VizieR Online Data Catalog: Changing-state quasars with CRTS (Graham+, 2020)
Abstract
The Catalina Real-time Transient Survey (CRTS; Drake et al. 2009ApJ...696..870D, Cat. J/ApJ/696/870) represents the best data currently available with which to systematically define sets of quasars with particular temporal characteristics. The CRTS archive (http://catalinadata.org) contains the Catalina Sky Survey data streams from three telescopes - the 0.7m Catalina Sky Survey (CSS) Schmidt and 1.5m Mount Lemmon Survey (MLS) telescopes in Arizona and the 0.5m Siding Springs Survey (SSS) Schmidt in Australia.
We use MIR W1 (3.4μm) and W2 (4.6μm) WISE data from the beginning of the mission in 2010 January through 2017 December, corresponding to the fourth year of NEOWISE operations (http://irsa.caltech.edu/wise). The Million Quasars (MQ) catalogue (http://quasars.org/milliquas.htm) v5.2 contains all spectroscopically confirmed type 1 QSOs, AGNs, and BL Lacs in the literature up to 2017 August 5. We cross-matched MQ against the CRTS data set with a 3" matching radius and find that 1411364 sources are covered by the full CRTS. We remove sources with less than 10 observations and blazars, obtaining a sample of 1139438 sources. After applying the optical variability constraints and the MIR variability constraint described in Section 3, our sample is reduced to 47451 sources. Of these 14412 have z<0.95 and multi-epoch SDSS spectra with at least 100 (500)d between epochs are available for 466 (266) objects. Finally, over the past 3yr, we have obtained second epoch spectra (all at least >500d after the initial SDSS epoch) for an additional 426 candidates using either the Double Spectrograph (DBSP) on the Hale 200" telescope at Palomar Observatory, the Low Resolution Imaging Spectrometer (LRIS) spectrograph, or the Echellette Spectrograph and Imager (ESI), both on the Keck I telescope at the W. M. Keck Observatory (see Table B1). Table 2 gives details of the 111 objects for which the Hβ/[OIII] ratio changes by >30 per cent. (3 data files).- Publication:
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VizieR Online Data Catalog
- Pub Date:
- February 2023
- Bibcode:
- 2023yCat..74914925G
- Keywords:
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- Black holes;
- QSOs;
- Spectra: optical;
- Photometry: infrared