# Source variability (7 columns)

- EP_CHI2PROB (E)

The χ^{2} probability (based on the null hypothesis) that
the source, as detected by any of the cameras, is constant.
The minimum value of the available camera probabilities (PN_CHI2PROB, M1_CHI2PROB, M2_CHI2PROB) is given.

PN_CHI2PROB (E)
SAS task `ekstest`

The χ^{2} probability (based on the null hypothesis) that
the source as detected by the PN camera is constant. The Pearson's
approximation to χ^{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 χ^{2} probability (based on the null hypothesis) that
the source as detected by the M1 camera is constant. The Pearson's
approximation to χ^{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 χ^{2} probability (based on the null hypothesis) that
the source as detected by the M2 camera is constant. The Pearson's
approximation to χ^{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 (χ^{2} probability < 1E-5, see PN_CHI2PROB, M1_CHI2PROB, M2_CHI2PROB) in at least one exposure
(see Sec. 3.2.8).

VAR_EXP_ID (4A)

If the source is detected as variable (that is, if VAR_FLAG is set to **T**rue), the
exposure ID ('S' or 'U' followed by a three-digit number) of the
exposure with the smallest χ^{2} probability is given
here.

VAR_INST_ID (2A)

If the source is detected as variable (that is, if VAR_FLAG is set to **T**rue), the
instrument ID (PN, M1, M2) of the exposure given in VAR_EXP_ID is listed here.