A. Majczyna

“Pi of the Sky” Detector

“Pi of the Sky” experiment has been designed for continuous observations of a large part of the sky, in search for astrophysical phenomena characterized by short timescales, especially for prompt optical counterparts of Gamma Ray Bursts (GRBs). Other scientific goals include searching for novae and supernovae stars and monitoring of blasars and AGNs activity. “Pi of the Sky” is a fully autonomous, robotic detector, which can operate for long periods of time without a human supervision. A crucial element of the detector is an advanced software for real-time data analysis and identification of short optical transients. The most important result so far has been an independent detection and observation of the prompt optical emission of the “naked-eye” GRB080319B.

Pi of the Sky Telescopes in Spain and Chile

Pi of the Sky is a system of robotic telescopes designed for observations of short timescale astrophysical phenomena, e.g. prompt optical GRB emissions. The apparatus is designed to monitor a large fraction of the sky with 12–13 m range and time resolution of the order of 1–10 seconds. In October 2010 the first unit of the new Pi of the Sky detector system was successfully installed in the INTA El Arenosillo Test Centre in Spain. We also moved our prototype detector from Las Campanas Observatory to San Pedro de Atacama Observatory in March 2011. The status and performance of both detectors is presented.

The catalog of short periods stars from the “Pi of the Sky” data

Based on the data from the ”Pi of the Sky” project we made a catalog of the variable stars with periods from 0.1 to 10 days. We used data collected during a period of two years (2004 and 2005) and classified 725 variable stars. Most of the stars in our catalog are eclipsing binaries - 464 (about 64%), while the number of pulsating stars is 125 (about 17%). Our classification is based on the shape of the light curve, as in t he GCVS catalog. However, some stars in our catalog were classified as of different type than in the GCVS catalog. We have found periods for 15 stars present in the GCVS catalog with previously unknown period.

Present status of Pi of the Sky telescopes

In October 2010 Pi of the Sky set up a new system, consisting of 4 cameras installed on a new mount, in El Arenosillo, in southern Spain. It was followed by moving the prototype system from Las Campanas Observatory (central Chile) to San Pedro de Atacama (northern Chile) in March 2011. In this paper our new sites, some details about observational conditions and first results in both observatories are described.

Hunting for Gamma Ray Bursts with Pi of the Sky telescopes in Chile and Spain

The Pi of the Sky is a system of wide field of view robotic telescopes, which search for short timescale astrophysical phenomena, especially for prompt optical GRB emission. The system was designed for autonomous operation, monitoring a large fraction of the sky with 12 − 13 range and time resolution of the order of 1− 10 seconds. System design and observation strategy were successfully tested with a prototype detector operational in 2004-2009 at Las Campanas Observatory, Chile, and moved to San Pedro de Atacama Observatory in March 2011. In October 2010 the first unit of the final Pi of the Sky detector system, with 4 CCD cameras, was successfully installed in the INTA El Arenosillo Test Centre in Spain. Three more units (12 CCD cameras) are being prepared for installation on a new platform in INTA, aiming at a total coverage of about 6 400 square degrees. Status and performance of the detectors is presented.

Parallax in Pi of the Sky project

Starting March 2011 the “Pi of the Sky” project has two observatories in use: in northern Chile and in southern Spain. Since then we are able to observe a parallax of objects, which pass close to the Earth. Simultaneous observations from two sites are very important to us, because this allows us to reject false flash observations, due to cosmic radiation, meteors, planes, etc. In this paper we present theoretical limitations of our parallax observations. Moreover, first results are shown.

Prompt optical observations of GRBs with “Pi of the Sky” system

The “Pi of the Sky” prototype apparatus observed prompt optical emission from extremely bright GRB080319B since the very beginning of the gamma emission. The burst occurred at redshift z = 0.937 and set the record of optical luminosity reaching 5.3 mag. The position of the burst was observed before, during and after the explosion by several telescopes and unprecedented coverage of optical light curve has been achieved. The combination of these unique optical data with simultaneous gamma‐ray observations provides a powerful diagnostic tool for the physics of the GRB explosion within seconds of its start. The “Pi of the Sky” prototype, working since 2004 in Las Campanas Observatory in Chile, consists of 2 cameras observing same 20°×20° fields in the sky with time resolution of 10 seconds. The prototype reacts to GCN alerts, but it has also its own algorithm for identification of optical flashes. The final system covering field of view of Swift or Fermi satellite will consist of 2 arrays of 16 cameras instal...

What is new on the second edition of the variable stars catalogue from the Pi of the Sky data

We present current status of the work on the second edition of the variable star catalogue. We used the data from the period from 2006 to 2007. Our catalogue contains about 1000 variable stars of different types. We determined periods for 34 variable stars, which already exists in the GCVS catalogue. For three of them we determined type of variability, previously unknown.

Pi of the Sky: modelling of the detector response for more effective search for optical GRB counterparts.

The ultimate goal of the “Pi of the Sky” apparatus is observation of optical flashes of astronomical origin and other light sources variable on short timescales, down to tens of seconds. We search mainly for optical emissions of Gamma Ray Bursts, but also variable stars, novae, blazars, etc. This task requires a precise photometry - accurate measurement of the source’s brightness (and it’s variability). “Pi of the Sky” single cameras’ field of view is about 20 ◊20 . This causes a significant deformation of a point spread function (PSF), reducing quality of brightness measurement with standard photometric algorithms. To improve photometry, an attempt to investigate PSF based on real star images was made. However, results turned out to be inconclusive due to miscellaneous sky-observing effects. Therefore we decided to perform laboratory measurements, using a CCD camera and an artificial light source as a star simulator. This work shows preliminary results of this study - a set of high resolution PSF shapes, pixel response and pixel sensitivity functions. Finally, an idea how to simulate a real star image in the “Pi of the Sky” system is presented.