IOTA/IOTA-ES occultation update for (636) Erika / 2UCAC 19993607 event on 2008 Mar 31, 02:22 UT Visible from Africa Summary ------- On 2008 Mar 31 UT, the 74 km diameter asteroid (636) Erika will occult a 12.3 mag star in the constellation Sagittarius for observers along a path across Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.4 mag to 14.6 mag (the magnitude of the asteroid) for at most 5.0 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: 42 * date and approx. time of event: 2008 Mar 31, 02:16 - 2008 Mar 31, 02:21 UT * midpoint of event [JD]: 2454556.5984625 * magnitude of target star: 12.3 * magnitude drop [mag]: 2.4 * estimated maximum duration [s]: 5.0 * Moon: 38 % sunlit, 22° distance * Sun: 98° distance * rough path description: Africa The occultation path -------------------- * approximate projected width [km]: 95 * 1 sigma uncertainty interval [path widths]: +/- 1.57 * 1 sigma uncertainty interval [seconds]: +/- 8.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .077 +/- .065) * 1 sigma uncertainty ellipse (major, minor, PA): ( .077", .065", 90° ) * approx speed of asteroid's shadow [km/s]: 14.9068 * website for maps: http://lunar-occultations.com/iota/asteroids/astrndx.htm http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 19993607 by 636 Erika on 2008 Mar 31 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 - 6 0 0 44 45 7 2 16 13 1 133 -35 44 10 38 45 19 58 .. .. .. .. .. .. - 5 0 0 44 5 4 2 16 13 2 134 -36 43 30 38 44 39 53 .. .. .. .. .. .. - 4 0 0 43 24 40 2 16 13 3 135 -36 42 50 16 43 59 27 .. .. .. 45 51 15 - 3 0 0 42 43 56 2 16 14 4 135 -36 42 9 35 43 18 39 .. .. .. 45 10 16 - 2 0 0 42 2 54 2 16 14 5 136 -36 41 28 37 42 37 33 .. .. .. 44 28 58 - 1 0 0 41 21 35 2 16 15 6 137 -36 40 47 22 41 56 10 39 2 7 43 47 20 0 0 0 40 40 1 2 16 16 7 137 -36 40 5 52 41 14 32 38 20 51 43 5 26 1 0 0 39 58 14 2 16 17 8 138 -36 39 24 10 40 32 40 37 39 23 42 23 17 2 0 0 39 16 15 2 16 19 9 139 -36 38 42 17 39 50 36 36 57 46 41 40 54 3 0 0 38 34 7 2 16 20 10 139 -36 38 0 15 39 8 22 36 16 0 40 58 20 4 0 0 37 51 52 2 16 22 11 140 -36 37 18 5 38 25 59 35 34 9 40 15 36 5 0 0 37 9 30 2 16 24 12 141 -36 36 35 50 37 43 31 34 52 13 39 32 45 6 0 0 36 27 5 2 16 26 13 141 -35 35 53 32 37 0 59 34 10 15 38 49 49 7 0 0 35 44 37 2 16 29 14 142 -35 35 11 11 36 18 24 33 28 16 38 6 49 8 0 0 35 2 10 2 16 31 15 143 -35 34 28 51 35 35 49 32 46 18 37 23 47 9 0 0 34 19 44 2 16 34 16 143 -35 33 46 34 34 53 15 32 4 23 36 40 46 10 0 0 33 37 22 2 16 37 17 144 -34 33 4 20 34 10 45 31 22 33 35 57 48 11 0 0 32 55 6 2 16 40 18 145 -34 32 22 12 33 28 20 30 40 50 35 14 54 12 0 0 32 12 57 2 16 44 19 145 -34 31 40 12 32 46 2 29 59 16 34 32 7 13 0 0 31 30 58 2 16 47 20 146 -33 30 58 21 32 3 54 29 17 51 33 49 28 14 0 0 30 49 10 2 16 51 21 147 -33 30 16 42 31 21 56 28 36 39 33 6 59 15 0 0 30 7 35 2 16 55 22 147 -33 29 35 16 30 40 12 27 55 41 32 24 43 16 0 0 29 26 15 2 16 59 24 148 -32 28 54 6 29 58 42 27 14 58 31 42 41 17 0 0 28 45 11 2 17 3 25 148 -32 28 13 11 29 17 28 26 34 32 31 0 55 18 0 0 28 4 26 2 17 8 26 149 -31 27 32 36 28 36 33 25 54 24 30 19 26 19 0 0 27 24 0 2 17 13 27 150 -31 26 52 20 27 55 58 25 14 38 29 38 17 20 0 0 26 43 56 2 17 18 28 151 -30 26 12 25 27 15 43 24 35 13 28 57 30 21 0 0 26 4 15 2 17 23 29 151 -29 25 32 54 26 35 52 23 56 11 28 17 5 22 0 0 25 24 58 2 17 28 30 152 -29 24 53 48 25 56 25 23 17 34 27 37 4 23 0 0 24 46 8 2 17 33 31 153 -28 24 15 7 25 17 25 22 39 23 26 57 29 24 0 0 24 7 45 2 17 39 32 153 -27 23 36 54 24 38 51 22 1 40 26 18 22 25 0 0 23 29 50 2 17 45 33 154 -27 22 59 9 24 0 47 21 24 25 25 39 43 26 0 0 22 52 26 2 17 50 34 155 -26 22 21 55 23 23 12 20 47 40 25 1 35 27 0 0 22 15 32 2 17 56 35 156 -25 21 45 12 22 46 8 20 11 26 24 23 58 28 0 0 21 39 12 2 18 3 36 157 -25 21 9 0 22 9 37 19 35 45 23 46 53 29 0 0 21 3 24 2 18 9 36 158 -24 20 33 23 21 33 40 19 0 37 23 10 22 30 0 0 20 28 11 2 18 15 37 158 -23 19 58 20 20 58 17 18 26 3 22 34 26 31 0 0 19 53 34 2 18 22 38 159 -22 19 23 52 20 23 30 17 52 4 21 59 6 32 0 0 19 19 33 2 18 29 39 160 -21 18 50 0 19 49 19 17 18 41 21 24 23 33 0 0 18 46 9 2 18 35 40 161 -21 18 16 46 19 15 45 16 45 55 20 50 18 34 0 0 18 13 23 2 18 42 41 162 -20 17 44 10 18 42 50 16 13 47 20 16 51 35 0 0 17 41 17 2 18 49 42 163 -19 17 12 13 18 10 34 15 42 17 19 44 4 36 0 0 17 9 50 2 18 56 42 164 -18 16 40 55 17 38 58 15 11 27 19 11 57 37 0 0 16 39 3 2 19 4 43 165 -17 16 10 17 17 8 2 14 41 16 18 40 31 38 0 0 16 8 57 2 19 11 44 166 -16 15 40 20 16 37 47 14 11 45 18 9 47 39 0 0 15 39 33 2 19 18 45 167 -15 15 11 4 16 8 14 13 42 55 17 39 45 40 0 0 15 10 51 2 19 26 45 169 -14 14 42 30 15 39 23 13 14 47 17 10 26 41 0 0 14 42 51 2 19 33 46 170 -14 14 14 39 15 11 15 12 47 21 16 41 49 42 0 0 14 15 34 2 19 41 46 171 -13 13 47 30 14 43 50 12 20 36 16 13 57 43 0 0 13 49 0 2 19 48 47 172 -12 13 21 4 14 17 8 11 54 35 15 46 49 44 0 0 13 23 10 2 19 56 48 173 -11 12 55 22 13 51 10 11 29 16 15 20 25 45 0 0 12 58 5 2 20 4 48 175 -10 12 30 24 13 25 57 11 4 40 14 54 47 46 0 0 12 33 43 2 20 11 49 176 -9 12 6 10 13 1 28 10 40 48 14 29 53 47 0 0 12 10 6 2 20 19 49 177 -8 11 42 40 12 37 44 10 17 40 14 5 45 48 0 0 11 47 15 2 20 27 49 179 -7 11 19 55 12 14 45 9 55 16 13 42 23 49 0 0 11 25 8 2 20 35 50 180 -6 10 57 55 11 52 31 9 33 36 13 19 47 50 0 0 11 3 46 2 20 43 50 182 -5 10 36 40 11 31 3 9 12 41 12 57 57 51 0 0 10 43 10 2 20 50 51 183 -4 10 16 10 11 10 20 8 52 30 12 36 53 52 0 0 10 23 19 2 20 58 51 184 -3 9 56 25 10 50 23 8 33 4 12 16 36 53 0 0 10 4 14 2 21 6 51 186 -2 9 37 26 10 31 12 8 14 23 11 57 5 54 0 0 9 45 55 2 21 14 51 187 -1 9 19 13 10 12 47 7 56 26 11 38 21 Uncertainty in time = +/- 9 secs [Prediction of 2008 Feb 14.0] Data for the target star ------------------------ * name: 2UCAC 19993607 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 18 11 04.7954 DE: -28 47 19.588 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .073, .064 ) * V mag [mag]: 12.3 * B mag [mag]: 0.0 * Apparent position with proper motion RA(deg): 272.9046299896 DE(deg): -28.7881365341 * Equation of equinoxes (radians) : 0.000041528544843 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (636) Erika approx. diameter [km]: 74 approx. diameter ["]: .042 distance from Earth [AU]: 2.41900 * orbital information: orbit source: Preston date of fit: 2008 Feb 13 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): 0.026, 0.013, 93° remarks: * orbital elements for (636) Erika : Mean anomaly = 298.33903235 deg Arg. of pericenter = 297.72571497 deg Long. of node = 34.78394496 deg Inclination = 7.92985480 deg Eccentricity = 0.17524365 Semimajor axis = 2.90926231 AU Perihelion dist = 2.39943255 AU Mag: H = 9.54, G = 0.15 Epoch of elements : MJD 54556.09900000 TDT (2008 Mar 31.099) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Mar 31 636 Erika 2h 21.8m UT 12.3 18 11 4.795-28 47 19.592UCAC 19993607 0.0 14.6 74 5.0 2.419 2.245 -8.04 48.4862 -28.786 145.60 4.26 2.3631 0.16469 0.60000 8.11843 -2.20987 -0.00570 -0.00003 2000 297.1276302008 325.00000297.725715 34.783945 7.9298550.17524365 2.9092623 2.3994326 9.5 5.00.15 RATE 1.9862310 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.077 0.065 90 2.57 0.066 0 54510.5020080331_993607 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Feb 15, 00:25 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org