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Math to convert MPAS into candelas per sq meter - How to



 
 
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Old April 7th 04, 01:11 AM
PrisNo6
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Default Math to convert MPAS into candelas per sq meter - How to

I am having a problem following how to convert MPAS into nits (
candelas per sq. meter ). Would someone please walk me through the
math for let's say an MPAS 0 and MPAS 1 star? I have reviewed Table
2.2 in Clark's _Visual Astronomy_ book; Schlyter's _Radiometry FAQ_ at
http://www.shell.linux.se/pausch/comp/radfaq.html#7 and Jan Hollan's
Luminance programs at http://www.astro.cz/utf/svetlo/compute/lum.php :

Clark for example computes:
MPAS cd / m^2
0 112700
5 1128

Schylter computes:
MPAS cd / m^2
0 109000
5 1090

Allen's Astrophysical Quantities gives:

1m_v = 0 star per square degree outside atmosphere 0.84 x 10^-2
nit's ( cd / m^2 )

I assume this works by applying Pogson's equation, but I'm having a
problem getting the units to come out properly - perhaps because MPAS
is circular and cd / m^2 are square?

Any pointers would be appreciated.

Regards - Kurt
 




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