with the dead-time fraction criteria of ${\rm DFT} > 0.9$. A further complication for precision timing was recently discovered by the HRC hardware team: the time-stamps for each event are mis-assigned to the following event. Based on the [VALID\_EVT\_COUNT]{} count rate of $\sim 500$ cps, the average error in the assigned photon arrival time is 2 ms or a 2% phase error for the Vela pulsar; assuming roughly Poisson fluctuations in the HRC count rate over the observation interval, the maximum error for any photon will be $\le 3$ ms. Thus, with 25 phase bins across the 88 ms pulsar period, few, if any, photons have been misassigned and we have taken no mitigating action to correct this error.

To compare directly the two observations, we reprocessed both data sets starting from the Level 0.5 event files using identical methods and filter/screening/processing criteria, compensating for incorrect keyword values, producing correct GTI extensions, etc. This resulted in a total of 50.3 ks and 45.3 ks integration times for the first and second observation, respectively. Despite all the initial discrepancies and artifacts in the two observations, this reprocessing produced effectively identical images, light curves and count rates. We are thus confident that 