DOI: 10.5281/zenodo.17515027
title: The Data for "QHSC: The Quasar Candidate Catalog for the Hyper Suprime-Cam Subaru Strategic Program"

description: We present the QHSC catalog — a machine-learning–selected sample of quasar candidates with photometric redshifts identified in the Wide layer of the HSC-SSP survey (Public Data Release 3). 

If you use the QHSC catalog or any part of this dataset in your research, please cite this Zenodo record and/or the related paper (Zhu et al. 2025, submitted to ApJS).

The complete QHSC catalog includes four distinct subsamples:1. A master sample based on HSC-only photometry.2. An HSC+WISE sample combining optical and mid-infrared WISE data.3. The GoldenU sample, incorporating near-infrared photometry from UKIDSS (e.g. HSC+WISE+UKIDSS).4. The GoldenV sample, incorporating near-infrared photometry from VISTA (e.g. HSC+WISE+VISTA).

These four subsamples are stored as separate FITS extensions within one catalog file named "QHSC.fits".

1. Python Example: Loading the QHSC Catalog

"""Pythonfrom astropy.table import Tablefrom astropy.io import fits

hdul = fits.open('<.../QHSC.fits>')

tbl_master   = Table.read(hdul['Master'])tbl_hsc_wise = Table.read(hdul['HSC+WISE'])tbl_goldenU  = Table.read(hdul['GoldenU'])tbl_goldenV  = Table.read(hdul['GoldenV'])"""

2. Columns Description

(Note: All magnitudes are given in the AB system.)--------------------------------------------

1.  object_id: Unique HSC object ID (64-bit integer)2.  ra: Right Ascension (J2000) from HSC3.  dec: Declination (J2000) from HSC4.  pQSO: Probability of the object being a quasar5.  z_ML: Photometric redshift estimated by the bsXGBoost model6.  z_ML_std: Model uncertainty of the estimated photometric redshift7.  ebv: Galactic extinction E(B−V) from the SFD dust map, scaled by a factor of 0.86... x_image_flag: HSC image quality flag for band x, where x ∈ {g, r, i, z, y}... flag_x_aper: Aperture photometry flag in HSC band x... mag_x_aper: Aperture magnitude in HSC band x... magerr_x_aper: Error of aperture magnitude in HSC band x... flag_x_psf: PSF photometry flag in HSC band x... mag_x_psf: PSF magnitude in HSC band x... magerr_x_psf: Error of PSF magnitude in HSC band x... flag_x_cmodel: CModel photometry flag in HSC band x... mag_x_cmodel: CModel magnitude in HSC band x... magerr_x_cmodel: Error of CModel magnitude in HSC band x

--------------------------------------------QHSC HSC+WISE--------------------------------------------

58. name_catwise: CatWISE2020 source name59. mag_W1: W1 magnitude from profile-fit photometry with motion correction60. magerr_W1: Error of W1 magnitude61. mag_W2: W2 magnitude from profile-fit photometry with motion correction62. magerr_W2: Error of W2 magnitude

--------------------------------------------QHSC Golden (UKIDSS)--------------------------------------------

63. id_ukidss: Unique UKIDSS source ID64. ukidss_survey: UKIDSS sub-survey name (e.g., LAS, DXS, or UDS)65. mag_J: UKIDSS J-band aperture corrected magnitude (2″ aperture diameter)66. magerr_J: Error of J-band magnitude from UKIDSS67. mag_H: UKIDSS H-band aperture corrected magnitude (2″ aperture diameter)68. magerr_H: Error of H-band magnitude from UKIDSS69. mag_K: UKIDSS K-band aperture corrected magnitude (2″ aperture diameter)70. magerr_K: Error of K-band magnitude from UKIDSS

--------------------------------------------QHSC Golden (VISTA)--------------------------------------------

63. id_vista: Unique VISTA source ID64. vista_survey: VISTA survey name (e.g., VIKING, VHS, VIDEO, or UltraVISTA)65. mag_J: VISTA J-band aperture corrected magnitude (2″ aperture diameter)66. magerr_J: Error of J-band magnitude from VISTA67. mag_H: VISTA H-band aperture corrected magnitude (2″ aperture diameter)68. magerr_H: Error of H-band magnitude from VISTA69. mag_Ks: VISTA Ks-band aperture corrected magnitude (2″ aperture diameter)70. magerr_Ks: Error of Ks-band magnitude from VISTA