Jan Štrobl

Primary Black Hole Spin in OJ 287 as Determined by the General Relativity Centenary Flare

OJ 287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts that are predictable in a binary black hole model. The model predicted a major optical outburst in 2015 December. We found that the outburst did occur within the expected time range, peaking on 2015 December 5 at magnitude 12.9 in the optical R-band. Based on Swift/XRT satellite measurements and optical polarization data, we find that it included a major thermal component. Its timing provides an accurate estimate for the spin of the primary black hole,

RTS2 — Remote Telescope System, 2nd Version

\chi =0.313\pm 0.01

Complicated variations in the early optical afterglow of GRB 090726

. The present outburst also confirms the established general relativistic properties of the system such as the loss of orbital energy to gravitational radiation at the 2% accuracy level, and it opens up the possibility of testing the black hole no-hair theorem with 10% accuracy during the present decade.

Cycles in the cataclysmic variable V795 Herculis

BART is a small remote controlled robotic CCD telescope, devoted to rapid observation of prompt gamma ray burst transients. During its operation since early 2001, it had three prompt observations with world‐competitive response time. The constraints to object magnitude were estimated and published in GCN circulars. Telescope is located in Astronomical Institute of the Czech Academy of Sciences in Ondřejov. This poster describes its new control system, named RTS2, which has been in service since February 2003.

BART: The Czech Autonomous Observatory

Aims. We report on the detection of an early rising phase of optical afterglow (OA) of a long GRB 090726. We resolve a complicated profile of the optical light curve. We also investigate the relation of the optical and X-ray emission of this event. Methods. We made use of the optical photometry of this OA obtained by the 0.5 m telescope of AI AS CR, supplemented by the data obtained by other observers, and the X-ray Swift/XRT data. Results. The optical emission peaked at ∼17. 5m ag(R )a tt −T0 ≈ 500 s. We find a complex profile of the light curve during the early phase of this OA: an approximately power-law rise, a rapid transition to a plateau, a weak flare superimposed on the center of this plateau, and a slowly steepening early decline followed by a power-law decay. We discuss several possibilities for explaining the short flare on the flat top of the optical light curve at t −T0 ≈ 500 s. Activity of the central engine is favored, although reverse shock cannot be ruled out. We show that power-law outflow with Θobs/Θc > 2.5 is the best case for the OA of GRB 090726. The initial Lorentz factor is Γ0 ≈ 230−530 in the case of propagation of the blast wave in a homogeneous medium, while propagation of this wave in a wind environment gives Γ0 ≈ 80−300. The value of Γ0 in GRB 090726 thus falls into the lower half of the range observed in GRBs and it may even lie on the lower end. We also show that both the optical and X-ray emission decayed simultaneously and that the spectral profile from X-ray to the optical band did not vary. This is true for both the time periods before and after the break in the X-ray light curve. This break can be regarded as achromatic. The available data show that neither the dust nor the gaseous component of the circumburst medium underwent any evolution during the decay of this OA, that is, after t − T0 < 3000 s. We also show that this OA belongs to the least luminous ones in the phase of its power-law decay, corresponding to what is observed for the ensemble of OAs of long GRBs.

BART: real time follow-up of GRBs since 2001

Aims. We investigate the photometric activity of the cataclysmic variable (CV) V795 Her. We pay attention to the time evolution of the length of its superhump cycle Psh. We investigate how well the superhump profile is reproduced in the individual phases Φsh of Psh. We also analyze the mutual relation of the intensity of the superhump light and the superimposed rapid intensity variations. Methods. We used the photometric V-band CCD observations obtained between 2008 and 2010. The observing run on a given night consisted of a dense series of V-band images (exp. time of 20 s), which enabled us to investigate the superhump profile and the superimposed rapid changes. Results. We identified several time segments characterized by a relatively stable Psh and mean intensity level. We find that inside such a segment, the smoothed profile of the intensity curve folded with Psh displays the largest scatter of the residuals of the mean profile in Φsh of the peak intensity and during the decay from this peak. A zone of quiescence occurs at Φsh ≈ 0.6−0.7. The profile of these residuals can be explained if the strength and luminosity of the spiral arms undergo large variations on a timescale much shorter than the segment’s duration, as predicted in a previously developed model, while the conditions for the disk precession remain much more stable. The formation of these arms is considerably faster than their fading. We find that the emission of the superimposed short cycle (∼0.01–0.02 d) in this CV depends on Φsh. We conclude that it does not come from pulsations of the white dwarf or, generally, from the close vicinity of this accretor. We argue that it is flickering with the site in the disk region that produces the superhump. This flickering is not located in the impact of the stream on the disk. V795 Her is a borderline case in the sense that its disk is close to the switch to the cool state. We explain the suppression of the thermal-viscous instability of the disk in V795 Her as caused by the tidal force that is also the reason for the superhumps. This tidal heating can also help to keep the accretion disks in other permanent superhumpers in the hot state.

A Decade of GRB Follow-Up by BOOTES in Spain (2003–2013)

The High Energy Astrophysics group of the stellar department of the Astronomical Institute in Ondřejov operates two small aperture robotic telescopes called BART and D50. Both telescopes are capable of making automatic followup observation of gamma-ray burst optical counterparts. This paper deals with the smaller telescope BART.

REMOTES: reliable and modular telescope solution for seamless operation and monitoring of various observation facilities

BART is a 25 cm aperture, intelligent robotic CCD telescope, devoted for observation of prompt gamma ray burst emission and early afterglow. It’s operating since early 2001. Till now, it responded to many GCN GRB alerts.

Operating a global network of autonomous observatories

The authors appreciate the auspices of INTA, IHSM-UMA/CSIC, and UMA as well as the financial support by the Junta de Andaluca and the Spanish Ministry of Economy and Competitiveness through the Research Projects P07-TIC-03094, P12-TIC2839, AYA2009-14000-C03-01, AYA 2010-39727-C03-01, and AYA-2015-71718-R. Martin Jelinek was supported by the postdoctoral fellowship of the Czech Academy of Sciences. This study was carried out in the framework of the Unidad Asociada IAA-CSIC at the Group of Planetary Science of ETSI-UPV/EHU. This work was supported by the Ikerbasque Foundation for Science. The Czech CVUT FEL team acknowledges the support by GA CR Grant 13-33324S.

Design of modular C++ observatory control system: from observatories to laboratories and back

Astronomers often need to put several pieces of equipment together and have to deploy them at a particular location. This task could prove to be a really tough challenge, especially for distant observing facilities with intricate operating conditions, poor communication infrastructure and unreliable power source. To have this task even more complicated, they also expect secure and reliable operation in both attended and unattended mode, comfortable software with user-friendly interface and full supervision over the observation site at all times. During reconstruction of the D50 robotic telescope facility, we faced many of the issues mentioned above. To get rid of them, we based our solution on a flexible group of hardware modules controlling the equipment of the observation site, connected together by the Ethernet network and orchestrated by our management software. This approach is both affordable and powerful enough to fulfill all of the observation requirements at the same time. We quickly figured out that the outcome of this project could also be useful for other observation facilities, because they are probably facing the same issues we have solved during our project. In this contribution, we will point out the key features and benefits of the solution for observers. We will demonstrate how the solution works at our observing location. We will also discuss typical management and maintenance scenarios and how we have supported them in our solution. Finally, the overall architecture and technical aspects of the solution will be presented and particular design and technology decisions will be clarified.