IOTA/IOTA-ES occultation update for (636) Erika / 2UCAC 19996239 event on 2008 Apr 03, 07:38 UT Visible from E Canada (low altitude) Summary ------- On 2008 Apr 03 UT, the 74 km diameter asteroid (636) Erika will occult a 11.9 mag star in the constellation Sagittarius for observers along a path across E Canada (low altitude). In the case of an occultation, the combined light of the asteroid and the star will drop by 2.8 mag to 14.6 mag (the magnitude of the asteroid) for at most 5.4 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: 84 * date and approx. time of event: 2008 Apr 03, 07:33 - 2008 Apr 03, 07:36 UT * midpoint of event [JD]: 2454559.81815417 * magnitude of target star: 11.9 * magnitude drop [mag]: 2.8 * estimated maximum duration [s]: 5.4 * Moon: 11 % sunlit, 63° distance * Sun: 101° distance * rough path description: E Canada (low altitude) The occultation path -------------------- * approximate projected width [km]: 132 * 1 sigma uncertainty interval [path widths]: +/- 0.61 * 1 sigma uncertainty interval [seconds]: +/- 4.3 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .039 +/- .025) * 1 sigma uncertainty ellipse (major, minor, PA): ( .039", .025", 91° ) * approx speed of asteroid's shadow [km/s]: 13.6983 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 19996239 by 636 Erika on 2008 Apr 3 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 ' " Longitude Longitude Longitude Longitude - 63 55 59 56 0 0 7 33 48 1 152 -17 - 65 7 22 - 62 43 51 ... .. .. - 61 14 47 - 62 56 52 55 0 0 7 33 49 2 153 -17 - 64 7 2 - 61 45 58 ... .. .. - 60 18 23 - 61 57 10 54 0 0 7 33 49 3 154 -17 - 63 6 14 - 60 47 23 ... .. .. - 59 21 8 - 60 56 49 53 0 0 7 33 50 4 155 -17 - 62 4 52 - 59 48 1 ... .. .. - 58 22 58 - 59 55 45 52 0 0 7 33 52 6 156 -17 - 61 2 55 - 58 47 50 - 62 23 52 - 57 23 50 - 58 53 55 51 0 0 7 33 54 7 156 -17 - 60 0 17 - 57 46 46 - 61 20 15 - 56 23 42 - 57 51 13 50 0 0 7 33 56 8 157 -17 - 58 56 53 - 56 44 45 - 60 16 0 - 55 22 28 - 56 47 36 49 0 0 7 33 58 9 158 -17 - 57 52 41 - 55 41 42 - 59 11 2 - 54 20 6 - 55 42 59 48 0 0 7 34 1 10 159 -17 - 56 47 33 - 54 37 33 - 58 5 17 - 53 16 30 - 54 37 16 47 0 0 7 34 5 11 160 -17 - 55 41 27 - 53 32 13 - 56 58 39 - 52 11 35 - 53 30 22 46 0 0 7 34 9 13 161 -17 - 54 34 15 - 52 25 36 - 55 51 2 - 51 5 15 - 52 22 12 45 0 0 7 34 13 14 162 -16 - 53 25 52 - 51 17 35 - 54 42 22 - 49 57 24 - 51 12 38 44 0 0 7 34 18 15 163 -16 - 52 16 11 - 50 8 5 - 53 32 31 - 48 47 55 - 50 1 32 43 0 0 7 34 23 16 164 -16 - 51 5 6 - 48 56 57 - 52 21 22 - 47 36 39 - 48 48 47 42 0 0 7 34 28 18 165 -15 - 49 52 28 - 47 44 1 - 51 8 49 - 46 23 27 - 47 34 13 41 0 0 7 34 35 19 166 -15 - 48 38 8 - 46 29 10 - 49 54 42 - 45 8 8 - 46 17 39 40 0 0 7 34 41 20 167 -14 - 47 21 56 - 45 12 10 - 48 38 51 - 43 50 31 - 44 58 54 39 0 0 7 34 49 21 168 -13 - 46 3 41 - 43 52 50 - 47 21 8 - 42 30 20 - 43 37 44 38 0 0 7 34 57 22 169 -13 - 44 43 11 - 42 30 54 - 46 1 19 - 41 7 20 - 42 13 52 37 0 0 7 35 5 24 170 -12 - 43 20 9 - 41 6 5 - 44 39 11 - 39 41 10 - 40 46 59 36 0 0 7 35 14 25 172 -11 - 41 54 19 - 39 38 1 - 43 14 28 - 38 11 26 - 39 16 42 35 0 0 7 35 24 26 173 -10 - 40 25 20 - 38 6 17 - 41 46 51 - 36 37 41 - 37 42 35 34 0 0 7 35 35 27 175 -9 - 38 52 47 - 36 30 24 - 40 16 0 - 34 59 18 - 36 4 4 33 0 0 7 35 46 28 176 -8 - 37 16 11 - 34 49 42 - 38 41 27 - 33 15 33 - 34 20 27 32 0 0 7 35 59 29 178 -6 - 35 34 55 - 33 3 24 - 37 2 41 - 31 25 26 - 32 30 49 31 0 0 7 36 12 30 180 -5 - 33 48 11 - 31 10 27 - 35 19 1 - 29 27 41 - 30 34 0 30 0 0 7 36 27 31 182 -4 - 31 55 0 - 29 9 25 - 33 29 38 - 27 20 29 - 28 28 23 29 0 0 7 36 43 32 184 -2 - 29 54 1 - 26 58 19 - 31 33 25 - 25 1 12 Latitude Latitude Latitude Latitude - 28 0 0 28 47 6 7 36 47 32 185 -1 28 7 22 29 27 35 27 19 53 30 18 6 - 27 0 0 28 20 35 7 36 55 33 186 -1 27 41 12 29 0 44 26 54 5 29 50 48 Uncertainty in time = +/- 5 secs [Prediction of 2008 Feb 28.0] Data for the target star ------------------------ * name: 2UCAC 19996239 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 18 13 52.4902 DE: -28 57 47.786 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .028, .022 ) * V mag [mag]: 11.9 * B mag [mag]: 0.0 * Apparent position with proper motion RA(deg): 273.6039314484 DE(deg): -28.9620679389 * Equation of equinoxes (radians) : 0.000040991632156 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (636) Erika approx. diameter [km]: 74 approx. diameter ["]: .043 distance from Earth [AU]: 2.37100 * orbital information: orbit source: Preston date of fit: 2008 Feb 27 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 889 number of rejected observations: 53 time covered by the observations: 1907 Mar 03 - 2007 Jul 25 1 sigma uncertainty ellipse (major, minor, PA): 0.027, 0.013, 93° remarks: * orbital elements for (636) Erika : Mean anomaly = 298.98171550 deg Arg. of pericenter = 297.72245397 deg Long. of node = 34.78356159 deg Inclination = 7.92978483 deg Eccentricity = 0.17524399 Semimajor axis = 2.90929390 AU Perihelion dist = 2.39945762 AU Mag: H = 9.54, G = 0.15 Epoch of elements : MJD 54559.31800000 TDT (2008 Apr 03.318) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Apr 3 636 Erika 7h 38.1m UT 11.9 18 13 52.490-28 57 47.792UCAC 19996239 0.0 14.6 74 5.4 2.371 2.093 -8.21 -33.0776 -28.960 66.28 5.50 7.6357 0.23792 0.79210 7.40800 -2.21367 -0.00566 -0.00004 2000 297.1309762008 325.00000297.722454 34.783562 7.9297850.17524399 2.9092939 2.3994576 9.5 5.00.15 RATE 1.9861990 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.039 0.025 91 1.61 0.026 0 54524.5020080403_996239 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 07, 13:35 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org