AllBRICQS: All-Sky Bright Quasar Survey

• AllBRICQS is a comprehensive survey of optically bright quasars defined by strict Gaia astrometric, morphology, and WISE mid-infrared criteria.
• The survey employs a simple yet effective Gaia+WISE selection to recover over 200 high-value quasar candidates previously missed by legacy searches.
• Its high completeness and purity enable detailed studies of black hole masses, variability, and cosmological phenomena like redshift drift.

The All-sky BRIght, Complete Quasar Survey (AllBRICQS) is a survey of optically bright quasars selected from all-sky satellite data, designed to discover the “last remaining” bright quasars at Galactic latitude $|b|>10^\circ$ using Gaia and WISE. Its published results comprise an initial southern release with 156 spectroscopically confirmed quasars, 140 of them newly identified, and a northern catalog with 62 newly confirmed quasars, together establishing a bright, nearly all-sky quasar sample defined primarily by Gaia $B_P$ and $R_P$ limits and simple astrometric, morphology, and mid-infrared criteria (Onken et al., 2022).

1. Survey concept and scientific rationale

AllBRICQS was formulated to make the bright quasar sky “essentially complete” down to $B_P < 16.5$ or $R_P < 16$ mag at $|b|>10^\circ$, motivated by the continued incompleteness of legacy bright-quasar searches despite decades of optical, radio, UV, and X-ray surveys (Onken et al., 2022). The survey is explicitly aimed at the optically brightest quasars, where the surface density is low, the scientific value of each object is high, and missed objects can materially affect bright-end demographics.

The scientific motivations stated for the survey include high-S/N and high-resolution follow-up, IGM and CGM absorption studies, black hole mass measurements, reverberation mapping, variability studies, and cosmological applications such as Sandage’s redshift drift test and improved constraints on the bright end of the quasar luminosity function (Onken et al., 2022). The northern catalog further frames the confirmed objects as resources for studies of quasar evolution, black holes, their environments, and host galaxies across multiple wavelengths (Choi et al., 8 Aug 2025).

“All-sky” is operational rather than literal. The published selection excludes the densest Galactic-plane regions through the latitude cut $|b| > 10^\circ$, and it also excludes many extended or blended sources through Gaia morphology filtering. The survey is therefore optimized for bright, point-like quasars rather than for low-latitude, host-dominated, or strongly lensed systems (Onken et al., 2022).

2. Definition of the bright sample and selection methodology

The primary AllBRICQS bright sample is defined in Gaia DR3 bands by

$B_P < 16.5 \quad \text{or} \quad R_P < 16.0,$

together with $|b| > 10^\circ$ (Onken et al., 2022). An extended subsample 0.5 mag fainter was also defined in the first release, and four quasars from that extended bin were included there (Onken et al., 2022).

Selection combines Gaia DR3 and WISE. From Gaia, the survey uses $B_P$, $B_P$0, and $B_P$1 photometry; parallaxes and proper motions; and the BP/RP excess factor. The Gaia-based cuts require parallax and proper motion to be consistent with zero at $B_P$2 significance, and

$B_P$3

which suppresses extended galaxies and strongly blended sources (Onken et al., 2022). The key WISE discriminant is the deliberately loose mid-infrared color cut

$B_P$4

chosen to maximize completeness at bright magnitudes while accepting some spectroscopic contamination (Onken et al., 2022).

Applying the Gaia astrometric and morphology cuts, the latitude cut, the bright Gaia magnitude limits, and $B_P$5 yields 290 candidates over the whole sky at $B_P$6 in the first AllBRICQS paper (Onken et al., 2022). The northern catalog retained the same core methodology and further defined two practical priority classes, with Priority 1 corresponding to $B_P$7 mag in the initial AllWISE-based prioritization and Priority 2 to $B_P$8 mag; nearly all stellar contaminants and ambiguous sources in that follow-up came from the latter class (Choi et al., 8 Aug 2025).

A central result of the survey is that this simple Gaia+WISE selection recovers quasars that Gaia DR3 itself did not identify as quasar candidates (Onken et al., 2022). The stated rationale is not algorithmic novelty but a transparent bright-end selection built around zero proper motion, point-like Gaia morphology, and a loose AGN mid-infrared excess.

3. Spectroscopic confirmation and published releases

The first published AllBRICQS release is based on southern follow-up with the ANU 2.3-m telescope at Siding Spring Observatory using WiFeS, an integral-field spectrograph with field of view $B_P$9 arcsec, $R_P$0 in both blue and red arms, and wavelength coverage $R_P$1–$R_P$2 Å. Observations were obtained from March to November 2022 with exposure times of 180–1500 s; the data were reduced with PyWiFeS, flux-calibrated in shape with spectrophotometric standards, rescaled to Gaia $R_P$3 and $R_P$4 photometry, and classified with MARZ. Typical S/N in the final 1D spectra is 10–50 per pixel, and the typical redshift uncertainty is $R_P$5 (Onken et al., 2022).

That southern release reported 156 spectroscopically confirmed quasars, 140 newly identified, spanning $R_P$6–3.93 (Onken et al., 2022). Of those, 152 satisfy the main magnitude cuts and four are slightly fainter, coming from the extended sample (Onken et al., 2022).

The second published release covers northern candidates at $R_P$7 and presents 75 observed AllBRICQS candidates, of which 62 are newly confirmed quasars, 5 remain unclassified, and 8 are stars (Choi et al., 8 Aug 2025). Spectroscopy was obtained with the Long-Slit Spectrograph on the 1.8-m telescope at Bohyunsan Optical Astronomy Observatory, YFOSC on the 2.4-m telescope at Lijiang Observatory, and BFOSC on the 2.16-m telescope at Xinglong Observatory (Choi et al., 8 Aug 2025).

The northern release emphasizes flux calibration under non-photometric conditions by scaling spectra with ZTF broadband photometry and determines redshifts using inverse-variance weighted cross-correlation methods (Choi et al., 8 Aug 2025). In formal terms, the cross-correlation fit minimizes

$R_P$8

with $R_P$9 the observed flux, $B_P < 16.5$0 the flux uncertainty, $B_P < 16.5$1 the template, and $B_P < 16.5$2 the optimal normalization (Choi et al., 8 Aug 2025).

4. Completeness, purity, and relation to Gaia-based catalogs

Within the AllBRICQS selection window—$B_P < 16.5$3, $B_P < 16.5$4 or $B_P < 16.5$5, Gaia astrometric and BP/RP-excess cuts, and $B_P < 16.5$6—the expected completeness is approximately $B_P < 16.5$7 (Onken et al., 2022). In the first paper this estimate is anchored empirically by tests on Milliquas broad-line quasars with Gaia $B_P < 16.5$8, $B_P < 16.5$9, and $R_P < 16$0, for which the Gaia proper-motion/parallax and excess-factor cuts reject $R_P < 16$1 of sources, while the $R_P < 16$2 cut removes only a small additional fraction (Onken et al., 2022).

The preliminary selection purity from the first spectroscopic campaign is also approximately $R_P < 16$3. The paper reports 166 observed candidates; after excluding four quasars slightly fainter than the official magnitude limits and four unclassified spectra, 152 of 158 “on-cut, classified” objects are quasars (Onken et al., 2022). In the northern release, the Priority 1 subset defined by $R_P < 16$4 reached a selection purity of $R_P < 16$5 (Choi et al., 8 Aug 2025).

A distinctive result is the mismatch between AllBRICQS and Gaia DR3’s own quasar classifiers. In the southern release, Gaia GLEAN includes 123 of 156 AllBRICQS quasars, whereas the Gaia DSC labels only 116 of 156 as “quasar”; 37 AllBRICQS quasars are labeled as stars, one as “physicalbinary,” and the extreme quasar J0529–4351 at $R_P < 16$6 is classified as a star with 99.98% probability (Onken et al., 2022). AllBRICQS therefore functions in part as a bright-end correction to Gaia DR3 classification failures.

The northern release also compares directly to Quaia. Of the 62 northern AllBRICQS quasars, 50 appear as quasar candidates in Quaia, corresponding to $R_P < 16$7 completeness relative to this bright sample; none of the 8 stars in the northern sample appear in Quaia (Choi et al., 8 Aug 2025). Using AllBRICQS spectroscopy as ground truth, the Quaia redshift catastrophic failure rates in that bright comparison are

$R_P < 16$8

illustrating that bright and unusual quasars can remain problematic even in Gaia-based all-sky catalogs (Choi et al., 8 Aug 2025, Storey-Fisher et al., 2023).

The northern paper further proposes stricter astrometric cuts,

$R_P < 16$9

as a way to reduce stellar contamination with little loss of quasar completeness in future releases (Choi et al., 8 Aug 2025).

5. Source properties, luminosities, and notable discoveries

The southern AllBRICQS sample spans $|b|>10^\circ$0–3.93 (Onken et al., 2022). The northern sample spans redshifts between 0.09 and 2.48 and a bolometric luminosity range

$|b|>10^\circ$1

(Choi et al., 8 Aug 2025). The published releases therefore cover bright quasars from nearby, host-influenced systems to some of the most luminous known high-redshift quasars.

Both releases derive continuum luminosities at standard rest-frame wavelengths. The southern paper measures median continuum fluxes in 20 Å windows at 1450 Å, 3000 Å, and 5100 Å, adopts a flat $|b|>10^\circ$2CDM cosmology with $|b|>10^\circ$3 and $|b|>10^\circ$4 km s$|b|>10^\circ$5 Mpc$|b|>10^\circ$6, applies Milky Way extinction corrections, and estimates bolometric luminosities with Runnoe et al. bolometric corrections through

$|b|>10^\circ$7

(Onken et al., 2022). The northern paper uses PyQSOFit on extinction-corrected spectra, fits the continuum over 4000–9000 Å with a power law plus a third-order polynomial, and again converts $|b|>10^\circ$8, $|b|>10^\circ$9, and $|b| > 10^\circ$0 to $|b| > 10^\circ$1 with empirical bolometric corrections (Choi et al., 8 Aug 2025).

The emblematic object in the first release is J0529–4351 at $|b| > 10^\circ$2, with $|b| > 10^\circ$3 mag and $|b| > 10^\circ$4 mag (Onken et al., 2022). From the rest-frame 1450 Å continuum luminosity the paper derives

$|b| > 10^\circ$5

and reports no evidence for significant lensing after tests using Gaia BP/RP excess statistics, DES imaging, searches for nearby counter-images, and variability data (Onken et al., 2022). The same paper notes that the source is radio-quiet, with no RACS DR1 detection within $|b| > 10^\circ$6, and X-ray faint, with no 2RXS counterpart within $|b| > 10^\circ$7 (Onken et al., 2022).

The northern release highlights several rare spectroscopic subtypes. J1356+3840 is a FeLoBAL quasar at $|b| > 10^\circ$8 with

$|b| > 10^\circ$9

described there as the brightest FeLoBAL quasar discovered to date (Choi et al., 8 Aug 2025). J0919+3557 is argued to be a weak-line quasar at $B_P < 16.5 \quad \text{or} \quad R_P < 16.0,$0, despite previous classifications as a galaxy or a star in public survey products (Choi et al., 8 Aug 2025). J0141+7307 at $B_P < 16.5 \quad \text{or} \quad R_P < 16.0,$1 and J1216+7948 at $B_P < 16.5 \quad \text{or} \quad R_P < 16.0,$2 show strong UV Fe II emission complexes (Choi et al., 8 Aug 2025).

These discoveries are consistent with the survey’s stated bright-end purpose: the sample contains ordinary broad-line quasars, but it also recovers rare BAL, FeLoBAL, weak-line, and extreme-luminosity objects that had been missed or misclassified in previous wide-area catalogs (Onken et al., 2022, Choi et al., 8 Aug 2025).

6. Position within the quasar-survey landscape and scientific uses

AllBRICQS is explicitly situated against the incompleteness of earlier bright-quasar searches such as the Palomar Bright Quasar Survey, the Hamburg surveys, Calán–Tololo, SDSS quasar targeting, and compiled catalogs like Milliquas (Onken et al., 2022). The first release argues that a substantial fraction of bright quasars were still absent from previous compilations: 140 of 156 AllBRICQS quasars in that release were newly identified, and several others had prior AGN identifications but lacked published redshifts or spectra (Onken et al., 2022).

The northern release shows that bright quasars selected by simple Gaia+WISE cuts can remain missing even inside major modern survey footprints. Eighteen of the 62 northern AllBRICQS quasars lie within the SDSS imaging footprint but are absent from SDSS DR16Q, and 22 lie within the DESI imaging footprint, though many are brighter than DESI’s lower $B_P < 16.5 \quad \text{or} \quad R_P < 16.0,$3-band targeting limit (Choi et al., 8 Aug 2025). The same paper reports that the optical–IR colors of these missed AllBRICQS quasars are statistically consistent with those of bright SDSS DR16Q quasars, implying that the omissions are not explained by a simple color anomaly (Choi et al., 8 Aug 2025).

The scientific uses emphasized by the AllBRICQS papers are those enabled by extreme brightness. These include detailed black hole characterization, virial mass estimates from broad-line widths, reverberation mapping, absorption-line studies of the IGM and CGM, and interferometric broad-line-region imaging. The first paper explicitly notes that the relation $B_P < 16.5 \quad \text{or} \quad R_P < 16.0,$4 makes the brightest quasars the best targets for GRAVITY/VLTI-type BLR imaging, and it identifies bright high-redshift quasars as attractive targets for Sandage’s redshift drift experiment (Onken et al., 2022).

Future directions stated in the published releases include completion of northern and full-sky spectroscopic coverage, refinement of selection near the Galactic plane, tighter astrometric filtering, and more detailed physical analysis of the confirmed objects, including black hole masses, Eddington ratios, and higher-resolution follow-up of exceptional sources such as J0529–4351 and J1356+3840 (Onken et al., 2022, Choi et al., 8 Aug 2025). Within that landscape, AllBRICQS occupies a specific niche: a deliberately simple, Gaia+WISE-selected, bright-end census intended to be both usable for immediate follow-up and explicit enough for completeness and purity to be quantified.