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The following table comes from Astrophysical Formulae by Kenneth R. Lang, California Institute of Technology, Pasadena, California and Tufts University, Medford, Massachussetts.

Symbol	Meaning	Value
c	Speed of light in vacuum	2.997924562(11) x 1010 cm sec-1
h = 2	Planck's constant	6.626196(50) x 10-27 erg s
= h / 2	Rationalized Planck's constant	1.0545919(80) x 10-27 erg s
k	Boltzmann's constant	1.380622(59) x 10-16 erg K-1
e	Elementary charge of an electron	4.803250(21) x 10-10 ESU
me	Rest mass of the electron	9.109558(54) x 10-28 g
G	Gravitational constant	6.6732(31) x 10-8 dyne cm2 g-2
NA	Avogadro's number	6.022169(40) x 1023 mole-1
a.m.u. = u	Atomic mass unit	1.660531(11) x 10-24 g
	Fine-structure constant	7.297351(11) x 10-3
e / m	Electron charge-to-mass ratio	5.272759(16) x 1017 esu g-1
R	Rydberg constant	1.09737312(11) x 105 cm-1
a0	Bohr radius	5.2917715(81) x 10-9 cm
h / (mc)	Compton wavelength	2.4263096(74) x 10-10 cm
r0 = e2 / (mc2)	Classical electron radius	2.817939(13) x 10-13 cm
R	Gas constant	8.31434(35) x 107 erg K-1 mole-1
	Stefan-Boltzmann constant	5.66961(96) x 10-5 erg cm-2 s-1 K-4
T	Thomson cross section	6.652453(62) x 10-25 cm2
au	Astronomical unit	1.49597892(1) x 1013 cm
pc	Parsec	3.0856(1) x 1018 cm
ly	Light year	9.4605 x 1017 cm = 6.324 x 104 au
M	Solar mass	1.989(2) x 1033 g
R	Solar radius	6.9598(7) x 1010 cm
L	Solar luminosity	3.826(8) x 1033 erg sec-1
eV	Electron volt   associated wavelength   associated wavenumber   associated frequency   associated energy   associated temperature	1.23963 x 10-4 cm 8.0671 x 103 cm-1 2.41838 x 1014 Hz 1.60184 x 10-12 erg 1.16059 x 104 °K