An Untriggered Search for Optical Bursts

Kehoe, R.; Akerlof, C.; Balsano, R.; Bloch, J.; Casperson, D.; Fletcher, S.; Gisler, G.; Lee, Brian; Marshall, Stuart; McKay, Timothy A.; Rykoff, E. S.; Smith, D. A.; Vestrand, Tom; Wren, J.

doi:10.1086/342231

Cited by 16 publications

(19 citation statements)

References 19 publications

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“…The primary goal of that experiment was prompt response to GRB triggers from satellites in order to measure the early light curves of GRB optical counterparts (Akerlof et al 1999(Akerlof et al , 2000bKehoe et al 2001). The normal operation of the ROTSE-I instrument was completely automatic requiring only periodic maintenance.…”

Section: Rotse-i Robotic Telescopementioning

confidence: 99%

“…Resulting improvements in the local distance scale and discoveries of supernovae enable more accurate estimates of cosmological parameters and stellar ages. A substantial contribution to the understanding of gamma-ray bursts (GRBs) has already been made by robotic follow-up telescopes of modest size such as ROTSE (Akerlof et al 2000b;Kehoe et al 2001) and LOTIS (Park et al 2002). Development of autonomous systems searching for optical flashes in real time will enable monitoring of a variety of fast and rare phenomena including the onset of optical emission from GRBs.…”

Section: Introductionmentioning

confidence: 99%

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Northern Sky Variability Survey: Public Data Release

Woźniak¹,

Vestrand²,

Akerlof³

et al. 2004

471

212

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The Northern Sky Variability Survey (NSVS) is a temporal record of the sky over the optical magnitude range from 8 to 15.5. It was conducted in the course of the first-generation Robotic Optical Transient Search Experiment (ROTSE-I) using a robotic system of four comounted unfiltered telephoto lenses equipped with CCD cameras. The survey was conducted from Los Alamos, New Mexico, and primarily covers the entire northern sky. Some data in southern fields between declinations 0 and À38 are also available, although with fewer epochs and noticeably lesser quality. The NSVS contains light curves for approximately 14 million objects. With a 1 yr baseline and typically 100-500 measurements per object, the NSVS is the most extensive record of stellar variability across the bright sky available today. In a median field, bright unsaturated stars attain a point-to-point photometric scatter of $0.02 mag and position errors within 2 00 . At Galactic latitudes jbj < 20 , the data quality is limited by severe blending due to the $14 00 pixel size. We present basic characteristics of the data set and describe data collection, analysis, and distribution. All NSVS photometric measurements are available for on-line public access from the Sky Database for Objects in Time-Domain ((SkyDOT)) at Los Alamos National Laboratory. Copies of the full survey photometry may also be requested on tape.

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Section: Rotse-i Robotic Telescopementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Northern Sky Variability Survey: Public Data Release

Woźniak¹,

Vestrand²,

Akerlof³

et al. 2004

471

212

View full text Add to dashboard Cite

show abstract

“…No candidate event was found in 125 hrs monitoring of a field of 256 deg 2 with ROTSE-I to a limiting magnitude of 15.7 (Kehoe et al 2002). Vanden Berk et al (2002 searched for color-selected transients within 1500 deg 2 of the Sloan Digital Sky Survey (SDSS) down to R=19 and found only one unusual transient which was later identified as a radio-loud AGN exhibiting strong variability (Gal-Yam et al 2002).…”

Section: Introductionmentioning

confidence: 91%

Constraining the GRB Collimation with a Survey for Orphan Afterglows

Rau

Greiner

Schwarz

2006

AIP Conference Proceedings

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Abstract. Gamma-ray bursts are believed to be produced in highly-relativistic collimated outflows. Support for this comes among others from the association of the times of detected breaks in the decay of afterglow light curves with the collimation angle of the jets. An alternative approach to estimate a limit on the collimation angle uses GRB afterglows without detected prompt-emission counterparts. Here we report on the analysis of a dedicated survey for the search of these orphan afterglows using the Wide Field Imager at the 2.2 m MPI/ESO telescope at La Silla, Chile. We monitored ∼12 deg 2 in up to 25 nights typically spaced by one to two nights with a limiting magnitude of R=23. Four previously unknown optical transients were discovered and three of these associated with a flare star, a cataclysmic variable and a dwarf nova. The fourth source shows indications for an extragalactic origin but the sparse sampling of the light curve prevents a reliable classification. We discuss the results in the context of the collimation of GRBs.

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“…The motivations driving the searches for GRB orphan afterglows have been discussed by various authors like Totani & Panaitescu (2002), Nakar & Piran (2002), Kehoe et al (2002), Groot et al (2003), Rykoff et al (2005) in the optical range, by Greiner et al (1999) for X-ray afterglows, and by Perna & Loeb (1998), Levinson et al (2002), Gal-Yam et al (2006) for radio afterglows. One difficulty of this task, however, is that we have little theoretical indication on the rate and luminosity of orphan afterglows, two parameters which are essential in designing a strategy to search these sources.…”

Section: Introductionmentioning

confidence: 99%

The CFHTLS real time analysis system: “optically selected GRB afterglows”

Malacrino¹,

Atteia²,

Boër

et al. 2006

A&A

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Aims. We describe a deep and wide search for optical GRB afterglows in images taken with MegaCAM at the Canada France Hawaii Telescope, within the framework of the CFHT Legacy Survey. Methods. This search is performed in near real-time thanks to a Real Time Analysis System (RTAS) called "Optically Selected GRB Afterglows", which has been installed on a dedicated computer in Hawaii. This pipeline automatically and quickly analyzes Megacam images to construct catalogs of astronomical objects, and compares catalogs made from images taken at different epochs to produce a list of astrometrically and photometrically variable objects. These objects are then displayed on a web page to be characterized by a member of the collaboration. Results. In this paper, we comprehensively describe the RTAS process from image acquisition to the final characterization of variable sources. We present statistical results based on one full year of operation, showing the quality of the images and the performance of the RTAS. The limiting magnitude of our search is r = 22.5 on average and the observed area amounts to 1178 square degrees. We have detected about 13 × 10 6 astronomical sources of which about 0.01% are found to vary by more than one tenth of a magnitude. We discuss the performance of our instrumental setup with a sample of simulated afterglows. This sample allows us to compare the efficiency of our search with previous works, to propose an optimal observational strategy, and to discuss general considerations on the searches for GRB optical afterglows. We postpone to a forthcoming paper the discussion of the characterization of variable objects we have found, and a more detailled analysis of the nature of those resembling GRB afterglows. Conclusions. The RTAS has been continuously operating since November 2004. Each month 15-30 square degrees are observed many times over a period of 2-3 nights. The real-time analysis of the data has revealed no convincing afterglow candidate so far.

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An Untriggered Search for Optical Bursts

Cited by 16 publications

References 19 publications

Northern Sky Variability Survey: Public Data Release

Northern Sky Variability Survey: Public Data Release

Constraining the GRB Collimation with a Survey for Orphan Afterglows

The CFHTLS real time analysis system: “optically selected GRB afterglows”

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