Acquisition Data

Processing

For each observation, after the observation has run and telemetry is available:

The acquisition and guide stats process

  • fetches the AGASC information for each star in the catalog
  • fetches the PCAD data at the end of the acquisition interval

and for each acquisition star determines

  • if that star was “successfully” acquired
  • what the observed magnitude and position of the star were in the last PCAD telemetry readout before the guide transition.

Acquisition data products

The acquisition database table may be retrieved with:

from mica.stats.acq_stats import get_stats
acq_data = get_stats()

Alternatively, the raw hdf5 may be read directly. It includes the following columns:

Column Description
obsid the obsid
obi observation interval number
acq_start acquisition datestart from kadi event
guide_start guide transition datestart from kadi event
guide_tstart guide transition start from kadi event in Chandra secs
one_shot_length one shot delta quaternion arc length in arcsecs for this obsid manvr
revision revision string representing the software version
slot ACA readout slot id
idx starcheck star catalog index id
type star catalog type (BOT or ACQ)
yang commanded y-angle position for center of readout window
zang commanded z-angle position for center of readout window
halfw acquisition search box half width
mag catalog MAG_ACA of acquisition star
acqid acquisition success indicator (boolean)
star_tracked (boolean) something tracked within 5 arcsecs during acq interval
spoiler_tracked (boolean) something tracked outside 5 arcsecs during acq interval
img_func image status at transition: can be None, star, spoiler, RACQ, SRCH
n_trak_interv number of intervals during acq when something was tracked
max_trak_cdy max “corrected” delta-y during acquisition
mean_trak_cdy mean “corrected” delta-y during acquisition
min_trak_cdy min “corrected” delta-y during acquisition
max_trak_cdz max “corrected” delta-z during acquisition
mean_trak_cdy mean “corrected” delta-z during acquisition
min_trak_cdz min “corrected” delta-z during acquisition
max_trak_mag max observed magnitude during acquisition
mean_trak_mag mean observed magnitude during acquisition
min_trak_mag min observed magnitude during acquisition
cdy “corrected” delta-y at guide transition
cdy “corrected” delta-z at guide transition
dy delta-y at guide transition
dz delta-z at guide transition
ion_rad ionizing radiation flag set at transition (boolean)
def_pixel defective pixel flag set at transition
mult_star multiple star flag set at transition
sat_pix saturated pixel flag set at transition
mag_obs observed magnitude at transition
yang_obs observed y-angle at transition
zang_obs observed z-angle at transition
agasc_id AGASC (catalog) id
color1 AGASC COLOR1, estimated B-V color
ra AGASC right ascension in degrees
dec AGASC declination in degrees
epoch AGASC EPOCH
pm_ra AGASC PM_RA, proper motion in ra in milli-arcsec/year
pm_dec AGASC PM_DEC, proper motion in dec in milli-arsec/year
var AGASC VAR, known or suspected varliable star
pos_err AGASC POS_ERR, position error in milli-arcsec
mag_aca AGASC MAG_ACA, ACA mag
mag_err AGASC MAG_ERR, (to be fixed, this should have been MAG_ACA_ERR)
mag_band AGASC MAG_BAND, integer code for spectral band
pos_catid AGASC POS_CATID, integer code for position catalog
aspq1 AGASC ASPQ1, integer spoiler code
aspq2 AGASC ASPQ2, integer proper motion flag
aspq3 AGASC ASPQ3, integer dist in 100m-arcsec to nearest Tycho2 star
acqq1 AGASC ACQQ1, mag diff to brightest star within 53.3” (unit 0.01mags)
acqq2 AGASC ACQQ2, mag diff to brightest star within 107” (unit 0.01mags)
acqq4 AGASC ACQQ4, mag diff to brightest star within 267.5” (unit 0.01mags)
n100_warm_frac estimated n100 fraction of CCD pixels for this observation
ccd_temp mean CCD temperature over 500 seconds surrounding guide transition
known_bad (boolean) ignore this star in standard processing
bad_comment reason to ignore a “known_bad” star

For the columns that reference “corrected” y-angle and z-angle, these have been corrected by the one-shot quaternion update used during the acquisition sequence.

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