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Questions about Swift? Try our guide to Swift or the guide to data processing and analysis. If these don't solve your problem, please feel free to e-mail us at swifthelp@le.ac.uk.

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We are located in the Department of Physics & Astronomy , at the University of Leicester (directions).

Problem with older versions of barycorr

This refers to versions of barycorr prior to HEASoft 6.22.. From HEASoft 6.22 onwards, the issue has been resolved.

A bug has been identified in how barycorr interacts with Swift files. Although the times of the actual events are corrected, the TSTART and TSTOP keywords of the last HDU extension are not. That is, for an event file with HDUs 0,1,2 and 3, HDUs 0,1 and 2 will have the correct header keywords, but HDU 3 will not (the UTFC and leapseconds correction will not have been applied). When running xrtlccorr, the code checks the TSTART and TSTOP keywords; if these have not been corrected properly, this can cause xrtlccorr to fail, thinking that the *xhdtc.hk file does not cover the entire event list interval.

The best solution to this problem is to install HEASoft 6.22 or higher! However, there is a work-around for older versions: the TSTART and TSTOP keywords in HDU 1 of the barycentrically-corrected *xhdtc.hk file should be changed to match the values in the barycentrically-corrected eventlist. This can either be done by opening the file in fv and inserting the corrected values, or by using fparkey. Alternatively, a dummy final (HDU 2) extension can be inserted into the *xhdtc.hk, which means the keywords in HDU 1 will be correctly updated.