Mission Overview

The K2 Bright Star Survey (HALO)

Primary Investigator: Benjamin Pope

HLSP Authors: Benjamin Pope

Released: 2019-08-21

Updated: 2019-08-21

Primary Reference(s): Pope et al. (2019)

Citations: See ADS Statistics

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Overview

The HALO project produces calibrated light curves of stars from K2 that are brighter than the saturation limit of the detector (~11th magnitude).  Light curves of 161 bright stars from K2 Campaign 4 and onwards are provided, derived from the unsaturated scattered-light "halo" around the stars.  Light curve creation relies on optimizing the weights of a linear combination of the pixel time series using a lagged Total Variation minimization, which is demonstrated to work on both saturated and unsaturated K2 targets.  After flux extraction from the halo apertures, the light curves are further corrected using the "k2sc" Gaussian Process systematics-correction code to further correct pointing residuals.

A GitHub repository is made available, and maintained, by the HALO team.  The repository includes scripts and notebooks to generate the HALO data set.

Data Products

Each target is organized into a subdirectory structure, based on the K2 Campaign it is found in.  Campaign directories are not zero-padded.  For Campaign 10, it follows the mission directory structure, where because the Campaign was split into two parts, the campaign directory for the second part of Campaign 10 is stored under:

<c102>/

The data file types:

 _lc.fits extracted light curve _lc.pdf summary plot showing K2SC detrending, raw flux map, HALO weight map, and periodograms _lc.png png version of the summary plot

The data extension (first extension) of the _lc.fits files consists of the following columns:

• TIME = time at mid-point of cadence, in K2 truncated Julian Day
• FLUX = HALO flux from the aperture (prior to running k2sc)
• FLUX_ERR = uncertainty in the FLUX column
• CENTROID_COL = ignore, use POS_CORR1 instead
• CENTROID_ROW = ignore, use POS_CORR2 instead
• QUALITY = quality flag, inherited from the mission data products
• CADENCENO = unique integer incremented by one with each cadence
• POS_CORR1 = column component of the local image motion calculated from the motion polynomials, in pixels relative to the Quarter's mid-cadence
• POS_CORR2 = row component of the local image motion calculated from the motion polynomials, in pixels relative to the Quarter's mid-cadence
• TR_POSITION = systematic trend related to (x,y) as found by the k2sc detrending
• TR_TIME = trend in time found by the k2sc detrending
• CORR_FLUX = FLUX - TR_POSITION + MEDIAN(TR_POSITION)

Note: The light curve file for 98 Tauri = EPIC 200173870, from Campaign 13 (hlsp_halo_k2_llc_200173870-c13_kepler_v1_lc.fits) was reduced poorly by the standard pipeline.  Instead, the FITS file here was reduced using a custom apertured selected by hand by the HALO team.

Data Access

HALO data products are available in the MAST Portal and astroquery.mast.  In addition, you can directly download the files from the table below.

MAST Portal

A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory. Download HALO light curves for a few targets.

MAST Astroquery

Search for, and retrieve, HALO data products programmatically based on a list of coordinates or target names.

In addition to the services above, you can download files using the table below.

EPIC ID Common Name Campaign Files
200007772 Taygeta 4 FITS | PDF | PNG
200007770 Merope 4 FITS | PDF | PNG
200007766 del1_Tau 4 FITS | PDF | PNG
200007771 Maia 4 FITS | PDF | PNG
200007768 Atlas 4 FITS | PDF | PNG
200007767 Alcyone 4 FITS | PDF | PNG
200007773 Pleione 4 FITS | PDF | PNG
200007765 gam_Tau 4 FITS | PDF | PNG
200007769 Electra 4 FITS | PDF | PNG
212573842 Spica 6 FITS | PDF | PNG
200062586 nu2_Sgr 7 FITS | PDF | PNG
200062592 Albaldah 7 FITS | PDF | PNG
200062593 Ascella 7 FITS | PDF | PNG
200062589 omi_Sgr 7 FITS | PDF | PNG
200062587 43_Sgr 7 FITS | PDF | PNG
200062588 Ainalrami 7 FITS | PDF | PNG
200062584 psi_Sgr 7 FITS | PDF | PNG
200062591 tau_Sgr 7 FITS | PDF | PNG
200062585 52_Sgr 7 FITS | PDF | PNG
200062590 ksi2_Sgr 7 FITS | PDF | PNG
200068397 73_Psc 8 FITS | PDF | PNG
200068392 eps_Psc 8 FITS | PDF | PNG
200068394 80_Psc 8 FITS | PDF | PNG
200068401 HR_161 8 FITS | PDF | PNG
200068396 60_Psc 8 FITS | PDF | PNG
200068398 WW_Psc 8 FITS | PDF | PNG
200068395 33_Cet 8 FITS | PDF | PNG
200068399 42_Cet 8 FITS | PDF | PNG
200068393 Revati 8 FITS | PDF | PNG
200068400 HR_243 8 FITS | PDF | PNG
200084007 FW_Vir 102 FITS | PDF | PNG
200084011 HD_107794 102 FITS | PDF | PNG
200084009 HR_4591 102 FITS | PDF | PNG
200084005 Zaniah 102 FITS | PDF | PNG
200084004 Porrima 102 FITS | PDF | PNG
200084008 HR_4837 102 FITS | PDF | PNG
200084010 HR_4613 102 FITS | PDF | PNG
200084006 21_Vir 102 FITS | PDF | PNG
200164169 24_Psc 12 FITS | PDF | PNG
200164168 83_Aqr 12 FITS | PDF | PNG
200164167 kap_Psc 12 FITS | PDF | PNG
200164172 HR_8921 12 FITS | PDF | PNG
200164173 81_Aqr 12 FITS | PDF | PNG
200164171 14_Psc 12 FITS | PDF | PNG
200164174 HR_8897 12 FITS | PDF | PNG
200164170 HR_8759 12 FITS | PDF | PNG
200173857 97_Tau 13 FITS | PDF | PNG
200173850 tau_Tau 13 FITS | PDF | PNG
200173843 Aldebaran 13 FITS | PDF | PNG
200173862 99_Tau 13 FITS | PDF | PNG
200173849 del3_Tau 13 FITS | PDF | PNG
200173874 HR_1554 13 FITS | PDF | PNG
200173845 tet2_Tau 13 FITS | PDF | PNG
200173854 15_Ori 13 FITS | PDF | PNG
200173867 HR_1403 13 FITS | PDF | PNG
200173846 tet1_Tau 13 FITS | PDF | PNG
200173856 HR_1684 13 FITS | PDF | PNG
200173866 80_Tau 13 FITS | PDF | PNG
200173869 105_Tau 13 FITS | PDF | PNG
200173847 kap1_Tau 13 FITS | PDF | PNG
200173853 11_Ori 13 FITS | PDF | PNG
200173872 HR_1633 13 FITS | PDF | PNG
200173864 53_Tau 13 FITS | PDF | PNG
200173859 kap2_Tau 13 FITS | PDF | PNG
200173878 85_Tau 13 FITS | PDF | PNG
200173860 81_Tau 13 FITS | PDF | PNG
200173868 89_Tau 13 FITS | PDF | PNG
200173871 HR_1576 13 FITS | PDF | PNG
200173876 HR_1755 13 FITS | PDF | PNG
200173877 HR_1459 13 FITS | PDF | PNG
200173858 HR_1585 13 FITS | PDF | PNG
200173855 HR_1427 13 FITS | PDF | PNG
200173870 98 Tau 13 FITS | PDF | PNG
200173848 ups_Tau 13 FITS | PDF | PNG
200173873 HR_1741 13 FITS | PDF | PNG
200173852 75_Tau 13 FITS | PDF | PNG
200173875 HR_1385 13 FITS | PDF | PNG
200173861 56_Tau 13 FITS | PDF | PNG
200173865 51_Tau 13 FITS | PDF | PNG
200173851 rho_Tau 13 FITS | PDF | PNG
200173844 eps_Tau 13 FITS | PDF | PNG
200182928 53_Leo 14 FITS | PDF | PNG
200182925 58_Leo 14 FITS | PDF | PNG
200182926 48_Leo 14 FITS | PDF | PNG
200182931 rho_Leo 14 FITS | PDF | PNG
200182930 43_Leo 14 FITS | PDF | PNG
200182929 35_Sex 14 FITS | PDF | PNG
200182927 65_Leo 14 FITS | PDF | PNG
200194921 28_Lib 15 FITS | PDF | PNG
200194911 Zubenelhakrabi 15 FITS | PDF | PNG
200194920 HR_5620 15 FITS | PDF | PNG
200194917 zet3_Lib 15 FITS | PDF | PNG
200194914 zet4_Lib 15 FITS | PDF | PNG
200194916 HR_5806 15 FITS | PDF | PNG
200194912 iot1_Lib 15 FITS | PDF | PNG
200194913 41_Lib 15 FITS | PDF | PNG
200194918 HR_5810 15 FITS | PDF | PNG
200194919 iot2_Lib 15 FITS | PDF | PNG
200194910 Dschubba 15 FITS | PDF | PNG
200194915 HR_5762 15 FITS | PDF | PNG
200194958 HD_138810 15 FITS | PDF | PNG
200200361 omi2_Cnc 16 FITS | PDF | PNG
200200360 omi1_Cnc 16 FITS | PDF | PNG
200200358 ksi_Cnc 16 FITS | PDF | PNG
200200728 45_Cnc 16 FITS | PDF | PNG
200200357 Acubens 16 FITS | PDF | PNG
200200359 eta_Cnc 16 FITS | PDF | PNG
200200356 Asellus_Australis 16 FITS | PDF | PNG
200200363 50_Cnc 16 FITS | PDF | PNG
200213055 68_Vir 17 FITS | PDF | PNG
200213053 82_Vir 17 FITS | PDF | PNG
200213057 HR_5106 17 FITS | PDF | PNG
200213056 80_Vir 17 FITS | PDF | PNG
200213054 76_Vir 17 FITS | PDF | PNG
200213067 Spica 17 FITS | PDF | PNG
200213058 HR_5059 17 FITS | PDF | PNG
200233190 HR_3264 18 FITS | PDF | PNG
200233186 gam_Cnc 18 FITS | PDF | PNG
200233191 50_Cnc 18 FITS | PDF | PNG
200233193 HR_3222 18 FITS | PDF | PNG
200233643 zet_Cnc 18 FITS | PDF | PNG
200233195 HR_3558 18 FITS | PDF | PNG
200233189 49_Cnc 18 FITS | PDF | PNG
200233644 25_Cnc 18 FITS | PDF | PNG
200233196 21_Cnc 18 FITS | PDF | PNG
200233187 eta_Cnc 18 FITS | PDF | PNG

Citations

Please remember to cite the appropriate paper(s) below and the DOI if you use these data in a published work.

Note: These HLSP data products are licensed for use under CC BY 4.0.