NICER Name
NICER
Purpose
This function estimates the amount of reddening a star is seen
through, based on its observed colors. Inputs
mag: An NBAND by NOBJECT array, or an NBAND vector. Each row of the
array represents an object, and the columns in that array list
the magnitudes of that object in NBAND different photometric
bands. If NBAND = 3, the colors are assumed to be (J,H,Ks). If
NBAND = 5, the colors are assumed to be (J,H,Ks,I1,I2). In
general, any set of magnitudes is allowed, as long as the
appropriate keyword variables are passed (see below).
dmag: The uncertainty on each magnitude measurement.
Keyword Parameters
color: A vector of the mean color of (unreddened) stars. An NBAND-1
vector. Each entry refers to the mean color formed by taking
mag_i - mag_i+1. For example, if NBAND = 3, the assumed
magnitudes are JHK, and the colors are J-H and H-K. Default
values are provided for (JHK) and (JHK I1 I2) if NBAND = 3
or 5. Otherwise, this vector must be provided.
covar: An NBAND-1 by NBAND-1 matrix, specifying the covariance of
colors of unreddened stars. This is provided for (JHK) and
(JHK I1 I2) if NBAND = 3 or 5. Otherwise, this matrix must
be provided.
ks: The reddening vector for each color. That is,
c_i(observed) = c_i(true) + Av * k. This is provided for
(JHK) and (JHK I1 I2) when NBAND = 3 or 5. Otherwise, this
vector must be provided.
Procedure
Algorithm taken from Lombardi and Alves 2001. Equation references
in code refer to that paper.
JHK extinction law taken from Lebofsky 1985
IRAC extinction law taken from Indebetouw, Mathis et al. 2005
Category
astrophysics
Modification History
Written by: Chris Beaumont July 2008
November 2008: cnb. Updated to incorporate IRAC bands 1 and 2
November 2009: cnb. Completely re-written to better generalize to
different photometric bands. Calling sequence changed.