ANNULAR/TOTAL ECLIPSE OF 3 OCTOBER 1986 - CENTERLINE DATA The following tables give centerline data for the annular/total solar eclipse of 03 October 1986 for elevations (flight altitudes) of 38000, 40000, and 42000 feet above mean seal level. The data are tabulated in intervals of 30 seconds along the entire path of totality. Data for one point, on either end of the totality track, are tabulated in the annular region. The tables contain the following information: U.T. - Universal Time of mid-eclipse for the given latitude and longitude. The Univeral Times tabulated are for an assumed Delta-T correction of 56.0 seconds. LONGITUDE - The geographic longitude of the shadow axis for the tabulated Universal Time. If a correction to the value of Delta-T employed for the computation of these data is to be applied the new longitude can be found from: NEWLONG = LONGITUDE - 0.00417807(DELTAT - NEWDELTAT), where DELTAT and NEWDELTAT are in seconds. Tabulated longitudes were computed assuming a value of Delta-T of 56.0 seconds. LATITUDE - The geographical latitude of the shadow axis for the tabulated Universal Time. In deriving these data the following numerical values have been used for the geodetic reference spheroid: Equitorial radius: 6378137 meters (IUGG, 1980 value) Flattening factor (f): 1/298.257 (IAU, 1976 value) DUR The duration of totality (or annularity) in seconds. The tabulated durations are for a smooth lunar limb and do not take into account variations which may arise from the lunar limb profile. Note, in these calculations the value of k is taken to be k=0.2725076 (where [k sin pi] is the sine of the apparent lunar semidiameter, pi is the lunar horizontal parallax. WID The projected width of the lunar shadow, i.e. the length of the major axis of the shadow ellipse, in kilometers. ALT The altitude of the sun above an astronomical horizon, in degrees (or 90 degrees - the zenith distance). Note that the apparent horizon, if unobstructed, will be depressed for elevations above mean sea level. ECCNTR - The eccentricity of the projected shadow ellipse. T - T indicates a type code, 1 for Total, 2 for annular. These data have been corrected for the effects of atmospheric refraction. The correction for refraction is accomplished by effectively increasing the observers elevation above sea level (see the Explanatory Supplement to the A.B.N.A., page 54). In order for this to have been done, mean atmospheric temperature/pressure profiles had to be adopted. The profiles employed were derived from observations compiled by Tverskoi (1965, see appended material). The temperatures and pressures assumed for the tracks, at the tabulated elevations, were obtained from a cubicle spline fit to these profiles. The degree of refraction, as a function of zenith distance, was computed as the ratio of two truncated power series parameterized by the pressure and temperature at a given elevation. (See the 1987 Astronomical Almanac, page B62). This was compared to the degree of refraction at sea level, to derive an effective refractive index for the airpath. From this, the observers effective elevation was derived (see Chauvenet, Vol. 1, p. 516). The centerline tracks for the 03 October 1986 eclipse, for the tabulated elevations above mean sea level (38000, 40000 and 42000 feet), are depicted on the accompanying orthographic projection map. The leftmost of the three roughly parallel curves is the centerline at 42000 feet, the center curve corresponds to an elevation of 40000 feet and the rightmost 38000 feet. The centerlines run, in Universal Time, from 18h55m to 1ghl6m. This completely covers the path of totality, but includes only a short segment of the path of annularity at the ends of the curves. Time tics for each minute of Universal Time are shown on the map. The coordinates of the points plotted on the eclipse map are taken from the tabulated centerline data. Glenn Schneider Space Telescope Science Institute 3700 San Martin Drive Johns Hopkins University Homewood Campus Baltimore, MD 21218