cheta.derived.comps.Comp_Quat#

class cheta.derived.comps.Comp_Quat(unit_system='eng')#

Bases: ComputedMsid

Computed MSID for returning the quaternion telemetry as a Quat object

This defines the following computed MSIDs based on the corresponding TDB MSIDs:

  • quat_aoattqt = AOATTQT[1-4]

  • quat_aoatupq = AOATUPQ[1-3]

  • quat_aocmdqt = AOCMDQT[1-3]

  • quat_aotarqt = AOTARQT[1-3]

Example:

>>> from cheta import fetch
>>> qatt = fetch.Msid('quat_aoattqt', '2022:001:00:00:00', '2022:001:00:00:04')
>>> qatt.vals
Quat(array([[-0.07434856, -0.55918674, -0.80432653,  0.18665828],
            [-0.07434854, -0.55918679, -0.8043265 ,  0.18665825],
            [-0.07434849, -0.55918674, -0.80432653,  0.18665829],
            [-0.07434849, -0.55918667, -0.80432653,  0.18665852]]))
>>> qatt.vals.equatorial
array([[193.28905806,  19.16894296,  67.36207683],
       [193.28905485,  19.1689407 ,  67.36208471],
       [193.28906329,  19.16893787,  67.36207699],
       [193.28908839,  19.16895134,  67.36206404]])

This computed MSID can be used with the MAUDE data source. Be aware that if the telemetry has a missing VCDU then there is a risk of getting a slightly incorrect quaternion. This would occur since the code uses nearest-neighbor interpolation to associate the four components of the quaternion with a single time. For back-orbit data this is rare, but for real-time data it is more likely.

msid_match = 'quat_(aoattqt|aoatupq|aocmdqt|aotarqt)'#
get_msid_attrs(tstart, tstop, msid, msid_args)#

Get the attributes required for this MSID.

Get attributes for computed MSID, which must include at least vals, bads, times, and may include additional attributes.

This MUST be supplied by sub-classes.

Parameters:

  • tstart – start time (CXC secs)

  • tstop – stop time (CXC secs)

  • msid – full MSID name e.g. tephin_plus_5

  • msid_args – tuple of regex match groups (msid_name,)

Returns:

dict of MSID attributes