Talk:JPL Small-Body Database
Latest comment: 6 years ago by Klbrain in topic Merge proposal
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Merge proposal edit
I oppose the merge with JPL Horizons On-Line Ephemeris System on the grounds that they are quite different things. The small-body database is for small solar system objects such as asteroids and comets. The JPL Horizons On-Line Ephemeris System provides position information at an arbitrary, user-chosen time for solar system objects, large and small. Jc3s5h (talk) 16:16, 11 February 2016 (UTC)
- I proposed it [the merge] because this is one of the many services offered by the database and makes little to no sense to talk of it outside of the context of the database. Headbomb {talk / contribs / physics / books} 19:17, 11 February 2016 (UTC)
- I don't understand what "it" refers to in Headbomb's statement "this is one of the many services offered by the database". I've never used the JPL Small-Body Database, but I have used the JPL Horizons On-Line Ephemeris System to produce position information about the Earth and Sun (neither of which is a small body). Looking at http://ssd.jpl.nasa.gov/sbdb.cgi it appears the small body database will provide general information, and orbital elements at the time the request is submitted, in one particular format. This information could be used to compute rough positions a little while in the past or future. Horizons, on the other hand, gives the user great flexibility to produce a table of positions at user-chosen times, and great flexibility about the format of the output. For example:
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Revised : Jul 31, 2013 Sun 10
PHYSICAL PROPERTIES (revised Jan 16, 2014):
GM (10^11 km^3/s^2) = 1.3271244004193938 Mass (10^30 kg) ~ 1.988544
Radius (photosphere) = 6.963(10^5) km Angular diam at 1 AU = 1919.3"
Solar Radius (IAU) = 6.955(10^5) km Mean density = 1.408 g/cm^3
Surface gravity = 274.0 m/s^2 Moment of inertia = 0.059
Escape velocity = 617.7 km/s Adopted sidereal per = 25.38 d
Pole (RA,DEC in deg.) = 286.13,63.87 Obliquity to ecliptic = 7 deg 15'
Solar constant (1 AU) = 1367.6 W/m^2 Solar lumin.(erg/s) = 3.846(10^33)
Mass-energy conv rate = 4.3(10^12 gm/s) Effective temp (K) = 5778
Surf. temp (photosphr)= 6600 K (bottom) Surf. temp (photosphr)= 4400 K (top)
Photospheric depth = ~400 km Chromospheric depth = ~2500 km
Sunspot cycle = 11.4 yr Cycle 22 sunspot min. = 1991 A.D.
Motn. rel to nrby strs= apex : RA=271 deg; DEC=+30 deg
speed: 19.4 km/s = 0.0112 AU/day
Motn. rel to 2.73K BB = apex : l=264.7+-0.8; b=48.2+-0.5
speed: 369 +-11 km/s
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Ephemeris / WWW_USER Thu Feb 11 13:16:02 2016 Pasadena, USA / Horizons
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Target body name: Sun (10) {source: DE431mx}
Center body name: Earth (399) {source: DE431mx}
Center-site name: GEOCENTRIC
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Start time : B.C. 0046-Mar-01 00:00:00.0000 UT
Stop time : B.C. 0046-Mar-18 00:00:00.0000 UT
Step-size : 1440 minutes
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Target pole/equ : IAU_SUN {East-longitude +}
Target radii : 696000.0 x 696000.0 x 696000.0 k{Equator, meridian, pole}
Center geodetic : 0.00000000,0.00000000,0.0000000 {E-lon(deg),Lat(deg),Alt(km)}
Center cylindric: 0.00000000,0.00000000,0.0000000 {E-lon(deg),Dxy(km),Dz(km)}
Center pole/equ : High-precision EOP model {East-longitude +}
Center radii : 6378.1 x 6378.1 x 6356.8 km {Equator, meridian, pole}
Target primary : Sun
Vis. interferer : MOON (R_eq= 1737.400) km {source: DE431mx}
Rel. light bend : Sun, EARTH {source: DE431mx}
Rel. lght bnd GM: 1.3271E+11, 3.9860E+05 km^3/s^2
Atmos refraction: NO (AIRLESS)
RA format : HMS
Time format : CAL
EOP file : eop.160210.p160503
EOP coverage : DATA-BASED 1962-JAN-20 TO 2016-FEB-10. PREDICTS-> 2016-MAY-02
Units conversion: 1 au= 149597870.700 km, c= 299792.458 km/s, 1 day= 86400.0 s
Table cut-offs 1: Elevation (-90.0deg=NO ),Airmass (>38.000=NO), Daylight (NO )
Table cut-offs 2: Solar Elongation ( 0.0,180.0=NO ),Local Hour Angle( 0.0=NO )
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Date__(UT)__HR:MN R.A._(ICRF/J2000.0)_DEC delta deldot
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$$SOE
b0046-Mar-01 00:00 00 22 29.81 +02 27 56.3 0.99958267877826 0.5283427
b0046-Mar-02 00:00 00 26 06.87 +02 51 35.1 0.99988826908971 0.5298142
b0046-Mar-03 00:00 00 29 43.97 +03 15 10.5 1.00019457360935 0.5308102
b0046-Mar-04 00:00 00 33 21.12 +03 38 42.2 1.00050130849781 0.5312997
b0046-Mar-05 00:00 00 36 58.35 +04 02 09.8 1.00080817311908 0.5312551
b0046-Mar-06 00:00 00 40 35.67 +04 25 33.2 1.00111485158637 0.5306509
b0046-Mar-07 00:00 00 44 13.10 +04 48 51.8 1.00142101371021 0.5294634
b0046-Mar-08 00:00 00 47 50.67 +05 12 05.4 1.00172631670640 0.5276733
b0046-Mar-09 00:00 00 51 28.39 +05 35 13.6 1.00203040941686 0.5252722
b0046-Mar-10 00:00 00 55 06.29 +05 58 16.0 1.00233294099758 0.5222714
b0046-Mar-11 00:00 00 58 44.36 +06 21 12.4 1.00263357569798 0.5187138
b0046-Mar-12 00:00 01 02 22.64 +06 44 02.4 1.00293201405681 0.5146835
b0046-Mar-13 00:00 01 06 01.14 +07 06 45.5 1.00322801836750 0.5103100
b0046-Mar-14 00:00 01 09 39.86 +07 29 21.5 1.00352143723193 0.5057604
b0046-Mar-15 00:00 01 13 18.83 +07 51 49.9 1.00381222210700 0.5012196
b0046-Mar-16 00:00 01 16 58.06 +08 14 10.3 1.00410042983202 0.4968629
b0046-Mar-17 00:00 01 20 37.55 +08 36 22.5 1.00438620947390 0.4928309
b0046-Mar-18 00:00 01 24 17.33 +08 58 26.1 1.00466977719778 0.4892139
$$EOE
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Column meaning:
TIME
Prior to 1962, times are UT1. Dates thereafter are UTC. Any 'b' symbol in
the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D.
date. Calendar dates prior to 1582-Oct-15 are in the Julian calendar system.
Later calendar dates are in the Gregorian system.
Time tags refer to the same instant throughout the universe, regardless of
where the observer is located.
The dynamical Coordinate Time scale is used internally. It is equivalent to
the current IAU definition of "TDB". Conversion between CT and the selected
non-uniform UT output scale has not been determined for UTC times after the
next July or January 1st. The last known leap-second is used over any future
interval.
NOTE: "n.a." in output means quantity "not available" at the print-time.
R.A._(ICRF/J2000.0)_DEC =
J2000.0 astrometric right ascension and declination of target center.
Adjusted for light-time. Units: HMS (HH MM SS.ff) and DMS (DD MM SS.f)
delta deldot =
Range ("delta") and range-rate ("delta-dot") of target center with respect
to the observer at the instant light seen by the observer at print-time would
have left the target center (print-time minus down-leg light-time); the
distance traveled by a light ray emanating from the center of the target and
recorded by the observer at print-time. "deldot" is a projection of the
velocity vector along this ray, the light-time-corrected line-of-sight from the
coordinate center, and indicates relative motion. A positive "deldot" means the
target center is moving away from the observer (coordinate center). A negative
"deldot" means the target center is moving toward the observer.
Units: AU and KM/S
Computations by ...
Solar System Dynamics Group, Horizons On-Line Ephemeris System
4800 Oak Grove Drive, Jet Propulsion Laboratory
Pasadena, CA 91109 USA
Information: http://ssd.jpl.nasa.gov/
Connect : telnet://ssd.jpl.nasa.gov:6775 (via browser)
telnet ssd.jpl.nasa.gov 6775 (via command-line)
Author : Jon.Giorgini@jpl.nasa.gov
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