BL Lac (VRO 42:22:01) : simultaneous radio and optical observations.

Andrew, B. H.; Harvey, G. A.; Medd, W. J.; Hackney, K. R.; Hackney, R. L.; Scott, R. L.; Smith, Alex; Leacock, R. J.; McGimsey, B. Q.; Epstein, E. E.; Montgomery, Jonathan; Mottmann, John; Pomphrey, R. B.

doi:10.1086/152938

Cited by 7 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Radio variability on time scales of 2 days was observed at cm and mm frequencies as early as 1971 (Kinman & Conklin 1971. Kinman & Conklin (1971), Hackney et al (1972), and Andrew et al (1974) found probable correlations between variations in the.radio regime and optical range on time scales of days and months, respectively, in OJ 287 and BL Lac. MacLeod et al (1971) confirmed rapid radio flares in BL Lac but could not confirm any correlations with optical variability.…”

Section: Historicalmentioning

confidence: 95%

See 1 more Smart Citation

Intraday Variability in Quasars and BL LAC Objects

Wagner¹,

Witzel²

1995

Annu. Rev. Astron. Astrophys.

639

588

View full text Add to dashboard Cite

Active galactic nuclei with flat radio spectra exhibit significant variations of continuum flux density on time scales of days or less throughout the entire wavelength range. These rapid variations dghtly constrain the diameters of the emitting regions and imply extremely high photon densities if the variations are intrinsic. At radio frequencies the flux densities of compact objects may flicker due to interstellar scintillation, and in all frequency bands microlensing by stars in intervening galaxies may introduce variations that are not intrinsic to the source. We review the characteristics of these variations in the various electromagnetic bands. Extrinsic mechanisms may affect the light curves of compact extragalactic sources, but close correlations between flares recorded in different bands strongly support the assumption that intraday variability is an intrinsic phenomenon. The apparent brightness temperatures in the radio regime exceed 1017 K and imply relativistic beaming with very high Doppler factors, coherent radiation mechanisms, or special geometric effects.

show abstract

Section: Historicalmentioning

confidence: 95%

“…Reports of very rapid (1 min) IR flares could not be confirmed (Wolstencroft et al 1982 Andrew et al 1974, Epstein et al 1972, Kikuchi et al 1973, Dreher et al 1986, de Bruyn 1988. The observations up to 1980 are discussed in Epstein et al (1980).…”

Section: Idv Across the Electromagnetic Spectrummentioning

confidence: 96%

Intraday Variability in Quasars and BL LAC Objects

Wagner¹,

Witzel²

1995

Annu. Rev. Astron. Astrophys.

639

588

View full text Add to dashboard Cite

show abstract

“…Individual objects have been studied in many papers, e.g. 3C 120 (Usher 1972), BL Lac (Andrew et al 1974;Tornikoski et al 1994a), PKS 0420-01 (Dent et al 1979), 3C 446 (Bregman et al 1988), OJ 287 (Kikuchi et al 1973;Kinman et al 1974;Usher 1979;Valtaoja et al 1987) and AO 0235+164 (Balonek & Dent 1980;Roy et al 2000;Raiteri et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Correlated radio and optical variations in a sample of AGN

Hanski

Takalo

Valtaoja

2002

A&A

View full text Add to dashboard Cite

Abstract. Radio light curves of 20 sources from the Metsähovi monitoring program are compared with optical light curves collected from the literature. The Discrete Correlation Function analysis is applied to the data sets. A new qualitative method to study correlations is introduced, where the radio light curves are replaced by model light curves consisting of exponential outbursts. The optical flux level is compared to the phase and flux level of the model flares. Seven sources show clear correlations using the DCF analysis with six more showing a possible correlation between optical and radio events with time lags from zero to several hundred days. For twelve sources at least one simultaneous optical and radio event is seen. For eleven sources, when comparing optical flux levels with the phase of the model radio outbursts, the optical flux levels were high at the peak of the model radio outbursts. For sixteen sources, when comparing the optical flux level with the radio model flare flux level, the optical flux level was high when radio flux level was high, as well.

show abstract