Emanom is a general tool for determining whether an EPIC MOS chip is
likely to be in an anomalous state, that is, having an anomalously
high quiescent particle background(QPB) below 
keV. It is
part of the goflib library of functions, subroutines, and tasks. It is
generally used with Extended Source Analysis package. The algorithm is
based on an updated version of Kuntz & Snowden (2008) which relies
upon the 2.5-5.0 keV/0.4-0.8 keV hardness ratio to identify
observations where the low energy band is anomalously high. The object
of this routine is to identify the chips whose QPB spectrum, for this
observation, is significantly different from their normal QPB
spectrum. This routine uses rather restrictive criteria and may not be
suitable for other uses. The work upon which this algorithm is based
will be published shortly.
For each chip experiencing anomalous states (currently MOS1-4, MOS1-5,
MOS2-2, and MOS2-5) this algorithm calculates the 2.5-5.0 keV/0.4-0.8
keV hardness ratio and compares that values to the noan_lim and
anom_lim values for that chip. If the hardness ratio is 
noan_lim the chip is considered good (G), and the QPB background
spectrum should be well characterised. If the hardness ratio is
anom_lim then the chip is considered bad (B), and the QPB
background spectrum cannot be constructed for this chip. If the
hardness ratio falls between noan_lim and anom_lim, then
the chip is considered intermediate (I), and the standard method for
constructing the QPB spectrum may be sufficient, but the user
should exercise caution. If there are so few counts in the spectrum
that the hardness ratio is not defined then the chip is considered to
be in an unknown state (U), and if the chip is not active it is
considered to be off (O).
The hardness ratios, the uncertainty in the hardness ratios, and the flag (B, G, I, O, or U) are reecorded in the header keywords ANOMHRn, ANOMHEn, and ANOMFLn respectively if writekeys is true.
Note that chips that are in anomalous states still have useable spectra at energies greater than 1 keV.
