THE UV-BRIGHT QUASAR SURVEY (UVQS): DR1

Presently, the only efficient means of studying the diffuse gas surrounding galaxies (a.k.a. halo gas or the circumgalactic medium, CGM) and in between galaxies (a.k.a. the intergalactic medium, IGM) is through absorption-line spectroscopy of luminous, background quasars (e.g., Tripp et al. 2008; Tumlinson et al. 2013; Tejos et al. 2014). Furthermore, because the principal transitions to diagnose gas lie at far-ultraviolet (FUV) wavelengths (λ_rest < 2000 Å), for z < 1 studies, one requires UV spectrometers on space-borne facilities. Currently, and for the foreseeable future, the Hubble Space Telescope (HST) affords the only opportunity for such research, primarily with the Cosmic Origins Spectrograph (COS). Given the modest aperture of HST, these observations are generally restricted to the brightest FUV quasars on the sky.

High-quality, FUV spectroscopy of z ∼ 1 quasars has enabled several unique experiments to study the CGM and IGM of the universe over the past ∼10 Gyr. These include: (1) the survey of highly ionized gas via the Ne viiiλλ770, 780 doublet and/or broad H i Lyα systems that may trace the elusive warm-hot ionized medium (e.g., Lehner et al. 2007; Meiring et al. 2013; Tejos et al. 2016); (2) the search for signatures of galactic and active galactic nucleus (AGN) feedback (e.g., Tripp et al. 2011); (3) the measurements of enrichment in galactic halos and optically thick gas (e.g., Lehner et al. 2013; Werk et al. 2013, 2014); and (4) revealing the structure of the cosmic web and its correlation to the large-scale structures traced by galaxies (e.g., Tejos et al. 2014). While each of these programs has had a scientific impact, they are limited by sample variance.

An efficient way to increase the volumes surveyed is to focus on those bright UV QSOs that maximize the redshift path covered, i.e., those with z_em ≳ 1. To date, only a small number of z ∼ 1 quasars have been observed with HST, primarily corresponding to the set of sources with very high FUV flux. These have been drawn from historical, large-area surveys for AGNs (e.g., the Palomar-Green Bright Quasar Survey and the Hamburg/ESO survey) and more recently the Northern Galactic pole footprint of the Sloan Digital Sky Survey (SDSS). Cross-matching the quasar sample of Flesch (2015) against the point-source catalog of the GALEX survey, one recovers ≈140 sources with z > 0.6 and FUV < 18 mag (fewer than 50 at z > 1). These are preferentially located within the SDSS footprint, which has extensively surveyed the Northern galactic pole for quasars (e.g., Schneider et al. 2010). Given that HST may observe nearly any position on the sky, we are motivated to perform an all-sky search for new, FUV-bright quasars across the sky. Indeed, progress in this area demands the discovery of new FUV-bright quasars.

The principal goal of our survey is to provide the community with a nearly complete set of UV-bright AGNs before the termination of the HST mission. We recognized that the combination of two NASA imaging missions—GALEX and WISE—enables a modern, all-sky search for UV bright quasars. These must be spectroscopically confirmed, however, before subsequent HST observations. Given our interest in FUV-bright sources, this implies optically bright candidates that can be spectroscopically confirmed on 3 m-class telescopes. The following manuscript provides the first data release (DR1) from our UV-bright Quasar Survey (UVQS). The main data products are available at the Mikulski Archive for Space Telescopes.⁵

This paper is organized as follows. Section 2 describes the UVQS candidate selection, focused on detecting z ∼ 1 quasars with FUV < 18 mag. The follow-up spectroscopy is discussed in Section 3 and the redshift analysis is described in Section 4. We present the primary results in Section 5. When relevant, we assume a ΛCDM cosmology with h = 0.7, Ω_m = 0.3, and Ω_Λ = 0.7.

With the explicit goal of discovering new FUV-bright quasars at z ∼ 1 across the sky, we developed color–color criteria, leveraging the all-sky surveys of the WISE and GALEX missions to (i) isolate AGNs and (ii) maximize the probability that these AGNs lie at ${z}_{{\rm{em}}}$ ≳ 1. For the first criterion, we followed the impressive results from the WISE team who demonstrated the clean separation of AGNs from stars, galaxies, and other astrophysical sources using WISE photometry (Stern et al. 2012). Specifically, Stern et al. (2012) showed that AGNs tend to exhibit $W1-W2\gt 0.4$ mag, with galaxies and stars having smaller values. Although this criterion may not capture all AGNs (e.g., Assef et al. 2010), we strongly expect that every UV-bright AGN satisfies the criterion. Indeed, we find that of the 1148 quasars at z < 1.5 from SDSS DR7 detected by GALEX (NUV < 19.0), all have $W1-W2\gt 0.625$ mag (Figure 1). The overwhelming majority of these have z < 0.8 (90%).

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Figure 1 also shows the FUV–NUV colors of these quasars. These were measured from the "photoobjall" catalog of the GALEXGR6Plus7 context at MAST and improved, where possible, using the MIS catalog ("bcscat_mis" Bianchi et al. 2014). We see that the majority of z < 0.8 quasars have $\mathrm{FUV}\mbox{--}\mathrm{NUV}\lt 0.3$ mag (60%) and that nearly all of the z > 0.8 quasars have a redder FUV–NUV color. We believe that this "reddening" primarily results from the presence of one or more Lyman limit systems (LLSs) in the redshift interval 0.5 < z < 0.8, whose continuum opacity reduces only the FUV flux. We infer that nearly every z ∼ 1 quasar exhibits at least one intervening LLS⁶ with ${N}_{{\rm{H}}{\rm{I}}}\gt {10}^{16.7}\;{\mathrm{cm}}^{-2}$.

With our photometric criteria established,

$$\begin{eqnarray}&&W1-W2\gt 0.6\;{\rm{mag}}\end{eqnarray} \tag{ 1 }$$

$$\begin{eqnarray}&&{\rm{FUV\mbox{--}NUV}}\gt 0.3\;{\rm{mag}}\end{eqnarray} \tag{ 2 }$$

$$\begin{eqnarray}&&{\rm{FUV}}\lt 18.5\;{\rm{mag}},\end{eqnarray} \tag{ 3 }$$

we cross-matched every source in the GALEXGR6Plus7 catalogs⁷ satisfying these criteria against the AllWISE Source Catalog. To avoid selecting already known quasars given the beam sizes of WISE and GALEX, we then eliminated any sources that lay within 5'' of a UV-bright quasar from SDSS DR7. This generated a list of 1450 primary candidates (Table 1). We discovered, during our analysis, that this candidate list includes hundreds of previously cataloged sources from other surveys. This includes the SDSS-III survey which included WISE-selected quasar targets (Pâris et al. 2014). Their primary WISE criteria, however, precluded overlap with our sample. Given that several of these surveys have known examples of false redshift identifications or do not provide the discovery spectra, we maintained the list and re-observed many of the brighter sources (FUV < 18 mag). Figure 2 shows an all-sky summary of the UVQS candidates, separated by FUV flux. The exclusion of the Galactic plane is obvious and the lower incidence of sources in the SDSS footprint is notable.

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In several of the observing runs, conditions were unexpectedly favorable and we exhausted the primary candidates at certain R.A. ranges. To fill the remaining observing time, we generated a secondary candidate list with one criterion modified: −0.5 < FUV–NUV < 0.3. This would permit a much higher fraction of low-z AGNs, but may also yield a few sources at z ∼ 1. This secondary set of candidates is provided in Table 2.

We proceeded to obtain discovery-quality longslit spectra (i.e., low-dispersion, large wavelength coverage, modest signal-to-noise ratio (S/N) of our UVQS candidates in one calendar year. Our principal facilities were: (i) the dual Kast spectrometer on the 3 m Shane telescope at the Lick Observatory; (ii) the Boller & Chivens (BCS) spectrometer on the Irénée du Pont 100'' telescope at the Las Campanas Observatory; and (iii) the Calar Alto Faint Object Spectrograph on the CAHA 2.2 m telescope at the Calar Alto Observatory (CAHA). We acquired an additional ≈20 spectra on larger aperture telescopes (Keck/ESI, MMT/MBC, Magellan/MagE) during twilight or under poor observing conditions. Typical exposure times were limited to ≲200 s, with adjustments for fainter sources or sub-optimal observing conditions. Table 3 provides a list of the observed candidates.

The two-dimensional (2D) spectral images and calibration frames were reduced with custom software, primarily the LowRedux package⁸ developed by J. Hennawi, X. Prochaska, and D. Schlegel. Briefly, the images were bias-subtracted, flat-fielded using quartz lamp spectral images, and wavelength-calibrated with arc-lamp exposures. Objects within the slit were automatically identified and optimally extracted to 1D spectra. These were fluxed after generating a sensitivity function from observations of spectrophotometric standard stars taken during each observing run. We did not carefully account for varying atmospheric conditions and we did not correct for slit-losses from variable seeing or atmospheric dispersion. Therefore, the reported fluxes are crude and not even especially accurate in a relative sense, particularly at the wavelength extrema. Although we occasionally obtained multiple exposures for a given source, these were not combined; the highest quality spectrum was analyzed. Upon visual inspection we assigned a spectral data quality number (SPEC_QUAL) to each spectrum. Our scale spans 0–5, in which 0 is poor, or unusable, and 5 is excellent. SPEC_QUAL values are a good proxy for S/N and are included in Table 3. Note that even spectra without spectral features may have a high SPEC_QUAL value.

The calibrated 1D spectra are published in DR1 and provided at https://archive.stsci.edu/prepds/uvqs. We also present a cutout, optical image of each source taken from the SDSS or DSS surveys. Figure 3 shows representative spectra from the UVQ DR1 sample, including examples of a Galactic star, a low-z AGN, and a z > 1 quasar (PHL 1288). At the S/N of these spectra (each of which has a spectral quality of 4 or 5), redshift identification is straightforward. We note that ≈50% of our spectra have this data quality and another 40% have SPEC_QUAL = 3, which we consider sufficient for redshift analysis.

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To estimate the redshift of each source, we employed modified versions of the SDSS IDLUTILS software designed to measure quasar redshifts in that survey (Schneider et al. 2010). Specifically, we smoothed the quasar eigenspectra of SDSS (file: spEigenQSO-55732.fits) to match the spectral resolution from each of our instruments and then fit these eigenspectra to each spectrum, minimizing χ². The algorithms provide the best redshift, the model eigenvalues, and a statistical estimate of the redshift uncertainty σ(z).

All of the 1D spectra were visually inspected by at least two authors using a custom GUI to assess the spectra quality. In parallel, we assessed the redshift measurement by examining the best fit to the data. As necessary (∼30% of the cases), we performed our own estimation of the redshift by identifying standard AGN emission features (primarily Mg ii and Hβ). We then refitted templates to the data using a restricted redshift interval. We assessed the final redshift estimate based on the data quality and the number of spectral features identified and assigned a numerical quality assessment Z_QUAL with a scale of 0 (no estimate possible) to 5 (excellent estimate). Typically, sources with one prominent emission feature with a high-confidence assignment were given Z_QUAL = 3. The majority of these are AGNs with z ≈ 0.5 where the Mg ii emission line occurs at λ ≈ 4000 Å and the expected Hβ emission feature falls redward of our spectral coverage. Many of these spectra show weak Balmer emission (e.g., Hγ) and/or continuum features that give high confidence to the reported redshift. Furthermore, associating the detected feature with another emission line (e.g., C iii]) is strongly disfavored due to the non-detection of other, expected features. When multiple emission features were detected at a common redshift, the quality of the redshift determinations is given a 4 or 5 on our scale. From the total candidate list (Tables 1 and 2), we measured a high-quality redshift (Z_QUAL ≥ 3) for 1121 unique sources.

In the following we assume that every source with a recessional velocity v_r ≡ zc < 500 $\mathrm{km}\;{{\rm{s}}}^{-1}$ is "Galactic," which we associate with the Galaxy and members of the Local Group. This included sources where the eigenspectra fits were poor yet a low v_r was indisputable (e.g., stars). Many of these were assigned z = 0 exactly. The remainder of UVQS sources are assumed to be extragalactic AGNs, and are presented in Table 4. We caution, however, that we have neither assessed the relative line-fluxes of these sources nor assessed the widths of emission lines to confirm AGN activity. On the other hand, every source has a $W1-W2$ color in excess of 0.6 mag and therefore has a high probability  of containing an AGN.⁹ Furthermore, nearly all of these sources exhibit at least one broad emission feature that is indicative of an AGN.

For the redshift uncertainty of the extragalactic sources, we have adopted the larger of σ(z) derived from the eigenspectra analysis and 0.003. The latter value represents a systematic uncertainty from our procedure and also allows for the uncertainties in deriving a systemic redshift from broad, far-UV emission lines (e.g., Richards et al. 2002). We note, however, that many of the sources with z < 0.5 exhibit [O iii] emission that may provide a smaller redshift uncertainty.

To assess the quality of our redshift estimates, we have compared our values against the Million Quasar Catalog (MILLIQUAS; v4.5) compiled by Flesch (2015). We restricted the MILLIQUAS sample to sources with spectroscopic redshifts (TYPE = A or Q) and we cross-matched in R.A., decl. to a 5 arcsec radius. In our first assessment, we noted two sources with a very large redshift difference: UVQSJ000856.77–235317.5 and UVQSJ231148.97+353541.4. In each of our spectra, there is a single broad emission feature. For UVQSJ000856.77–235317.5, we had initially identified the feature as C iii] emission, yet corresponding C iv emission is not apparent. Therefore, we revised our evaluation to mark this line as Mg ii emission and revised the redshift accordingly; it is consistent with the previously cataloged value. The other source is a similar case with the line identifications reversed; we have specified the line to be Mg ii emission. If the line were C iii], as previously assumed, the quasar should have shown Mg ii emission. Given that there are also weak features at the expected wavelengths of H γ and H β for our preferred redshift, we have maintained our estimate for the source redshift.

Figure 4 summarizes the differences in redshifts $\delta z\equiv {\rm{\Delta }}z/(1+z)$ between our measurements and those previously reported in the literature. Ignoring the anomalous cases described above, we measure an rms of 0.002 for the 191 sources with z > 0.1.

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We present a histogram of the sources with well-constrained redshifts (Z_QUAL ≥ 3) in Figure 5. For the primary candidates (black), there are two distributions at z ≈ 0.1 and z ≈ 0.5. The former are low-z AGNs, while the other set contains our desired targets. These exhibit a tail of redshifts to nearly z = 2. As expected, the sources drawn from our secondary list of candidates (gray) are primarily at z < 0.3; only one has a redshift higher than 0.5. Finally, the inset to Figure 5 shows the redshift measurements corresponding to ${v}_{{\rm{r}}}\lt 1000\;\mathrm{km}\;{{\rm{s}}}^{-1}$. Again, we define those with ${v}_{{\rm{r}}}\lt 500\;\mathrm{km}\;{{\rm{s}}}^{-1}$ to be Galactic, although several could arise from the Local Group or beyond.

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5.1. The UVQS Sample of New UV-bright Quasars

The principal goal of the UVQ Survey is to generate a new sample of FUV-bright quasars at z ∼ 1. This motivated our target color criteria and subsequent observing strategy. With over 1000 sources analyzed, we may reassess the survey design and efficacy. Figure 6 presents the UV and WISE colors of the AGN measured in UVQS DR1, which includes both the primary ($\mathrm{FUV}\mbox{--}\mathrm{NUV}\gt 0.3$ mag) and secondary (−0.5 < FUV–NUV < 0.3) candidates. As the source redshifts increase from z = 0.1–2, their observed UV and near-IR colors redden. We expect that the UV trend is due primarily to Lyman limit opacity from intervening H I gas, although a flattening of the AGN SED at approximately 1000 Å could contribute (e.g., Telfer et al. 2002; Lusso et al. 2015). The evolution in W1–W2 color must be intrinsic, i.e., it is related to the k-correction, which shifts from the rest-frame near-IR toward the optical with increasing AGN redshift (e.g., Assef et al. 2010; Stern et al. 2012). In hindsight, we recognize that one could more efficiently target z ∼ 1 quasars by adjusting the $W1-W2$ cut to a larger value (e.g., 1.1 mag).

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The efficacy of our survey can be assessed in terms of the fraction of AGNs recovered from the total number of sources observed. These results are presented in Figure 7, restricting to the primary candidates. Of 1040 primary candidates observed, we recovered a secure redshift for an extragalactic AGN for 86% of the objects. The remainder are split rather evenly between Galactic sources, poor spectra, and sources without an evident spectral feature. These are discussed further in the following sections.

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Restricting to the z > 0.6 quasars from UVQS DR1 that were not listed in the v4.5 of the MILLIQUAS catalog, Figure 8 shows the sky distribution of these new sources. As expected, the majority of the new discoveries occur outside of the SDSS footprint, i.e., toward the Southern Galactic pole. Inspecting several of the sources within the SDSS footprint, we find they have good photometry and presume they were simply not targeted due to fiber collisions.

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In Figure 9, we compare the FUV magnitudes and estimated luminosities (without corrections for Galactic extinction) of the new UVQS DR1 AGNs. These are compared against previously known sources; specifically, we show a 2D histogram of all sources from the MILLIQUAS catalog lying within 5 arcsec¹⁰ of an FUV-detected source in the GALEXGR6Plus7 photoobjall catalog. At z > 0.5, the UVQS DR1 AGNs are among the brightest and most luminous FUV sources known. A follow-up analysis studying the Eddington ratio, host galaxies, and galactic environment of these extreme sources could be valuable. Given the high efficiency of our survey, we expect that the community has now identified nearly every FUV-bright quasar on the sky. The only exceptions will be within the areas not surveyed by GALEX and the few lucky sources that shine through the dust of the Galactic plane.

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One of the most luminous quasars from our survey, UVQSJ015454.68–071222.2 (z = 1.289, FUV = 17.07 mag; Figure 3), has an interesting history that is worth relating. This source was cataloged in 1962 by Haro & Luyten as PHL 1228 (Haro & Luyten 1962). Based on its color and coordinates, those authors identified the source as a candidate faint blue halo star toward the South Galactic pole. Indeed, a number of their candidates have since been confirmed as extragalactic AGNs. Clearly, a systematic redshift survey of the complete PHL catalog is warranted.

Table 4.  UVQ DR1 AGNs

Name	z	σ(z)a	Z_QUALb	New?c
UVQSJ000000.15-200427.7	0.291	0.003	4	Y
UVQSJ000503.70-391747.9	0.652	0.003	3	N
UVQSJ000609.57-261140.5	0.648	0.003	3	Y
UVQSJ000741.00-635145.8	0.559	0.003	3	N
UVQSJ000750.78+031733.1	1.101	0.003	4	N
UVQSJ000755.67+052818.8	1.098	0.003	4	Y
UVQSJ000856.77-235317.5	0.844	0.003	3	N
UVQSJ001015.62-624045.1	0.850	0.003	3	Y
UVQSJ001121.73-200212.1	1.226	0.003	4	Y
UVQSJ001155.60-240438.8	0.767	0.003	3	N
UVQSJ001521.62-385419.1	0.633	0.003	3	Y
UVQSJ001637.90-054424.8	0.074	0.003	5	Y
UVQSJ001641.88-312656.6	0.360	0.003	5	N
UVQSJ001653.66-530932.6	0.914	0.003	3	Y
UVQSJ001655.68+054822.9	1.060	0.003	3	Y
UVQSJ001705.14-312536.4	0.838	0.003	3	N
UVQSJ001753.32-142310.9	0.945	0.003	3	Y
UVQSJ001859.75+061931.9	0.767	0.003	3	Y
UVQSJ001903.85+423809.0	0.113	0.003	5	Y
UVQSJ002049.31-253829.0	0.645	0.003	3	N
UVQSJ002051.30-190126.8	0.962	0.003	3	N

Notes.

^aRedshift uncertainty was derived from a template fit to the spectrum. We report a minimum redshift error of 0.003 from systematic uncertainties. ^bRedshift quality: 0—No constraint, 3—Confident, 5—Excellent. ^cSource is greater than 10 arcsec offset any quasar in the MILLIQUAS catalog (v4.5) with a published spectroscopic redshift.

Only a portion of this table is shown here to demonstrate its form and content. A machine-readable version of the full table is available.

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5.2. Other Sources

Figure 10 shows an all-sky plot of the other UVQS sources: AGNs at z < 0.6, sources with good spectra but without a precise redshift, and Galactic sources. Not surprisingly, the latter are primarily located near the Galactic plane. In DR1, we observed 66 sources satisfying our color criteria (including 24 with FUV–NUV < 0.3 mag) whose spectra yield a recessional velocity ${v}_{{\rm{r}}}\lt 500\;\mathrm{km}\;{{\rm{s}}}^{-1}$. These are listed in Table 5. Spectra for a representative set are shown in Figure 11. These objects include hot stars, white dwarfs, planetary nebulae, and Herbig Ae/Be stars, all of which have high surface temperatures explaining their high UV fluxes. It is more difficult, however, to explain their $W1-W2$ colors. Several of the sources have WISE fluxes near their detection limit, i.e., poor photometry may explain their inclusion. Another set has substantial extinction ($E(B-V)\gt 0.3$ mag). The remainder, however, may be chance superpositions with a low-mass star. Finally, we note that from the full set of Galactic sources we identify a small sample with highly unusual spectra (e.g., Margon et al. 2016).

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Table 5.  UVQ DR1 Galactic Sources

Name	l	b	W1	W2	$E(B-V)$
	(°)	(°)	(mag)	(mag)	(mag)
UVQSJ000717.69+421646.6	114.2718	−19.8486	12.44	11.51	0.07
UVQSJ002255.11−024418.7	106.0850	−64.6733	13.25	12.12	0.03
UVQSJ002324.11+704009.9	120.5946	7.9250	7.28	6.58	0.95
UVQSJ002452.54−015335.4	107.6594	−63.9745	9.56	8.69	0.03
UVQSJ002715.37+224158.1	115.6634	−39.8307	13.15	11.96	0.04
UVQSJ004433.61+241919.7	120.9291	−38.5229	11.41	10.81	0.05
UVQSJ011219.70−735126.0	300.9427	−43.1902	9.66	8.52	0.04
UVQSJ012138.72−735841.0	300.0898	−42.9831	9.98	9.31	0.05
UVQSJ013450.10+305445.0	133.7961	−31.0421	14.86	13.79	0.05
UVQSJ015159.68−250314.9	207.6540	−76.2551	17.82	16.34	0.01
UVQSJ025637.57+200537.2	158.9238	−33.8856	7.84	7.22	1.24
UVQSJ033900.56+294145.6	161.1830	−20.4629	7.61	6.83	0.22
UVQSJ035056.00−204815.9	214.1511	−48.7234	9.66	9.02	0.07
UVQSJ035859.45+561112.5	146.9221	2.3142	5.43	4.36	0.96
UVQSJ043243.03+255230.8	172.8867	−14.8704	6.25	5.48	1.37
UVQSJ045640.88+482057.8	158.6602	3.2547	8.55	7.84	0.65
UVQSJ045846.26+295036.7	173.4658	−7.9023	4.87	3.93	0.54
UVQSJ055504.39+073650.6	199.5921	−8.8793	11.93	11.21	0.59
UVQSJ060819.93−715737.4	282.5738	−29.0191	13.15	11.11	0.09
UVQSJ074955.94+355630.0	184.2155	26.7155	14.47	13.22	0.05
UVQSJ075320.02+154647.6	205.2586	20.6404	10.04	9.04	0.03
UVQSJ080430.46+645952.8	151.2065	32.0840	8.93	7.84	0.05
UVQSJ084551.18+600914.1	156.3057	37.4128	17.17	16.43	0.08
UVQSJ100201.71+631122.0	148.2491	44.7185	14.69	14.02	0.02
UVQSJ110923.71−762320.9	296.9168	−14.7238	7.23	6.47	0.68
UVQSJ114758.55+283156.2	203.5315	75.9099	16.31	15.60	0.02
UVQSJ125927.77+273810.5	49.3078	88.1476	13.89	13.09	0.01
UVQSJ130340.80−453722.7	305.1720	17.1955	14.82	13.78	0.09
UVQSJ144109.61−283020.9	330.3496	28.4600	16.15	15.48	0.10
UVQSJ145840.40−315439.7	332.1683	23.6398	16.26	15.63	0.14
UVQSJ151250.86−380731.6	331.3257	16.8283	10.86	9.68	0.11
UVQSJ154144.91+645352.3	99.5381	43.7046	14.68	13.86	0.03
UVQSJ162104.41−001610.7	13.3195	32.7354	12.76	11.95	0.11
UVQSJ162954.57+340706.0	55.5065	43.0309	17.65	16.32	0.02
UVQSJ165308.43+052323.2	23.7178	28.6949	15.54	14.48	0.12
UVQSJ165427.11−022700.4	16.2867	24.5149	12.85	11.87	0.28
UVQSJ165528.14+314556.5	53.6062	37.3588	17.07	16.22	0.03
UVQSJ174506.57−020844.1	23.2521	13.6944	11.08	10.04	0.41
UVQSJ180338.08−593009.5	334.2886	−17.4199	16.38	15.76	0.11
UVQSJ182754.20+095854.6	39.2363	9.7232	8.68	7.93	0.18
UVQSJ182847.85+000839.8	30.4732	5.1018	5.18	4.14	2.75
UVQSJ184635.12−232648.2	11.3414	−9.4477	10.20	9.39	0.43
UVQSJ184722.00−412632.5	354.4815	−16.8549	13.24	12.17	0.07
UVQSJ185026.03−223422.9	12.5279	−9.8712	11.81	10.89	0.40
UVQSJ185807.27+251417.3	56.3445	9.8431	15.19	14.44	0.28
UVQSJ190319.80+603553.6	91.0096	21.9990	14.24	13.56	0.05
UVQSJ190535.95−331138.0	3.8947	−17.1953	13.09	12.23	0.10
UVQSJ191423.34−323416.9	5.2059	−18.6908	14.58	13.65	0.10
UVQSJ191628.22−090236.7	27.6472	−9.6415	11.07	10.18	0.31
UVQSJ191652.27−310717.3	6.8342	−18.6662	13.17	12.34	0.09
UVQSJ191723.48−393646.8	358.3460	−21.6053	10.25	9.52	0.12
UVQSJ192210.62−313038.8	6.8718	−19.8639	13.44	12.54	0.11
UVQSJ192420.60−305822.8	7.5794	−20.1116	14.66	13.89	0.08
UVQSJ193037.67−502817.4	347.4837	−26.6214	16.17	15.49	0.06
UVQSJ193625.31−591135.8	337.8759	−28.7204	17.13	16.43	0.09
UVQSJ195006.99−502846.6	348.0512	−29.6809	16.49	15.56	0.04
UVQSJ195151.72−054816.6	34.6144	−16.0731	4.71	3.82	0.16
UVQSJ195838.50−135653.9	27.6059	−21.0742	6.58	5.96	0.33
UVQSJ201508.85+124215.2	54.1969	−12.1123	9.99	9.08	0.18
UVQSJ205321.33−385543.6	3.4324	−39.6203	14.81	13.77	0.05
UVQSJ210229.90−501631.7	348.5034	−41.1883	15.70	15.01	0.04
UVQSJ220030.64+682822.8	108.2571	10.6202	7.39	6.53	0.33
UVQSJ224840.11−064246.4	62.3103	−54.4269	16.75	16.11	0.04
UVQSJ232847.35+051451.4	88.1689	−51.9569	11.52	10.72	0.07
UVQSJ233145.86+720122.5	116.8008	10.1061	16.28	15.29	0.53
UVQSJ234823.76−112802.1	76.4925	−68.4481	16.64	15.86	0.03

Note. UVQS DR1 sources with recessional velocity ${v}_{{\rm{r}}}\lt 500\;\mathrm{km}\;{{\rm{s}}}^{-1}$. Reddening $E(B-V)$ estimates are based on the Schlegel et al. (1998) extinction maps.

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There are 93 sources with a good quality spectrum (SPEC_QUAL ≥ 3) for which we cannot recover a secure redshift. The majority of these have been previously cataloged as blazars (or BL Lac objects). Examining Figure 10, we note these sources are distributed across the sky, consistent with an extragalactic origin. Table 6 lists the sample of these unknowns.

Table 6.  UVQ DR1 Unknown Sources

Name	l	b	FUV	NUV
	(°)	(°)	(mag)	(mag)
UVQSJ000009.65−163441.4	71.9317	−74.1194	18.48	17.72
UVQSJ001444.02−223522.6	59.5364	−80.5220	18.39	17.34
UVQSJ001529.53−360535.3	341.1397	−78.2250	18.23	17.70
UVQSJ004038.09−505756.5	307.1282	−66.0744	17.43	16.77
UVQSJ005116.64−624204.3	302.9636	−54.4270	18.31	17.84
UVQSJ010018.69−741815.9	302.1140	−42.8097	17.55	17.12
UVQSJ012031.66−270124.6	213.6632	−83.5246	18.20	17.36
UVQSJ013955.76+061922.4	144.0255	−54.5508	17.64	17.19
UVQSJ022239.60+430207.8	140.1429	−16.7669	17.70	16.88
UVQSJ024440.30−581954.5	278.4481	−53.0779	18.48	18.09
UVQSJ024553.03−803533.7	297.4299	−35.2790	18.43	17.29
UVQSJ041652.49+010523.8	191.8145	−33.1591	18.06	17.71
UVQSJ044924.69−435008.9	248.8052	−39.9188	15.89	15.34
UVQSJ045953.82−464958.1	252.6989	−38.1225	18.38	18.03
UVQSJ050925.96+054135.3	195.4054	−19.6361	18.47	17.48
UVQSJ051354.64−305318.5	233.6318	−33.3244	18.07	17.72
UVQSJ053850.36−440508.9	250.0828	−31.0896	17.96	16.58
UVQSJ054357.22−553207.3	263.5150	−31.4742	18.12	17.74
UVQSJ055417.57−383951.1	244.6776	−27.1526	15.86	14.58
UVQSJ055942.72−660908.1	275.9131	−29.8399	18.27	17.71
UVQSJ063146.38−642615.1	274.2555	−26.3760	17.17	16.65
UVQSJ065046.48+250259.5	190.2825	10.9956	18.08	17.44
UVQSJ070031.25−661045.2	276.7686	−23.7595	18.11	17.45
UVQSJ072153.46+712036.3	143.9811	28.0176	15.40	14.67
UVQSJ073807.39+174219.0	201.8465	18.0706	18.48	17.33
UVQSJ080949.18+521858.2	166.2451	32.9104	17.16	16.71
UVQSJ085448.87+200630.6	206.8121	35.8209	18.27	17.42
UVQSJ085500.56−150523.7	241.8511	18.8133	18.38	17.62
UVQSJ090226.91+205046.5	206.6753	37.7519	18.42	17.80
UVQSJ090534.98+135806.4	215.0300	35.9597	17.85	17.25
UVQSJ091037.03+332924.4	191.1205	42.4663	17.17	16.44
UVQSJ091552.39+293323.9	196.6498	42.9348	17.44	16.83
UVQSJ101234.19−301226.7	266.6004	21.2358	16.58	16.72
UVQSJ101504.13+492600.7	165.5339	52.7122	16.72	16.27
UVQSJ102356.17−433601.5	276.5969	11.6016	18.03	17.30
UVQSJ103744.29+571155.5	151.7712	51.7826	18.43	17.69
UVQSJ110436.60−390352.8	281.2378	19.2650	16.69	16.88
UVQSJ112048.05+421212.5	167.8538	66.1628	18.18	17.66
UVQSJ113405.66−494455.5	290.3338	11.2217	16.65	16.91
UVQSJ113601.74−523515.8	291.4799	8.5992	17.22	17.69
UVQSJ113858.26−452304.3	289.8239	15.6348	15.85	16.11
UVQSJ114946.72−005456.6	272.5734	58.2743	17.23	17.65
UVQSJ115034.76+415440.0	159.1108	70.6800	18.33	17.69
UVQSJ115255.65−172239.3	283.5971	43.2867	18.45	17.96
UVQSJ115315.22−153637.1	282.9313	44.9899	17.28	16.52
UVQSJ115628.86−284431.8	288.6213	32.5978	15.88	16.29
UVQSJ115643.52−313925.4	289.5217	29.7860	17.35	17.19
UVQSJ121241.46−063309.9	285.9713	55.0380	17.28	16.92
UVQSJ121623.79−380242.8	295.3691	24.3114	17.49	17.32
UVQSJ121752.08+300700.6	188.8749	82.0529	16.65	16.05
UVQSJ122121.94+301037.1	186.3587	82.7345	16.75	16.29
UVQSJ122131.68+281358.4	201.7355	83.2880	17.16	16.48
UVQSJ123212.01−421750.5	299.1374	20.4326	16.77	16.83
UVQSJ123730.73−201829.0	298.5057	42.4440	18.05	17.20
UVQSJ124312.73+362743.9	133.0071	80.5046	17.12	16.37
UVQSJ125535.09−270230.8	304.0707	35.8207	16.66	16.88
UVQSJ130059.12−360619.8	305.0909	26.7262	18.28	17.31
UVQSJ130421.00−435310.2	305.3908	18.9239	17.50	16.83
UVQSJ130737.98−425938.9	306.0779	19.7787	17.56	16.85
UVQSJ130748.03−101758.5	309.5316	52.3624	16.63	16.72
UVQSJ132225.65−325431.5	310.4044	29.5130	17.95	16.25
UVQSJ140450.90+040202.2	343.3271	61.0101	17.44	17.08
UVQSJ141649.18−334117.3	322.6069	25.9006	17.44	17.34
UVQSJ141946.61+542314.8	98.3006	58.3118	17.71	16.75
UVQSJ142700.39+234800.0	29.4873	68.2076	16.26	15.66
UVQSJ143917.46+393242.8	68.8479	64.4232	17.83	17.26
UVQSJ150101.86+223806.3	31.4457	60.3502	17.35	16.69
UVQSJ154256.97+612955.0	95.3924	45.3923	17.92	17.11
UVQSJ155543.17+111124.6	21.9093	43.9637	16.08	15.38
UVQSJ161020.67−035506.1	7.9353	32.8755	18.49	18.31
UVQSJ175132.81+093900.7	34.9194	17.6452	18.39	17.32
UVQSJ180314.75+554245.0	83.9878	28.7766	18.32	17.43
UVQSJ183849.18+480234.4	76.9498	21.8288	17.80	17.21
UVQSJ190748.98−530021.4	343.8994	−23.7303	18.49	18.20
UVQSJ190926.48−793848.1	314.5806	−27.4588	15.78	15.99
UVQSJ192833.35−220353.7	16.7052	−17.7157	16.39	16.69
UVQSJ200549.12−754848.0	318.6171	−30.7726	18.28	18.13
UVQSJ200925.39−484953.6	350.3731	−32.6008	15.52	15.13
UVQSJ202053.28−650159.8	330.9495	−33.8002	18.16	17.97
UVQSJ205349.78−042429.8	43.6864	−29.1253	18.34	18.10
UVQSJ213924.16−423520.3	358.3175	−48.3262	17.22	16.61
UVQSJ215459.97+071949.8	65.3423	−35.1428	17.98	17.66
UVQSJ215852.06−301332.0	17.7305	−52.2458	13.87	13.48
UVQSJ222358.40−251043.5	27.8277	−56.9682	16.69	16.20
UVQSJ230029.52−172411.0	47.9236	−62.6290	18.23	17.78
UVQSJ231731.98−453359.6	342.0701	−63.7783	18.43	17.85
UVQSJ232444.66−404049.4	350.1952	−67.5844	17.29	16.82
UVQSJ233913.22−552350.8	322.8252	−58.8535	17.83	16.40
UVQSJ235123.69−454336.0	331.6648	−67.9074	18.50	18.09

Note. UVQS DR1 sources with good spectral quality but where no precise redshift could be measured.

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Finally, 48 of the brightest primary candidates (FUV < 17.5 mag) went unobserved. Nearly all of these are well resolved in the SDSS or DSS imaging and were dismissed as having z ≪ 1. Three of the sources–J124735.07-035008.2, J221153.89+184149.9, J221712.27+141420.9—went unobserved due to errors in bookkeeping or insufficient observing time. We will endeavor to provide spectra of these sources in our second data release.

We have performed an all-sky survey for z ∼ 1, FUV-bright quasars selected from GALEX and WISE photometry. The majority of these candidates lie toward the Southern Galactic Pole, i.e., outside the SDSS footprint. We confirmed 256 AGNs at z > 0.6, 155 of which had no previously reported spectroscopic redshift. Altogether, the UVQS DR1 includes 217 previously uncataloged AGNs with FUV < 18 mag, which are excellent targets for absorption-line analysis using HST/COS. Indeed, a handful of these AGNs are already scheduled for Cycle 24 observations. In our second data release of UVQS, we expand the search to NUV-bright AGNs at z ∼ 1.

We kindly thank Kate Rubin and Neil Crighton for their twilight observations of several candidates. T.R.M. and J.T. acknowledge support for this project from the STScI Director's Discretionary Research Fund under allocation D0001.82451. J.X.P. and N.T. acknowledge partial support from the National Science Foundation (NSF) grant AST-1412981. J.F.H. acknowledges generous support from the Alexander von Humboldt Foundation in the context of the Sofja Kovalevskaja Award. The Humboldt Foundation is funded by the German Federal Ministry for Education and Research.

This work is based on data obtained from Lick Observatory, owned and operated by the University of California. We thank the Mount Hamilton staff of Lick Observatory for assistance in acquiring the observations.

This publication makes use of observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut fur Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Some of the Keck data were obtained through the NSF Telescope System Instrumentation Program (TSIP), supported by AURA through the NSF under AURA Cooperative Agreement AST 01-32798 as amended. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

This publication 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, and NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology. WISE and NEOWISE are funded by the National Aeronautics and Space Administration.

Facilities: Shane (Kast Double spectrograph), Du Pont (Boller & Chivens spectrograph), CAO:2.2m (Calar Alto Faint Object Spectrograph), Keck:II (Echellette Spectrograph and Imager), MMT (MMT Blue Channel), Magellan:Clay (Magellan Echellette).