ROTSE-III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of γ-ray burst (GRB) afterglows as close as possible to the start of γ-ray emission. ROTSE-III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events

Aharonian, F.

Akerlof, C. W.

Ashley, M. C. B.

Barthelmy, S.

Gehrels, N.

Gogus, Ersin

Guver, T.

Göğüş, Ersin

Güver, T.

Horns, D.

Kiziloglu, U.

Kızıloğlu, Ü.

Krimm, H. A.

McKay, T. A.

Ozel, M.

Phillips, A.

Quimby, R. M.

Rowell, G.

Rujopakarn, W.

Rykoff, E. S.

Schaefer, B. E.

Smith, D. A.

Swan, H. F.

Vestrand, W. T.

Wheeler, J. C.

Wren, J.

Yost, S. A.

Yuan, F.

Özel, M.

English

Sabanci University Research Database

Astron. Nachr. / AN 327, No. 8, 803 – 805 (2006) / DOI 10.1002/asna.200610683Status of the ROTSE-III telescope networkS.A. Yost1,, F. Aharonian2, C.W. Akerlof1, M.C.B. Ashley3, S. Barthelmy4, N. Gehrels4, E. Go¨g˘u¨s¸5,T. Gu¨ver5, D. Horns6, ¨U. Kızılogˇlu7, H.A. Krimm4, T.A. McKay1, M. ¨Ozel8, A. Phillips3, R.M. Quimby9,G. Rowell6, W. Rujopakarn1, E.S. Rykoff1, B.E. Schaefer10, D.A. Smith11, H.F. Swan1, W.T. Vestrand12,J.C. Wheeler9, J. Wren12, and F. Yuan11 University of Michigan, 2477 Randall Laboratory, 450 Church St., Ann Arbor, MI, 481042 Max-Planck-Institut fu¨r Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany3 School of Physics, University of New South Wales, Sydney, NSW 2052, Australia4 NASA Goddard, Greenbelt, MD 207715 Sabancı University, Orhanlı-Tuzla 34956 Istanbul, Turkey6 Max-Planck-Institut fu¨r Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany7 Middle East Technical University, 06531 Ankara, Turkey8 C¸anakkale Onsekiz Mart ¨Universitesi, Terziogˇlu 17020, C¸anakkale, Turkey9 Department of Astronomy, University of Texas, Austin, TX 7871210 Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 7080311 Guilford College, Greensboro, NC 2741012 Los Alamos National Laboratory, NIS-2 MS D436, Los Alamos, NM 87545Received 2006 Apr 10, accepted 2006 May 17Published online 2006 Aug 22Key words gamma rays: bursts – instrumentation: photometric – instrumentation: photometry – telescopesROTSE-III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observationsof γ-ray burst (GRB) afterglows as close as possible to the start of γ-ray emission. ROTSE-III is fulfilling its potential forGRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events.c© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim1 IntroductionROTSE-III is the successor to the ROTSE-I instrument ofthe 1990s, designed to hunt for long-wavelength counter-parts to the brief, intense flashes of γ-rays (GRBs) (for anoverview of GRB properties and models see a recent re-view by Piran 2005). GRB models predicted “afterglow”light at longer wavelengths, surviving to later times thanthe energetic events themselves (e.g., Rees & Meszaros1992). The Compton Gamma-Ray Observer (1991–2000,see http://cossc.gsfc.nasa.gov) provided prompt but highlyuncertain GRB positions, several degrees across. This drovethe ROTSE-I design to a wide field of view (FOV) system,16 degrees across (see Akerlof et al. 2003).While a wide FOV required design tradeoffs in the in-strument sensitivity, it had advantages, including the abilityto observe a large fraction of the sky every night, leading tothe Northern Sky Variability Survey (Wozniak et al. 2004).The survey is still being mined for data. This includes stu-dent projects studying bright variable stars (e.g., Cepheids,RR Lyrae stars associated with high velocity clouds), aswell as the production of a catalog of contact binary stars(Gettel et al. 2005), and studies to correlate X-ray emissionwith contact binaries (Geske et al. 2005). Corresponding author: sayost@umich.eduGiven ROTSE-I’s success, while ROTSE-III was de-signed in response to improvements in GRB positions, itkept a wide FOV (1.85 degrees) to continue searches foruntriggered optical transients. The four ROTSE-III instru-ments are at Siding Springs Observatory, Australia, McDon-ald Observatory, Texas, the H.E.S.S. site near Mt. Gams-berg, Namibia, and Bakirlitepe, Turkey. With their globaldistribution, it is always night at at least one ROTSE-IIIsite, leading to the motto that “the sun never rises on theROTSE empire”. Each telescope has a 0.45 m aperture andoperates unfiltered (with a peak sensitivity at red wave-lengths), reaching a limiting magnitude of 17 in a 5-secondexposure under good conditions. The custom mounts per-mit horizon-to-horizon slew and settling within 6–8 sec-onds. The clamshell enclosures are automated, with weatherstations to indicate dangerous conditions. It is neverthelessimportant to have people on site regularly, and all collabo-rations were chosen to place ROTSE telescopes at observa-tories. For further details, see Akerlof et al. (2003).2 ROTSE-III operationROTSE-III’s rapid responses are designed to observe a largefraction of GRBs at early times and constrain, with thegoal of understanding, the envelope of early behaviours.c© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim804 S.A. Yost et al.: Status of the ROTSE-III telescope networkThe Gamma-Ray Coordinates Network (GCN) (Barthelmy1998) provides triggers and disseminates information fromGRB observers, who may identify optical or radio counter-parts. This drives other observations, such as spectroscopy,and acts as an informal network for one type of astronomi-cal observation.The ROTSE sites are quite remote, thus all communi-cation with the telescopes is text-based and low-bandwidth.Large image files remain at the telescope until the data drivefills up and is swapped out. The images are reduced at thetelescopes, with calibrated object lists and JPEG imagessent to the University of Michigan for each exposure.ROTSE’s scheduler is dynamic, with a target file forthe night. This includes a sky patrol and particular fieldsto monitor. Desired cadence and maximum number of ex-posures can be specified. After each exposure, the sched-uler rechecks all target observabilities and priorities (includ-ing cadence) to determine the next target. ROTSE presentlycannot schedule a timed observation.All ROTSE operations are interruptible given a GRBalert that the control computer determines is above the min-imum observable elevation. It will abort, dumping any pre-vious exposure and slewing to new coordinates within 6–8 seconds. It then takes a preset series of exposures (105-second, 10 20-second, and then 3 hours of 60-second im-ages). An old alert is overridden by a newer one.ROTSE’s operation is visible to the public on the Webat: http://www.rotse.net/The /operation/ subpage shows the present status andallows access to the JPEGs or GIFs of images taken bythe telescopes. There is a private area where collaboratorscan access webpages for responses to burst alerts. Thesepages show images of the GRB position, flagging any newand/or variable objects in the field. The telescopes gener-ate match structures of objects in the images taken duringan alert to determine such afterglow candidates, and to pro-duce lightcurves from them. There is a further page compar-ing the error box to the DSS1 archive image. These are usedby ROTSE collaborators to identify optical counterparts toGRBs.3 ROTSE ResultsWhen not observing GRB positions, ROTSE-III performsits sky patrol and targeted observations. The sky patrolsearches for untriggered GRB afterglows, using its auto-mated data analysis pipeline to find candidates. The pipelinecompares object lists for the night’s patrol to the archivalsky patrol history, and flags likely new objects that passquality checks (see Rykoff et al. 2005a). The candidatesmust be checked by hand to determine whether they areasteroids, or non-GRB transients such as cataclysmic vari-ables with a quiescent state below ROTSE’s sensitivity. The1 http://archive.stsci.edu/cgi-bin/dss formpatrol has not to date found any untriggered GRB after-glows. It has yielded supernovae discoveries in dwarf galax-ies (SN2005cg, Rykoff et al. 2005b; SN2005ch, Rykoff2005).The targeted observations include a supernova search,yielding dwarf novae (Quimby et al. 2005b, 2005c), andseveral supernovae (e.g., SN2004gk, Quimby et al. 2004;SN2005cr, Quimby et al. 2005a). The global array has beenused to observe a microquasar in outburst (Smith 2005), andcomet 9P/Tempel for the Deep Impact project (Meech et al.2005)ROTSE-III is now fulfilling its promise, with typicalresponses to ordinary GRBs sometimes resulting in opti-cal imaging during the prompt GRB γ-ray emission phase.These are possible when a trigger is promptly disseminatedfor a GRB of duration ∼ 30 s or greater, with 3 ROTSE-III cases to date: GRB 050401, GRB 051109A, and GRB051111.GRB 050401 further demonstrated the diversity inprompt GRB optical behaviour. There were two previousdetections: the ROTSE-I observation of 990123 (an extraor-dinarily bright GRB), with a prompt optical excess uncor-related with the GRB (Akerlof et al. 1999), and the RAP-TOR detections or GRB 041219 (an extraordinarily longGRB), with prompt optical light correlated with the GRBlightcurve (Vestrand et al. 2005). GRB 050401 showed nooptical excess relative to the later afterglow decay (Rykoff etal. 2005c). The more recent events are still being analyzed.3.1 Future networking prospectsROTSE is focused upon its primary (GRB) science goalsfor the duration of the Swift mission, which is expected tobe for the next three years. Improvements in its network willbe dedicated to accomplishing these goals. These could in-clude automating some of its counterpart announcements tothe GCN in the most definite cases, and networking withlocal collaborators at the ROTSE sites. An example of thelatter would be sending an automated notice to the H.E.S.S.operators when the local ROTSE has detected a counterpart.4 ConclusionThe ROTSE-III network is responding well to its goals forGRB optical studies, pushing back optical responses to theγ-ray emission. It performs scientifically interesting obser-vations when not on GRB alert, with the network shared bythe collaborators directly logging into the telescope com-puters and adding to the object queue list.Acknowledgements. The ROTSE project is made possible bygrants from NASA, NSF, and the Australian Research Coun-cil, and through participation and support from the Universityof Michigan, University of Texas, Max-Planck-Institut fur Kern-physik, Los Alamos National Laboratory, and the University ofNew South Wales.c© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.an-journal.orgAstron. Nachr. / AN (2006) 805The Digitized Sky Surveys were produced at the STScI (U.S.Government grant NAG W-2166). The surveys’ images are basedon photographic data from Palomar’s Oschin Schmidt Telescopeand the UK Schmidt Telescope, digitized with the permission ofthese institutions.ReferencesAkerlof, C., Balsano, R., Barthelmy, S., et al.: 1999, Nature 398,400Akerlof, C.W., Kehoe, R.L., McKay, T.A., et al.: 2003, PASP 115,132Barthelmy, S.D., Butterworth, P.S., Cline, T.L., et al.: 1998, in:C.A. Meegan, R.D. Preece, T.M. Koshut (eds.), Gamma-RayBursts: 4th Huntsville Symposium, AIP Conf. Proc. 428, 99Geske, M.T., Gettel, S.J., McKay, T.A.: 2005, AJ, accepted (astro-ph/0509820)Gettel, S.J., Geske, M.T., McKay, T.A.: 2005, AJ, accepted (astro-ph/0509819)Meech, K.J., Ageorges, N., A’Hearn, M.F.: 2005, Science 310, 265Piran, T.: 2005, RMP 76, 1143Quimby, R., Gerardy, C., Hoeflich, P. et al.: 2004, IAUC 8446Quimby, R., Mondol, P., Castro, F.: 2005a, IAUC 8552Quimby, R., Sellers, M., Mondol, P. et al.: 2005b, Astronomer’sTelegramm 658Quimby, R., Sellers, M., Mondol, P. et al.: 2005c, Astronomer’sTelegram 481Rees, M.J., Meszaros, P.: 1992, MNRAS 258, 41Rykoff, E.S.: 2005, IAUC 8539Rykoff, E.S., Aharonian, F., Akerlof, C.W. et al.: 2005a, ApJ 631,1032Rykoff, E.S., Quimby, R., Shetrone, M., Rostopchin, S.: 2005b,IAUC 8537Rykoff, E.S., Yost, S.A., Krimm, H.A., et al.: 2005c, ApJ 631,L121Smith, D.A.: 2005, Astronomer’s Telegramm 486Vestrand, W.T., Wozniak, P.R., Wren, J.A., et al.: 2005, Nature435, 178Wozniak, P.R., Vestrand, W.T., Akerlof, C.W. et al.: 2004, AJ 127,2436www.an-journal.org c© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Status of the ROTSE-III telescope network

c 2006 WILEY-VCH Verlag GmbH&Co.KGaA, WeinheimAbstractROTSE‐III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of γ ‐ray burst (GRB) afterglows as close as possible to the start of γ ‐ray emission. ROTSE‐III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events. (© 2006 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)S.A. Yost, F. Aharonian, C.W. Akerlof, M.C.B. Ashley, S. Barthelmy, N. Gehrels, E. Gögüs, T. Güver, D. Horns, Ü. Kızıloglu, H.A.Krimm, T.A.McKay,M. Özel, A. Phillips, R.M. Quimby, G. Rowell,W. Rujopakarn, E.S. Rykoff, B.E. Schaefer, D.A. Smith, H.F. Swan,W.T.Vestrand, J.C. Wheeler, J.Wren, and F. Yua

Yost, S.

Akerlof, C.

Ashley, M.

Gogus, E.

Krimm, H.

McKay, T.

Quimby, R.

Rykoff, E.

Hage, B.

Smith, D.

et al.

Adelaide Research & Scholarship

Astronomische Nachrichten

ROTSE-III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of gamma-ray burst (GRB) afterglows as close as possible to the start of gamma-ray emission. ROTSE-III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

İstanbul Üniversitesi Açık Erişim Sistemi

Akerlof

Barthelmy

Geske

Gettel

Meech

Piran

Quimby

Rees

Rykoff

Smith

Vestrand

Wozniak

Crossref

ROTSE-III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of γ-ray burst (GRB) afterglows as close as possible to the start of γ-ray emission. ROTSE-III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA

Ashley, M. C.B.

Gögüs, E.

Kiziloǧlu, Ü

LSU Scholarly Repository (Louisiana State Univ.)

http://research.sabanciuniv.edu/159/1/3011800000486.pdf

Status of the ROTSE-III telescope network

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Sabanci University Research Database

Adelaide Research & Scholarship

İstanbul Üniversitesi Açık Erişim Sistemi

Crossref

LSU Scholarly Repository (Louisiana State Univ.)