# Source variability (5 columns)

- PN_CHI2PROB (E)
SAS task
`ekstest`

The Chi^{2} probability (based on the null hypothesis) that
the source as detected by the PN camera is constant. The Pearson's
approximation to Chi^{2} for Poissonian data was used, in
which the model is used as the estimator of its own variance (see
the documentation of `ekstest` for a more detailed
description). If more than one exposure (that is, time series) is
available for this source the smallest value of probability was
used. See Sec. 3.1.4
for more details.

M1_CHI2PROB (E)
SAS task `ekstest`

The Chi^{2} probability (based on the null hypothesis) that
the source as detected by the M1 camera is constant. The Pearson's
approximation to Chi^{2} for Poissonian data was used, in
which the model is used as the estimator of its own variance (see
the documentation of `ekstest` for a more detailed
description). If more than one exposure (that is, time series) is
available for this source the smallest value of probability was
used. See Sec. 3.1.4
for more details.

M2_CHI2PROB (E)
SAS task `ekstest`

The Chi^{2} probability (based on the null hypothesis) that
the source as detected by the M2 camera is constant. The Pearson's
approximation to Chi^{2} for Poissonian data was used, in
which the model is used as the estimator of its own variance (see
the documentation of `ekstest` for a more detailed
description). If more than one exposure (that is, time series) is
available for this source the smallest value of probability was
used. See Sec. 3.1.4
for more details.

VAR_FLAG
(L)

The flag is set to **T**rue if this source was detected as
variable (Chi^{2} probability < 1E-5, see PN_CHI2PROB, M1_CHI2PROB, M2_CHI2PROB) in at least one exposure
(see Sec. 3.3.7).

VAR_EXP_ID (13A)

If the source is detected as variable (that is, if VAR_FLAG is set to **T**rue), the
exposure ID of the exposure with the smallest Chi^{2}
probability is given here.