Source variability (13 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.
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 2XMM UG Sec. 3.1.4 for more details but note also changes described in 3XMM UG 3.6.
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 2XMM UG Sec. 3.1.4 for more details but note also changes described in 3XMM UG 3.6.
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 2XMM UG Sec. 3.1.4 for more details but note also changes described in 3XMM UG 3.6.
PN_FVAR (E) SAS task ekstest: The fractional RMS variability amplitude (deriving from the normalised excess variance) measured in the PN timeseries of the detection. Where multiple PN exposures exist, it is for the one giving the largest probability of variability (PN_CHI2PROB). This quantity provides a measure of the amplitude of variability in the timeseries, above purely statistical fluctuations. See Sec. 3.9 for more details. This column is new in 3XMM-DR4.
PN_FVARERR (E) SAS task ekstest: The error on the fractional RMS variability amplitude for the PN timeseries of the detection (PN_FVAR). See Sec. 3.9 for more details. This column is new in 3XMM-DR4.
M1_FVAR (E) SAS task ekstest: The fractional RMS variability amplitude (deriving from the normalised excess variance) measured in the MOS1 timeseries of the detection. Where multiple MOS1 exposures exist, it is for the one giving the largest probability of variability (M1_CHI2PROB). This quantity provides a measure of the amplitude of variability in the timeseries, above purely statistical fluctuations. See Sec. 3.9 for more details. This column is new in 3XMM-DR4.
M1_FVARERR (E) SAS task ekstest: The error on the fractional RMS variability amplitude for the MOS1 timeseries of the detection (M1_FVAR). See Sec. 3.9 for more details. This column is new in 3XMM-DR4.
M2_FVAR (E) SAS task ekstest: The fractional RMS variability amplitude (deriving from the normalised excess variance) measured in the MOS2 timeseries of the detection. Where multiple MOS2 exposures exist, it is for the one giving the largest probability of variability (M2_CHI2PROB). This quantity provides a measure of the amplitude of variability in the timeseries, above purely statistical fluctuations. See Sec. 3.9 for more details. This column is new in 3XMM-DR4.
M2_FVARERR (E) SAS task ekstest: The error on the fractional RMS variability amplitude for the MOS2 timeseries of the detection (M2_FVAR). See Sec. 3.9 for more details. This column is new in 3XMM-DR4.
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 2XMM UG Sec. 3.2.8). Note that where a timeseries is not available or insufficient points are left in the timeseries after applying background flare GTIs, the value is set to NULL or Undefined
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.