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J/AJ/137/5022     Variability of radio-bright BL Lac objects   (Nieppola+, 2009)

Long-term variability of radio-bright BL Lacertae objects. Nieppola E., Hovatta T., Tornikoski M., Valtaoja E., Aller M.F., Aller H.D. <Astron. J., 137, 5022-5036 (2009)> =2009AJ....137.5022N
ADC_Keywords: BL Lac objects ; Radio sources Keywords: BL Lacertae objects: general - galaxies: active - methods: statistical - radiation mechanisms: non-thermal - radio continuum: galaxies Abstract: Radio-bright BL Lacertae objects (BLOs) are typically very variable and exhibit prominent flaring. We use a sample of 24 BLOs, regularly monitored at Metsahovi Radio Observatory, to get a clear idea of their flaring behavior in the radio domain and to find possible commonalities in their variability patterns. Our goal was to compare the results given by computational timescales and the observed variability parameters determined directly from the flux curves. Also, we wanted to find out if the BLO flares adhere to the generalized shock model, which gives a schematic explanation for the physical process giving rise to the variability. We use long-term monitoring data from 4.8, 8, 14.5, 22, 37, 90, and 230GHz, obtained mainly from the University of Michigan and Metsahovi Radio Observatories. The structure function, discrete correlation function, and Lomb-Scargle periodogram timescales, calculated in a previous study, are analyzed in more detail. Also, we determine flare durations, rise and decay times, and absolute and relative peak fluxes from the monitoring data. Description: Our sample has been selected from the BLO sample monitored at the Metsahovi Radio Observatory for more than 20 years. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 65 24 The source sample of 24 BLOs table2.dat 56 128 The most significant timescales obtained for the sample sources using the structure function, the discrete correlation function and the Lomb-Scargle periodogram
See also: J/A+A/445/441 : SED of BL Lacertae objects (Nieppola+, 2006) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Source Source name (HHMM+DDMM) 10- 21 A12 --- OName Other name 24- 25 I2 h RAh Right ascension (J2000) 27- 28 I2 min RAm Right ascension (J2000) 30- 33 F4.1 s RAs Right ascension (J2000) 35 A1 --- DE- Declination sign (J2000) 36- 37 I2 deg DEd Declination (J2000) 39- 40 I2 arcmin DEm Declination (J2000) 42- 45 F4.1 arcsec DEs Declination (J2000) 47- 51 F5.3 --- z ?=- Redshift 53- 56 F4.1 --- Dvar ?=- Doppler boosting factor of the source taken from Hovatta et al. (2009A&A...494..527H) 58- 60 A3 --- Class [HILBL] BLO class (High, Intermediate or Low energy-peaked BL Lac) according to Nieppola et al. (2006, Cat. J/A+A/445/441) 62 A1 --- Flare [*] Flare analysis (1) 64- 65 I2 --- r_z ?=- Redshift reference (2)
Note (1): indicates whether the source is included in the flare analysis. See the text for details. Note (2): References as follows: 1 = Britzen et al., 2008, Cat. J/A+A/484/119 2 = Carangelo et al., 2003A&A...412..651C 3 = Cohen et al., 1987ApJ...318..577C 4 = De Grijp et al., 1992, Cat. J/A+AS/96/389 5 = Hewitt & Burbidge, 1987ApJS...63....1H 6 = Hewitt & Burbidge, 1989ApJS...69....1H 7 = Lawrence et al., 1986AJ.....91..494L 8 = Nilsson et al., 2008A&A...487L..29N 9 = Smith & Nair, 1995PASP..107..863S 10 = Sowards-Emmerd et al., 2005, Cat. J/ApJ/626/95 11 = Stickel et al., 1988A&A...191L..16S 12 = Stickel et al., 1989, Cat. III/175 13 = Stickel et al., 1991ApJ...374..431S 14 = Stickel et al., 1993, Cat. J/A+AS/98/393 15 = Tytler & Fan, 1992ApJS...79....1T 16 = Ulrich et al., 1975ApJ...198..261U 17 = Vermeulen et al., 1995ApJ...452L...5V 18 = Weistrop et al., 1984BAAS...16..521W 19 = Wiklind & Combes, 1997A&A...328...48W 20 = Wright et al., 1983MNRAS.205..793W.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Source Source name (HHMM+DDMM) 10- 21 A12 --- OName Other name 23- 27 F5.1 GHz nu Observation frequency 29- 30 A2 --- l_TSF [≥] Limit flag on TSF 32- 37 F6.3 yr TSF ? Structure function timescale (1) 39- 44 F6.3 yr TDCF ? Discrete correlation function timescale (1) 46- 51 F6.3 yr TP ? Lomb-Scargle periodogram timescale (1) 53- 56 A4 --- Note Note(s) on timescales (2)
Note (1): All time scales are in the observer's frame. Note (2): Note on timescales as follows: 1 = faint source 2 = multiple time scales 3 = exceptionally large errors in TDCF
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 08-Nov-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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