Long-term Monitoring of Molonglo Calibrators

Gaensler, B. M.; Hunstead, R. W.

doi:10.1071/as00072

Cited by 41 publications

(61 citation statements)

References 24 publications

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“…Many of the afterglow candidates detected had a 5σs flux significance and therefore large errors. As a result, it was difficult to test for variability in the radio light curves by deriving a reduced χ 2 to a weighted mean fit (Gaensler & Hunstead 2000). We therefore based our identification of a coincident radio source as a confirmed AMI-detected GRB radio afterglow using the following criteria:…”

Section: Radio Counterpart Selection Criteriamentioning

confidence: 99%

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

Anderson

Staley

Horst

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present the Arcminute Microkelvin Imager (AMI) Large Array catalogue of 139 gamma-ray bursts (GRBs). AMI observes at a central frequency of 15.7 GHz and is equipped with a fully automated rapid-response mode, which enables the telescope to respond to highenergy transients detected by Swift. On receiving a transient alert, AMI can be on-target within two minutes, scheduling later start times if the source is below the horizon. Further AMI observations are manually scheduled for several days following the trigger. The AMI GRB programme probes the early-time (< 1 day) radio properties of GRBs, and has obtained some of the earliest radio detections (GRB 130427A at 0.36 and GRB 130907A at 0.51 days post-burst). As all Swift GRBs visible to AMI are observed, this catalogue provides the first representative sample of GRB radio properties, unbiased by multi-wavelength selection criteria. We report the detection of six GRB radio afterglows that were not previously detected by other radio telescopes, increasing the rate of radio detections by 50% over an 18-month period. The AMI catalogue implies a Swift GRB radio detection rate of 15%, down to ∼ 0.2 mJy/beam. However, scaling this by the fraction of GRBs AMI would have detected in the Chandra & Frail sample (all radio-observed GRBs between 1997 − 2011), it is possible ∼ 44 − 56% of Swift GRBs are radio bright, down to ∼ 0.1 − 0.15 mJy/beam. This increase from the Chandra & Frail rate (∼ 30%) is likely due to the AMI rapid-response mode, which allows observations to begin while the reverse-shock is contributing to the radio afterglow.

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Section: Radio Counterpart Selection Criteriamentioning

confidence: 99%

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

Anderson

Staley

Horst

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…We quantify the flux variation using two methods, calculating the (1) modulation index m, i.e., standard deviation divided by the mean as used by Gaensler & Hunstead (2000), and (2) a linear fit spanning the six epochs. Moreover, we checked all sources for any variation in shape.…”

Section: Measuring Source Variabilitymentioning

confidence: 99%

Discovery of a Meter-Wavelength Radio Transient in the Swire Deep Field: 1046+59

Jaeger

Hyman

Kassim

et al. 2012

The Astronomical Journal

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We report the results of a low frequency radio variability and slow transient search using archival observations from the Very Long Array. We selected six 325 MHz radio observations from the spring of 2006, each centered on the Spitzer-Space-Telescope Wide-area Infrared Extragalactic Survey (SWIRE) Deep Field: 1046+59. Observations were spaced between one day to three months, with a typical single-epoch peak flux sensitivity below 0.2 mJy beam −1 near the field pointing center. We describe the observation parameters, data post-processing, and search methodology used to identify variable and transient emission. Our search revealed multiple variable sources and the presence of one, day-scale transient event with no apparent astronomical counterpart. This detection implies a transient rate of 1 ± 1 event per 6.5 deg 2 per 72 observing hours in the direction of 1046+59 and an isotropic transient surface density Σ = 0.12 deg −2 at 95% confidence for sources with average peak flux density higher than 2.1 mJy over 12 hr.

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“…MRC B1549À790: Flat-spectrum source, known to vary at 843 MHz (Gaensler & Hunstead 2000); S 178 relies on extrapolation and may be unreliable.…”

Section: Comments On Individual 178 Mhz Estimatesmentioning

confidence: 99%

The Molonglo Southern 4 Jy Sample (MS4). I. Definition

Burgess

Hunstead

2006

Astron J

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We have defined a complete sample of 228 southern radio sources at 408 MHz with integrated flux densities S 408 > 4:0 Jy, Galactic latitude jbj > 10 , and declination À85 < < À30 . The main finding survey used was the Molonglo Reference Catalogue. We describe in detail how the Molonglo Southern 4 Jy sample (MS4) was assembled and its completeness assessed. Sources in the sample were imaged at 843 MHz with the Molonglo Observatory Synthesis Telescope to obtain positions accurate to about 1 00 , as well as flux densities and angular sizes; follow-up radio and optical observations are presented in Paper II. Radio spectra for the MS4 have been compiled from the literature and used to estimate flux densities at 178 MHz. The strong-source subset of MS4, with S 178 > 10:9 Jy (SMS4), provides a southern sample closely equivalent to the well-studied northern 3CRR sample. Comparison of SMS4 with 3CRR shows a reassuring similarity in source density and median flux density between the two samples.

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Long-term Monitoring of Molonglo Calibrators

Cited by 41 publications

References 24 publications

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

Discovery of a Meter-Wavelength Radio Transient in the Swire Deep Field: 1046+59

The Molonglo Southern 4 Jy Sample (MS4). I. Definition

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