XMM-Newton SAS Home Page
XMM-Newton Science Analysis System

ewavelet (ewavelet-3.12) [xmmsas_20211130_0941-20.0.0]

Output Files

  1. EPIC ewavelet source list. The source list will contain the following columns: SRC_NUM, IMAX, JMAX, X_IMA, Y_IMA, X_IMA_ERR, Y_IMA_ERR, RA,DEC, RADEC_ERR, SCTS, SCTS_ERR, WSCALE, WCORR, XYCORR, RATE, EXTENT, EXT_ERR, EXP_MAP and BG_MAP.

    Most of them can also be found in the tasks eboxdetect and emldetect. New are:

    1. IMAX, JMAX: pixels (integer) where the maximum correlation value was found (X_IMA, Y_IMA give a refined measurement of the position)
    2. WSCALE: the wavelet scale at which the source was found. This gives an indication of the source extent (in Gaussian $\sigma$). Note that if the value is comparable to the point spread function one is probably dealing with a point source.
    3. WCORR: the maximum correlation value ($C_{i,j}$ in this description).
    4. EXTENT and EXT_ERR: gives the source extent (in image pixels) and its error (not correcting for the spread function). It is defined as $\sigma'\sqrt{8\ln 2}$ (see eq. 6). This corresponds to the FWHM for a Gaussian.
    5. XYCORR: Correlation value between X and Y. Large values are an indication of an elongated source with a position angle around 45$^\circ$.
  2. FITS image containing the final background map generated and used by ewavelet.
  3. A fits image with the “reconstructed image”: the detected sources are represented by Gaussians with $\sigma =$wavelet scale and normalization the number of counts found by the algorithm. This image will make it easy to compare results of the task with the input image.

XMM-Newton SOC -- 2021-11-30