| BZs >gnuplot.ps Acta Polytechnica Vol. 51 No. 2/2011 Robotic Astronomy and the BOOTES Network of Robotic Telescopes A. J. Castro-Tirado on behalf of the BOOTES Collaboration Abstract The Burst Observer and Optical Transient Exploring System (BOOTES), started in 1998 as a Spanish-Czech collabo- ration project, devoted to a study of optical emissions from gamma ray bursts (GRBs) that occur in the Universe. The first two BOOTES stations were located in Spain, and included medium size robotic telescopes with CCD cameras at the Cassegrain focus as well as all-sky cameras, with the two stations located 240 km apart. The first observing station (BOOTES-1) is located at ESAt (INTA-CEDEA) in Mazagón (Huelva) and the first light was obtained in July 1998. The second observing station (BOOTES-2) is located at LaMayora (CSIC) inMálaga and has been operating fully since July 2001. In 2009 BOOTES expanded abroad, with the third station (BOOTES-3) being installed in Blenheim (South Island, New Zealand) as result of a collaboration project with several institutions from the southern hemisphere. The fourth station (BOOTES-4) is on its way, to be deployed in 2011. Keywords: Robotic Astronomy, Stellar Astrophysics, variable stars. 1 Introduction Robotic astronomical observatories were first devel- oped in the 1960s by astronomers after electrome- chanical interfaces to computers became common at observatories. Nowadays there more than 100 spread worldwide (Fig. 1). See [1] for an overview. Here are some important definitions in the field of Robotic As- tronomical Observatories1: Automated scheduled telescope (Robot): A tele- scope that performs pre-programmed observa- tions without immediate help of a remote ob- server (e.g. avoiding an astronomer moving the mount by hand). Remotely operated (remote) telescope Robot: A telescope system that performs remote observa- tions following the request of an observer. Autonomous Robot (observatory): A telescope that performs various remote observations and is able to adapt itself to changes during task ex- ecution without any kind of human assistance (e.g. weather monitoring; the system must not endanger humans!). Fig. 1: Distribution of robotic telescopes in the world 1following the consensus reached after one hour of discussion amongst the 80 participants who attended the “Workshop in Robotic Autonomous Observatories”, held in Málaga (Spain) on May 18–21, 2009. 16 Acta Polytechnica Vol. 51 No. 2/2011 BOOTES (the Burst Observer and Optical Tran- sient Exploring System, BOOTES), started in 1998 as a Spanish-Czech collaboration project [2] devoted to the study of optical emissions from gamma ray bursts (GRBs) that occur in the Universe. Nowadays it consists of 4 stations, three of them hosting 60 cm fast slewing robotic telescopes aimed at contributing significantly to various scientific fields. 2 The BOOTES network of robotic telescopes 2.1 BOOTES-1 The first robotic astronomical observatory in Spain was placed in the INTA’s Estación de Sondeos At- mosféricos (ESAt) at the Centro de Experimentación de el Arenosillo in Mazagón (Moguer, Huelva). It has an extraordinary sky close to the Atlantic ocean with more than 300 clear nights a year, limited to the East by the Doñana National Park. For the first two years after 1998, BOOTES pro- vided rapid follow-up observations for more than 40 GRBs detected by Batse aboard the CGRO until it was turned off in May 2000. It consisted of a 0.2 m Schmidt-Cassegrain reflector telescope (at f/10) with a CCD camera at the Cassegrain focus, providing a 40′ ×30′ FOV and a couple of CCD cameras attached to the main optical tube providing a 16◦ × 11◦ FOV. Since 2001, with the new location of the exist- ing enclosure 100 m away from the original site, and with the addition of the second enclosure (dubbed BOOTES-1B to distinguish it from BOOTES-1A, the old one), various setups have been accomplished, the current one, as of summer 2010, being as follows: • A 0.3 m diameter Schmidt-Cassegrain reflector telescope (f/10) mounted on a Paramount mount with a narrow field CCD (1 528×1 024 pix) cam- era attached to the main optical tube: 30′ × 20′ FOV. • A wide field CCD camera (4 096 × 4 096 pix) at- tached to a 400 mm f/2.8 lens providing a 5◦×5◦ FOV. • An all-sky CCD camera (CASANDRA-1): 180◦ FOV. See [3]. 2.2 BOOTES-2 The BOOTES-2 robotic astronomical station was officially opened on 7 Nov 2001 and it is located at CSIC’s Estación Experimental de La Mayora in Algarrobo Costa (Málaga). It is limited to the South by the Mediterranean sea and to the North by the Tejeda-Almijara Mountains Nature Park with Maroma peak (2.068 m. a.s.l.). Unlike the two domes of the BOOTES-1 station 200 km away, its dome is controlled by a hydraulic opening system controlled automatically according to the existing weather conditions. BOOTES-2 at first hosted a 0.3-m Schmidt- Cassegrain reflector telescope (f/10), which was re- placed in 2009 by a 0.6 m Ritchey-Chrétien fast slewing telescope. This was officially opened on 27 Nov 2009. Thus, the new configuration in the BOOTES-2 station has the following instruments: • The TELMA (TELescopio MAlaga) Ritchey- Chrétien reflector telescope (0.6 m, f/8, see Fig. 2) with an EMCCD narrow field camera with variou filters (clear, Johnson R., Sloan g’r’i’ and UKIRT Z and Y-band filters) providing a 10′ × 10′ FOV. • An all-sky camera (CASANDRA-2) providing a 180◦ FOV. Fig. 2: The TELMA 0.6 m telescope at the BOOTES-2 astronomical station 17 Acta Polytechnica Vol. 51 No. 2/2011 2.3 BOOTES-3 The BOOTES-3 robotic astronomical station was the first installation of the BOOTES Network outside Spain. It was officially opened on 27 Feb 2009. It is located at Vintage Lane, Blenheim (New Zealand), one of the best places for observing the night sky in the southern hemisphere. Similarly to the BOOTES-1 station, its dome is controlled by electric motors, which are controlled automatically according to the existing weather con- ditions. BOOTES-3 hosts a 0.6 m Ritchey-Chrétien fast slewing telescope, which is dubbed the YA (Yock- Allen) Telescope, in honour of Prof. Phil A. Yock and Eng. Bill H. Allen, in recognition of their en- couraging support. The BOOTES-3 station has the following instru- ments: • The YA (Yock-Allen) Ritchey-Chrétien reflec- tor telescope (0.6 m, f/8) with an EMCCD nar- row field camera (clear, Johnson B, Sloan g’r’i’ and UKIRT Z and Y-band filters) providing a 10′ × 10′ FOV. • The All-sky camera (CASANDRA-3) providing a 180◦ FOV. See Fig. 3. Fig. 3: The YA 0.6 m telescope in Blenheim (New Zealand) depicted against the centre of the Milky Way in an image recorded by CASANDRA-3. The fourth sta- tion (BOOTES-4) will be deployed in 2011 3 BOOTES Scientific Goals The BOOTES scientific goals are multifold, and are detailed below. 3.1 Observation of the GRB error box simultaneously to GRB occurrence Although the first detected optical counteparts were not brighter than 19th mag a few hours after the burst, there have been several GRBs for which the optical transient emission has been detected simulta- neously to the gamma-ray event, with magnitudes in the range 5–10. The faint transient emission that was detected a few hours after the event is a consequence of the expanding remnant that the GRB leaves be- hind it. This provides information about the sur- rounding medium, but not about the central engine itself. The fast slewing 0.6 m BOOTES telescopes are producing important results in this field [4]. See Fig. 4. Fig. 4: Optical afterglow lightcurves of some GRBs de- tected by BOOTES and rapidly imaged (within 1 min) after detection by scientific satellites In this respect, coordinated observations of GRBs in various filters is most essential, as only a few GRBs have exceptionally bright optical counterparts. Ob- servers are of course interested in collecting as much data as possible, with the best possible resolution. One of the goals of the observers is to take spectra of the transient while it is bright enough, so that the transient redshift and other properties can be mea- sured. Using data taken with different filters, one can construct the spectral energy distribution of the event and estimate the object redshift. Networked RTS telescopes (like BOOTES) at favourable loca- tions can simultaneously observe objects in different filters. The idea is to enable these telescopes to com- municate with each other and provide simultaneous images in two or more filters. This system should balance the need to take some data with the possi- bility of taking data in multiple filters. This can be achieved by sending commands to take images in dif- ferent filters when the system knows that it has at 18 Acta Polytechnica Vol. 51 No. 2/2011 least some images of the event. This kind of deci- sion is best made in a single component-observation coordinator. The coordinator will be connected to two or more telescope nodes. It will collect information from GCN and from all connected nodes. A node will report to the coordinator when it receives a GCN notice, when it starts its observation and as soon as it gets an im- age passed through the astrometry and it contains the whole error area of the GRB. It will also report when the transient detection software identifies a pos- sible optical transient. When the coordinator receives messages about correct observation by two telescopes, it will decide which filter should be followed at which telescope, and will send out commands to carry out further observations. The coordinator will periodically re- visit its observing policy, and send out commands to change filter accordingly. As the system is “running against the clock” for the first few minutes after the GRB event, trying to capture the most interesting part of the transient light curve, it cannot wait for completion of the tran- sient source analysis. In the case of two telescopes, the coordinator will command different filters as soon as it knows that both telescopes have acquired the relevant field. The current astrometry routines take a few seconds to run, and it is expected that obser- vations with different filters can already have started within this time-frame. 3.2 The detection of optical flashes (OTs) of cosmic origin These events could be unrelated to GRBs and could constitute a new type of different astrophysical phe- nomenon (perhaps associated to QSOs/AGNs). If some of them are related to GRBs, the most recent GRB models predict that there should be a large number of bursting sources in which only transient X-ray/optical emission should be observed, but no gamma-ray emission. The latter would be confined in a jet-like structure and pointing towards us only in a few cases. 3.3 Monitoring a range of astronomical objects These are astrophysical objects ranging from galac- tic sources such as comets (Fig. 5), cataclysmic vari- ables, recurrent novae, compact X-ray binaries to ex- tragalactic sources such as distant supernovae and bright active galactic nuclei. In the later case, there are hints that sudden and rapid flares occurs, though of smaller amplitude. 4 Networking One step further from GRB observation is coordi- nated observation of targets — e.g. observation of variable stars for more than 12 hours (i.e. taking ad- vantage of telescopes in different time zones). The observer should contact the coordinator, and either add a new target, or select a predefined target which he/she wants to observe. The coordinator should list for the observer telescopes which can observe the tar- get of his/her choice, and propose filters and exposure times. The observer can then decide which telescopes are to be used, and the coordinator will send observation requests to the nodes, and will collect back infor- mation about observation progress. Currently only observer-selected coordinated observations are envi- sioned. When that works properly, the observer can be replaced by network scheduling software. Fig. 5: The evolution of comet 17P/Holmes following the October 2007 outburst, imaged on a nightly basis with the BOO-2 telescope in Spain. The FOV is 10′ ×10′ in all frames 19 Acta Polytechnica Vol. 51 No. 2/2011 5 Conclusions Robotic Telescopes are opening a new field in As- trophysics in terms of optimizing the observing time, with some of them able to provide pre-reduced data. The big advantage is that they can be placed in re- mote locations where human life conditions will be hostile (Antartica now, the Moon in the near future). BOOTES (http://www.iaa.es/bootes) is an example of such a telescope system. Technological develop- ment in various fields is much involved, and some robotic astronomical observatories are moving to- wards intelligent robotic astronomical observatories. One immediate application of small/medium size robotic telescopes is in the study of GRBs, which can be considered the most energetic phenomenon in the Universe. In combination with space missions like Integral, Swift andFermi, they are used for trigger- ing larger size instruments in order to perform more detailed studies of host galaxies and intervening ma- terial on the line of sight. These robotic astronomy observatories will provide a unique opportunity to unveil the high-z Universe in years to come. Acknowledgement We are very grateful for the support given by the Space Sciences and Electronics Technologies De- partment at INTA, through project IGE 4900506, to the special action DIF2001-4256-E supported by the Technology and Science Ministry (MCyT), and also to the Spanish research projects AYA2001-1708, AYA2002-0802, AYA2004-01515, AYA2007-6377 and AYA 2009-C14000-C03-01 granted by the Spanish Ministry of Science and Education and Innovation and Technology (with FEDER funding). The de- velopment of the BOOTES Network has been also possible thanks to the support of Junta de An- dalućıa through Excellence Research Projects P06- FQM-2192 and P07-TIC-3094. The Czech contri- bution is supported by the Ministry of Education and Youth of the Czech Republic, Projects ES02 and ES36. References [1] Castro-Tirado, A. J.: Robotic Autonomous Ob- servatories: A Historical Perspective, in Ad- vances in Astronomy, issue on Robotic Astron- omy, (edited by A.J. Castro-Tirado et al.), article id. 570489, 2010. (http://www.hindawi.com/ journals/aa/2010/570489.html) [2] Castro-Tirado, A. J. et al.: The Burst Ob- server and Optical Transient Exploring System (BOOTES), A&AS 138, 583, 1999. [3] Castro-Tirado, A. J. et al.: A very sensitive all-sky CCD camera for continuous recording of the night sky, in Advanced Software and Con- trol for Astronomy II. Edited by Bridger, Alan; Radziwill, Nicole M. Proceedings of the SPIE, Vol. 7019, 2008, pp. 70191V–70191V–9. [4] Jeĺınek, M. et al.: Four Years of Realtime GRB Follow-up by BOOTES-1B (2005–2008), in Ad- vances in Astronomy, special issue on Robotic Astronomy (edited by A. J. Castro-Tirado et al.), 2010, arXiv1001.2147. Alberto J. Castro-Tirado E-mail: ajct@iaa.es IAA-CSIC, Glorieta de la Astronomı́a s/n E-18008 Granada, Spain 20