The CFHTLS Real Time Analysis System "Optically Selected GRB Afterglows"
arXiv:astro-ph/0605749 · doi:10.1051/0004-6361:20065599
Abstract
We describe a wide and deep search for optical GRB afterglows on images taken with MegaCAM at the Canada France Hawaii Telescope, within the framework of the CFHT Legacy Survey. This search is performed in near real-time thanks to a Real Time Analysis System called "Optically Selected GRB Afterglows", which has been completely realized and installed on a dedicated computer in Hawaii. This pipeline automatically and quickly analyzes Megacam images and extracts from them a list of astrometrically and photometrically variable objects which are displayed on a web page for validation by a member of the collaboration. In this paper, we comprehensively describe the RTAS process. We also present statistical results based on nearly one full year of operation, showing the quality of the images and the performance of the RTAS. Finally, we compare the efficiency of this study with similar searches, propose an ideal observational strategy using simulations, and discuss general considerations on the searches for GRB afterglows independently of the prompt emission. This is the first of a series of two papers. A second paper will discuss the characterization of variable objects we have found, as well as the GRB afterglow candidates and their nature. We will also estimate or at least constrain the collimation factor of GRB using the totality of the Very Wide Survey observations.
11 pages, 10 Figures, 5 Tables
References in corpus (32)
- Spectra and Light Curves of Gamma-Ray Burst Afterglows
- Unsteady Outflow Models for Cosmological Gamma-Ray Bursts
- Optical and Long Wavelength Afterglow from Gamma-Ray Bursts
- Beaming in Gamma-Ray Bursts: Evidence for a Standard Energy Reservoir
- Jets in GRBs
- The Dynamics and Light Curves of Beamed Gamma Ray Burst Afterglows
- How to Tell a Jet from a Balloon: A Proposed Test for Beaming in Gamma Ray Bursts
- Shocked by GRB 970228: the afterglow of a cosmological fireball
- The afterglow, the redshift, and the extreme energetics of the gamma-ray burst 990123
- GRB Energetics and the GRB Hubble Diagram: Promises and Limitations
- Gamma-ray burst beaming: a universal configuration with a standard energy reservoir?
- Optical and Radio Observations of the Afterglow from GRB990510: Evidence for a Jet
- Physical Parameters for the Afterglows of GRB 980703, 990123, 990510, and 991216 Determined from Modeling of Multi-Frequency Data
- Failed gamma-ray bursts and orphan afterglows
- Orphan GRB radio afterglows: Candidates and constraints on beaming
- The Detectability of Orphan Afterglows
- On Beaming Effects in Afterglow Light Curves
- A Complete Survey of the Transient Radio Sky and Implications for Gamma-Ray Bursts, Supernovae, and other Relativistic Explosions
- GRB afterglow light curves in the pre-Swift era - a statistical study
- The Deep Lens Survey Transient Search I : Short Timescale and Astrometric Variability
- Orphan Afterglows of Collimated Gamma-Ray Bursts: Rate Predictions and Prospects for Detection
- A Search for Untriggered GRB Afterglows with ROTSE-III
- The difficulty in using orphan afterglows to measure gamma-ray burst beaming
- Constraining the Beaming of Gamma-Ray Bursts With Radio Surveys
- The nature of the DLS fast transients
- Can the jet steepen the light curves of GRB afterglow?
- SDSS J124602.54+011318.8: A Highly Variable AGN, Not an Orphan GRB Afterglow
- The Faint Sky Variability Survey I: Goals and data reduction process
- SDSS J124602.54+011318.8: A Highly Luminous Optical Transient at z=0.385
- An Untriggered Search for Optical Bursts
- Search for GRB afterglows in the ROSAT all-sky survey
- The CFHTLS Real Time Analysis System "Optically Selected GRB Afterglows"