Mission Overview

Hubble Catalog of Variables (HCV)

 

Primary Investigator: Alceste Bonanos

HLSP Authors: Alceste Bonanos, Antonella Nota, Paule Sonnentrucker, Rick White

Released: 2019-09-24

Updated: 2019-09-24

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

DOI: 10.17909/t9-m29s-xg91

Citations: See ADS Statistics

Read Me

 
Examples of different types of HCV variable objects.
Example Light Curves Of HCV Variables

Example light curves for different types of variable sources in the HCV catalog. From left to right and top to bottom are the light curves of a classical nova in M87, an AGN in HDF North, a classical Cepheid in M101, SN 2012cg in NGC 4424, an LPV in M31, a RR Lyrae in M31 (phased with P=0.688 days), two Cepheids in NGC 4424 and NGC 3982 with sparse light curves, and a variable in NGC 4535.  Figure from Bonanos et al. 2019.

HCV color-magnitude diagram for IC 1613.
HCV Color-Magnitude Diagram For IC 1613

Color-magnitude diagram for IC 1613 showing the location of the multi-filter variable candidates (MFVCs) and single-filter variable candidates (SFVCs) in the field. Many of the candidate variables lie on the instability strip.  Figure from Bonanos et al. 2019.

Overview

The Hubble Catalog of Variables (HCV) is the first full, homogeneous, catalog of variable sources found in the Hubble Source Catalog (HSC), which is built out of publicly available images obtained with the WFPC2, ACS and WFC3 instruments onboard the Hubble Space Telescope. The HCV is the deepest catalog of variables available. It includes variable stars in our Galaxy and nearby galaxies, as well as transients and variable active galactic nuclei. The HCV contains 84,428 candidate variable sources (out of 3.7 million HSC sources that were searched for variability) with V <= 27 mag; for 11,115 of them the variability is detected in more than one filter. The number of data points in a light curve range from 5 to 120, the time baseline ranges from under a day to over 15 years, while ~8% of variables have amplitudes in excess of 1 mag.  Two catalogs are provided in this HLSP: a catalog of variables, and a catalog of objects that are "constant" within 5-sigma of their median absolute deviation (MAD).

The catalog of variables lists for each source the equatorial coordinates, MatchID, GroupID, subgroup, the pipeline classification flag, the expert-validation classification flag, the number of existing instrument and filter combinations for the source, the name of the instrument and filter combination.  The filter combination includes: the filter detection flag (set to "1" if variability is detected, or "0" if not), the variability quality flag, the number of measurements in the light curve, the HSC magnitude, the corrected magnitude, the MAD value, and the reduced chi^2 value.  For all multi-filter variable candidates, there are extra columns for each additional instrument and filter combination, in which the source is classified as a variable candidate.

The catalog of constant sources contains the sources that fall below the 5-sigma detection threshold of the HCV pipeline. These include constant sources and low-amplitude variables that are below the detection threshold. For each source, the columns show the equatorial coordinates, the MatchID, the GroupID, the subgroup, the number of instrument and filter combinations in which individual sources are observed, follwed by the name of each instrument and filter combination for which the following data are given: the number of measurements in the light curve, the HSC magnitude, the corrected magnitude, the MAD value, and the reduced chi^2 value.

Data Products

The two catalogs, and associated README files, follow this naming convention:

hlsp_hcv_hst_wfpc2-acs-wfc3_all_multi_v1_<ext>

where:

  • <ext> is the data file type

Data file types:

_const-cat.dat Catalog of objects that fall below the 5-sigma detection limit.  Corresponds to Table 10 in Bonanos et al. 2019.
_const-cat-readme.txt README file for the catalog of constant objects, describing the columns in the file on a byte-by-byte basis.
_var-cat.dat Catalog of variable objects.  Corresponds to Table 9 in Bonanos et al. 2019.
_var-cat-readme.txt README file for the catalog of variable objects, describing the columns in the file on a byte-by-byte basis.

Data Access

The HCV catalogs are available in a variety of services, including the HCV Explorer developed by the ESAC Science Data Centre.

The MAST Catalogs Interface

catalogs.mast

Search the variable object catalog through the catalogs.mast web form. The same form can be used to query the Hubble Source Catalog v2 or v3.
HCV Explorer Interface

HCV Explorer

A new online web tool to access and visualize the HCV. Developed by the ESDC, the tool offers interactive and connected exploration of the HCV.
Link to MAST CasJobs.

MAST CasJobs

A web-based SQL interface to query and cross-match between catalogs. Export tables, saved queries, long query submissions.
Link to Python notebook tutorials.

Notebook Tutorial #1

Python notebook tutorial on how to use the HCV using the HSC catalog interface API. Simpler to use, but less powerful, than the CasJobs module.
Notebook Tutorial #2

Notebook Tutorial #2

Python notebook tutorial on how to use the HCV using the MAST CasJobs module. More powerful, but more complex, than the catalogs interface API.

The README and catalog files may also be downloaded in their entirety using the table below.

NOTE: The format of the downloadable tables linked below are not finalized, and will be updated once work is completed at CDS. Until then, the tables may not be readable by standard software functions.  You can always export some or all of the table rows using the other interfaces, like MAST CasJobs.

Catalog File README File Catalog Size

hlsp_hcv_hst_wfpc2-acs-wfc3_all_multi_v1_var-cat.dat

hlsp_hcv_hst_wfpc2-acs-wfc3_all_multi_v1_var-cat-readme.txt

202 MB

hlsp_hcv_hst_wfpc2-acs-wfc3_all_multi_v1_const-cat.dat

hlsp_hcv_hst_wfpc2-acs-wfc3_all_multi_v1_const-cat-readme.txt

7.2 GB

 

 

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.

References