Campaign Features and Events
The open cluster M67 was observed by collecting a 400x400 region of sky near the core of the cluster in modules 6.1 and 6.2. See the image below. These data are grouped into 72 custom apertures, each with a 50x50 pixel mask or smaller. Their data are listed by custom aperture number at the MAST in the range 200008644--200008715.
The tiling of the M67 open cluster is shown in green on mod.outs 6.1 and 6.2 of C5.
The Trans-Neptunian Object TNO (126154) 2001 YH140 was observed in Campaign 5 by creating 565 1 x n pixel target definitions (where n ranges from 4 to 21) that cover the path of the TNO. The custom aperture numbers range from 200008716 to 200009280.
Noted Data Anomalies
Approximately 55.5 days after the start of C5, we note a small (~4000 electrons per cadence) increase in the median dark level that lasts approximately a day. The event is likely caused by a Coronal Mass Ejection, and its size is small compared to other normal variations seen in the dark level. This change in dark level is part of the normal calibration process that occurs in the CAL module.
One Argabrightening event was seen in the observed background level approximately 38 days into the campaign and affects a majority of the channels. This event is flagged on bit 13 in the QUALITY column of the light curve and target pixel files for those targets on the affected channels.
Light Curve Quality
The dominant systematic present in K2 simple aperture photometry light curves is a sawtooth shape that is due to the roll of the spacecraft approximately every 6 hours. The PDC module of the Kepler Pipeline uses Principle Component Analysis to remove this signal in addition to other systematics. Below, we examine observed noise levels in the PDC light curves for C5, Data Release 7.
Table giving 6.5-hr CDPP as a function of magnitude.
The figure above shows the CDPP measured for all targets as a function of Kepler magnitude. Dim targets have poorer overall photometric precision than bright targets, but can look better because the residual sawtooth falls below the noise floor. The saturated targets tend to have the lowest CDPP, but often show a residual sawtooth. Also, the photometric precision is generally better near the center of the focal plane where the variations in roll angle produce less pixel motion. All cadences coincident with a definite thruster firing are gapped.