|Type:||Java Task -|
|Import:||from herschel.hifi.pipeline.level0 import DoTimeCorrTask|
This task corrects the observation time (especially for HRS) because the
original obstime is the time of the last integration. As HRS can have several integrations where WBS generally only has 1, there exists a discrepancy between the obstime in HRS and WBS.
This task tries to correct for this effect, by correcting the obstimes to the beginning of the first integration. When a backend has only 1 integration, no correction is applied. This is true for most WBS measurements, and for quite some of HRS.
The formula in use is
obs_time = obs_time - f * (del + t_acc + 12ms)*(n_integr - 1)
n_integr is the number of integrations.
t_acc derives form "duration" for HRS and from "scancount" for WBS.
del is a delay 40ms for fastchop bbids (3225, 6042, 6043, 6053 and 6054) and 1ms otherwise. f is a parallel factor: 2 for fastchop and 1 otherwise.
When a correction is applied, the description field of the obstime is appended with " (corrected)".
The task is part of the Level0Pipeline.
|Example 1: doTimeCorr|
The timeline product (observation) to be passed to the module.