Observations.dat (of asteroidal occultations) The Observations.dat file contains all the observations of asteroidal occultations. It is a fixed record-length file (151 bytes) with the following data structure: Header line 1 Columns Format Definition 1 A1 Header flag [= '*'] 2 - 21 A20 Asteroid number and name 22 - 29 yyyymmdd Year/month/day of the event. If event extends past 24hrs, specify the earlier date, and specify hours greater than 24h, as needed. 30 - 43 A14 Star number: HIP xxxxx Hipparcos number pppp-nnnnn-x Tycho2 number 2Uxxxxxxxx UCAC2 number 44 - 54 hhmmss.ssss RA of star J2000, at epoch 55 - 65 -ddmmss.sss Dec of star J2000, at epoch 66 - 71 _hh.hh Zero time for motions 72 - 79 F8 RA motion of asteroid (sec/hr) 80 - 87 F8 2nd order RA motion (sec/hr/hr) 88 - 94 F7 Dec motion of asteroid ("/hr) 95 -101 F7 2nd order Dec motion ("/hr/hr) 102-108 F7.4 Parallax of asteroid (") 109-149 A11 blank 128-137 I4,I3,I3 Year, month and day of last update to any data item in the event record. 138-139 A2 blank 140-149 I4,I3,I3 Year, month and day of last edit of any observation record in the event record 150-151 A2 CR/LF sequence Header line 2 Columns Format Definition 1 A1 Header flag [= '#'] 2 - 7 F6.2 Mv of star 8 - 13 F6.2 Mv of asteroid 14 - 18 A5 Asteroid diameter (km) 19 A1 space 20 - 25 F6.1 X coord of best-fit ellipse (km) 26 - 31 F6.1 Y coord of best-fit ellipse (km) 32 - 37 F6.1 Major axis of best-fit ellipse (km) 38 - 43 F6.1 Minor axis of best-fit ellipse (km) 44 - 49 F6.1 PA of major axis of best-fit ellipse 50 - 55 F6.1 Separation of 2nd star (milli-arcsecs) 56 - 61 F6.1 PA of 2nd star 62 - 63 A2 blank 64 A1 Code for fit quality 0 not fitted 1 UT only [no fit, just relative location of star and asteroid] 2 poor fit 3 good fit 4 excellent fit 66 - 71 F6.1 Standard deviation - Major axis (km) 72 - 77 F6.1 Standard deviation - Minor axis (km) 78 - 83 F6.1 Standard deviation - PA of Major axis (deg) 84 - 89 F6.1 Standard deviation - Separation (milli-arcsecs) 90 - 95 F6.1 Standard deviation - PA of 2nd star (deg) 96 -101 F6.1 Standard deviation - centre of ellipse - X (km) 102-107 F6.1 Standard deviation - centre of ellipse - Y (km) 108-119 A12 blank 120 I1 Include Miss events in solution 121 I1 Solve for major axis (1 = yes) 122 I1 Solve for minor axis (1 = yes) 123 I1 Solve for PA of major axis (1 = yes) 124 I1 Solve for separation of 2nd star (1 = yes) 125 I1 Solve for PA of 2nd star (1 = yes) 126 I1 Solve for a circular solution (1 = yes) 127-149 A23 blank 150-151 A2 CR/LF sequence Header line 3 Columns Format Definition 1 A1 Header flag [= '^'] 2 - 12 F11.6 UT of event used to position the plot 13 - 21 F9.1 Geocentric X of ellipse (km) at event time 22 - 29 F8.1 Geocentric Y of ellipse (km) at event time 30 - 39 F10.1 Geocentric X of ellipse (km) at conjunction 40 - 47 F8.1 Geocentric Y of ellipse (km) at conjunction 48 - 55 F8.1 Geocentric distance (km) at conjunction 56 - 61 A6 " T = " 62 - 65 I4 year 66 A1 < > 67 - 68 I2 month 69 A1 < > 70 - 79 F10.7 day at conjunction (dd.ddddddd) 80 - 85 A6 " Sep =" 86 - 93 F8.4 Separation at conjunction (arcSecs) 94 - 98 A5 " PA =" 99 -106 F8.3 PA at conjunction (deg) 107-113 A7 " dSep =" 114-119 F6.1 Uncertainty in separation (masec) 120-126 A7 " dUT =" 127-135 F9.7 Uncertainty in UT of conjunction (days) 136-140 A5 " N = " 141-144 I4 Number of chords used in analyis Observation lines Columns Format Definition 1 - 3 A3 Sequence number for observer 4 - 40 A37 Observer identifier 41 A1 Space 42 - 52 -dddmmss.ss Site longitude (east positive) 53 - 61 -ddmmss.s Site latitude (north positive) 62 - 66 A5 Site altitude (m) 67 A1 Code for Datum: < >= WGS84 N = NAD1927 E = EP1950 T = Tokyo G = GSBN80 * = unspecified, or other. 68 - 70 I3 Telescope Aperture (cm) 71 A1 Telescope type < >= unstated 1 = Refractor 2 = Newtonian 3 = Schmidt-Cassegrain 4 = Dobsonian 5 = Binoculars 6 = Other 7 = None 72 A1 Stability < >= unstated 1 = Steady 2 = Slight flickering 3 = Strong flickering 73 A1 Transparency < >= unstated 1 = Clear 2 = Fog 3 = Thin cloud <2 [mag loss <2 mag.] 4 = Thick cloud >2 [mag loss >2 mag. 5 = Broken opaque cloud [that is, observed thru gaps in the cloud] 6 = Star faint 7 = By averted vision 74 A1 Time Source < >= unstated 1 = GPS - video inserted 2 = GPS - other linking 3 = Video + audio time signal 4 = Tape Recorder + time signal 5 = Eye-ear + time signal 6 = Stopwatch 7 = Radio broadcast - calibrated 8 = Other 75 - 83 hhmmss.ss UT of disappearance 84 A1 Event code. D for main star d for 2nd star M for miss C for Not Seen - eg because of cloud P for data point based on predictions 85 - 88 F4.2 Accuracy for D (secs) 89 - 92 F4.2 Personal equation (secs) 93 I1 Weight for D (<>, 0 to 5) 94 -102 hhmmss.ss UT of reappearance 103 A1 Event code. R for main star r for 2nd star M for miss C for Not Seen - eg because of cloud P for data point based on predictions 104-107 F4.2 Accuracy for R (secs) 108-111 F4.2 Personal equation (secs) 112 I1 Weight for R (<>, 0 to 5) 113 A1 Method code _ Visual, with PE applied 1 Visual, with predetermined PE applied (not observer's estimate) 2 Visual, no PE applied 3 Video with frame analysis 4 Video, photo, or photoelectric 5 Only duration timed 6 Drift scan methods (CCD, photo) 7 Preliminary times only 114 A1 Plot code < >= plot both x = plot none y = plot D only z = plot R only 115-119 F5.2 Adjustment to time base of observer, to fit to other observations 120-149 A30 Free text comments 150-151 A2 CR/LF sequence At the end of each event there is a blank record. The file Observations.inx is an index file for the Observations.dat file. The field definition for this file is as follows: Columns Format Meaing 1 - 4 yyyy year .. of event. If observations extend past 24hrs, use the earlier date 6 - 7 mm month 9 - 10 dd day 11 - 17 I6 asteroid number 19 - 31 A13 asteroid name 33 - 35 I4 number of observation records 37 - 41 I5 record number in the file of the first header line for the event