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B/astorb       Orbits of Minor Planets                     (Bowell+ 2014)

The Asteroid Orbital Elements Database, version 2018-Jan-14 Bowell E. <Lowell Observatory (1999-2014)>
ADC_Keywords: Minor planets Introduction: astorb.dat is an ASCII file of high-precision osculating orbital elements, ephemeris uncertainties, and some additional data for all the numbered asteroids and the vast majority of unnumbered asteroids (multi-apparition and single-apparition) for which it is possible to make reasonably determinate computations. It contains 30769 orbits computed by the author. Each orbit, based on astrometric observations downloaded from the Minor Planet Center, occupies one 264-column record. Acknowledgment and Attribution: The research and computing needed to generate astorb.dat were funded principally by NASA grant NAGW-1470, and in part by the Lowell Observatory endowment. astorb.dat may be freely used, copied, and transmitted provided attribution to Dr. Edward Bowell and the aforementioned funding sources is made. Hypertext links to this WWW site are welcome. See also: : The Astorb database at Lowell Obs. B/comets : Database of orbital elements of comets (Rocher, 2007) II/190 : IRAS Minor Planet Survey (Tedesco 1992) File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file astorb.dat 276 746697 The catalog of Orbits (2014-01-05) astorb.html 80 818 Introductory text to "astorb.dat" (HTML version) astorb.txt 78 445 Introductory text to "astorb.dat" (plain ascii)
Byte-by-byte Description of file: astorb.dat
Bytes Format Units Label Explanations
1- 6 I6 --- Planet [1,]?+ Asteroid number (blank if unnumbered) 8- 25 A18 --- Name Name or preliminary designation. 27- 41 A15 --- CompName Orbit Computer. 43- 47 F5.2 mag H Absolute magnitude H parameter (1) 49- 53 F5.2 --- G Slope magnitude parameter (1) 55- 58 F4.2 mag B-V ? Color index (see E.F.Tedesco, pp.1090-1138) 60- 64 F5.1 km Diam ? IRAS diameter (see E.F.Tedesco, pp.1151-1161; catalog II/190) 66- 69 A4 --- IRAScl IRAS Taxonomic classification 72- 74 I3 --- Xflg [0/31] Planet-crossing code (4) 76- 78 I3 --- Oflg [0/255] Orbit computation code (5) 80- 82 I3 --- Sflg [0/31] Survey observation code (6) 84- 86 I3 --- MPCC [0/7] MPC critical-list code (7) 88- 90 I3 --- LowC [0/5] Lowell Observatory discovery code (8) 92- 94 I3 --- FlaC [0/10] Flagstaff Station Code (9) 96-100 I5 --- Narc Orbital arc, days, spanned by observations used in orbit computation. 102-105 I4 --- Nobs Number of observations used in orbit computation. 107-114 A8 "YYYYMMDD" Epoch Epoch of osculation, yyyymmdd (TDT) (2) 116-125 F10.6 deg M Mean anomaly (3) 127-136 F10.6 deg omega Argument of perihelion (3) 138-147 F10.6 deg Omega Longitude of ascending node (3) 148-157 F10.6 deg i Inclination (3) 159-168 F10.8 --- e Eccentricity (3) 169-181 F13.8 AU a Semimajor axis (3) 183-190 I8 "YYYYMMDD" DateOrb Date of orbit computation 192-198 E7.1 arcsec CEU ?=0 Current Ephemeris Uncertainty (10) 200-207 E8.1 arcsec/d dCEU ?=0 Rate of change of CEU (10) 209-216 I8 "YYYYMMDD" DateCEU ?=0 Date of CEU 218-224 E7.1 arcsec PEU0 ?=0 Next Peak Ephemeris Uncertainty (PEU) (11) 226-233 I8 "YYYYMMDD" DatePEU0 ?=0 Date of PEU0 235-241 E7.1 arcsec PEU1 ?=0 Largest PEU in 10 years from DatePEU0 (11) 243-250 I8 "YYYYMMDD" DatePEU1 ?=0 Date of PEU1 252-258 E7.1 arcsec PEU2 ?=0 As PEU1, assuming that two observations were made at DatePEU0 (11) 260-267 I8 "YYYYMMDD" DatePEU2 ?=0 Date of PEU2 268 A1 --- mod [a*] added or updated (12) 269-276 I8 "YYYYMMDD" modDate ? Date of last modification (12)
Note (1): Absolute magnitude H, mag [see E. Bowell et al., pp. 549-554, in "Asteroids II", R. P. Binzel et al. (eds.), The University of Arizona Press, Tucson, 1989 and more recent Minor Planet Circulars]. Note that H may be given to 2 decimal places (e.g., 13.41), 1 decimal place (13.4) or zero decimal (13.), depending on its estimated accuracy. H is given to two decimal places for all unnumbered asteroids, even though it may be very poorly known. Note (2): The epoch is the Julian date (TDT) ending in 00.5 nearest the date the file was created. Thus, as the file is updated, epochs will succeed each other at 100-day intervals on or after Julian dates ending in 50.5 (19960308, 19960616, 19960924, 19970102,...) Note (3): the osculating elements are heliocentric, on J2000 Note (4): Planet-crossing asteroids (Note: Because some orbits are very poor (or erroneously linked), there may be errors in assignment of these parameter values) The values are: 1 = Earth-crossing asteroid (ECA), according to Shoemaker et al.'s definition (In "Asteroids", pp. 253-282, T. Gehrels, ed., The University of Arizona Press, Tucson, 1979 ). Some ECAs are currently Amors (q.v.). ECAs have been identified prior to May 1991. After that date, asteroids having q < 1.0167 AU have been assumed to be ECAs. Thus, in the latter group, some may not be ECAs, and some asteroids assumed to be Amors may be ECAs. 2 = Asteroids having perihelia less than the aphelion distance of the Earth (1.0167 AU), but which are not ECAs. 4 = Amors (1.0167 < q < 1.3 AU) (but see also type 1). 8 = Mars crossers (1.3 < q < 1.6660 AU). 16 = Outer-planet crossers (excluding Jupiter Trojans). n = Asteroids (excluding Mars and Jupiter Trojans) that cross both inner- and outer-planet orbits. For example, n=24 crosses the orbits of Mars (q < 1.6660 AU) and Jupiter (Q > 4.950 AU). Note (5): Orbit computation. 1 = Orbits derived from uncertainly, perhaps erroneously linked observations. 2 = Eccentricity assumed. 4 = Eccentricity and semimajor axis assumed. 8 = For numbered asteroids, omitted observations have resulted in degradation of a so-called orbit-quality parameter (OQP, see K. Muinonen and E. Bowell, Icarus 104, 255-279, 1993), generally by more than 0.1. The corresponding ephemeris uncertainty has increased by about 25% or more. 16 = OQP degrades by more than 0.1 if unsubstantiated observations (e.g., one-night apparitions) are omitted. 32 = Orbit derived from data containing observations not in Minor Planet Center files 64 = H is unknown; H = 14 mag assumed. 128 = Asteroid sought, but not found. n = Sum of preceding entries. For example, n=3 pertains to an uncertainly linked orbit for which the eccentricity was assumed. Note (6): Asteroids observed during the course of major surveys. Our definition includes asteroids that were observed but not discovered during the course of a survey. 1 = Palomar-Leiden survey (PLS) asteroids. 2 = Palomar-Leiden T-2 survey asteroids. 4 = Palomar-Leiden T-3 survey asteroids. 8 = U.K. Schmidt Telescope-Caltech asteroid survey (UCAS) asteroids. 16 = Palomar-Leiden T-1 survey asteroids. n = Asteroids observed in more than one survey. For example, n=3 denotes an asteroid observed in both the PLS and T-2 surveys. Note (7): Minor Planet Center (MPC) critical-list numbered asteroids. 1 = Lost asteroid. 2 = Asteroids observed at only two apparitions. 3 = Asteroids observed at only three apparitions. 4 = Asteroids observed at four or more apparitions, last more than ten years ago. 5 = Asteroids observed at four or more apparitions, only one night in last ten years. 6 = Other poorly observed asteroids observed at four or more apparitions. 7 = Absolute magnitude poorly known (not on MPC critical-list). Note (8): Lowell Observatory and related discoveries 1 = Asteroids discovered by E. Bowell. 2 = Non-Bowell discoveries from Lowell search programs. 3 = Discovered jointly by E. Bowell and another person connected with Lowell search programs. Note (9): Rank, in decreasing importance, for our collaborative program of astrometry using the transit circle of the U.S. Naval Observatory Flagstaff Station. 10 = Exceptionally important, to be observed frequently. Principally space mission targets and occultation candidates. 9 = Asteroids useful for mass determination. 8 = Asteroids for which one or two additional nights' observation are required to satisfy orbit-update requirements. Asteroids of type 6:7 whose ephemeris uncertainties are between 2 and 5 arcsec within the next ten years or so. 7 = Bowell unnumbered discoveries whose ephemeris uncertainties are less than 2 arcsec within the next ten years or so. MPC critical-list asteroids. 6 = Planet-crossers of type 6:5. 5 = Numbered asteroids whose ephemeris uncertainties are between 2 and 5 arcsec within the next ten years or so. Unnumbered asteroids that should be numberable after one or two more nights' observation. Note (10): The current 1-σ ephemeris uncertainty CEU and its rate of change dCEU indicate whether an asteroid ought to be located in an observer's field of view. A CEU greater than all three of the peak ephemeris uncertainties (PEU) implies that the asteroid's ephemeris uncertainty is currently greater than at any time in the next ten years. Such asteroids are prime targets for observation because their orbits are subject to the greatest improvement for years to come. Note that, because ephemeris uncertainties have been computed using 2-body rather than n-body error propagation (see K. Muinonen and E. Bowell, Icarus 104, 255-279, 1993), uncertainties for Earth-approaching asteroids may have been misestimated by a factor of several. Note (11): Peak ephemeris uncertainties generally occur near opposition or conjunction (the latter are more prevalent for Earth-crossing asteroids). The next PEU [parameter PEU0] usually indicates the best time to make astrometric observations for orbit improvement, as will the PEU over the next 10 years [parameter PEU1]. Special effort should be made to observe asteroids whose next PEUs are the greatest during the next 10 years [i.e., parameter PEU0 exceeds both parameters PEU1 and PEU2]. Parameter PEU2 may be used to quantify the amount of orbital improvement that would result from observing at or near the date of next PEU. For example, if the next PEU is 1.2D+02 arcsec, and parameter PEU2 has value 6.0D+00 arcsec, a 20-fold ephemeris improvement (and approximately equal improvement in the uncertainties of the orbital elements) could be made. Note that numbered asteroids whose orbits are satisfactory have all three PEUs less than about 2 arcsec (absolute). Consequently, numbered asteroids whose ephemeris uncertainties, as indicated by the CEU and PEUs, at any time exceed about 2 arcsec should be targeted for observation. Unnumbered asteroids whose ephemeris uncertainties [as per parameter PEU2] could be brought below about 2 arcsec, would probably then be candidates for numbering. A parameter PEU2 PEU greater than a parameter PEU1 PEU implies that observing at or near the date of the next PEU [parameter PEU0] may actually cause ephemeris and orbit degradation. Thus, there is no point in making such observations unless they are numerous and/or of high accuracy. Note (12): the two columns "mod" and "modDate" are added at CDS and precises the date of the last modification of the number of observations (columns "Nobs" and "Narc"). The column "mod" contains an "a" for the date of addition of the asteroid, and a "*" for the date of last change in the number of observations. Note that the date is only approximative to about 1 week.
History: * The orbital elements of the Asteroids are regularly (weekly) updated from October 1996 on from the Lowell server at
(End) CDS Catalogues Service 2009-May-10
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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