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Topic: BL Lacertae

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BL Lac

BL Lac object

3C273

Quasar

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	Jeborics, or Galactic Points
		BL Lacertae(la-SER-tie) is the prototype of a class of bizarre quasar-like galaxies, and I have found it to have an influence in astrology as a member of the class of deep-sky objects which I have dubbed jeborics, (JEB-or-iks), a nonsense term coined by Dane Rudhyar and first proposed by Al H. Morrison.
		BL Lacertae was originally classified as a faint variable star when it was detected and cataloged in 1930 in the constellation Lacerta the Lizard, which lies in the northern Milky Way east of
		In the sky, BL Lacertae is located not far to the northwest of the faint star 4 Lacertae, near the border between Lacerta and Cygnus the Swan, at declination +42 degrees, 2 minutes, 1 second, right ascension 22 hours, 9 minutes, 30 seconds.
	www.geocities.com /mahtezcatpoc/jeborics.html (1868 words)

	AAVSO: BL Lac, January 2001 Variable Star of the Month
		It is the prototype of the BL Lac class of Active Galactic Nuclei (AGN).
		BL Lac was one of only two known (non-cepheid) extragalactic variable stars at the time.
		BL Lac objects & blazars are highly variable and exhibit a featureless spectrum.
	www.aavso.org /vstar/vsots/0101.shtml (1395 words)

	GTN: BL Lac Objects
		BL Lac objects are named after the protype object which was first believed to be a variable star in our galaxy.
		This amounts to a change in brightness of nearly a factor of 20, and a few BL Lac objects have been reported to undergo changes in brightness of a factor of 100.
		A number of BL Lac objects are known in the vicinity of clusters of galaxies so this provides indirect evidence in support of their extragalactic nature.
	gtn.sonoma.edu /public/resources/active_galaxies/bl_lac_objects.php (290 words)

	eSky: Lacerta
		Others, such as the supergiant 4 Lacertae, are highly luminous stars, but they are thousands of light years from Earth, and so appear even fainter than the nearer stars of the constellation.
		Though Lacerta is relatively lacking in interesting objects, it does lie on the Milky Way, and as we would expect it is not entirely devoid of features.
		Lacerta outlines a region that falls between two spiral arms of our Galaxy: hence its stars are generally distant and faint as seen from Earth.
	www.glyphweb.com /esky/constellations/lacerta.html (313 words)

	THE CFHT IMAGING SURVEY OF BL LACERTAE OBJECTS II:
		Various subsamples of BL Lacs with unique qualities (e.g., presence/absence of weak emission lines, high/low optical core dominance or polarization, Xray vs. radio selected, etc.) have statistically similar clustering properties further arguing that these BL Lacs are all members of the same AGN class.
		Contrary to the expectations of unification schemes for BL Lacs, the clustering environments of BL Lacs, at both high and low redshift, are more similar to those of FR 2 radio galaxies and quasars than to those of FR 1's.
		As a minimum the "parent population" of BL Lacs must be modified to exclude the brightest cluster galaxies (BCGs) in rich clusters at low redshift.
	casa.colorado.edu /Publications/preprints/1996/sepdec/303.shtml (493 words)

	Whitney Wills: LONG TERM MONITORING OF BL LACERTAE OBJECTS WITH THE BELL OBSERVATORY AT WESTERN KENTUCKY UNIVERSITY
		BL Lacs are the most extreme example of an AGN with highly variable continuum emission as one of their defining characteristics.
		The defining characteristics of BL Lacertae objects are large amplitude continuum variability at all wavelengths, a featureless optical continuum, and large amplitude, highly variable polarization.
		Both 0716+714 and BL Lacertae were observed in the B and I filters, while OJ 287 and 3C 66A were observed in the V and I filters.
	www.batse.msfc.nasa.gov /colloquia/abstracts_summer03/wills.html (617 words)

	Wikinfo \| Lacerta (Site not responding. Last check: 2007-11-05)
		Lacerta (genitive Lacertae, abbreviation Lac), the Lizard, is one of the minor constellations.
		The active galaxy BL Lacertae is one of the notable objects within this constellation.
		BL Lac was discovered quite early, and first believed to be a star, and therefore named like variable stars.
	www.wikinfo.org /wiki.php?title=Lacerta (177 words)

	BL Lacertae Object -- from Eric Weisstein's World of Astronomy
		They are distant quasar-like objects with no spectral lines which are often highly variable (by up to a factor of 100 over a few months).
		Most theorists believe that observations of BL Lacs are detecting a jet of material moving at close to the speed of light towards the observer.
		However, BL Lacs may be caused by microlensing of individual stars in intervening galaxies (Ostriker and Vietri 1990).
	scienceworld.wolfram.com /astronomy/BLLacertaeObject.html (129 words)

	Pasano B (Site not responding. Last check: 2007-11-05)
		BL Lacertae objects are the most extreme members of a class of objects known as Active Galactic Nuclei.
		In the case of BL Lac objects, the jets are aligned with the line of sight, and the radiation is being beamed directly at us.
		The defining characteristics of BL Lac objects are large amplitude continuum variability at all wavelengths, a featureless optical continuum, and large amplitude, highly variable polarization.
	campus.murraystate.edu /services/URSA/web2/LindsayHopper.htm (167 words)

	SAO Observers - AGN - BL Lac (Site not responding. Last check: 2007-11-05)
		BL Lacertae objects (BL Lac for short) exhibit no absorption or emission lines but have a strong continuum stretching from radio through X-ray wavelengths.
		BL Lac is a galaxy that is the prototype of its class.
		BL Lac objects are most likely produced when we view the active core of an elliptical galaxy almost directly through the central opening of the accretion disk.
	astronomy.swin.edu.au /sao/SAO_Observers/BLLac.html (171 words)

	BL Lac's Correlated Gamma-Ray and Optical Flare
		Observations of a Correlated Gamma-Ray and Optical Flare for BL Lacertae
		BL Lacertae (z=0.069) is one of about 60 blazars that have been detected by the EGRET instrument on the Compton Gamma Ray Observatory (CGRO) over the last 6 yr (Hartman et al.
		BL Lac is the prototypical object for a class of active galactic nuclei (AGNs) that typically have very weak emission and absorption lines and are characterized by variability in continuum emission and polarization (Peterson 1997).
	ecf.hq.eso.org /~ralbrech/sepdec97apjl/975555.html (2201 words)

	Optical Variability of the Blazar BL Lacertae (Site not responding. Last check: 2007-11-05)
		BL Lacertae, a complex, highly variable blazar, has been observed at optical wavelengths for 13 years with Colgate University’s Foggy Bottom Observatory 16” telescope equipped with a CCD camera.
		During this period BL Lac varied between R = 14.4 and 12.4; at least two distinct flares were observed.
		The variability timescale and profile of these flares during this outburst period are examined in both magnitude and flux.
	departments.colgate.edu /physics/students/sresearch02/tanguay.htm (137 words)

	Excess of Mg II Absorbers in BL Lac Objects
		BL Lac objects are thought to be low-luminosity radio galaxies (Fanaroff-Riley 1974 class 1 sources, hereafter FR 1's) whose jet synchrotron and inverse-Compton emissions are Doppler-boosted (Blandford and Rees 1978; Urry and Padovani 1995).
		The detailed properties of many (but not all) BL Lac objects are consistent with this scenario, including (1) their presence in luminous early-type host galaxies (Abraham, Crawford, and McHardy 1992; Wurtz, Stocke, and Yee 1996) in poor clusters of galaxies (Wurtz et al.
		It is the high-z (z>0.5) BL Lac objects that are most discrepant in their properties, many of which have higher radio power levels than FR 1's and weak, quasar-like emission lines in their optical spectra (e.g., see Fig.
	ecf.hq.eso.org /~ralbrech/novdec97apjl/975444.html (3341 words)

	Untitled Document (Site not responding. Last check: 2007-11-05)
		The core of the elliptical galaxy BL Lacertae (BL Lac) is one of the most extreme examples of active galactic nuclei (AGN).
		It is the prototype member of the radio-loud BL Lac class of AGN and displays all the signposts of relativistic beaming from a compact nuclear engine: one-sided superluminal radio components, highly variable radio flux and polarization, and high optical polarization.
		At the University of Iowa we have been monitoring the parsec-scale structure of the radio core of BL Lac since 1980.
	phobos.physics.uiowa.edu /rlm/research/bllac (132 words)

	BL Lac object - Wikipedia, the free encyclopedia (via CobWeb/3.1 planetlab1.cs.virginia.edu) (Site not responding. Last check: 2007-11-05)
		A BL Lac object, BL Lacertae object, or BL Lac is a type of active galaxy with an active galactic nucleus (AGN).
		In the unified scheme of radio-loud active galactic nuclei, the observed nuclear phenomenology of BL Lacs is interpreted as due to the effects of the relativistic jet that is pointing towards the observer.
		BL Lacs are believed to be intrinsically identical to low power radio galaxies but with the jet closely aligned to the line of sight of the observer.
	en.wikipedia.org.cob-web.org:8888 /wiki/BL_Lac_object (263 words)

	Multifrequency Observations of BL Lacertae in 1997 (Site not responding. Last check: 2007-11-05)
		[103.12] Multifrequency Observations of BL Lacertae in 1997
		The blazar BL Lacertae experienced one of its brightest flares yet observed during the summer of 1997.
		We analyzed the broadband spectral variations of BL Lac during the outburst, especially noting the variability in the spectral slope.
	www.aas.org /publications/baas/v29n5/aas191/abs/S103012.html (126 words)

	BL LACERTAE OPTICAL CAMPAIGN (JULY-AUGUST 2000)
		WEBT observers have organized an optical campaign on BL Lacertae contemporaneous with the high-energy campaign coordinated by Markus Boettcher involving X-ray and TeV observatories such as BeppoSAX, RXTE, STACEE, CAT, HEGRA.
		Our purpose is to monitor BL Lac in the optical bands from one week before to one week after the high-energy campaign, that is from July 17 to August 11, with particularly dense coverage in the central period.
		A preliminary R-band light curve of BL Lac in the last days is available in postscript format (data from Torino, University of Victoria, Clark and Coyote, and Palomar Observatories).
	www.to.astro.it /blazars/2200.htm (820 words)

	BL Lacertae (Site not responding. Last check: 2007-11-05)
		The multiwavelength spectrum of BL Lacertae during its July 1997 outburst is analyzed in terms of different variations of the homogeneous leptonic jet model for the production of high-energy radiation from blazars.
		Our analysis indicates that in BL Lacertae, un like other BL Lac objects, the broad emission line region plays an important role for the high-energy emission.
		In the appendix, we describe the formalism in which the process of Comptonization of reprocessed accretion disk photons is treated in the previously developed blazar jet simulation code which we use.
	www.phy.ohiou.edu /~mboett/bllac.html (135 words)

	1992 Abstracts (Site not responding. Last check: 2007-11-05)
		In every BL Lacertae object in which polarization structure was detected, the polarization position angle of the knots is nearly parallel to the VLBI structural axis.
		The preferred polarization direction in the jets is explained by the fact that plane perpendicular shock waves are common in these sources; the origin of the absence of the preferred polarization direction in the core components is unclear.
		These results support an early conclusion that it cannot be the case that a significant number of BL Lacertae objects are gravitationally microlensed images of more distant quasars, since the characteristic VLBI polarization structures observed in these two types of objects are very different.
	www.ras.ucalgary.ca /abstracts/1992/1992.html (821 words)

	BL Lac Objects (Site not responding. Last check: 2007-11-05)
		BL Lacertae objects (BL Lac for short) exhibit no emission lines but have a strong continuum stretching from rf through X-ray frequencies.
		Here are some light curves at different wavelengths illustrating the variability in intensity of BL Lac and some other active galaxies.
		The name remains from an original mis-identification of the prototype of such galaxies as a variable star in our own galaxy that was named BL Lacertae.
	csep10.phys.utk.edu /astr162/lect/active/BLlac.html (143 words)

	[No title] (Site not responding. Last check: 2007-11-05)
		We present evidence for the first detection of gamma rays from the extragalactic object BL Lacertae.
		Observations of BL Lacertae between 22 GHz and 375 GHz were also taken between 1995 January 24 and 1995 February 14 and the flux levels for those measurements are similar to the historical average values for this object.
		This reduction should result from processes intrinsic to BL Lacertae because it is near enough to Earth that intergalactic background IR fields should not significantly reduce the flux of gamma rays to which the Whipple Observatory telescope is sensitive.
	cfa-www.harvard.edu /ep/preprint/novdec96/4451.html (251 words)

	1993 Abstracts (Site not responding. Last check: 2007-11-05)
		Is 1308+326 A BL Lacertae object or a quasar?
		This argues against the view that the more luminous BL Lac objects are simply an extension of the quasar/OVV population, or that most BL Lac objects are gravitationally microlensed images of distant quasars.
		Other properties are generally consistent with the view the BL Lac objects are normal radio galaxies whose jets make a small angle to the line of sight.
	www.ras.ucalgary.ca /abstracts/1993/1993.html (1255 words)

	BL Lacertae concept from the Astronomy knowledge base (Site not responding. Last check: 2007-11-05)
		BL Lacertae concept from the Astronomy knowledge base
		High energy peaked BL Lac object (2 facts) (HBL)
		X-ray selected BL Lac object (2 facts) (SBL)
	www.site.uottawa.ca:4321 /astronomy/BLLacertae.html (158 words)

	Blazar in the Web - BL Lac, blazar, quasar, agn, variability, monitoring, jet emission, multiwavelenght, X-ray ... (Site not responding. Last check: 2007-11-05)
		This radio-loud extragalactic objects are optically violent variable quasars, flat-spectrum quasars, high polarized quasars, and BL Lacertae (BL Lac) type objects, which display extremely intense, broad and rapidly varing electromagnetic emission, from radio to gamma-rays in some case.
		This emission is thought to originate in a relativistic plasma jet which is probably to be powered and accelerated by a billion solar mass fl hole in gravitational accretion.
		It is an electronic newsletter dedicated to research and refereed publications on the BL Lac and blazar phenomena, observationally as well as theoretically.
	astro.fisica.unipg.it /blazarsintheweb.htm (880 words)

	bl - OneLook Dictionary Search
		B.L, bl : Encarta® World English Dictionary, North American Edition [home, info]
		BL, bl : The American Heritage® Dictionary of the English Language [home, info]
		Phrases that include bl: bl lacertae object, bl albertus magnus, bl anthony della chiesa, bl bl b l b l, bl ceti, more...
	www.onelook.com /q/bl????rd (194 words)

	[No title]
		It is also interesting, that some BL Lacs are now interpreted as quasars.
		For some BL Lac's with a featureless spectrum, there is no measured z-value.
		In the cases of the "Double Quasar" 0957+561 (KHQ 56) and the triple object PG 1115+080 (KHQ 81) the spectra are identical, which led to the interpretation of a gravitional lense.
	www.klima-luft.de /steinicke/KHQ/khq_e.htm (850 words)

	THE EXTREME ULTRAVIOLET SPECTRUM OF THE BL LACERTAE OBJECT PKS2155-304 (Site not responding. Last check: 2007-11-05)
		The Extreme Ultraviolet Spectrum of the BL Lacertae Object PKS2155-304
		We carried out two spectroscopic observations of the BL Lacertae object PKS 2155-304 with the Extreme Ultraviolet Explorer during 1993 June (~ 111 ksec) and July (~ 157 ksec).
		The source was detected in the ~ 75 - 110 Å range during both epochs, but the two spectra differ in detail, and the flux has increased by ~ 60 % between the two observations.
	www.cea.berkeley.edu /euve/sci/Resources_pubs_abstracts_pks21_koni.html (234 words)

	The Blazar List - The Perugia BL Lac, quasar & blazar list, optical observation, variability, finding chart, light ... (Site not responding. Last check: 2007-11-05)
		In late 1990 at Perugia University Observatory we began to develop an Automatic Imaging Telescope (AIT) able to obtain photometric BVRcIc observations of predefined lists of objects without the presence of the users.
		This instrument is now dedicated to the monitoring of a sample of about 40 blazars, quasars, and BL Lac objects with the principal aims of searching for possible typical time scales and spectral variability.
		In 8 years of blazar monitoring, we have collected more than 22000 photometric points (till the year 2000), contributing to get the largest existing database on many sources.
	astro.fisica.unipg.it /PGblazar/tabella2000.htm (288 words)

	[No title]
		The ROSAT X-ray spectra of BL Lacertae objects
		BL Lacertae objects in the ROSAT All-Sky Survey: new objects and comparison of different search techniques.
		The recognition of BL Lac objects: effects on redshift distributions, missing objects and cosmological evolution
	www.columbia.edu /~fms5/w267.html (792 words)

	BL Lacertae Objects: recent papers (Site not responding. Last check: 2007-11-05)
		Landt, P. Padovani, P. Giommi, 2002, "The classification of BL Lacertae objects: the Ca H&K break",
		Invited Review at the `BL Lac Phenomenon' Meeting, Turku, Finland, June 1998, ASP Conf.
		P. Padovani, P. Giommi, F. Fiore, 1997, "Are the X-ray Spectra of Flat-Spectrum Radio Quasars and BL Lacertae Objects Different?",
	www.eso.org /~ppadovan/bllacs_papers.html (219 words)

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