Kepler K2 Light Curves reduced by the HAT team

The K2 HAT light curves are provided as gzipped CSV text files. A Python module is available to read these files into a Python dict. Light curve files contain a metadata header describing the K2 target, a list of all columns contained in the file, and finally, comma-separated lines for all columns. An example is shown below:

# METADATA
# objectid = UCAC4-470-046291, kepid = 201713071, ucac4id = UCAC4-470-046291, kepmag = 15.2070
# ra = 181.3130, decl = 3.8616, ndet = 3826, k2campaign = 1
# fovccd = 6, fovchannel = 11, fovmodule = 4
# qualflag = 1, bjdoffset = 2454833.0, napertures = 2
# aperpixradius = 2.60,3.00
#
# COLUMNS
# 000 - BJD - time in Baryocentric Julian Date
# 001 - BGV - Background value (ADU)
# 002 - FRN - frame number (detection serial number)
# 003 - XCC - x coordinate on module
# 004 - YCC - y coordinate on module
# 005 - IM05 - K2 instrumental magnitude (aperture 05)
# 006 - IE05 - K2 instrumental mag. error (aperture 05)
# 007 - IQ05 - K2 instrumental mag. quality flag (aperture 05)
# 008 - EP01 - EPD magnitude (aperture 01)
# 009 - EQ01 - EPD mag. quality flag (aperture 01)
# 010 - TF05 - TFA magnitude (aperture 05)
# 011 - CF01 - Cosine filtered magnitude (aperture 01)
#
# LIGHTCURVE
2456808.1787827,233.38000,1,1816.740,2120.740,15.21386,0.00709,G,15.12384,-3,nan,15.20313
2456808.1992152,233.17000,2,1816.730,2120.740,15.21433,0.00710,G,15.12504,-3,nan,15.20401
2456808.2196477,232.54000,3,1816.730,2120.760,15.21432,0.00710,G,15.12707,-3,nan,15.20534
2456808.2400802,233.71000,4,1816.720,2120.770,15.21593,0.00709,G,15.12836,-3,nan,15.20755
2456808.2605127,232.79000,5,1816.700,2120.780,15.21345,0.00710,G,15.12647,-3,nan,15.20470
2456808.2809451,233.40000,6,1816.690,2120.790,15.21635,0.00709,G,15.12928,-3,nan,15.20792
2456808.3013776,233.35000,7,1816.690,2120.800,15.21714,0.00710,G,15.13056,-3,nan,15.20901
2456808.3218102,233.22000,8,1816.680,2120.790,15.21508,0.00708,G,15.12825,-3,nan,15.20645
2456808.3422427,232.67000,9,1816.680,2120.790,15.21431,0.00706,G,15.12913,-3,nan,15.20668
...
        

Types of light curves

There are two types of light curves available:

full light curve
This light curve contains all available magnitude measurements (K2 raw, EPD, TFA, cosine-filtered) for all photometric apertures used by the K2 HAT photometric pipeline.
best aperture light curve
This light curve contains only the magnitude measurements for the photometric apertures deemed as the best available for the object. The best apertures are those for which the median absolute deviation of the light curve magnitude measurements is the smallest. Each type of magnitude measurement reported may have its own 'best' aperture.

NOTE: If the photometric extraction does not succeed or is noted as unreliable, a light curve may not have a 'best' photometric aperture, in which case, the 'best aperture' light curve will contain K2 raw (IM), EPD (EP), TFA (TF), and cosine-filtered (CF) magnitude measurements from photometric aperture 17. Use the object-summary.csv file associated with each K2 campaign field to find the best apertures for each object.

Light curve metadata

The light curve files contain the following metadata:

Light curve columns

All light curve files will always contain the following columns.

Columns for magnitude measurements are provided as a group for each photometric aperture. These are listed below. XX is the number of the aperture, ranging from 00 to 35. Not all of these columns may be present in the light curve. For some campaigns, the detrended (EPXX) magnitude, TFA (TFXX) magnitude, or cosine-filtered (CFXX) magnitude may have been normalized to the median Kepler magnitude of the object and centered about 0.0.

Photometric apertures

The K2 HAT photometric pipeline uses the following photometric apertures. Not all of these may be used for a reduction.

Aperture number Aperture radius in pixels
002.50
012.60
022.70
032.80
042.90
053.00
063.10
073.20
083.30
093.40
103.50
113.55
123.60
133.65
143.70
153.75
163.80
173.85
183.90
193.95
204.00
214.05
224.10
234.15
244.20
254.25
264.30
274.35
284.40
294.50
304.60
314.70
324.80
334.90
345.00
355.10