Spitzer Kepler Survey (SpiKeS) Data at the Exoplanet Archive
Contents
Project Overview
The Spitzer Kepler Survey (SpiKeS) provides high-precision 3.6 and 4.5µm photometry of the ~200,000 stars monitored during the original Kepler survey. We have surveyed the entire Kepler field in Cygnus, but not any of the areas studied by the successor K2 mission. Our primary purpose was to create a sufficiently precise data set to allow searches for low-level infrared excess around the Kepler-monitored stars (Figure 1), so that we could identify the presence of circumstellar dust and unresolved companions.
(Click image to enlarge)
Figure 1: Sky plot of all sources in the SpiKeS catalog of the original Kepler field in the constellation of Cygnus. We also highlight two instances of infrared excess in the Kepler-monitored sources. KIC 3852667 is an example of warm dust around an A-type supergiant star discovered in the SpiKeS data. The blackbody fit is to the 2MASS and SpiKeS data with the WISE data plotted for comparison. KIC 6954726 is a previously identified Be star also with a fit to the 2MASS and SpiKeS data with the WISE data plotted for comparison.
We succeeded in achieving a measurement precision on the Kepler stars better than the absolute calibration uncertainty of the Spitzer data, estimated to be ~2.4%. This was done through precise reduction and removal of known systematic effects at the individual exposure level. Details of the data reduction and early results are presented in Werner et al. 2021.
The primary goal of SpiKeS was to provide a precise catalog and so completeness was sacrificed for precision resulting in 174,667 IRAC1/3.6µm sources and 179,896 IRAC2/4.5µm sources out of the ~200,000 sources monitored by Kepler.
A key advance of SpiKeS over the Wide-Field Infrared Survey Explorer (WISE) data for the study of the Kepler stars comes from improvements in spatial resolution. Based on comparisons between the two catalogs we estimate that at least ~2% (~4000) of the WISE sources in the Kepler field are double or multiple. Such contamination is reduced in the Spitzer data because of its smaller beam size of 1.8-2'' vs. the WISE beam size of 6''. Potentially unresolved WISE sources, where two or more Spitzer sources are more closely spaced than the WISE beam size, are identified with a flag in the SpiKeS catalog.
Data Holdings
| Data Set | Download Link | Approx. Download Size | Description |
|---|---|---|---|
| SpiKeS | SpiKeS-Final-201515.csv | 122 MB | A text file in CSV format containing Spitzer photometry with additional data from other archives. |
The catalog contents, as detailed below, have the photometric results from the SpiKeS survey matched to several other surveys so that the data can be used more easily for various astrophysics projects. The catalog cross-correlations are based on the best matches within one arcsecond.
The source catalogs for each column entry are identified after the name of each column header and links to each of the catalogs are provided at the end of the list.
There are three flags for the SpiKeS data. The first two alert the user whether the source is saturated or may have had a non-linearity correction applied during the original pipeline reduction in channels IRAC1 and IRAC2. The third flag identifies sources that may be unresolved in the WISE data (AllWISE and CatWISE2020) and so may not match the similar channel WISE catalog magnitudes of WISE1 and WISE2.
Flags and their descriptions from the other catalogs that are cross-matched to SpiKeS are also included.
| Column Header | Description |
|---|---|
| Kepid (KIC1) | KepID [KIC number] |
| KOI (NASA-EA2) | Kepler Object of Interest Number (e.g., K07474.01) |
| Kepler Name (NASA-EA) | Kepler Planet Name (e.g., Kepler-1 b) |
| ra (KIC) | RA J2000 from KIC [deg] |
| dec (KIC) | Dec J2000 from KIC [deg] |
| I1 flux (SpiKeS3) | IRAC1 flux density [mJy] |
| I1 unc (SpiKeS) | IRAC1 uncertainty [mJy] |
| I1 mag (SpiKeS) | IRAC1 magnitude [mag] |
| I1 mag unc (SpiKeS) | IRAC1 magnitude uncertainty [mag] |
| I1 n obs (SpiKeS) | IRAC1 number of observations |
| I2 flux (SpiKeS) | IRAC2 flux density [mJy] |
| I2 unc (SpiKeS) | IRAC2 uncertainty [mJy] |
| I2 mag (SpiKeS) | IRAC2 magnitude [mag] |
| I2 mag unc (SpiKeS) | IRAC2 magnitude uncertainty [mag] |
| I2 n obs (SpiKeS) | IRAC2 number of observations |
| SpiKeS Flags (SpiKeS) | Flags from SpiKeS survey |
| Kepmag (KIC) | Kepler-band magnitude [mag] |
| tm designation (2MASS4) | 2MASS designation |
| jmag (2MASS) | J band magnitude [mag] |
| jmag err (2MASS) | J band error [mag] |
| hmag (2MASS) | H band magnitude [mag] |
| hmag err (2MASS) | H band error [mag] |
| kmag (2MASS) | Kshort band magnitude [mag] |
| kmag err (2MASS) | Kshort band error [mag] |
| ALLWISE | WISE All-Sky Data Release catalog name |
| RAJ2000 (AllWISE5) | RA J2000 from AllWISE [deg] |
| DEJ2000 (AllWISE) | Dec J2000 from AllWISE [deg] |
| W1mag (AllWISE) | W1 magnitude [mag] |
| W2mag (AllWISE) | W2 magnitude [mag] |
| W3mag (AllWISE) | W3 magnitude [mag] |
| W4mag (AllWISE) | W4 magnitude [mag] |
| e W1mag (AllWISE) | Mean W1 magnitude error [mag] |
| e W2mag (AllWISE) | Mean W2 magnitude error [mag] |
| e W3mag (AllWISE) | Mean W3 magnitude error [mag] |
| e W4mag (AllWISE) | Mean W4 magnitude error [mag] |
| ID (AllWISE) | Unique WISE source ID |
| cc flags (AllWISE) | Contamination and confusion flag |
| ext flg (AllWISE) | Extended source flag |
| var flg (AllWISE) | Variability flag |
| qph (AllWISE) | Photometric quality flag |
| ang Dist W | Angular distance from SpiKeS sources [arcsec] |
| CatWISE6 | CatWISE release catalog name |
| RAJ2000 (CatWISE) | RA J2000 from CatWISE [deg] |
| DEJ2000 (CatWISE) | Dec J2000 from CatWISE [deg] |
| W1mag C (CatWISE) | W1 magnitude [mag] |
| W2mag C(CatWISE) | W2 magnitude [mag] |
| e W1mag C(CatWISE) | Mean W1 magnitude error [mag] |
| e W2mag C(CatWISE) | Mean W2 magnitude error [mag] |
| Teff (Mathur et al.7) | Stellar Effective Temperature [Kelvin] |
| Teff err1 (Mathur et al.) | Temperature error + [Kelvin] |
| Teff err2 (Mathur et al.) | Temperature error - [Kelvin] |
| logg (Mathur et al.) | Stellar Surface Gravity [log10(cm/sec2)] |
| logg err1 (Mathur et al.) | log(g) error + [log10(cm/sec2)] |
| logg err2 (Mathur et al.) | log(g) error - [log10(cm/sec2)] |
| feh (Mathur et al.) | Stellar Metallicity [dex] |
| feh err1 (Mathur et al.) | FeH error + [dex] |
| feh err2 (Mathur et al.) | FeH error - [dex] |
| mass (Mathur et al.) | Stellar Mass [Solar Masses] |
| mass err1 (Mathur et al.) | Mass error + [Solar masses] |
| mass err2 (Mathur et al.) | Mass error - [Solar masses] |
| radius (Mathur et al.) | Stellar Radius [Solar radii] |
| radius err1 (Mathur et al.) | Stellar radius error + [Solar radii] |
| radius err2 (Mathur et al.) | Stellar radius error - [Solar radii] |
| dens (Mathur et al.) | Stellar Density [gm/cm3] |
| dens err1 (Mathur et al.) | Stellar density error + [gm/cm3] |
| dens err2 (Mathur et al.) | Stellar density error - [gm/cm3] |
| av (Mathur et al.) | Av Extinction [mag] |
| av err1 (Mathur et al.) | Av error + [mag] |
| av err2 (Mathur et al.) | Av error - [mag] |
| Gaia id8 | Unique Gaia identifier |
| RA ICRS (Gaia) | Barycentric RA J2015.5 from Gaia [deg] |
| DE ICRS (Gaia) | Barycentric Dec J2015.5 from Gaia [deg] |
| rest (Gaia) | Bailer-Jones+ 2018 estimated distance [pc] |
| b rest (Gaia) | Lower bound on the confidence interval of the estimated distance [pc] |
| B rest (Gaia) | Upper bound on the confidence interval of the estimated distance [pc] |
| rlen (Gaia) | Length scale used in the prior for the distance estimation [pc] |
| ResFlag (Gaia) | Result flag |
| ModFlag (Gaia) | Number of modes in the posterior |
| parallax (Gaia) | Absolute stellar parallax [mas] |
| parallax error (Gaia) | Standard error of parallax [mas] |
| pmra (Gaia) | Proper motion in right ascension direction [mas/yr] |
| pmra error (Gaia) | Standard error of proper motion in right ascension direction [mas/yr] |
| pmdec (Gaia) | Proper motion in declination direction [mas/yr] |
| pmdec error (Gaia) | Standard error of proper motion in declination direction [mas/yr] |
| angDist G (Gaia) | Angular separation from SpiKes sources [arcsec] |
- KIC = Kepler Input Catalog (https://archive.stsci.edu/kepler/kic.html)
- NASA-EA = NASA Exoplanet Archive (https://exoplanetarchive.ipac.caltech.edu/cgi-bin/TblView/nph-tblView?app=ExoTbls&config=cumulative)
- SpiKeS = Spitzer Kepler Survey
- 2MASS = Two Micron All-Sky Survey from the Infrared Science Archive (https://irsa.ipac.caltech.edu/Missions/2mass.html)
- AllWISE = Wide-Field Infrared Survey Explorer catalog from the first year of WISE and NEOWISE sky coverage from IRSA (https://irsa.ipac.caltech.edu/cgi-bin/Gator/nph-scan?submit=Select&projshort=WISE)
- CatWISE2020 = Wide-Field Infrared Survey Explorer catalog from the first 8 years of WISE and NEOWISE sky coverage from IRSA (https://irsa.ipac.caltech.edu/cgi-bin/Gator/nph-scan?submit=Select&projshort=WISE)
- Mathur et al. = "Revised Stellar Properties of Kepler Targets for the Q1-17 (DR25) Transit Detection Run" Mathur, S., Huber, D., Batalha, N. M., et al. 2017, ApJS,229, 30 (https://iopscience.iop.org/article/10.3847/1538-4365/229/2/30)
- Gaia = Gaia DR2 ( https://vizier.u-strasbg.fr/viz-bin/VizieR-3?-source=I/345/gaia2)
Flags
SpiKeS Flags
Three column flags*: 0 = no flag set, 1 = flag set (e.g. 0,0,1 or 1,0,1)
Column 1: IRAC1 no viable observation (I1_n_obs = 0) or above nominal saturation magnitude (I1 mag = 10.1) which means it is either saturated or has had a saturation correction applied within the pipeline reduction.
Column 2: IRAC2 no viable observation (I2_n_obs = 0) or above nominal saturation magnitude (I2 mag = 9.4) which means it is either saturated or has had a saturation correction applied within the pipeline reduction.
Column 3: Potentially unresolved source in WISE beam.
* Note that the flags are preceded by an underscore so spreadsheet programs will recognize the column as a text column and not a number column.
AllWISE
cc flags
Contamination and confusion flag. Four-character string, one character per band [W1/W2/W3/W4], that indicates the photometry and/or position measurements of a source may be contaminated or biased due to proximity to an image artifact. The type of artifact that may contaminate the measurements is denoted by the following codes. Lower-case letters correspond to instances in which the source detection in a band is believed to be real but the measurement may be contaminated by the artifact. Upper-case letters are instances in which the source detection in a band may be a spurious detection of an artifact.
- D,d - Diffraction spike. Source may be a spurious detection of (D) or contaminated by (d) a diffraction spike from a nearby bright star on the same image, or
- P,p - Persistence. Source may be a spurious detection of (P) or contaminated by (p) a short-term latent image left by a bright source, or
- H,h - Halo. Source may be a spurious detection of (H) or contaminated by (h) the scattered light halo surrounding a nearby bright source, or
- O,o (letter "o") - Optical ghost. Source may be a spurious detection of (O) or contaminated by (o) an optical ghost image caused by a nearby bright source, or
- 0 (number zero) - Source is unaffected by known artifacts. A source extraction may be affected by more than one type of artifact or condition. In this event, the cc_flags value in each band is set in the following priority order: D,P,H,O,d,p,h,o,0. The full tally of artifacts affecting a source in each band is given in the w?cc_map and w?cc_map_str columns.
A source can appear in the AllWISE Source Catalog even if it is flagged as a spurious artifact detection in a band if there is a reliable detection in another band that is not flagged as a spurious artifact detection (see V.3.b). Entries in the AllWISE Reject Table may be flagged as spurious detections of artifacts in all bands.
CAUTION: Non-zero cc_flags values in any band indicate the measurement in that band may be contaminated and the photometry should be used with caution.
ext flg
Extended source flag. This is an integer flag, the value of which indicates whether or not the morphology of a source is consistent with the WISE point spread function in any band, or whether the source is associated with or superimposed on a previously known extended object from the 2MASS Extended Source Catalog (XSC). The values of the ext_flg indicate the following conditions:
- 0 - The source shape is consistent with a point-source and the source is not associated with or superimposed on a 2MASS XSC source
- 1 - The profile-fit photometry goodness-of-fit, w?rchi2, is >3.0 in one or more bands.
- 2 - The source falls within the extrapolated isophotal footprint of a 2MASS XSC source.
- 3 - The profile-fit photometry goodness-of-fit, w?rchi2, is >3.0 in one or more bands, and The source falls within the extrapolated isophotal footprint of a 2MASS XSC source.
- 4 - The source position falls within 5" of a 2MASS XSC source.
- 5 - The profile-fit photometry goodness-of-fit, w?rchi2, is >3.0 in one or more bands, and the source position falls within 5" of a 2MASS XSC source.
CAUTION: WISE profile-fit (w?mpro) and standard aperture (w?mag) measurements are optimized for point sources and will systematically underestimate the true flux of resolved objects. If a source entry has ext_flg>0, you may wish to examine the large aperture photometry or the elliptical aperture photometry, which are measured using areas that are scaled from 2MASS XSC morphologies.
var flg
Variability flag. The variability flag is a four-character string, one character per band, in which the value for each band is related to the probability that the source flux measured on the individual WISE exposures was not constant with time. The probability calculation uses the standard deviation of the single exposure flux measurements, w?sigp1, as well as the band-to-band flux correlation significance, q12,q23,q34. The probability is computed for a band only when there are at least six single-exposure measurements available that satisfy minimum quality criteria. A value of "n" in a band indicates insufficient or inadequate data to make a determination of possible variability. Values of "0" through "9" indicate increasing probabilities of variation. Values of "0" through "5" are most likely not variables. Sources with values of "6" and "7" are likely flux variables, but are the most susceptible to false-positive variability. Var_flg values greater than "7" have the highest probability of being true flux variables in a band.
CAUTION: Estimation of flux variability is unreliable for sources that are extended (ext_flg>0), and sources whose measurements are contaminated by image artifacts in a band (cc_flags[b] != '0').
qph
(Note this is shortened identifier for the ph_qual flag on the IRSA database)
Photometric quality flag. Four character flag, one character per band [W1/W2/W3/W4], that provides a shorthand summary of the quality of the profile-fit photometry measurement in each band, as derived from the measurement signal-to-noise ratio.
- A - Source is detected in this band with a flux signal-to-noise ratio w?snr>10.
- B - Source is detected in this band with a flux signal-to-noise ratio 3<w?snr<10.
- C - Source is detected in this band with a flux signal-to-noise ratio 2<w?snr<3.
- U - Upper limit on magnitude. Source measurement has w?snr<2. The profile-fit magnitude w?mpro is a 95% confidence upper limit.
- X - A profile-fit measurement was not possible at this location in this band. The value of w?mpro and w?sigmpro will be "null" in this band.
- Z - A profile-fit source flux measurement was made at this location, but the flux uncertainty could not be measured. The value of w?sigmpro will be "null" in this band. The value of w?mpro will be "null" if the measured flux, w?flux, is negative, but will not be "null" if the flux is positive. If a non-null magnitude is present, it corresponds to the true flux, and not the 95% confidence upper limit. This occurs for a small number of sources found in a narrow range of ecliptic longitude which were covered by a large number of saturated pixels from 3-Band Cryo single-exposures, as described in V.1.b.iii.
Gaia
ResFlag
- 0 = failed estimate (r_est, r_lo, r_hi are all NaN)
- 1 = rest is the mode (highest if the posterior is bimodal); brest/B rest define the lower/upper limits of the highest density interval (HDI) containing 68% of the posterior probability
- 2 = rest is the median; brest/B rest define the lower/upper limits of the equal-tailed interval (ETI), containing 68% of the posterior probability
ModFlag
[1/2] Number of modes in the posterior (modality_flag)
Acknowledgments
We thank the ever-helpful staff of the Spitzer Science Center for helping us to develop the protocols, under which the AORs for each tile of the complete survey could be submitted. The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). This work is based in part on observations made with the Spitzer Space Telescope, which was operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. This publication also makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This work has made use of data from the European Space Agency (ESA) mission Gaia, processed by the Gaia Data Processing and Analysis Consortium. Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The following software programs were used to generate this catalog: Astropy (Astropy Collaboration et al. 2013, 2018), TOPCAT (Taylor 2005), SExtractor (Bertin & Arnouts1996). Finally, we would like to thank the NASA Exoplanet Archive and IPAC for their help in making this data available to the community.
Requested Data Acknowledgment
If you make use of SpiKeS data from the NASA Exoplanet Archive, please include the following acknowledgement:
"This paper makes use of data from SpiKeS: The Spitzer Kepler Survey (Werner et al. 2021) as provided by the SpiKeS team to the NASA Exoplanet Archive."
Last updated: 15 June 2021
