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NOTICE:
This Legacy journal article was published in Volume 4, February 1994, and has not been
updated since publication. Please use the search facility above to find regularly-updated information about
this topic elsewhere on the HEASARC site.
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Table 2
Additional units allowed within OGIP datasets & software
Quantity Unit Meaning Notes
String
plane angle deg degree of arc 1.745533 x 10-2 rad
arcsec second of arc 4.848137 x 10-6 rad
arcmin minute of arc 2.90888 x 10-4 rad
time min minute (incl sidereal time if appropriate)
h hour (incl sidereal time if appropriate)
d day 8.64 x 104 s
yr year (Julian) 3.15576 x107 s (365.25 d)
energy + eV electron volt 1.602177 x 10--19 J
erg erg 10-7 J
length angstrom angstrom 10-10 m
AU astronomical unit 1.49598 x 1011 m
lyr light year 9.460530 x 1015 m
+ pc parsec 3.0857 x 1016 m
events count counts
photon photons
flux density + Jy jansky 10-26 W m-2 Hz-1
mag (stellar) magnitude (see text)
+ Crab 'crab' (see text)
magnetic field G gauss 10-4 T
area pixel (image/detector) pixel
barn barn 10-28 m2
Miscellaneous 'units'
chan (detector) channel
bin numerous applications (including the 1-d analog of pixel)
voxel 3-d analog of pixel
byte (computer) byte
+ - addition of prefixes for decimal multiples & submultiples are allowed
(see Section 2.3)
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