Investigation of optical variability in 3C 66A

Folsom, G. H.; Wingert, D. W.; Williamon, R. M.

doi:10.1086/111868

Cited by 6 publications

(7 citation statements)

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“…The optical counterpart of the radio source 3C 66A was first identified by Wills & Wills (1974); derived a redshift z = 0.444 from a broad emission feature identified with a Mg II line. The classification as a BL Lac object is also supported by the high optical polarisation (16%, Mead et al 1990) and by the brightness variability with an amplitude of about 2 mag (Folsom et al 1976;Miller & McGimsey 1978).…”

Section: Introductionmentioning

confidence: 85%

X-ray and optical observations of BL Lac objects: 3C 66A (B0219+428) and ON 325 (B1215+303)

Perri

Massaro

Giommi

et al. 2003

A&A

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Abstract.We report the results of new observations of the two BL Lac objects 3C 66A and ON 325 performed with BeppoSAX and of nearly simultaneous photometric measurements in the bandpasses from I to B. 3C 66A was observed in January 1999 and in July 2001: its X-ray flux was F(2−10 keV) = 2.0−12 erg cm −2 s −1 in January 1999 and F(2−10 keV) = (2.6 ± 0.6) × 10 −12 erg cm −2 s −1 in July 2001. In both observations the X-ray spectrum can be fitted by a single power law with an energy index 1.2 ± 0.1, steeper than that measured in the optical, equal to 0.86 ± 0.05. The BeppoSAX observation of ON 325 was performed in December 1998 when its X-ray flux was F(2−10 keV) = 8 +3 −4 × 10 −13 erg cm −2 s −1 . The X-ray spectrum cannot be fitted by a single power law, but it is found to be well represented by a broken power law with a break energy at around 4 keV and energy indices equal to 1.48 ± 0.12 and −0.57 ± 0.63. Both sources are characterised by a synchrotron-dominated emission at energies lower than a few keV, with a sharp flattening toward higher energies due to the inverse Compton component. We obtained satisfactory modelling of the overall spectral energy distributions, from the optical to low energy X-rays, with logparabolic laws.

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Section: Introductionmentioning

confidence: 85%

X-ray and optical observations of BL Lac objects: 3C 66A (B0219+428) and ON 325 (B1215+303)

Perri

Massaro

Giommi

et al. 2003

A&A

Self Cite

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“…Its polarization variations are very large (from 10% to 22%; Smith et al 1987). The source was not very active in the B band in the years before 1991, only a few small outbursts having been observed (e.g., Barbieri et al 1982;Folsom et al 1976). Sillanpää et al (1991) observed a 1.4 mag flare during 1985 October.…”

Section: +428 (3c 66a)mentioning

confidence: 96%

Optical Monitoring of Three Gamma-Ray-loud BL Lacertae Objects in 1999-2002

Zhang

Zhao

et al. 2004

Astron J

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We present the results of optical photometric (BVRI ) monitoring of three gamma-ray-loud BL Lac objects (3C 66A, PKS 0735+178, and BL Lacertae) in 1999-2002. During our observations, these objects showed significant rapid variations: 3C 66A and PKS 0735+178 exhibit short-timescale ($1 hr) variability in the B band, and BL Lac exhibits intraday variability in B and V. We find that there is a strong correlation between brightness and color for 3C 66A and BL Lac. We have analyzed the relationship between optical variability and gamma-ray variability and discuss theoretical models for gamma-ray-loud BL Lac emission. We have found shorter time variability for 3C 66A and PKS 0735+178 compared with previous reports.

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“…No clear evidence for intraday variability has been observed (e.g. Folsom et al 1976;Miller & McGimsey 1978;Takalo et al 1992a;Xie et al 1992). Carini & Miller (1991) have reported on variations as fast as 0.09T0.02 mag/hr, which they claim to suggest a characteristic time scale for the variations in 3C 66A of 12 hours.…”

Section: History Of 3c 66amentioning

confidence: 97%

“…Note the much higher brightness observed during this campaign. The average magnitudes have previously been 15.5 in B and 15.0 in V. The historical light curve is based on data taken from the following references: Barbieri et al (1982), Brindle et al (1986), Corso et al (1986Corso et al ( , 1988, Folsom et al (1976), Miller & McGimsey (1978), Holmes et al (1984), Maccagni et al (1987), Mead et al (1990), Moles et al (1985), Pica et al (1980), Sillanpaa et al (1991), Sitko et al (1985), Smith et al (1987), Takalo (1991), Takalo et al (1992bTakalo et al ( , 1994, Valtaoja et al (1991), Worral et al (1986), and Xie et al (1987Xie et al ( , 1988aXie et al ( ,b, 1990Xie et al ( -1992, Wills & Wills (1974).…”

Section: History Of 3c 66amentioning

confidence: 99%

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Monitoring of 3C 66A during an extended outburst. I. The light curves

Takalo¹,

Sillanpää²,

Pursimo³

et al. 1996

Astron. Astrophys. Suppl. Ser.

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Abstract. -We present results from a two year intensive monitoring of BL Lac object 3C 66A (PKS 0219+428).This object was observed in outburst during these two years. It reached the brightest ever observed magnitude on V=13.59 (1.2.1995) and on K=10.59 (15.2.1994). The optical and infrared light curves are characterised by randomly distributed fast flares, lasting a few days and well defined outbursts lasting a week or two. On top of these flares we can occasionally see small amplitude microvariability. No clear correlation can be found between the spectral behaviour and the occurrence of these flares. In the radio bands 3C 66A was quite faint and very stable compared to the optical variations. The light curves will be presented with preliminary analysis and discussions on the possible causes for the observed variations.

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Investigation of optical variability in 3C 66A

Cited by 6 publications

References 0 publications

X-ray and optical observations of BL Lac objects: 3C 66A (B0219+428) and ON 325 (B1215+303)

X-ray and optical observations of BL Lac objects: 3C 66A (B0219+428) and ON 325 (B1215+303)

Optical Monitoring of Three Gamma-Ray-loud BL Lacertae Objects in 1999-2002

Monitoring of 3C 66A during an extended outburst. I. The light curves

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