 - 38 0 0 48 9 57 7 40 9 69 141 -8 48 3 38 48 16 15 47 10 59 49 9 16 - 37 0 0 48 22 39 7 40 13 70 143 -7 48 16 22 48 28 57 47 23 52 49 21 48 - 36 0 0 48 34 55 7 40 17 70 146 -6 48 28 39 48 41 12 47 36 18 49 33 54 - 35 0 0 48 46 44 7 40 21 70 148 -5 48 40 29 48 53 0 47 48 17 49 45 33 - 34 0 0 48 58 7 7 40 25 70 151 -5 48 51 53 49 4 21 47 59 49 49 56 46 - 33 0 0 49 9 3 7 40 28 70 154 -4 49 2 50 49 15 16 48 10 54 50 7 33 - 32 0 0 49 19 33 7 40 32 70 157 -3 49 13 21 49 25 45 48 21 33 50 17 54 - 31 0 0 49 29 37 7 40 36 71 159 -3 49 23 26 49 35 48 48 31 46 50 27 49 - 30 0 0 49 39 16 7 40 40 71 162 -2 49 33 5 49 45 26 48 41 32 50 37 19 - 29 0 0 49 48 29 7 40 43 71 165 -1 49 42 19 49 54 38 48 50 53 50 46 24 - 28 0 0 49 57 16 7 40 47 71 167 -1 49 51 8 50 3 25 48 59 49 50 55 4 - 27 0 0 50 5 39 7 40 51 71 170 0 49 59 31 50 11 47 49 8 19 51 3 19 Uncertainty in time = +/- 5 secs Prediction of 2012 Aug 7.0 Data for the target star ------------------------ * name: TYC 2420-00380-1 * constellation : Auriga * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 06 17 07.2268 DE: +31 05 46.665 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .025, .027 ) * V mag [mag]: 9.7 * B mag [mag]: 10.9 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (2154) Underhill approx. diameter [km]: 21 approx. diameter ["]: .013 distance from Earth [AU]: 2.24900 * orbital information: orbit source: Preston date of fit: 2012 Aug 06 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 888 number of rejected observations: 13 time covered by the observations: 1958 Apr 08 - 2011 Nov 28 1 sigma uncertainty ellipse (major, minor, PA): 0.054, 0.047, 91° remarks: * orbital elements for (2154) Underhill : Mean anomaly = 319.04701044 deg Arg. of pericenter = 119.61921772 deg Long. of node = 0.92734282 deg Inclination = 7.74613723 deg Eccentricity = 0.12389139 Semimajor axis = 2.63759563 AU Perihelion dist = 2.31082025 AU Mag: H = 12.77, G = 0.15 Epoch of elements : MJD 56193.32000000 TDT (2012 Sep 23.320) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Sep 23 2154 Underhill 7h 40.8m UT 9.7 6 17 7.227 31 5 46.67TYC 2420-00380-1 10.9 17.5 21 1.0 2.249 3.457 7.20 -23.4752 31.095 62.88 -0.28 7.6796 -0.05458 0.32050 11.35277 1.84077 -0.00554 0.00020 2000 318.2831222012 920.00000119.619218 0.927343 7.7461370.12389139 2.6375956 2.310820212.7 5.00.15 RATE 2.3008680 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.060 0.054 91 5.19 0.054 0 0-2-5 056146.0020120923_0380-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Aug 06, 20:50 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org