The Zadko Telescope: the Australian Node of a Global Network of Fully Robotic Follow-up Telescopes

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1 The Zadko Telescope: the Australian Node of a Global Network of Fully Robotic Follow-up Telescopes David Coward, Myrtille Laas-Bourez, Michael Todd To cite this version: David Coward, Myrtille Laas-Bourez, Michael Todd. The Zadko Telescope: the Australian Node of a Global Network of Fully Robotic Follow-up Telescopes. Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE). Workshop Gaia Fun-SSO : follow-up network for the Solar System Objects, Nov 2010, France. 1 vol., 149 p., <hal > HAL Id: hal Submitted on 22 Jun 2011 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2 The Zadko Telescope: the Australian Node of a Global Network of Fully Robotic Follow-up Telescopes Coward, D 1, Laas-Bourez, M 1, Todd, M. 2 1 School of Physics, University of Western Australia, Crawley WA 6009, Australia 2 Department of Imaging and Applied Physics, Bldg 301, Curtin University of Technology Introduction The Zadko Telescope (ZT) see Coward et al. (2010), is a purpose built 1 meter, robotic telescope, located about 80 km north of Perth, Western Australia. It was designed to monitor a previously unchartered region of the transient sky. The Zadko Telescope is the only meter class telescope capable of deep imaging between the east coast of Australia and South Africa at similar latitude. The Zadko Telescope, operated by UWA, is the Australian node of the TAROT robotic telescope network. As the main southern hemisphere node of the TAROT network, it enables much larger coverage of the sky for participation in frontier optical transient science projects. The so called transient Universe' consists of astronomical phenomena that vary rapidly in brightness on a time-scale of seconds to days. Transient searches with optical telescopes are designed to respond to Alerts from other detectors (which may only have relatively poor localization on the sky) and also to search for new transient sources. Transient search telescopes need to respond rapidly (to catch events before they fade away), to be very sensitive and be capable of tracking fast moving faint sources. Fig. 1 The 1-m f/4 Cassegrain Zadko Telescope is fully robotic and employs the same control software as the TAROT telescopes (located in France and Chile). An automated image processing pipeline produces calibrated FITS images to external users via a web-based interface. 59

3 Gaia-Fun-Sso Workshop Proceedings 1. Zadko Telescope Science In addition to linking the ZT to satellite detectors, the ZT can respond robotically to Alerts sent from the Laser Interferometric Gravitational Observatory, and in the future the Square Kilometer Array radio telescope. This type of science has been termed `multi-messenger' astronomy. It utilizes different parts of the electromagnetic spectrum, in near real-time, to provide a clearer understanding of exotic phenomena that have previously eluded a complete description from observations restricted to a narrow part of the electromagnetic spectrum. Other active science programs include the search for rare inner-earth asteroids, Mars and Earth Trojan asteroids, main-belt asteroids and potentially hazardous asteroids. Projects that are either just commencing or in planning stage include: Alert follow-up of targets from GAIA satellite (exoplanets, NEOs, supernova, GRBs, flare stars etc.), Supernova search in nearby galaxies, Exoplanet follow-up and a survey of star forming regions in nearby galaxies. The ZT demonstrated its science capability during a pilot program in 2009 (Coward et al. 2010) Over a period of several months, 12 new asteroids were discovered, corresponding to a discovery rate of asteroids per square degree per hour of observing time. From 2008 Sept to 2009 Sept, 5 gamma-ray burst (GRB) afterglows were imaged with photometric magnitude estimates with the ZT. Two of them, GRBs and , with respective redshifts of 4.3 and 4.1, are among the most distant optical transients imaged by an Australian telescope. 2. Zadko Telescope Robotic Imaging Capabilities The Zadko Telescope is a fully robotic facility that is capable of autonomous operation and remote access to image data. Table 1 below shows the core-features of the telescope hardware and imager. GPS Primary Mirror Mount Focal length FOV Max slew speed CCD Camera Sensitivity at 3 sigma Average seeing Table 1 Zadko Telescope key features deg S deg E & Alt 50m 1 m Equatorial Fork 4.04 m 23.6 arcmin squared 3 deg per second Andor 436 Marconi back illuminated chip m=21 with 180s 2 4 arcsec (highly variable) To coordinate the complex tasks of telescope scheduling, imaging and archiving, a centralized cluster of database servers called CADOR (Coordination et Analyse des Données des Observatoires Robotiques) see Bourez-Laas et al., (2008), Klotz et al., (2008), located in France, forms the core of the network. CADOR is undergoing upgrades to incorporate the ZT and manage scheduling and data from all three telescopes in the network. Presently, the ZT is controlled by a local suite of independently running programs, ROS (Robotic Observatory Software) developed by our TAROT partners. The main functions of ROS are listed in Table 2 and the structure of the pipeline is shown in fig. 2: 60

4 Coward D.M. et ali Fig. 2 A flow diagram of the core procedures performed by the Robotic Observatory control Software (ROS) on the Zadko Telescope. The ZT operates in Alert Mode after receipt of a high priority Alert from an external facility. In this mode, the scheduling is dynamically changed to accommodate the higher priority imaging tasks. Currently, the ZT receives Alerts from the Gamma Ray Burst Coordinated Network and the Laser Interferometric Gravitational Observatory. In the near future, it will also receive triggers from neutrino detectors and radio telescopes. When not in Alert mode, the scheduler selects those imaging tasks that are the next highest priority. After acquiring a raw image from the telescope, which is stored on local disk, a standard set of processing operations is performed on a copy of each image. Calibration frame corrections (bias, dark, and flats) are applied. The final 8-Mb calibrated images are made available for download via a webpage to authorized users, who can then perform their own image processing tasks. 3. Zadko Telescope and GAIA follow-up The 1-m ZT has the potential to contribute to the core goals of the GAIA follow-up network. Firstly, and most importantly, it is fully robotic and uses a control system and automated image pipe-line that has been successfully employed for many years for GRB follow-up on the TAROT network. It allows for receiving automated alerts using computer socket connection, and automatic image processing for science by external users via web-page download. In the future, we plan to implement the VoEvent protocol, which may become the standard for communicating alerts between observatories. In addition to GAIA science validation and follow-up, the ZT could participate in the GBOT (Ground Based Optical Tracking) program. GBOT will use regular scheduled optical observations of the satellite position to optimize the astrometric accuracy of GAIA observations. Such a program can be implemented on ZT as part of ROS. In Feb-Mar 2011, the ZT is participating in imaging tests of the Planck satellite and minor planets to determine the suitability for GBOT. 61

5 Gaia-Fun-Sso Workshop Proceedings Conclusion ZT has been operating as a fully robotic facility from early It core science objectives are the study of gamma ray burst afterglows and optical transients using automated alerts from other facilities and satellites. The geographic location of the ZT is important for the follow-up of a host of transients, from space-debris to cosmological gamma ray bursts. The automated control software can be adapted to respond to different types of alerts, including ones from the Swift Satellite and gravitational-wave observatories. There is excellent potential for the facility to play an important role in the follow-up of GAIA alerts, both for science validation and science follow-up of Gaia alerts. Furthermore, the ZT can potentially be used for the automated optical astrometric monitoring of GAIA for the GBOT program. In 2011, the ZT will be tested to determine its suitability for GBOT participation. In late 2011 and early 2012, the infrastructure for the facility will be upgraded to enable the above participation in GAIA related science. References Bourez-Laas M., et al., 2008, CADOR and TAROT: a virtual observatory, Proc. SPIE, 7019, Coward et al., 2010, The Zadko Telescope: A southern hemisphere telescope for optical transient searches, multi-messenger astronomy and education, Publications of the Astronomical Society of Australia, 27(3), 331 Klotz A., et al., 2008, Robotic Observations of the Sky with TAROT: , PASP, 120,