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constants - list of useful constants
Here we tabulate some
convenience values we often use in astronomy. Only a few are available in
programs that use nemoinp(1NEMO)
3.1415926 pi, math [nemoinp: pi]
2.7182818 e, math
57.295780 Degrees per radian (180/pi)
206264.81 Arcseconds per Radian (3600*180/pi)
2.35482 STOF = 2*sqrt(2*ln(2)) - the FWHM/sigma of a gaussian
1.13309 BOF (beam oversampling factor) = 1.13309 * (FWHM/PIXEL)^2 = pi/(4*ln(2))
1.4826 rms = 1.4826*MAD (Median Absolution Deviation)
3.26163 pc/ly
6.6743e-11 G, grav constant in MKS units [nemoinp: G]
299792.458 c, speed of light, in km/s [nemoinp: c]
3.155693e7 yr, seconds in a year
149597870.700 AU, in km, as per IAU 2009 resolution B2
3.08567758e13 pc, defined as 648000/pi*AU, as per IAU 2015 resolution B2,
in km
1.989e30 Solar Mass, in kg
5.974e24 Earth Mass, in kg
6378.1 Earth Radius, in km
1420.405751786 HI spectral line, in MHz
115.2712018 CO(1-0) spectral line, in GHZ
29.786 average earth orbital speed around sun, km/s
0.4638 earth rotation speed at equator, km/s
Galactic constants such as distance to the galactic center (8.5
kpc) or orbital speed of LSR (220 km/s) , are still subject to change.
See also mkgalorbit(1NEMO)
.
ccdstat(1NEMO)
, ccdsmooth(1NEMO)
, mkgalorbit(1NEMO)
,
units(5NEMO)
, data(5NEMO)
Peter Teuben
inc/cgs.h constants in CGS units
inc/mks.h constants in MKS units
inc/stdinc.h PI
data NEMO standard repository area for data files.
21-aug-2020 created PJT
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