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 to a depth of 12<sup>m</sup>−13<sup>m</sup> and with time resolution of the order of 10 seconds. Custom designed CCD cameras are equipped with Canon lenses f = 85 mm, f/d = 1.2 and cover 20° × 20° of the sky each. The final system with 16 cameras on 4 equatorial mounts was completed in 2014 at the INTA El Arenosillo Test Centre in Spain.<p> </p> GRB160625B was an extremely bright GRB with three distinct emission episodes. Cameras of the Pi of the Sky observatory in Spain were not observing the position of the GRB160625B prior to the first emission episode. Observations started only after receiving Fermi/GBM trigger, about 140 seconds prior to the second emission. As the position estimate taken from the Fermi alert and used to position the telescope was not very accurate, the actual position of the burst happened to be in the overlap region of two cameras, resulting in two independent sets of measurements. Light curves from both cameras were reconstructed using the Luiza framework. No object brighter than 12.4<sup>m</sup> (3σ limit) was observed prior to the second GRB emission. An optical flash was identified on an image starting -5.9s before the time of the Fermi/LAT trigger, brightening to about 8m on the next image and then becoming gradually dimmer, fading below our sensitivity after about 400s.<p> </p> Emission features as measured in different spectral bands indicate that the three emission episodes of GRB160625B were dominated by distinct physics process. Simultaneously observations in gamma-rays and optical wavelengths support the hypothesis that this was the first observed transition from thermal to non-thermal radiation in a single GRB. Main results of the combined analysis are presented.
"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<sup>m</sup>-13<sup>m</sup> range and time resolution of the order of 1 - 10 seconds. For now there are two working "Pi of the Sky" observatories: in San Pedro de Atacama (Chile) and near Mazagón in Southern Spain. In this paper we report on the status of the project, as well as recent observation of asteroid 2004<i>BL</i><sub>86</sub>, which passed the Earth in late January 2015, DG CVn outburst in 2014, satellites observations and our future plans.
Pi of the Sky is a system of wide field-of-view robotic telescopes designed for observations of short timescale astrophysical phenomena, especially for prompt optical GRB emission. The apparatus was designed for autonomous operation, follows the predefined observing strategy and adopts it to the actual conditions, monitoring a large part of the sky with time resolution of the order of 1 - 10 seconds and range 12m-13m.
Observation strategy and system design was successfully tested with a prototype detector working 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. Simultaneous observations from locations in Chile and Spain allow a systematic search for optical transients of cosmological origin. Accurate analysis of data arising from a wide-field system like Pi of the Sky is a real challenge because of a number of factors that can influence the measurements. We have developed a set of dedicated algorithms which remove poor quality measurements, improve photometric accuracy and allow us to reach uncertainties as low as 0.015– 0.02 mag.
Three more units (12 CCD cameras) are being prepared for installation on a new platform in INTA, aiming at a total coverage of about 6400 square degrees. Status and performance of the detectors is presented.
GLORIA stands for “GLObal Robotic-telescopes Intelligent Array”. GLORIA will be the first free and open-access
network of robotic telescopes of the world. It will be a Web 2.0 environment where users can do research
in astronomy by observing with robotic telescopes, and/or analyzing data that other users have acquired with
GLORIA, or from other free access databases, like the European Virtual Observatory. GLORIA project will
define free standards, protocols and methodology for controlling Robotic Telescopes and related instrumentation,
for conducting so called on-line experiments by scheduling observations in the telescope network, and for
conducting so-called off-line experiments based on the analysis of astronomical meta-data produced by GLORIA
or other databases.
Luiza analysis framework for GLORIA was based on the Marlin package developed for the International Linear
Collider (ILC), data analysis. HEP experiments have to deal with enormous amounts of data and distributed
data analysis is a must, so the Marlin framework concept seemed to be well suited for GLORIA needs. The
idea (and large parts of code) taken from Marlin is that every computing task is implemented as a processor
(module) that analyzes the data stored in an internal data structure and created additional output is also added
to that collection. The advantage of such a modular approach is to keep things as simple as possible. Every
single step of the full analysis chain that goes eg. from raw images to light curves can be processed separately
and the output of each step is still self consistent and can be fed in to the next step without any manipulation.
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.
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.
Gamma-Ray Bursts (GRB) are short impulses of gamma radiation (time duration ranges from 0.1 to 100 s) distributed
almost isotropically across the sky. Most probably they arise during explosions or collisions of stars at cosmological
distances. In this paper we discuss their origin, properties and current models. The methods of their observations will be
also described. At the end short summary of "Pi of the Sky" GRBs observations will be presented, mainly focused on
the naked-eye burst GRB080319B.
The "Pi of the Sky" system was initially created for searching of optical partners of gamma ray bursts [5,7]. The system
is located in Chile and consists of two CCD cameras on a common mounting base . Currently, it performs various
astronomical observations [1,5,7,8]. Among others, system also records passages of satellites and fragments of Earth's
artificial satellites, so called "space debris". Since now, this kind of data was identify as a disturbing transient signal and
team members usually focus on identify and eliminating it. Handle of this problem is especially important, because
software algorithm which search for optical companion of gamma ray bursts focus on transient phenomena events.
On the other hand, comparison of the "Pi of the Sky" system parameters with different facilities which are used for
space debris searching and monitoring shows, that its properties are similar to some of those systems. It means, that it
should be possible, to obtain valuable data of artificial satellites motion analyzing "Pi of the Sky" data. Moreover,
expected in the near future system upgraded to 6 small telescopes equipped totally with 24 CCD detectors system 
will cover a major part of the sky (field of view of each detector equals 20 x 20 degrees) which gives possibility of
visual measurements objects up to 16 magnitude. It will be an unusual advantage in the field of system categories with
that size. In the paper, we would like to shortly describe a space debris community activities, present properties of
selected systems which are using for space debris surveys and finally examples of observational data will be presented.
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° x 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.
Real-time analysis of data from optical telescopes becomes very important topic in the modern astronomy. Particularly
interesting and important is fast automatic identification of short optical transients. Many violent and interesting
processes occur on very short timescales. Such kind of processes may be related to gamma-ray bursts, but there are also
other interesting processes in the short time regime. One of the biggest problems with their investigation is fast
detection and distribution, which would allow deeper studies in the most interesting phase of the event. Thus
development of real-time pipelines for identification of optical transients is a very hot topic. Another issue which
becomes important is that data streams produced by modern astronomical experiments becomes larger and larger,
which requires real-time analysis and pre-selection of only most interesting data. We present implementation of such a
pipeline dedicated to identification of optical transients in the "Pi of the Sky" experiment.
The "Pi of the Sky" robotic telescope has been designed for monitoring of a significant fraction of the sky with good
time resolution and range. The main goal of the "Pi of the Sky" detector is to look for short timescale optical transients
arising from various astrophysical phenomena, mainly for optical counterparts of Gamma Ray Burst (GRB). System
design, observations methodology as well as developed algorithms also make this detector a sophisticated instrument
looking for novae and supernovae stars and monitoring of blasars and AGNs activity. Final detector consists of two sets
of 16 cameras, one camera covering field of view of 20°x20°. It follows that the full system will cover field of view of
SWIFT BAT satellite. The final system is under construction now. Required hardware and software tests were
performed with a prototype located in Las Campanas Observatory in Chile since June 2004. The most important result
by the "Pi of the Sky" prototype so far was an independent detection and observation of the prompt optical emission
from the naked-eye GRB080319B.
The main aim of the "Pi of the Sky" experiment is to search for optical flashes associated with the gamma ray bursts.
The detector also allows us to study other kinds of short timescale astrophysical phenomena. During everyday
observations "Pi of the Sky" detector collects many measurements of interesting objects like blazars, quasars, variable
stars etc. It is very important to make this data available to other experiments as fast as possible. Dedicated WWW
interface connected with the "Pi of the Sky" database in Chile was created to provide on-line access to selected objects.
The interface allows quick and easy accesses to the "Pi of the Sky" data right after all measurements processes are
"Pi of the Sky" is a detector designed for search for optical flashes of the cosmic origin in the sky. Its primary goal is to look for optical afterglows associated with the gamma ray bursts (GRB), but it is also good to tool to study any kind of short timescale astrophysical phenomena. The apparatus consists of two arrays of 16 cameras each, which allow for simultaneous observation of big fraction of the sky. Due to on-line data analysis in the real time, it has self-triggering capability and can react to external triggers with negative time delay. The prototype with two cameras has been installed at Las Campanas (Chile) and was operational in period since June 2004 till August 2005 and upgraded in June 2006. Database for storing large amount of astronomical measurements was developed. The general idea of experiment, apparatus and data analysis in the experiment will be presented.
The main aim of the "Pi of the Sky" experiment is a search for short optical transients in the sky. During each night the whole sky is scanned two times, at the beginning and at the end of the night. This paper describes the basic analysis carried out on the sky scan data and its preliminary results.
There is currently no experiment running that can perform non-accidental observations of Gamma Ray Bursts (GRB) optical counterparts from their very beginning, not mentioning seconds before the GRB. The main reason is the time that even small telescopes need for moving to the burst coordinates after receiving a trigger from a satellite and the time of the trigger propagation itself. "π of the Sky" project overcomes this obstacle by introducing an array of CCD cameras aimed at simultaneous observations of large sky area - and thus the location of the GRB source during and even before the burst itself. The price for this solutions is, however, a lower magnitudo range, reaching only about 14<sup><i>m</i></sup> - 15<sup><i>m</i></sup>. In this paper we present a preliminary analysis, based on most of the currently available optical lightcurve measurements, indicating that a significant fraction of GRB optical counterparts should lie in this range.
"Pi of the Sky" is a detector designed for search for optical flashes of cosmic origin in the sky. Its primary goal is to look for optical afterglows associated with the gamma ray bursts (GRB) but it is capable to detect also other optical transients of extragalactic origin. The apparatus consists of two arrays of 16 cameras each, which allow for simultaneous observation of large part of the sky. Thanks to on-line data analysis in real time, it has self-triggering capability and can react to external triggers with negative time delay. The prototype with two cameras has been installed at Las Campanas (Chile) and is operational from July 2004. General idea of experiment, the apparatus and its performance will be presented.
The main aim of the "π of the Sky" project is all night monitoring of a large sky area in search for GRB optical counterparts. Contrary to the most of existing experiments, "π of the Sky" does not rely on satellite GRB triggers only, but independently detects optical flashes in the sky and later seeks an association with a satellite alert. This approach requires an efficient self-triggering system, capable of reducing the rate of flash candidates to an amount suitable for a human-eye analysis. This paper covers main aspects of our flash recognition algorithms, briefly describing main false event types that are encountered as well as cuts designed to eliminate them. Physical results based on the data gathered by the "π of the Sky" apparatus prototype during it's first year of operation are presented.
"Pi of the Sky" is a detector designed for search for optical flashes of the cosmic origin in the sky. Its primary goal is to look for optical afterglows associated with the gamma ray bursts (GRB), but it is capable to detect also other optical transients of extragalactic origin. The apparatus consists of two arrays of 16 cameras each, which allow for simultaneous observation of the whole sky. Due to on-line data analysis in the real time, it has self-triggering capability and can react to external triggers with negative time delay. The prototype with two cameras has been installed at Las Campanas (Chile) and is operational from July 2004. General idea of experiment, the apparatus and its performance will be presented. Physical results will be reviewed and perspectives for the future will be outlined.
Perhaps the most powerful cosmic processes ever observed are gamma ray bursts (GRB). So far, phenomena responsible for GRB have not been unambiguously identified. In the present paper we propose an approach completely different from the classical one. It employs experimental techniques developed for particle physics. Presented project is pioneering research in the unexplored so far domain of cosmic phenomena on the time scale of seconds. Both the rate of signal in question and the rate of unexpected background are not known. Therefore we decided to divide the project into two phases: phase I -- two CCD cameras, phase II - a system of cameras covering all sky. The phase I is well defined whereas detailed realization of phase II will depend strongly on results and experience gained in phase I.
We present optimized performance of algorithms developed for detection of point like, visible light bursts in the sky. The algorithms based on analysis of series of consequtive images and detecting local differences between them were tested on simulated data obtained by inserting images of stars of different magnitudes at random positions. We discuss the choice of parameters which results in the maximal detection efficiency and simultaneously keeps the number of false detections as low as possible.