- ID:
- ivo://CDS.VizieR/J/AJ/139/390
- Title:
- Optically selected BL Lac objects from SDSS-DR7
- Short Name:
- J/AJ/139/390
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 723 optically selected BL Lac candidates from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) spectroscopic database encompassing 8250deg^2^ of sky; our sample constitutes one of the largest uniform BL Lac samples yet derived. Each BL Lac candidate has a high-quality SDSS spectrum from which we determine spectroscopic redshifts for ~60% of the objects. Redshift lower limits are estimated for the remaining objects utilizing the lack of host galaxy flux contamination in their optical spectra; we find that objects lacking spectroscopic redshifts are likely at systematically higher redshifts.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/651/61
- Title:
- Optically thick absorbers near luminous quasars
- Short Name:
- J/ApJ/651/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With close pairs of quasars at different redshifts, a background quasar sight line can be used to study a foreground quasar's environment in absorption. We search 149 moderate-resolution background quasar spectra from Gemini, Keck, the MMT, and the SDSS to survey Lyman limit systems (LLSs) and damped Ly{alpha} systems (DLAs) in the vicinity of 1.8<z<4.0 luminous foreground quasars. A sample of 27 new quasar-absorber pairs is uncovered with column densities 10^17.2^cm^-2^<NH<10^20.9^cm^-2^ and transverse (proper) distances of 22h^-1^kpc<R<1.7h^-1^Mpc from the foreground quasars.
- ID:
- ivo://CDS.VizieR/J/ApJS/185/511
- Title:
- Optical microvariability of S5 0716+714
- Short Name:
- J/ApJS/185/511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We monitored the BL Lac object S5 0716+714 in the optical band during 2008 October and December and 2009 February with a best temporal resolution of about 5 minutes in the BVRI bands. Four fast flares were observed with amplitudes ranging from 0.3 to 0.75mag. The source remained active during the whole monitoring campaign, showing microvariability in all days except for one. The overall variability amplitudes are {Delta}B~0.89, {Delta}V~0.80, {Delta}R~0.73, and {Delta}I~0.51mag. Typical timescales of microvariability range from 2 to 8hr. The overall V-R color index ranges from 0.37 to 0.59. Strong bluer-when-brighter chromatism was found on internight timescales. However, a different spectral behavior was found on intranight timescales. A possible time lag of ~11 minutes between B and I bands was found on one night. The shock-in-jet model and geometric effects can be applied to explain the source's intranight behavior.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/334
- Title:
- Optical/MIR properties of Type 1 AGNs
- Short Name:
- J/MNRAS/472/334
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated the connection between the mid-infrared (MIR) and optical spectral characteristics in a sample of 82 Type 1 active galactic nuclei (AGNs), observed with Infrared Spectrometer on Spitzer (IRS) and Sloan Digital Sky Survey (SDSS, DR12). We found several interesting correlations between optical and MIR spectral properties: (i) as starburst significators in MIR increase, the equivalent widths (EWs) of optical lines H{beta}NLR and FeII, increase as well; (ii) as MIR spectral index increases, EW([OIII]) decreases, while fractional contribution of AGN (RAGN) is not connected with EW([OIII]); (iii) The log([OIII]5007/H{beta}NLR) ratio is weakly related to the fractional contribution of polycyclic aromatic hydrocarbons (RPAHs). We compare the two different MIR and optical diagnostics for starburst contribution to the overall radiation (RPAH and Baldwin, Philips & Terlevich diagram, respectively). The significant differences between optical and MIR starburst diagnostics were found. The starburst influence to observed correlations between optical and MIR parameters is discussed.
- ID:
- ivo://CDS.VizieR/J/AZh/72/447
- Title:
- Optical Monitoring of Quasar 3C345
- Short Name:
- J/AZh/72/447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of long-term monitoring of the quasar 3C345 from 1984 to 1991 are presented. Observations has been conducted on the Byurakanskii station of the St. Petersburg Astronomical Institute since 1968 in the B band, and consist of 365 brightness estimates obtained over the course of 219 nights.
- ID:
- ivo://CDS.VizieR/J/ApJ/828/78
- Title:
- Optical monitoring of the Seyfert I NGC 3516
- Short Name:
- J/ApJ/828/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From 2013 April to 2014 April, we performed X-ray and optical simultaneous monitoring of the type 1.5 Seyfert galaxy NGC 3516. We employed Suzaku and five Japanese ground-based telescopes-the Pirka, Kiso Schmidt, Nayuta, MITSuME, and the Kanata telescopes. The Suzaku observations were conducted seven times with various intervals ranging from days or weeks to months, with an exposure of ~50ks each. The optical B-band observations not only covered those of Suzaku almost simultaneously, but also followed the source as frequently as possible. As a result, NGC 3516 was found in its faint phase with a 2-10keV flux of 0.21-2.70x10^-11^ergs/s/cm^2^. The 2-45keV X-ray spectra were composed of a dominant variable hard power-law (PL) continuum with a photon index of ~1.7 and a non-relativistic reflection component with a prominent Fe-K{alpha} emission line. Producing the B-band light curve by differential image photometry, we found that the B-band flux changed by ~2.7x10^-11^ergs/s/cm^2^, which is comparable to the X-ray variation, and we detected a significant flux correlation between the hard PL component in X-rays and the B-band radiation, for the first time in NGC 3516. By examining their correlation, we found that the X-ray flux preceded that in the B band by 2.0_-0.6_^+0.7^ days (1{sigma} error). Although this result supports the X-ray reprocessing model, the derived lag is too large to be explained by the standard view, which assumes a "lamppost"-type X-ray illuminator located near a standard accretion disk. Our results are better explained by assuming a hot accretion flow and a truncated disk.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A60
- Title:
- Optical-NIR catalog of AKARI NEP Deep Field
- Short Name:
- J/A+A/566/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an 8-band (u*, g', r', i', z', Y, J, Ks) optical to near-infrared deep photometric catalogue based on the observations made with MegaCam and WIRCam at CFHT, and compute photometric redshifts, zph in the North Ecliptic Pole (NEP) region, where AKARI infrared satellite carried out deep survey at near to mid infrared wavelength. We designed the catalogue to include sources detected in z' band with counterparts in at least one of the other bands, and found 85797 sources in the NEP field. Comparing with galaxy spectroscopic redshifts, photometric redshift dispersion {sigma}({Delta}z/(1+z)) is 0.032 and catastrophic failure rate {Delta}z/(1+z)>0.15 is 5.8% at z<1. Our redshifts are highly accurate with z'<22 at zph<2.5 and for fainter sources with z'<24 at z<1.
- ID:
- ivo://CDS.VizieR/J/MNRAS/450/3137
- Title:
- Optical/NIR light curves of SN 2009ib
- Short Name:
- J/MNRAS/450/3137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical and near-infrared photometry and spectroscopy of SN 2009ib, a Type II-P supernova in NGC 1559. This object has moderate brightness, similar to those of the intermediate-luminosity SNe 2008in and 2009N. Its plateau phase is unusually long, lasting for about 130d after explosion. The spectra are similar to those of the subluminous SN 2002gd, with moderate expansion velocities. We estimate the ^56^Ni mass produced as 0.046+/-0.015M_{sun}_. We determine the distance to SN 2009ib using both the expanding photosphere method (EPM) and the standard candle method. We also apply EPM to SN 1986L, a Type II-P SN that exploded in the same galaxy. Combining the results of different methods, we conclude the distance to NGC 1559 as D=19.8+/-3.0Mpc. We examine archival, pre-explosion images of the field taken with the Hubble Space Telescope, and find a faint source at the position of the SN, which has a yellow colour [(V-I)_0_=0.85mag]. Assuming it is a single star, we estimate its initial mass as M_ZAMS_=20M_{sun}_. We also examine the possibility, that instead of the yellow source the progenitor of SN 2009ib is a red supergiant star too faint to be detected. In this case, we estimate the upper limit for the initial zero-age main sequence (ZAMS) mass of the progenitor to be ~14-17M_{sun}_. In addition, we infer the physical properties of the progenitor at the explosion via hydrodynamical modelling of the observables, and estimate the total energy as ~0.55x10^51^erg, the pre-explosion radius as ~400R_{sun}_, and the ejected envelope mass as ~15M_{sun}_, which implies that the mass of the progenitor before explosion was ~16.5-17M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/1941
- Title:
- Optical/NIR photometry of OGLE-2012-SN-006
- Short Name:
- J/MNRAS/449/1941
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical observations of the peculiar Type Ibn supernova (SN Ibn) OGLE-2012-SN-006, discovered and monitored by the Optical Gravitational Lensing Experiment-IV survey, and spectroscopically followed by Public ESO Spectroscopic Survey of Transient Objects (PESSTO) at late phases. Stringent pre-discovery limits constrain the explosion epoch with fair precision to JD=2456203.8+/-4.0. The rise time to the I-band light-curve maximum is about two weeks. The object reaches the peak absolute magnitude M_I_=-19.65+/-0.19 on JD=2456218.1+/-1.8. After maximum, the light curve declines for about 25 d with a rate of 4 mag (100 d)^-1^. The symmetric I-band peak resembles that of canonical Type Ib/c supernovae (SNe), whereas SNe Ibn usually exhibit asymmetric and narrower early-time light curves. Since 25 d past maximum, the light curve flattens with a decline rate slower than that of the ^56^Co-^56^Fe decay, although at very late phases it steepens to approach that rate. However, other observables suggest that the match with the ^56^Co decay rate is a mere coincidence, and the radioactive decay is not the main mechanism powering the light curve of OGLE-2012-SN-006. An early-time spectrum is dominated by a blue continuum, with only a marginal evidence for the presence of HeI lines marking this SN type. This spectrum shows broad absorptions bluewards than 5000 {AA}, likely OII lines, which are similar to spectral features observed in superluminous SNe at early epochs. The object has been spectroscopically monitored by PESSTO from 90 to 180 d after peak, and these spectra show the typical features observed in a number of SN 2006jc-like events, including a blue spectral energy distribution and prominent and narrow ({nu}_FWHM_~1900 km/s) HeI emission lines. This suggests that the ejecta are interacting with He-rich circumstellar material. The detection of broad (10^4^ km/s) OI and CaII features likely produced in the SN ejecta (including the [OI] {lambda}{lambda}6300,6364 doublet in the latest spectra) lends support to the interpretation of OGLE-2012-SN-006 as a core-collapse event.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/118
- Title:
- Optical obs. of GRB 180205A with COATLI
- Short Name:
- J/ApJ/872/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical photometry of the afterglow of the long GRB 180205A with the COATLI telescope from 217s to about 5d after the Swift/BAT trigger. We analyze this photometry in conjunction with the X-ray light curve from Swift/XRT. The late-time light curves and spectra are consistent with the standard forward-shock scenario. However, the early-time optical and X-ray light curves show atypical behavior; the optical light curve exhibits a flat plateau while the X-ray light curve shows a flare. We explore several scenarios and conclude that the most likely explanation for the early behavior is late activity of the central engine.
