XMM-Newton Science Analysis System


omfastshift (omfastshift-1.26) [xmmsas_20230412_1735-21.0.0]

Comments

• FAST mode data is not binned by the DPU. The drifts from the ODF OM Tracking History Auxiliary File need to be corrected for BPE only.

• All events are assumed to occur in the centre of their pixel. The output integer pixel coordinate value is the integer truncation of the real coordinate value.

• For FAST mode, in addition to a tracking frame time, a FAST mode time slice (FMTS) is defined with duration $\sim$ SAMPTIME*10ms, where SAMPTIME is integer (i.e. integer multiples of a CCD frame)

• Each event is tagged with a time stamp (FTCOARSE+FTFINE) corresponding to the specific FMTS integration within each tracking frame integration, in which each event occurred. This allows the possibility to apply a `fine shift' to each event corresponding to the spacecraft drift, after each FMTS integration.

• omfastshift produces by default a corrected event list in which all events within a FMTS are shifted back to the reference frame using drifts calculated from a linear interpolation of the tracking frame drifts in the OM Tracking History auxiliary data file.

• A corrected event list in which all events within a tracking frame are shifted back to the reference frame using the tracking frame drifts can be called for by the setting flag interp_flag = F on the command line

• It is worth noting that there exists cases in which a FMTS crosses a tracking frame boundary. Although events may belong to two tracking frames, all events within the FMTS are given the same event timestamp and are treated equivalently.

• The drift-corrected OM FAST mode event list contains 4 additional columns: the corrected X and Y pixel coordinates and OBT time for each event and a flag denoting whether the shift-corrected event falls within the defined science window. This flag is necessary since the s/c drift causes the science window to sample a region of the sky larger than the science window. When these events are drift-corrected they may fall outside the GO defined science window area. A value of WIN_FLAG=0 is given for all events outside the science window, and WIN_FLAG=1 for all events in the science window.

• TLMIN and TLMAX are required by EVSELECT.