PoS(HEASA2015)007 http://pos.sissa.it/ ∗ [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] Copyright owned by the author(s) under the terms of the Creative Commons c Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). H.J. van Heerden University of the Free State, NelsonE-mail: Mandela Drive, , 9301, South Africa A. Martin-Carrillo School of Physics, University College Dublin,E-mail: Belfield, Dublin 4, Ireland L. Klindt University of the Free State, NelsonE-mail: Mandela Drive, Bloemfontein, 9301, South Africa L. Hanlon School of Physics, University College Dublin,E-mail: Belfield, Dublin 4, Ireland D. Murphy School of Physics, University College Dublin,E-mail: Belfield, Dublin 4, Ireland P.J. Meintjes University of the Free State, NelsonE-mail: Mandela Drive, Bloemfontein, 9301, South Africa B. van Soelen University of the Free State, NelsonE-mail: Mandela Drive, Bloemfontein, 9301, South Africa I.P. van der Westhuizen University of the Free State, NelsonE-mail: Mandela Drive, Bloemfontein, 9301, South Africa Optical observations of Very High Energyfrom Sources the Boyden PoS(HEASA2015)007 Speaker. Multi-wavelength observations of very highemission energy processes at sources work can in these place systemsthe better as well spectral constraints as energy on the location distributions the of of thisnents emission. Active that For Galactic radiate example, at Nuclei lower (AGN) (radio displayemission to is two UV/X-ray) the result and distinct of higher compo- a (X-ray simple one todifferent zone gamma-ray) components. model, energies. correlations Such should If correlations be the observable are, between however, these lation, more but complicated show than variations a based simple on linearundertake re- colour multi-wavelength and observations spectral of distribution. known Itwavelength TeV is gamma-ray correlations. therefore sources important We to are to establish beginningTeV multi- a AGN/Blazars, from long the term Boyden optical Observatory, using, monitoringscopes. in campaign particular, the of Additional Watcher known Robotic observations Tele- arethe capable 20-inch with telescope the recently Boyden obtainedpresent 1.5-m from an the telescope overview of South as the African new well monitoring Astronomical asoverview campaign Observatory. of which with the is We Boyden being Observatory, undertaken and as the well status as of a the brief available telescopes. ∗ Copyright owned by the author(s) under the terms of the Creative Commons c Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). 3rd Annual Conference on High Energy18-20 June in 2015 Southern Africa -HEASA2015, University of Johannesburg, Auckland Park, South Africa PoS(HEASA2015)007 ) 2 (2FHL) B. van Soelen ]. The observa- 3 ). 3 5 m diameter primary . These observations include 2 . ] (Section 2 TeVCat 1152 pixel array), which records a field of × 2 ]. Second Catalog of Hard Fermi-LAT sources 4 100 GeV) sources will increase with the development > and AGILE) and ground based Imaging Air Cherenkov Tele- Fermi telescope, which was decommissioned at the SAAO in January 2015, is 172 known TeV sources listed in the 1 82 m focal length (f/15.6). Photometric observations are undertaken using an . 24’E) between 1927 to 1933 [ ◦ S, 26 0 Boller & Chivens 02 On 15 October 2015. http://tevcat.uchicago.edu/ UFS-Boyden 1.5-m reflector is in a Cassegrain configuration, with a 1 The Boyden Observatory was originally established as a southern station of the Harvard Col- Here, we briefly review the available facilities available at the Boyden Observatory (Section The Boyden Observatory, operated by the Department of Physics at the University of the Multi-wavelength places important constraints on the underlying physics of astro- There are currently 1 2 ◦ ]). However, gamma-ray bursts (GRBs), which are regularly detected at GeV energies, have yet 1 Apogee U55 Back-illuminated CCD camera (770 tory moved to its current location,(29 approximately 25 km North-East of Bloemfontein, South Africa mirror and a 23 2.1 UFS-Boyden 1.5-m telescope lege Observatory, in Peru, through funding provided by the Boyden Fund in 1887 [ 2. The Boyden Observatory detections of Pulsar WindApproximately Nebula, 40 pulsars, per cent binary of systemsassociated sources with are and AGN associated in Active with the Galactic AGN recently[ (compared Nuclei released to (AGN). 75 per centto that be are detected at TeV energies. and report on aknown recent TeV AGN monitoring sources, using campaign the begun Watcher Robotic to Telescope [ provide additional optical constraints on Free State (UFS), currently hosts twoWatcher science Robotic telescopes, Telescopes the (which UFS-Boyden is 1.5-m operated telescope0.5-m by and the the University College of Dublin).currently being A installed, third, and the is close to being operational. nomical sources. Lower energy (radio to optical)information multi-wavelength observations which provide can significant complement the highobserved energy observations by (X-ray satellites to gamma-ray) (e.g. of sources The Boyden Observatory 1. Introduction scopes (e.g. H.E.S.S., MAGIC, VERITAS). South Africansuch multi-wavelength are well (optical placed and to radio) provide African observations, Astronomical Observatory, through Boyden Observatory, the Hartebeesthoek Radio current Astronomyvatory, Obser- facilities KAT-7) as (e.g. well South as future developmentstrue (e.g. for Square the Kilometre H.E.S.S. Array). telescope,and since This VHE it is particularly is observations located of in sourcesobservation Namibia, possible. of making Very simultaneous The High radio, Energy requirement optical (VHE, forof the lower Cherenkov energy, Telescope multi-wavelength Array (CTA), whichat will VHE. greatly increase the observational sensitivity PoS(HEASA2015)007 , . 0 1 , i 0 , r 0 B. van Soelen Boller & Chivens ]. Time not used for 6 and Clear filters. The c Image credit: D. Murphy. ,I c 1k) with clear, V, R, g × and interfaced through the custom 3 ] and the low-mass X-ray binary V404 7 The telescope system is shown in Fig. 5 3 The telescope system is connected to the Gamma- 4 ]. 5 10 arcmin field of view. × ˇ CR (Czech Republic), IAA (Spain) and the UFS. The system is currently 60 seconds. The telescope system was established by UCD (Ireland) in ∼ 7 arcmin. The filter wheel is equipped with U, B, V, R . program. 3 × The Watcher Robotic Telescope located at the Boyden observatory. 5 . ]. 9 SPICA , 8 http://www.dfmengineering.com/ http://gloria-project.eu Further information on the Watcher Telescope is available at http://watchertelescope.ie/. The most recently installed telescope at the Boyden observatory is the 0.5-m The Watcher Robotic Telescope, is a dedicated Gamma-ray Burst (GRB) monitoring telescope, Recent observations with Watcher of GRB 120711A were reported by [ , and OIII filters, and a 10 3 4 5 α Figure 1: GRB observations is used to observe,been in particular, reported blazar on sources. the Observations cataclysmic have variable also ASASSN-15ni recently [ 2.3 20-inch telescope ray Coordination Network (GCN) andGRB can automatically sources slew within and beginpartnership observations with of AsÚ potential AV H- Cyg [ telescope. It was originallyfore installed being at moved the in 1972 RepublicIn to Observatory 2014/2015 the in the Sutherland Johannesburg, telescope site in of was 1968, the decommissioned, be- South was African transported Astronomical to Observatory. the Boyden observatory in equipped with an Andor iXon 888 electron-multiplying CCD (1k and forms part of the GLORIA project [ 2.2 Watcher Robotic Telescope The Boyden Observatory view of 2 telescope is driven viawritten a DFM Engineering control system PoS(HEASA2015)007 0 is the M MKAPFILE / B. van Soelen PHOTCAL frames, N Differential photometry was 6 filters. c ) M , 1 and I i − − c c . m i !# , h 2 c i ( 1 , ] where each comparison has been weighted 2 c σ 1 − σ 1 13 N = ∑ i

4 1 1 target N N = ∑ i m " = . The sources are included in the Watcher scheduler = ◦ c + ω 2 t 12 corr σ , + v u u t target m ] for recent examples). In order to complement such observations, we procedures were followed to perform bias and flat-field correction (dark ) associated with the comparison star over all i 12 , c , σ 11 IRAF , packages and aperture optimization was performed using the 10 is the weighted mean magnitude of all comparisons stars on a frame, and i c is the measured error of the target. When the apparent magnitudes of the comparison stars t m h σ DAOPHOT / http://www.lsw.uni-heidelberg.de/projects/extragalactic/charts/ The standard Photometry was performed for the target and for comparison stars suggested in the Lan- In order to maximize the potential results of the observations an initial set of 17 brighter (V = Various studies have looked at optical variability and the correlation to multi-wavelength re- 6 IRAF where and set to observe approximately onceGRB a day, alerts). depending on Each observational constraints visitbands. (e.g. typically weather, consists of 6 observations, of 1 minute each in the V, R and i The corrected magnitude is calculated by weighted mean magnitude of all comparison starspoint over is all calculated frames. as The error on each corrected data where are known, the mean offset between the instrumental and apparent magnitudes is also corrected for. with the mean error ( dessternwarte Heidelberg-Königstuhl AGN finding chart service. 3.2 Data reduction and analysis current effects are negligible). The standardpackages. photometric measurements were done using the undertaken following a weighted mean approach [ 12.81 - 17.75) known TeV emittingAll AGN were sources selected are for south inclusion in of the Declination monitoring campaign. sults (see e.g. [ began a long term,monitor multi-colour known monitoring TeV sources campaign in usingresults April are 2015. the presented Watcher below. The Robotic outline of Telescope the to monitoring3.1 programme and Source initial Selection 3. TeV monitoring campaign The Boyden Observatory February 2015, and the base installedmissioning. on the The 12th telescope of is Mayequipped 2015. a with The Cassegrain a telescope (f/18) photoelectric is design photometer, currently with and in U, when com- B, completed, V, R the system will be PoS(HEASA2015)007 B. van Soelen 7 mag in a period of . 0 57174 57172 ∼ V ∆ , respectively. In each figure, 4 57172 57170 to 2 57170 57168 57168 57166 5 57166 57164 MJD MJD 57164 7) peaking around MJD 57164. This event is coincident with 57162 . 57162 57164 57160 − 57160 8 . 57158 ]. 57158 57154 14 ∼ 57156 57156 Differential light curve for PKS 2155-304 for the second two week in May 2015. The target is Differential light curve for AP Lib for the second two week in May 2015. The target is indicated 57154 57154 14 15 16 14 15 14.2 14.3 14.4 14.7 13.8 13.9 14.1 14.1 14.2 14.3 14.4 14.5 14.6 15.2 15.4 15.6 15.8 16.2 14.2 14.4 14.6 14.8 14.6 14.8 15.2 15.4 15.6 15.8 The preliminary results for the monitoring of AP Lib, PKS 2155-304 and PKS 1510-089

10 days (MJD

R-mag V-mag R-mag V-mag Figure 3: indicated by the solid blue circles, while a comparison star is indicated by the open grey boxes. Figure 2: by the solid blue circles, while a comparison star is indicated by the open grey boxes. the increase in TeV gamma-rays19th of reported May by 2015 the [ MAGIC gamma-ray telescope on the 18th and during the second two weeks of May 2015 are shown in Figs. The Boyden Observatory 3.3 Preliminary results the solid blue circles indicate thethree target, sources while show the indications open of greyis short boxes particular time show true scale one for variability comparison PKS as star.∼ 1510-089 expected All for which blazar shows a sources. clear This increase of PoS(HEASA2015)007 ]. For 64 and 32 and . . 15 2 2 = = B. van Soelen V V ∆ ∆ 57172 ]. Multi-wavelength stud- 15 ] have found 12 57170 ]. Observations of these sources are ]. Similarly, PKS 1510-089, which is 14 57168 11 , 16 2 was found by [ 57166 ∼ R 6 ∆ 1 for AP Lib using the ATOM telescope [ 57164 . R MJD ∆ ]. 57162 12 57160 57158 6 year period [ 7 year period and similarly ∼ ∼ 57156 Differential light curve for PKS 1510-089 for the second two week in May 2015. The target is 43 over a 41 over a 57154 . . 15 15 3 2 15.2 15.8 14.2 14.4 14.6 14.8 14.4 14.6 14.8 15.2 15.4 15.6

Multi-wavelength observations are important to constrain the emission processes in VHE Statistical studies of AGN require large and long term monitoring of sources. The data col- The preliminary results shown above present the feasibility of using the Watcher Robotic Tele-

= =

R-mag V-mag R R one of only a few∆ FSRQs detected at VHE, has had reported optical variability of sources. Here we have presented the facilitiespresented available preliminary at the results Boyden from Observatory and ourhigh have planned briefly energy emitting long AGN. term Initial monitoring resultssource, programme show PKS of the 1510-089, variability known expected an very for opticalreported these flare increase sources. in event For TeV has gamma-rays one been reported observed by MAGIC which [ corresponds to a recently 5. Conclusions lected with the Watcher Telescope willthis provide an aim. additional resource It thatincreasing is will contribute the our towards number intention of to monitoredmatching extend of sources, this integration improving times monitoring the to programme target dataprovide brightness), beyond collection notification the of, strategies this automation for (e.g. of initial example, the better flare phase, data like reduction by events, which and can providing public access to data. scope for a long termpected monitoring as campaign we of have AGN purposefullyhave, targets. chosen for The brighter, example, variability known found detected variable variabilityPKS here sources. of 2155-304, is long Previous ex- term observations optical observations by, for example,ies [ have also recently been reported by, for example, [ on-going. Figure 4: indicated by the solid blue circles, while a comparison star is indicated by the4. open grey Discussion boxes. The Boyden Observatory ∆ PoS(HEASA2015)007 , 45 (2001) (2013) ATel -ray , 61 γ 113 B. van Soelen PASP , (2014) A39 (2015) A69 (2014) 135 571 573 , Belknap Press, Cambridge, 789 2FHL: The Second Catalog of Hard Fermi-LAT (2014) 84 7 (2015) 567 MAGIC detects an increased activity from PKS 1510-089 7542 (2014) A79 , Long and short term variability of seven blazars in six 562 ATel , Occasional Publication, no. 2 of the Institute and Department of , A technique for ultrahigh-precision CCD photometry -LAT Collaboration), The Harvard College Observatory Significant colour change of ASASSN-15ni observed with the UCD Watcher Optical monitoring campaign of V404 Cyg with the Watcher Robotic Significant decrease in the average optical emission from V404 Cyg GRB 120711A: an intense INTEGRAL burst with long-lasting soft Comprehensive Monitoring of Gamma-Ray Bright Blazars. I. Statistical Study Longterm optical monitoring of bright BL Lacertae objects with ATOM: (2015) Fermi Long-term monitoring of PKS 2155-304 with ATOM and H.E.S.S.: investigation (2015) Long term variability of the blazar PKS 2155-304, in the proceedings of the ICRC Status update of the Watcher Robotic Telescope, EAS Publications Series 7718 7875 , Blazar Monitoring with the Watcher Robotic Telescope, in the proceedings of Third , Boyden Observatory -ray correlations in different spectral states, A&A ATel ATel γ , , , (2015) arXiv:1503.02664 (2015) Spectral variability and multiwavelength correlations, A&A A. Wierzcholska et al. J. Chevalier et al. Massachusetts (1971) 7729 A. Sandrinelli, S. Covino, A. Treves near-infrared/optical bands, A&A M.E. Everett & S.B. Howell, 1428 R. Mirzoyan et al. (MAGIC Collaboration), at very high energy gamma-rays (2015) arXiv:1509.03104 telescope Telescope K.E. Williamson et al. of Optical, X-Ray, and Gamma-Ray Spectral Slopes, ApJ A. Abramowski et al. A. Martin-Carrillo et al. A. Martin-Carrillo et al. A. Martin-Carrillo et al. of optical/ A. Martin-Carrillo et al. sources M Topinka et al., B.Z. Jones & L.G. Boyd, A.H. Jarrett, Astronomy, University of the Orange Free State (1985) P. Tisdall et al. Workshop on Robotic Autonomous Observatories, Revista(2014) Mexicana 71 de Astronomia y Astrofisica emission and a powerful optical flash, A&A M. Ackermann et al. ( 487 BvS, IPvdW and LK acknowledge the financial assistance of the National Research Founda- [8] [9] [6] [7] [4] [5] [2] [3] [1] [15] [16] [13] [14] [10] [11] [12] tion (NRF). This work isdation based of on the South research Africa supported forIreland in the (grant part 07/RFP/PHYF295) grant by and 87919. the the EU National LH FP7 Research acknowledges (grant Foun- support agreement no. from 283783 ScienceReferences ). Foundation The Boyden Observatory Acknowledgments