CDS

2007A&A...470..857P

Query : 2007A&A...470..857P

2007A&A...470..857P - Astronomy and Astrophysics, volume 470, 857-863 (2007/8-2)

The long-term optical spectral variability of BL Lacertae.

PAPADAKIS I.E., VILLATA M. and RAITERI C.M.

Abstract (from CDS):

We present the results from a study of the long-term optical spectral variations of BL Lacertae, using the long and well-sampled B and R-band light curves of the Whole Earth Blazar Telescope (WEBT) collaboration, binned in time intervals of 1 day. We study the relation between the long-term spectral variations and the respective flux variations of the source. Using cross-correlation techniques to investigate whether there are any delays between the flux variations in different energy bands and between the flux and spectral variations. The relation between spectral slope and flux (the spectrum gets bluer as the source flux increases) is well described by a power-law model, although there is significant scatter around the best-fitting model line. To some extent, this is due to the spectral evolution of the source (along well-defined loop-like structures) during low-amplitude events, which are superimposed on the major optical flares, and evolve on time scales of a few days. The B and R-band variations are well correlated, with no significant, measurable delays larger than a few days. On the other hand, we find that the spectral variations lead those in the flux light curves by ∼4 days. During at least the largest amplitude flares, the B-band variations appear to evolve faster than those in the R band. We confirm the ``bluer-when-brighter'' mild chromatism of the long-term variations, and we show that it can be explained if the flux increases/decreases faster in the B than in the R band. We also report the discovery of the lag between spectral and flux changes. These two features can be explained in terms of Doppler factor variations due to changes in the viewing angle of a curved and inhomogeneous emitting jet.

Abstract Copyright: ∼

Journal keyword(s): galaxies: active - galaxies: quasars: general - galaxies: jets - galaxies: BL Lacertae objects: general - galaxies: BL Lacertae objects: individual: BL Lacertae

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023 		#notes
1 NAME BL Lac BLL 22 02 43.2913536816 +42 16 39.979416792   15.66 14.72     ~ 2215 1

Query : 2007A&A...470..857P

Basic data :
NAME BL Lac -- BL Lac
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types: 		Rad (2010AJ,B3,...), gam (2AGL,3EG,...), X (2009A&A,1AXG,...), BLL (2010ApJ,[VV2000b],...), Bla (2012ApJ,[DGT2001],...), QSO (2009ApJS,QSO,...), * (PLX,UCAC2,...), V* (2018AJ,AN,...), AGN (2011ApJ), smm (JCMTSE,JCMTSF), MIR (AKARI,WISE), IR (IRAS,[MJR2015]), NIR (2MASS), FIR (2015A&A), Opt (ATO)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) : 		22 02 43.2913536816 +42 16 39.979416792 (Optical) [ 0.0089 0.0105 90 ] A 2020yCat.1350....0G
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) : 		22 00 39.3732819544 +42 02 08.493248503 [ 0.0089 0.0105 90 ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) : 		092.5895829969987 -10.4411578855454 [ 0.0089 0.0105 90 ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr : 		0.008 0.018 [0.012 0.013 90] A 2020yCat.1350....0G
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz : 		V(km/s) 19974 [~] / z(spectroscopic) 0.069 [~] / cz 20686 [~]
   D 2011NewA...16..503M
Syntax of parallax is : 'value quality [error] bibcode'
  • value : parallax value
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • [error] : mean error
  • bibcode : bibcode of the parallax reference
Parallaxes (mas): 		1.9 [3.5] E 1995GCTP..C......0V
Syntax of angular size is : "maj-axis min-axis angle (wtype) quality bibcode"
  • maj-axis : major axis size (arc minutes)
  • min-axis : minor axis size (arc minutes)
  • angle : orientation angle (in degrees)
  • (wtype) : wavelength class for the origin of the angular size (Rad, mm, IR, Opt, UV, Xray, Gam)
  • quality : flag of quality of the angular size values ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the angular size reference
Angular size (arcmin): 		0.0000105 0.0000057 17 (Rad) D 2010AJ....139.1713C
Syntax of fluxes (or magnitudes) is : "filter-name (System) flux-value [error] quality MultVarFlags bibcode"
  • filter-name : U, B, V, R, I, G, J, H, K, u, g, r, i, z
  • (System) : may be AB (default is Vega)
  • flux-value : value of flux or magnitude
  • [error] : error value
  • quality : flag of quality of the flux value ( A=best quality -> E=worst quality, {� } =unknown quality)
  • MultVarFlags : Mult is zero or one char (J) for joined photometry ; Var can be zero or two chars (V[0-4])
  • bibcode : bibcode of the flux reference
Fluxes (6) :
B 15.66 [~] D 2010A&A...518A..10V
V 14.72 [~] D 2010A&A...518A..10V
G 13.773007 [0.012811] C 2020yCat.1350....0G
J 12.201 [0.029] C 2003yCat.2246....0C
H 11.295 [0.037] C 2003yCat.2246....0C
K 10.485 [0.022] C 2003yCat.2246....0C
SIMBAD within arcmin
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay Simbad points in this preview
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Some important notes on this object about identifications and objects associations.
notes:

The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (101) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

QSO B2200+420 1FLE J2203+4214 RGB J2202+422 XSS J22023+4226
2AGL J2202+4214 GB6 J2202+4216 RGB J2202.7+4216 [BDW2002] q2200+4202
AKARI-IRC-V1 J2202433+421640 GB6 B2200+4202 RORF 2200+420 [CAB95] IRAS F22006+4202
AN 363.1929 87GB 220040.2+420203 RX J2202.7+4216 [CGL99] 23
ATO J330.6803+42.2777 ICRF J220243.2+421639 1RXS J220244.4+421626 [DGT2001] B2200+420
1AXG J220245+4217 IERS B2200+420 S4 2200+42 [HB93] 2200+420
B3 2200+420 INTREF 1067 S4 2200+420 [IN88] 2200+420
BWE 2200+4202 IRAS F22006+4202 SWIFT J2202.8+4218 [KRL2007b] 392
CJ1 2200+420 JCMTSE J220243.3+421637 SWIFT J2202.8+4216 [LC2007] 80
CJF B2200+420 JCMTSF J220243.3+421637 TeV J2202+422 [MGL2009] BZB J2202+4216
CLASS J220243.2912+421639.975 JVAS J2202+422 TIC 353622691 [MJR2015] 3610
DA 571 JVAS B2200+420 TXS 2200+420 [MML2015] 5BZB J2202+4216
2E 2200.6+4202 1Jy 2200+420 UCAC2 46472356 [VV2000b] J220243.3+421639
2E 4558 1Jy 2200+42 USNO 770 [VV2003b] J220243.3+421639
3EG J2202+4217 2MASS J22024329+4216400 V* BL Lac [VV2006b] J220243.3+421639
3EG J2202+4225 MITG J220245+4216 VLSSr J220243.8+421643 [VV2010b] J220243.3+421639
EGR J2204+4225 MY 220039.2+421611.9 VLSS J2202.7+4216 [VV98b] J220243.3+421639
1ES 2200+42.0 NAME BL Lac VRO 42.22.01 [W72] 2200+42
0FGL J2202.4+4217 NEWPS5 J2202+4216 VSOP J2202+4216 [WCO2009] J220247+421737
1FGL J2202.8+4216 NVSS J220243+421640 WB 2200+4202 AAVSO 2158+41
2FGL J2202.8+4216 OHIO Y 401 WISE J220243.29+421640.0 Gaia DR3 1960066225988786048
3FGL J2202.7+4217 PBC J2202.7+4217 WISE J220243.29+421639.9 Gaia DR1 1960066221690852224
4FGL J2202.7+4216 PKS 2200+420 WMAP 58 Gaia DR2 1960066225988786048
1FHL J2202.7+4216 PLX 5322.02 WMAP J2202+4217
2FHL J2202.7+4216 QSO J2202+4216 WN B2200.6+4202
3FHL J2202.7+4216 RFC J2202+4216 2XMMi J220243.3+421639

References (2215 between 1850 and 2023) (Total 2215)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Collections of Measurements


velocities : 8    V* : 1    PLX : 1    PM : 3   

   

Observing logs


herschel : 94    ISO : 11    IUE : 11   

   

External archives :

Archive data at HEASARC - High-Energy Astrophysics Science Archive Research Center

Data at NED - NASA/IPAC Extragalactic Database : NAME BL Lac

Link by name to the catalogue in VizieR :

AKARI-IRC-V1 J2202433+421640 BWE 2200+4202 2E 4558 3EG J2202+4217 3EG J2202+4225
IERS B2200+420 IRAS F22006+4202 2MASS J22024329+4216400 MITG J220245+4216 NVSS J220243+421640
PKS 2200+420 1RXS J220244.4+421626 UCAC2 46472356 V* BL Lac VSOP J2202+4216
WISE J220243.29+421640.0 WISE J220243.29+421639.9 WMAP J2202+4217 WN B2200.6+4202 Gaia DR3 1960066225988786048
Gaia DR1 1960066221690852224 Gaia DR2 1960066225988786048

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2023.09.30-18:52:29

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