Source variability (7 columns)

EP_CHI2PROB (E): The χ² 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.
This column was not given in 2XMMp.
PN_CHI2PROB (E) SAS task ekstest: The χ² probability (based on the null hypothesis) that the source as detected by the PN camera is constant. The Pearson's approximation to χ² 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 χ² probability (based on the null hypothesis) that the source as detected by the M1 camera is constant. The Pearson's approximation to χ² 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 χ² probability (based on the null hypothesis) that the source as detected by the M2 camera is constant. The Pearson's approximation to χ² 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 True if this source was detected as variable (χ² 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 True), the exposure ID ('S' or 'U' followed by a three-digit number) of the exposure with the smallest χ² probability is given here.
VAR_INST_ID (2A): If the source is detected as variable (that is, if VAR_FLAG is set to True), the instrument ID (PN, M1, M2) of the exposure given in VAR_EXP_ID is listed here.
This column was not given in 2XMMp.