Magnitude => sun & asteroids & comets
Posted: 02.05.2009, 20:44
http://ssd.jpl.nasa.gov/?horizons_doc#s ... quantities
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9. Vis mag. & Surf Bright
Approximate (apparent) visual magnitude & surface brightness. Value
for Pluto includes Charon. The Sun's altitude above the Saturn ring-plane
is not considered for Saturn. When the Moon is at phase angles < 7 deg.
(within 1 day of full), the computed magnitude tends to be ~ 0.12 too
small. Surface brightness is returned for asteroids only if a radius is
known. It is the average visual magnitude of a square-arcsecond of the
illuminated portion of the apparent disk. For observing sites not on the
Earth or Moon, planet and satellite values are not available. Sun, comet
and asteroid values are. Units are (none) and VISUAL MAGNITUDES PER SQUARE
ARCSECOND.
Magnitude laws:
Sun
APmag= M - 5 + 5*log10(d), where M=4.83, d=distance from Sun (parsecs)
Asteroids
APmag= H + 5*log10(delta) + 5*log10(r) -2.5*log10((1-G)*phi1 + G*phi2)
Comets
T-mag=M1 + 5*log10(delta) + k1*log10(r)
N-mag=M2 + 5*log10(delta) + k2*log10(r) + phcof*beta
Surface brightness:
S-brt= V + 2.5*log10(k*PI*a*b')
Labels: APmag S-brt (Non-comet with known dimensions)
APmag (Non-comet with unknown dimensions)
T-mag N-mag (comets; total & nuclear magnitudes)