Specifications

60 AUTOSTAR CCD PHOTOMETRY
Terms and Definitions
It is very important to define terms and keep them straight. The
following is a list of definitions used in the equations for extinction
determination.
Measured Data (Standard Star)
I Star Counts V Star Counts
R Star Counts B Star Counts
Calculated Data (Corrected for 1.0 second integration time)
I Star Counts Corrected V Star Counts Corrected
R Star Counts Corrected B Star Counts Corrected
Equations
Magnitudes are first calculated on the instrumental scale, then
converted to the natural system, and finally transformed to
magnitudes on the standard system.
Instrumental Magnitude Calculations
i = –2.5 * log
10
(I Star Counts) v = –2.5 * log
10
(V Star Counts)
r = –2.5 * log
10
(R Star Counts) b = –2.5 * log
10
(B Star Counts)
Where:
i = Instrumental I Magnitude v = Instrumental V Magnitude
r = instrumental R Magnitude b = Instrumental B Magnitude
The I, R, V, and B Star Counts are normalized to counts per
second. The basic equations for removing the atmospheric effects
on the data are:
i
o
= i – k'
i
* X
v
o
= v – k'
v
* X
r
o
= r – k'
r
* X
b
o
= b – k'
b
* X
k'
vi
=k'
v
– k'
i
k'
v
=k'
v
k'
vr
=k'
v
– k'
i
k'
bv
=k'
b
– k'
v
k'
ri
=k'
r
– k'
i