Mission Overview
KBonus-Background ("KBONUS-BKG")
Primary Investigator: Jorge Martinez-Palomera
HLSP Authors: Jorge Martinez-Palomera, Christina Hedges, and Jessie Dotson
Released: 2023-11-01
Updated: 2023-11-01
Primary Reference(s): Martinez-Palomera et al. 2023
DOI: 10.17909/7jbr-w430
Citations: See ADS statistics
Slideshow
Overview
KBONUS-BKG uses the Linearized Field Deblending (LFD) method, a Point Spread Function (PSF) photometry algorithm, to create PSF light curves. Gaia DR3 data is used as an input catalog to extract 606,900 light curves, from which 406,548 correspond to background sources and 200,352 are Kepler targets. PSF models were fitted using Kepler's full-frame images and later evaluated in the Target Pixel Files (TPFs) of Kepler targets. The LFD method provides a mean PSF estimate and a perturbed PSF that corrects for systematics within an observing quarter. Additionally, aperture photometry is estimated directly from the PSF shape per source and optimized for flux completeness and contamination. The PSF light curves have comparable quality as those computed by the Kepler pipeline, with combined differential photometric precision (CDPP) values under 100 ppm for sources brighter than G = 16. The light curve files include PSF, aperture photometry, and relevant extraction metrics. A full description of this dataset can be found in Martinez-Palomera et al. (2023) and the Python library PSFMachine that was used to extract the light curves for this data set. See Jupyter Notebook tutorials on how to load the light curves and what to expect in the FITS files.
Data Products
KBONUS-BKG provides 606,900 light curves, a catalog of extracted sources, a catalog of specific objects of interest, and bundle tarball files for specific types of sources of interest for quick download.
Data file naming convention:
hlsp_kbonus-bkg_kepler_kepler_<target>_kepler_v1.0_<prodtype>.<ext>
where:
- <target> represents the source ID, e.g., "kic-005732587" if the source exists in the Kepler Input Catalog or "gaia-dr3-2126999613236789376" if not, for lightcurves. For catalogs and bundles, it is the name of the interested specific sources, one of "source" for all lightcurve sources, "mstars" for M dwarfs, " wd" for white dwarfs, or "kois-nns" for all the KOIs and their neighbors within a 30'' radius.
- <prodtype> represents the product type, for instance, "lc" for lightcurves, "cat" for catalogs", or "tar.gz" for compressed tarballs of interested sources.
- <ext> is the extension of the file, one of "fits" or "tar.gz".
Data file types:
_lc.fits | Lightcurves |
_cat.fits | Catalogs |
_lcf.tar.gz | Bundled lightcurves |
Lightcurve Files
Lightcurve FITS files contain multiple extensions, which consist of LIGHTCURVE BinTables and APERTURE images for quarters where the sources were detected. Therefore, the number of extensions varies for sources. The LIGHTCURVE STITCHED is the main extension containing the fully stitched time series. The LIGHTCURVE_Q extensions contain the light curve for single quarters. This extension contains per-quarter metrics and other measurements such as centroid and PSF model chi-square values. The APERTURE_Q extension contains the pixel mask of the corresponding quarter used for the aperture photometry in the shape of the TPF of origin. The FITS files are structured to work seamlessly with the lightkurve package. In this way, users can easily load the stitched light curve into a LightCurve object.
Description of the columns available in the LIGHTCURVE STITCHED extension
Column | Field | Format | Units | Description |
---|---|---|---|---|
1 | Time |
float64 |
BJD - 2454833 |
Time value in BKJD |
2 |
Cadenceno |
int32 | - |
Cadence number |
3 | Quarter | int32 | - | Quarter number |
4 |
Flux |
float64 |
e−/s |
PSF flux from stitched quarters |
5 |
Flux_err |
float64 | e−/s |
PSF flux error from stitched quarters |
6 | SAP_flux | float64 | e−/s |
SAP flux from stitched quarters |
7 |
SAP_flux_err |
float64 | e−/s |
SAP flux error from stitched quarters |
8 |
PSF_flat_flux |
float64 | e−/s | PSF flux from stitched quarters after flattening |
9 |
PSF_flat_flux_err |
float64 | e−/s |
PSF flux error from stitched quarters after flattening |
10 |
SAP_quality |
int32 | - |
Quality flag from the TPF |
11 |
Flatten_mask |
int32 | - |
Quality flag from the flattening process |
Description of the columns available in the LIGHTCURVE_Q extension
Column | Field | Format | Units | Description |
---|---|---|---|---|
1 |
Cadenceno |
int32 | - |
Cadence number |
2 | Time |
float64 |
BJD - 2454833 |
Time value in BKJD |
3 |
Flux |
float64 |
e−/s |
Corrected PSF flux |
4 |
Flux_err |
float64 | e−/s |
Corrected PSF flux error |
5 | SAP_flux | float64 | e−/s |
SAP flux |
6 |
SAP_flux_err |
float64 | e−/s |
SAP flux error |
7 |
Centroid_Column |
float64 | pix |
Centroid column value |
8 |
Centroid_Row |
float32 | pix |
Centroid row value |
9 |
SAP_quality |
int32 | - |
Quality flag from the TPF |
10 |
SAP_BKG |
float64 | e−/s |
SAP background flux |
11 |
Red_chi2 |
float32 | - |
Reduced chi-squared value between PSF model and data |
12 |
PSF_flat_nova |
float64 | e−/s | Mean PSF flux |
13 |
PSF_flat_nova_err |
float64 | e−/s | Mean PSF flux error |
Source Catalogs
The catalog (hlsp_kbonus-bkg_kepler_kepler_source-list_kepler_v1.0_cat.fits) released with this work contains the list of extracted sources resulting in a light curve FITS file. It also contains extraction metrics and availability flags that can be used to filter sources. The detailed column description is as follows.
Column | Field | Format | Units | Description |
---|---|---|---|---|
1 |
gaia designation |
string |
- |
Gaia designation number |
2 |
ra |
float32 | deg |
Right Ascension |
3 |
dec |
float32 |
deg |
Declination |
4 |
sap_mean_flux |
float32 | e−/s |
Mean of SAP flux |
5 |
sap_mean_flux_err |
float32 | e−/s |
Mean of SAP flux error |
6 |
psf_mean_flux |
float32 | e−/s |
Mean of PSF flux |
7 |
psf_mean_flux_err |
float32 | e−/s |
Mean of PSF flux error |
8 |
flfrcsap |
float32 | - |
Minimum detected SAP flux fraction |
9 |
crowdsap |
float32 | - |
Minimum detected SAP crowding |
10 |
npixsap |
float32 | - |
Minimum detected SAP number of pixels |
11 |
psffrac |
float32 | - |
Minimum detected PSF fraction |
12 |
pertrati |
float32 | - |
Mean detected perturbed/mean PSF ratio |
13 |
pertstd |
float32 | - |
Minimum detected perturbed PSF standard |
14 |
psf_avail |
string | - |
String encoding PSF flux availability per quarter |
15 | sap_avail | string | - |
String encoding SAP flux availability per quarter |
16 |
psf_fraction_flag |
string | - |
String encoding PSF fraction quality per quarter |
17 |
phot_g_mean_mag |
float32 | mag |
Gaia G band mean magnitude |
18 |
phot_bp_mean_mag |
float32 | mag |
Gaia BP band mean magnitude |
19 |
phot_rp_mean_mag |
float32 | mag |
Gaia RP band mean magnitude |
20 |
tpf_org |
int32 | - |
TPF where sources were detected |
21 | kic | int32 | - |
Kepler input catalog number |
22 | kic_sep | float32 | arcsec | Distance to KIC source |
23 | kepmag | float32 | mag | Kepler magnitude |
24 | file_name | string | - |
FITS file name |
The KOIs and neighbors catalog (hlsp_kbonus-bkg_kepler_kepler_kois-nns-catalog_kepler_v1.0_cat.fits) has the following columns.
Column | Field | Format | Units | Description |
---|---|---|---|---|
1 | gaia_designation | String | - | Gaia designation number |
2 | ra | Float32 | deg | Right Ascension |
3 | dec | Float32 | deg | Declination |
4 | kic | Int32 | - | Kepler input catalog number |
5 | fname | String | - | Light curve FITS file name |
6 | nn_koi | Int32 | - | Nearest KOI |
7 | nn_dist | Float32 | arcsec | Distance to nearest KOI |
The M-stars catalog (hlsp_kbonus-bkg_kepler_kepler_mstars_kepler_v1.0_lcf.tar.gz) has the following columns.
Column | Field | Format | Units | Description |
---|---|---|---|---|
1 | gaia_designation | String | - | Gaia designation number |
2 | ra | Float32 | deg | Right Ascension |
3 | dec | Float32 | deg | Declination |
4 | kic | Int32 | - | Kepler input catalog number |
5 | fname | String | - | Light curve FITS file name |
The white dwarfs catalog (hlsp_kbonus-bkg_kepler_kepler_wd_kepler_v1.0_lcf.tar.gz) has the following columns.
Column | Field | Format | Units | Description |
---|---|---|---|---|
1 | gaia_designation | String | - | Gaia designation number |
2 | ra | Float32 | deg | Right Ascension |
3 | dec | Float32 | deg | Declination |
4 | kic | Int32 | - | Kepler input catalog number |
5 | fname | String | - | Light curve FITS file name |
6 | Pwd | Float32 | - | White dwarf probability |
Data Access
Lightcurves are available in the MAST Portal (web-based, cross-mission search interface) and Astroquery (Python package to search for and download files from Python scripts you write). We also provide a bulk download cURL script for all lightcurves below. Catalogs and bundled lightcurves for specific targets can be accessed via the direct download table below.
Portal Advanced Search:
Set the Provenance Name filter to KBONUS-BKG and the target names or the RA/Dec filters to the interested field of view in the Portal Advanced Search to find individual lightcurves. Each observation in the Portal contains a single source's lightcurve. Note that since the total number of KBONUS-BKG is larger than the load limit (50,000) and the download limit (500,000), you can use the direct download bulk script below to download all lightcurves or narrow down your search for specific lightcurves using the RA/Dec filters.
Astroquery Access:
The lightcurves can also be retrieved programmatically by using the astroquery—mast module. See the code example below for counting the total number of observations and retrieving and downloading lightcurve files. See more examples in Astroquery and API filter parameters.
from astroquery.mast import Observations
# Getting the total observation counts
print(Observations.query_criteria_count(provenance_name= "kbonus-bkg"))
# Filtering observations by Gaia DR3 target names and RA/Dec
gaia_obs = Observations.query_criteria(provenance_name= "kbonus-bkg", target_name ="*GAIA DR3*", s_ra=[293.2, 294.5], s_dec=[50.5, 51.5])
# Getting the product list
data_products = Observations.get_product_list(gaia_obs)
print(data_products)
# Download the observations
Observations.download_products(data_products)
-
A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory
-
Search for and retrieve KBONUS-BKG data products programmatically.
Bulk download script | File size | Total data size after download | Description |
---|---|---|---|
4.0 KB | 4.8 TB | lftp script to download all lightcurves | |
29 MB |
4.8 TB | cURL script to download all lightcurves | |
hlsp_kbonus-bkg_kepler_lightcurves_all_kepler_v1_chunkdl.zip |
6.8 MB | 4.8 TB | Compressed cURL scripts. Each uncompressed script will download 50,000 lightcurves. |
The catalog released with this work contains the list of extracted sources resulting in a light curve FITS file. It also contains extraction metrics and availability flags that can be used to filter sources. The catalogs can be accessed via direct links below.
Files | File Size | Description |
---|---|---|
hlsp_kbonus-bkg_kepler_kepler_source-catalog_kepler_v1.0_cat.fits | 140 MB | Source catalog for all lightcurves |
hlsp_kbonus-bkg_kepler_kepler_kois-nns-catalog_kepler_v1.0_cat.fits | 2.6 MB |
Lightcurves listed in the NASA Exoplanet Archive, including confirmed and false positive candidates. It also includes the light curves of neighbor sources around each KOI in a 30′′ radius. There are ∼ 32, 000 light curve files. This data bundle is helpful for users who desire to explore false-positives candidates and their neighbors. |
hlsp_kbonus-bkg_kepler_kepler_mstars-catalog_kepler_v1.0_cat.fits | 2.0 MB | Source catalog for M dwarfs;
It contains a total of ∼ 20, 000 sources. |
hlsp_kbonus-bkg_kepler_kepler_wd-catalog_kepler_v1.0_cat.fits | 24 KB | Source catalog for white dwarfs |
To facilitate data access to specific source types, the team has created the following data bundles:
Files | File Size | Description |
---|---|---|
hlsp_kbonus-bkg_kepler_kepler_kois-nns_kepler_v1.0_lcf.tar.gz |
204 GB |
Lightcurve bundle for KOIs and neighbors |
134 GB |
Lightcurve bundle for M Dwarfs | |
373 MB |
Lightcurve bundle for White Dwarfs; It contains a total of ∼ 90 light curves. |