Blazar optical spectrum

3. txt. This source has shown two relatively bright outbursts, in April and November 2016. The spectral energy distributions (SEDs) are dominated by two components, one at lower energies (radio-optical-UV), and one at higher energies (X-ray/ Quasars, blazars, and gamma rays. Impact of the magnetic ﬁeld strength, power spectrum, and coherence length For the examples presented in this section we take the blazar 1ES0229+200, located at a red-shift z ˇ0:14. Four lters (BV Johnson and RI Cousins) were used on a majority of the nights. We discuss SED ﬁts for a sample blazar ﬂare in Section 5. This object has been studied across a wide range of wavelengths. of Michigan Radio Researchers have identified a new blazar-like narrow-line Seyfert 1 galaxy that emits gamma-ray radiation. Optical archival spectra of blazar candidates of uncertain type in the 3rd Fermi Large Area Telescope Catalog N. 6 −10 keV spectra can be well represented by a broken power-law An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in Various quasi-periods for the long-term variability of the radio emission, optical emission, and structural position angle of the inner part of the parsec-scale jet in the blazar 0716+714 have been … The result is a detector that encompasses a cubic kilometer of solid ice. The blazar 3C 454. In this work we present a new optical spectrum of PKS 0447-439, and report on the analysis and results of such observations. 6035, where the optical depth to primary gamma rays of the highest observed energies is τ ⩾ 5. 4 keV band, taken from the ROSAT Archive or from Swift-XRT catalogs, or in a few cases from other sources, in erg cm-2 s-1. 3 is a blazar classified as a high polarized quasar (HPQ) with a We present simultaneous optical and X-ray data from Swift for a sample of FSRQs We reexamine the original 'blazar spectral sequence' and suggest that the Jan 16, 2019 Daily light curve of the VHE γ-ray emission from BL Lacertae above 200 across the electromagnetic spectrum from radio to very high-energy 1995). 38+603131. 258. 19+100605. 3C 66A is an intermediate z blazar with z = 0. To this end, we report optical spectroscopic observations of a sample of five γ-ray blazar candidates selected on the basis of their infrared Wide-field Infrared Survey Explorer (WISE) colors or The gamma-ray blazar quest: new optical spectra, state of art and future perspectives F. g. of material around a blazar. “Fermi has been monitoring some 2,000 blazars for a decade, which is how we were able to identify this blazar as the neutrino source,” said Regina Caputo, a coordinator for the Fermi Large Area Telescope collaboration. Figures from. The spectrum is plotted as a ratio to the 2–12 keV fitted power law (inclusive of Galactic absorption). In addition we report optical spectroscopic observations of 4 WISE sources associated with known gamma-ray blazars without a ﬁrm classiﬁcation or redshift estimate. Tweet. For all of these latter sources we conﬁrm a BL Lac classiﬁca- Evaluating Optical Classification for Fermi Blazar Candidates with a Statistical Method Using Broadband Spectral Indices Abstract We find that 34% of the radio-selected BCUs (583 BCUs) are BL Lac-like and 20% are FSRQ-like, at a 90% level of confidence. • Compact and flat spectrum of α> -0. . disk, at the blue end of the optical spectrum. 02 (PKS B0106+013) is a high redshift blazar (optical coord: R. We report multi-colour optical monitoring of the intra-day variable blazar S5 0716+71 with a dense temporal coverage over a total duration of 4 weeks in February/March 1994. , 1996. The blazar population comprises BL Lacs and flat-spectrum radio quasars , which are, respectively, featureless optical spectrum objects and strong broad Blazars in radio band. Intro. 36. The Large Area Telescope (LAT) has discovered more than three thousand gamma-ray sources and m Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. Davis University of Colorado at Boulder julie. The Whole Earth Blazar Telescope (WEBT) is an international consortium of astronomers created in 1997, with the aim to study a particular category of Active Galactic Nuclei (AGN) called blazars, which are characterized by strong and fast brightness variability, on time scales down to hours or less. FTBx-5235 - optical spectrum analyzer New, compact OSA designed to measure channel power and wavelength, characterize Remote PHY deployments and analyze DWDM networks. TNG, KPNO, and OAN Observations of Blazar Candidates of Uncertain Type in the Northern Hemisphere [HEAP] large outbursts while other blazar types do not. We found a maximum soft lag of ∼ 1 hr between the UV and soft X-ray band which can be understood if the magnetic ﬁeld of the emitting region is ∼ 5. We report the results of optical monitoring for a sample of 11 blazars including 10 BL Lacertae objects (BL Lacs) and one flat spectrum radio quasar. To iden-tify potential candidates for a more in depth study in the future, we observed 192 of the brightest blazars in the northern hemisphere for a year in optical wavelengths with our 16" ROVOR tele-scope. Massaro et al 2016 Astrophysics and Space Science 361 . V. (2008), based on the published U, B, V, R and I band data. and the blazar ﬂare is estimated to be at the 3˙level (20). 5+1007. Marek Sikora1, RafalModerski1,GregM. Emission in the V and J bands rose more gradually than did the γ-rays and soft X-rays, though all peaked at nearly the same time. In addition, we report optical spectroscopic observations of four WISE sources associated with known γ-ray blazars without a firm classification or red: strict simultaneous optical, UV, Xray spectra corrected for absorption and host galaxy influence Swift/BAT spectra no cutoff detected up to 100keV → extreme blazar!! spectral index of XMM spectrum describe 0. 2000) Highfrequency peaked BL Lacs (HBLs): Lowfrequency component We report on a gamma-ray blazar optical monitoring programme that is underway that can provide both short-term and long-term optical variability data for key southern hemisphere sources. 3C454. 5 billion light-years away in the Cancer The shapes of the power spectral densities of blazar light curves indicate that the Dec 30, 2016 carried out observations of the optical spectrum (from 4000 to 7000 3C 454. Blazar Evolution With Cosmic Archaeology Apr 25, 2013 Peering into the past, KIPAC scientists use Fermi gamma-ray telescope observations to unlock the story of blazar evolution over the history of the Universe. To perform The X-ray flux of the blazar in the 0. Some strong absorption lines that arise in the host galaxy rather than the AGN itself are also identified. The high redshift (z=0. Ten sources are being monitored in this programme, with a focus on PKS 2155-304 and PKS 2005-489 during the austral winter of 2013. SED ν ν CR Figure: blazar, Urry & Padovani 95. Searching for neutrino emission IceCube monitors the whole sky and has maintained essentially continuous observations since 5 Based on their optical emission properties, astronomers divide blazars into two classes: flat-spectrum radio quasars (FSRQs) which feature prominent and broad optical emission lines, and BL A single extragalactic neutrino observed by the IceCube detector at the South Pole has been traced back to its origin in distant blazar By the end of the 1950s the resolution of radio telescopes was sufficient to be able to identify specific radio sources with optical counterparts, leading to the discovery of quasars. However, only a handful of blazars are studied regularly. Blazars are among the most energetic phenomena in the universe and are an important topic in extragalactic astronomy. SAMPLE SELECTION AND DATA ANALYSIS The SMARTS blazar sample was initially (in 2008) deﬁned If some members of this sample are truly blazar-like objects, they should demonstrate some of the classic characteristics of this class of AGN. are conﬁrmed by the Swift satellite observations of the blazar S5 0014+813, at the redshift z=3. Crossref. Ghisellini et al . ( optical) spectra show only narrow emission lines (if any at all). Month The Astrophysical Multimessenger Observatory Network (AMON) has been built with the purpose of enabling near real-time coincidence searches using data from leading multimessenger The two Fermi instruments have been surveying the high-energy sky since August 2008. Blazar Classification Quasars: Lowfrequency component from radio to optical/UV Highfrequency component from Xrays to γrays, often dominating total power Peak frequencies lower than in BL Lac objects (Hartman et al. The observed emission from a blazar is greatly enhanced by relativistic effects in the jet, a process termed relativistic beaming. This source was detected during a very high γ-ray activity state in 2012 March by the Large Area Telescope on board Fermi, becoming the γ-ray flaring blazar at the highest redshift detected so far. There is growing evidence to suggest that the black hole mass has been previously underestimated with the Hb line width for certain Active Galactic Nuclei (AGN). 5 (Fν ν α. Blazar: 4. Abstract. Key words:blazars, black holes, variability 1. 1-2. 259 The sample of a-ray blazar candidates lists 14 sources. Oct 4, 2017 1. 3 between 2007 and 2009 (Table1). Summary & Outlook. The AQ6376 is the latest version of our bench-top optical spectrum analyzer extending the wavelength coverage well beyond the NIR range of our previous models into the MWIR region from 1500 to 3400 nm. The light curves of the blazar were derived relative to two compar- This blazar, known as TXS 0506+056, is located at the center of a galaxy about 4 billion light years from Earth. , 1992, Takalo et al. We examine the signiﬁcance of the γ-ray signal from the sources direction and time with a gamma-ray flare from the blazar TXS 0506+056. Blazar SEDs GLAST MW Team (D Thompson) Synchrotron Inv. A thermal spectrum peaking in the ultraviolet region and faint optical emission lines are also present in OVV quasars, but faint or non-existent in BL Lac objects. The 0. The average of the comparison stars were used as a basis of diﬀerential photometry with respect to the blazar for all observations. Optical spectropolarimetry of the object in the quiescent state suggests a trend of increasing Since its first optical identification by Wills and Wills (1974), the object has been observed in the complete EM spectrum particularly in the radio bands by Aller et al. Evidence for long-term variability behavior of optical spectral index with time was presented by Zheng et al. 366. We found an excess of high-energy neutrino events, with respect to atmospheric backgroun ds, at that position between 3. 2015, 2017) or thanks to infrared colors of \gamma -ray blazar OJ 287 is a BL Lac object located 3. 4. 1ES 0229+200 has a hard TeV spectrum and was detected up to in optical, UV Abstract. The spectrum of two blazar objects, 1ES 1959+650 and 1ES 2344+514, are analyzed for evidence of interactions with the Extragalactic Background Light (EBL), using combined data from the Very Energetic Radiation Imaging Telescope Array System and the Fermi Gamma-ray Space Telescope, By analyzing the distinct curvature across the combined spectrum, we infer that the very-high energy (VHE) gamma Obtaining measurements across the spectrum is challenging, especially on short timescales, so GLAST team members will communicate with other astronomers, who can point various ground- and space-based telescopes at flaring blazars. 1 m telescope of the Observatorio Astronomico Guillermo Haro (OAGH) in Mexico toward the blazar 3C 454. these properties include high optical polarization, extreme optical variability, flat-spectrum radio emission associated with May 10, 2019 Optical archival spectra and further observations from SOAR and OAGH . , 1978, Lanzetta et al. By DAWN LEVY. this paper, we will present evidence that 50746 is a blazar (Flat Spectrum Radio Quasar) and more specifically, a new member of the MeV blazar class1. A. = 01h 08m 38. The flat spectrum radio quasar 3C 279 was the first bright γ-ray blazar reported by the EGRET instrument aboard the Compton Gamma-Ray Observatory to show strong and rapidly variable γ-ray To find out how far away the blazar was, Romani and Sowards-Emmerd used the Hobby-Eberly Telescope (HET), an optical instrument in a remote part of Texas, to obtain spectral patterns of visible It is spread out through the entire electromagnetic spectrum—the true rainbow that extends far beyond the colors that our eyes can detect and includes radio waves, X-rays, gamma rays, and more. Overview The authors have undertaken a survey, the Deep X-Ray Radio Blazar Survey (DXRBS), of archived, pointed ROSAT Position Sensitive Proportional Counter (PSPC) data for blazars by correlating the ROSAT WGACAT database with several publicly available radio catalogs, restricting their candidate list to serendipitous flat radio spectrum sources (Alpha r <= 0. 4 GHz, highly variable fluxes in the radio, optical, and X-ray bands, and a possible detection of TeV γ-ray emission. Through the construction of its spectral energy distribution, we are conﬁdent that its optical-ultraviolet (UV) emission is thermal in origin. 3 exhibited a strong flare seen in gamma-rays, X-rays, and optical/NIR bands during 3--12 December 2009. 1 The optical spectrum of SDSS J214530. Observations of the optical spectrum (4000 to 7000 Angstroms) and at near-infrared frequencies were carried out with the 2. Many of the γ-ray objects listed in the Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidates of uncertain type (BCUs), either because they show multifrequency behavior similar to blazars but lacking optical spectra in the literature, or because the quality of such spectra is too low to confirm their nature. Swift detected this source with all its three instruments, from the optical to the hard X-rays. The optical ﬂux is weakly polarized with rapid variations of the degree and direction of polarization, while the polarization of the 43 GHz radio core remains steady, perpendicular to the jet direction. ATel #12479; Alessandro Marchini (Astronomical Observatory, Department of Physical Sciences, Earth and Environment (DSFTA), University of Siena - Italy), Giacomo Bonnoli, Lorenzo Bellizzi, Vincenzo Millucci, Riccardo Paoletti, Leonardo Stiaccini, Stefano Truzzi, Sofia Ventura (DSFTA, University of Siena - Italy), Paolo Da Vela Even though the FSRQ have strong broad emission lines like Type 1 objects, they are noted in the ``Type 0'' column in Table 1 because they have the same blazar-like continuum emission as BL Lac objects. Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. Even with this signiﬁcantly shows a blazar-like spectrum with weak emission lines with EW ˘7 Å, yielding a red-shift estimate of z = 0:36. We analyse the following observables: size of the pair halo and spectrum. It’s just such an honor to be giving this talk in celebration of a person that we all share a tremendous admiration for: Gerry Neugebauer. [8] were among the ﬁrst to list the following observational properties for BL Lac objects: They (a) exhibit a featureless optical spectrum; Other instruments operating at optical, radio and X-ray wavelengths also made detections. The ASCA results were found to be consistent with reanalysed data from two earlier ROSAT observations. 2. 69. Academia. The new galaxy, designated SDSS J211852. As previously stated, our optical spectroscopic campaign was carried out both observing -ray blazar candidates and searching major optical databases and surveys. davis@colorado. In Fall 2005, 50746 was the target of an X-ray (Swzft and Suzaku), optical, and radio campaign. The very-high-energy (VHE, $\gtrsim 100$ GeV) $\gamma$-ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optic on day time scales, while mild variations were observed in the optical/UV emissions. • Substantial uncertainty in spectral types. The combined PN camera data of revolutions 324–671. Dr. 3 reveals the structure and physics of its ’blazar zone’. , 1ES 0229+200) Abstract. 5, could offer insights into Blazar's wiki: A blazar is a very compact quasar (quasi-stellar radio source) associated with a presumed supermassive black hole at the center of an active, giant elliptical galaxy. In Section 6, we present the summary and conclusions. TNG, KPNO, and OAN Observations of Blazar Candidates of Uncertain Type in the Northern Hemisphere [HEAP] We use the strong detection of the source with VERITAS observations in conjunction with multi-wavelength observations from VLBA, Fermi-LAT, Swift-XRT, and FLWO 48" optical telescope to solidify the classification of the source as an extreme HBL (a fairly rare type of blazar) and explore its properties across the electromagnetic spectrum. (2009) presented a optical photometry result of blazar OJ 287 from 2002 to 2007. We report results of a multi-band monitoring campaign of the flat spectrum radio quasar TXS 0536+145 at redshift 2. On the other hand, 2MASX J0324+3410 also exhibits some behavior which is characteristic of blazars, including a flat radio spectrum above 1 GHz, a compact core plus a one-sided jet structure on mas-scale at 8. Relativistic beaming. 254 show the optical spectrum of one of the BL Lac classi-255 fled from our analysis together with two cases of wrong 258 classifications and a quasar. Blazar: 3. 3). We report VLA radio observations of the blazar TXS 0506+056, following its identification as the potential astrophysical origin of the extremely high energy neutrino event IceCube-170922A (GCN #21916). We have described an empirical division of AGN according to radio and optical/ultraviolet properties. 3) faintest BL Lac objects (extreme HBLs) are dominated by host galaxy because of the faint jet emission (e. Crossref Blazar SED and extreme HBL population • Fainter blazars show higher peak frequency (known as blazar sequence) • Optical emission of some nearby (z<~0. Álvarez Crespo et al 2016 Astrophysics and Space Science 361 . 260 Three of them were selected as TeV BL Lac candi-261 dates (TBC) on the basis of their IR-to-X Triggered by this controversy, we have proposed new optical observations with the Gemini South telescope to perform further spectroscopic analysis with very high S/N ratio (˘200-500). 96−073227. Fan et al. The optical modules are sealed into basketball-size spheres of borosilicate glass to withstand the crushing pressure and are designed to spot the signature flashes of light that occur when a neutrino smashes into an atom in the clear ice. 4, clas-siﬁed as a BZB at unknown redshift, lying within the positional uncertainty region of the UGS 3FGL J2145. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): We present an analysis of the optical spectra available in the Sloan Digital Sky survey data release nine (SDSS dr9) for the blazars listed in the ROMA-BZCAT and for the γ-ray blazar candidates selected in our previous investigations that lying within the survey footprint have still an uncertain classification. Prompted by this association, we investigated 9. June 18, 2004 'Blazar' illuminates era when stars and galaxies formed. The source WISEJ064459. Madejski2,3 ABSTRACT Recent multi-wavelength observations of 3C454. broad emission line in the optical spectrum is present, it is classiﬁed as Flat Spectrum Radio Quasar (FSRQ), otherwise it is a BL Lacerate (BL Lac) object. , 1993). FSRQ -- `Red’ Blazar Compton Flat optical (FSRQ spectrum) Faint IC X-ray High z {LBL – intermediate {Low peak BL Lac HBL -- `Blue’ Blazar Blue Optical (BL Lac spectrum) Bright Syn X-ray Low z Blazar. = +01 35’ 00”, z = 2:099). 3 exhibited a strong flare seen in γ-rays, X-rays and optical/near-infrared bands during 2009 December 3–12. Thank you, George, for that very, very generous introduction. 444 (Miller et al. With the assumption of the flatter rather than isotropic velocity distribution of gases in the broad-line region of AGN, we investigated the properties of Narrow Line Seyfert 1 (NLS1) galaxies, like the black hole mass and the Start date . MWIR WAVELENGTH with internal gas purge and cut filter. edu ABSTRACT The standard model for propagationof gammaraysfrom veryhigh energy(VHE, E≥100GeV) blazars through the universe requires an understanding of the diﬀuse extragalactic TeV BLAZAR Observations, Diffuse backgrounds in the optical & infrared The effect on the spectrum of the source 1ES 1101-232 of the. 70, where S Nu ~ Nu-Alpha r). RO_Spectral_Index The radio-to-optical spectral index of the blazar. Ackermann et al, 2011 (2LAC) OPTICAL SPECTROSCOPY OF BRIGHT FERMI LAT BLAZARS data provide identifications for 10 newly discovered γ-ray flat spectrum radio quasars and six Sep 19, 2016 blazar candidates of uncertain type (BCUs), either because they show multifrequency behaviour similar to blazars but lacking optical spectra The word blazar is today associated to BL Lac Objects and Flat-Spectrum Radio radio quasar (FSRQ), prominent emission lines in the optical spectrum;. edu is a platform for academics to share research papers. Optical spectroscopic observations of gamma-ray blazar candidates VIII: the 2016–2017 follow up campaign carried out at SPM, NOT, KPNO and SOAR telescopes PKS 2123−463: a γ-ray blazar at high redshift 895 particlebackground,isparametrizedbytheﬁleiso_p7v6source. ν spectrum. 7. In an article posted June 10 to the Astrophysical Journal Letters website, astrophysicists at Stanford report We calculate the gamma-ray spectrum of a distant blazar, PKS 1424 + 240, located at redshift z ⩾ 0. 3, in particular during its gi-ant outburst in 2005, put severe constraints on the location of the ’blazar zone’, its dissipative nature, and high energy radiation mechanisms. Though some fluke astrophysical phenomena may shine brighter than a blazar for a few minutes or less, blazars keep up the light show for the long haul. GR_Photon_Flux The gamma-ray flux of the blazar in the 1-100 GeV band, taken from Fermi, in photons cm-2 s-1. ) • Flat radio spectrum is caused by superposition of self-absorbed synchrotron emission Nov 2, 2018 The emission arises from a relativistic jet in PKS 2247−131, as an optical spectrum only shows a few weak absorption lines, typical of the BL ponent peaked at relatively low frequency (infrared-optical), while most XBL The spectral energy distributions (SED) of blazars were interpreted as a. '-ray blazar candidates. Conclusions First detailed optical polarization measurements are reported for the blazar CGRaBS J0211+1051 performed during 2011 January 30 to February 3. While the latter show broad emission lines and thermal hump often associ- Investigating TeV Gamma Ray Propagation: Establishing Blazar/Absorber Sightline Properties Julie D. Spec sheet (PDF) Specifically, to be classified as a blazar an AGN must be seen with one of the following properties: high radio-brightness accompanied by flatness of the radio spectrum high optical polarization, strong optical variability on very short timescales (less than few days). 5 years of IceCube neutrino observations to search for excess emission at the position of the blazar. • BL Lac z distribution systematically biased. Blazars are among the most violent phenomena in the universe and are an important topic in extragalactic astronomy. Initially, NASA’s Fermi Gamma-ray Space Telescope observed that TXS 0506+056 was several times brighter than usually seen in its all-sky monitoring. 2. AN OPTICAL APPROACH. Strittmatter et al. 2 The normalizations of both components in the background model were allowed to vary freely during the spectral point ﬁtting. Along with gravitational waves, the find adds more options for “multimessenger” astronomy A blazar is an active galactic nucleus (AGN) with a relativistic jet directed very nearly towards A thermal spectrum peaking in the ultraviolet region and faint optical emission lines are also present in OVV quasars, but faint or non-existent in BL Abstract. Neutrinos on Ice: Astronomers’ Long Hunt for Source of Extragalactic “Ghost Particles” Pays Off. The energies are adjusted to the rest frame of the blazar (the observed frame range covered is identical to that in Fig. 997) blazar B2 1308+326 was observed contemporaneously at x-ray, optical and radio wavelengths in June 1996. The emission arises from a relativistic jet in PKS 2247−131, as an optical spectrum only shows a few weak absorption lines, typical of the BL Lacertae sub-class of the blazar class of active A thermal spectrum peaking in the ultraviolet region and faint optical emission lines are also present in OVV quasars, but faint or non-existent in BL Lac objects. The radio observations were taken with the 26-m diameter U. Relativistic beaming The observed emission from a blazar is greatly enhanced by relativistic effects in the jet, a process termed relativistic beaming . This spectrum can be compared with the spectrum shown in Figure 1. The light curves of the blazar were derived relative to two compar- Since its first optical identification by Wills and Wills (1974), the object has been observed in the complete EM spectrum particularly in the radio bands by Aller et al. Multifrequency observations are required to study its spectral energy distribution and determine the position of the two peaks. 1996, 1997; Valtonen 2007). 005 – 100 keV These ideas are confirmed by the Swift satellite observations of the blazar S5 0014+813, at the redshift z= 3. Depending on the fre-quency of the ﬁrst peak, the BL Lac objects are further clas-siﬁed into low (LBL), intermediate (IBL), and high energy (HBL) peaked objects. 7, although not featuring a clear radio counterpart, shows a blazar-like spectrum with weak emission lines with EW ~ 7 Å, yielding a redshift estimate of z = 0. The optical and IR light curves for the monitored blazars through July 2010 are shown in Figure 1. Blazars were highly represented among these early quasars, and indeed the first redshift was found for 3C 273 — a highly variable quasar which is also a blazar. The x-ray observations were performed with ASCA. Introduction Depending on their optical spectra, blazars are generally divided into two classes – BL Lac type objects and Flat Spectrum Radio Quasars (FSRQs). 8s, Decl. The bulk speed of the plasma Using data from the Hubble Space Telescope, researchers noticed that the emission spectrum from blazar PKS 1424+240 deviated from what was expected, possibly indicating something new about the emission mechanisms of blazars, the extragalactic background light, or the propagation of gamma-ray photons Blazar : radio-loud AGN whose relativistic jet points in the direction of the observer → emission from the jet dominates over any other AGN component (the disk, the BLR, the X-ray corona,…) → non-thermal emission from radio to gamma-rays, and extreme variability Flat-Spectrum-Radio-Quasars: optical spectrum with broad emission lines Fig. Emission in the V and J bands rose more gradually than did the gamma diﬀers, but ranges from 40-128 nights in the optical, and 13-98 nights for the near-infrared. On the basis of this result, we con-sider the hypothesis that the blazar TXS 0506+056 has been a source of high-energy neutrinos beyond that single event. The ﬂat spectrum radio quasar 4C +01. A blazar is a very compact and highly variable energy source associated with a presumed supermassive black hole at the center of a host galaxy. Radio–optical ﬂux behaviour and spectral energy distribution of the intermediate blazar GC 0109+224 Stefano Ciprini, 1,2 Gino Tosti, Harri Ter¨asranta3 and Hugh D. Apr 22, 2019 Relations between the flux densities (F) and spectral indices ( ) can The long- term optical variabilities of blazars have been discussed by Jan 30, 2003 Blazars are believed to be radio galaxies with their jets oriented at relatively . The observations were pointed Optical Spectroscopy of VHE and VHE Candidate Blazars SLAC Blazar Workshop March 13th, 2015 Caitlin Johnson David Williams Amy Furniss Xavier Prochaska Michele Fumagalli Caitlin Johnson, UCSC SLAC Blazar Workshop March 13th, 2015 optical–IR variations, frequency-dependent variability ampli-tude, and color–magnitude relations for our sample of blazars. New clues on the emission models of the extreme blazar 1ES 0229+200 for blazars. Aller4 1Physics Department and Astronomical Observatory, University of Perugia, via Pascoli, 06123 Perugia, Italy 2INFN, Perugia Section, via Pascoli, 06123 Perugia, Italy PDF | The blazar 3C454. Near-simultaneous optical data were obtained in optical and gamma rays. Through the construction of its spectral energy distribution, we are confident that its optical-ultraviolet (UV) emission is thermal in The optical spectrum of the Seyfert 2 galaxy NGC 1667 is shown, with important emission lines identified (Ho, Filippenko, and Sargent 1993). Extremely bright optical state of the flaring blazar PKS 0346-27. Kirill Sokolovsky (MPIfR, Bonn) has requested the assistance of AAVSO observers to obtain optical photometry of the blazar-type quasars 3C 273 and 3C 279 during 2011. 6 δ−1/3 G. blazar optical spectrum