Transient Double-Beam Spectrograph for the 2.5-m Telescope of the Caucasus Mountain Observatory of SAI MSU

Potanin, S.; Belinski, A. A.; Dodin, A. V.; Желтоухов, С. Г.; Lander, V. Yu.; Постнов, К. А.; Savvin, A. D.; Татарников, А. М.; Черепащук, А. М.; Cheryasov, D.; Chilingarian, Igor; Shatsky, N. I.

doi:10.1134/s1063773720120038

Cited by 39 publications

(14 citation statements)

References 30 publications

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“…Their optical positions are provided in Table 11. We carried out spectroscopy and photometry of the candidate optical counterparts of the eROSITA transients using a number of telescopes and instruments, namely the CCD-photometer (CMO RC600; Berdnikov et al 2020) on the RC600 60-cm telescope of the Caucasus Mountain Observatory of the Sternberg Astronomical Institute (CMO SAI MSU, Russia), the ADAM low and medium resolution spectrograph (Afanasiev et al 2016;Burenin et al 2016) and the Andor iKon-M imaging camera on the AZT-33IK 1.6-m telescope (Kamus et al 2002) of the Sayan Observatory (Russia), the T ÜBITAK Faint Object Spectrograph and Camera 4 (TFOSC) on the Russian-Turkish 1.5-m Telescope (RTT150) of the T ÜBITAK National Observatory (Turkey), the Transient Double-Beam Spectrograph (TDS; Potanin et al 2020) and the NBI CCD-photometer on the 2.5-m telescope of CMO SAI MSU (Russia), the SCORPIO-2 universal focal reducer (Afanasiev & Moiseev 2011) on the BTA 6-m telescope of the Special Astrophysical Observatory (Russia), and the 1), while the arrow shows the object for which optical spectroscopy was performed.…”

Section: Late-phase X-ray Spectramentioning

confidence: 99%

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First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6

Sazonov

Gilfanov

Медведев

et al. 2021

Monthly Notices of the Royal Astronomical Society

101

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We present the first sample of tidal disruption events (TDEs) discovered during the SRG all-sky survey. These 13 events were selected among X-ray transients detected in the 0 < l < 180○ hemisphere by eROSITA during its second sky survey (10 June–14 December 2020) and confirmed by optical follow-up observations. The most distant event occurred at z = 0.581. One TDE continued to brighten at least 6 months. The X-ray spectra are consistent with nearly critical accretion on to black holes of a few × 103 to 108 M⊙, although supercritical accretion is possibly taking place. In two TDEs, a spectral hardening is observed 6 months after the discovery. Four TDEs showed an optical brightening apart from the X-ray outburst. The other 9 TDEs demonstrate no optical activity. All 13 TDEs are optically faint, with Lg/LX < 0.3 (Lg and LX being the g-band and 0.2–6 keV luminosity, respectively). We have constructed a TDE X-ray luminosity function, which can be fit by a power law with a slope of −0.6 ± 0.2, similar to the trend observed for optically selected TDEs. The total rate is estimated at (1.1 ± 0.5) × 10−5 TDEs per galaxy per year, an order of magnitude lower than inferred from optical studies. This suggests that X-ray bright events constitute a minority of TDEs, consistent with models predicting that X-rays can only be observed from directions close to the axis of a thick accretion disk formed from the stellar debris. Our TDE detection threshold can be lowered by a factor of ∼2, which should allow a detection of ∼700 TDEs by the end of the SRG survey.

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Section: Late-phase X-ray Spectramentioning

confidence: 99%

“…The spectra were obtained in a range of 3600-7500 Å with a 1 arcsec slit, at a spectral resolution of ∼1500. The spectrograph and data reduction are described in Potanin et al (2020). Photometry at the CMO's RC600 telescope was carried out using the Andor iKon-L camera with 2048 × 2048 pixels and a pixel scale of 0.67 arcsec.…”

Section: O N C L U S I O N Smentioning

confidence: 99%

First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6

Sazonov

Gilfanov

Медведев

et al. 2021

Monthly Notices of the Royal Astronomical Society

101

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“…Andor Newton 940P cameras with a E2V CCD42-10 512×2048 pixel arrays are used as the detectors. A detailed description of the instrument is given in Potanin et al (2020). The observations were carried out with a long slit of width 1.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Spectroscopic Variability of the Compact Planetary Nebula Hb 12

Ikonnikova,

Shaposhnikov,

Esipov

et al. 2021

Preprint

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We present the results of our new low-resolution spectroscopic observations of the young compact planetary nebula Hb 12 performed in 2011-2020 with SAI MSU telescopes. We have measured the intensities of more than 50 nebular emission lines in the spectral range λ3687-9532, detected interstellar absorption features, and conducted a search for absorptions belonging to the possible secondary component of the central star. The extinction coefficient has been estimated from the Balmer decrement to be c(Hβ)=1.15±0.07. The distance has been found by analyzing the interstellar extinction maps to be D ≈ 2400 pc. We have traced the history of the spectroscopic observations of Hb 12, beginning with the first spectra taken by Aller (1951) in 1945. We have detected a systematic increase in the relative intensities of the nebular [O III] λ4959 and λ5007 lines and a decrease in the relative intensity of the auroral [O III] λ4363 line, which has led to an increase in the observed flux ratio F (λ4959 + λ5007)/F (λ4363) by a factor of ∼4 from 1945 to the present time. The [O III]/[O II] line ratio F (λ4363)/F (λ3727 + λ3729) remains constant, suggesting that the degree of ionization, on average, for the nebula is invariable. The temperature of the exciting star has been estimated to be T ≈ 41 000 K. We conclude that a decrease in the electron temperature and, possibly, electron density in the [O III] line formation region is mainly responsible for the spectroscopic variability.

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“…2020 with a cadence of about 5 days. The telescope is equipped with the medium resolution optical Transient Double-beam Spectrograph (TDS), with Andor Newton 940P cameras using CCDs E2V CCD42-10, and a volume phase holographic grating (Potanin et al 2020). The slit width in most cases was 1.…”

Section: Spectral Observations At Cmo Sai Msumentioning

confidence: 99%

Multi-Wavelength Monitoring and Reverberation Mapping of a Changing Look Event in the Seyfert Galaxy NGC 3516

Oknyansky,

Brotherton,

Tsygankov

et al. 2021

Preprint

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We present the results of photometric and spectroscopic monitoring campaigns of the changing look AGN NGC 3516 carried out in 2018 to 2020 covering the wavelength range from the X-ray to the optical. The facilities included the telescopes of the CMO SAI MSU, the 2.3-m WIRO telescope, and the XRT and UVOT of S wi f t. We found that NGC 3516 brightened to a high state and could be classified as Sy1.5 during the late spring of 2020. We have measured time delays in the responses of the Balmer and He II λ4686 lines to continuum variations. In the case of the best-characterized broad Hβ line, the delay to continuum variability is about 17 days in the blue wing and is clearly shorter, 9 days, in the red, which is suggestive of inflow. As the broad lines strengthened, the blue side came to dominate the Balmer lines, resulting in very asymmetric profiles with blueshifted peaks during this high state. During the outburst the X-ray flux reached its maximum on 1 April 2020 and it was the highest value ever observed for NGC 3516 by the Swift observatory. The X-ray hard photon index became softer, ∼1.8 in the maximum on 21 Apr 2020 compared to the mean ∼0.7 during earlier epochs before 2020. We have found that the UV and optical variations correlated well (with a small time delay of 1-2 days) with the X-ray until the beginning of April 2020, but later, until the end of Jun. 2020, these variations were not correlated. We suggest that this fact may be a consequence of partial obscuration by Compton-thick clouds crossing the line of sight.

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Transient Double-Beam Spectrograph for the 2.5-m Telescope of the Caucasus Mountain Observatory of SAI MSU

Cited by 39 publications

References 30 publications

First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6

First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6

Spectroscopic Variability of the Compact Planetary Nebula Hb 12

Multi-Wavelength Monitoring and Reverberation Mapping of a Changing Look Event in the Seyfert Galaxy NGC 3516

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Transient Double-Beam Spectrograph for the 2.5-m Telescope of the Caucasus Mountain Observatory of SAI MSU

Cited by 39 publications

References 30 publications

First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z &lt; 0.6

First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z &lt; 0.6

Spectroscopic Variability of the Compact Planetary Nebula Hb 12

Multi-Wavelength Monitoring and Reverberation Mapping of a Changing Look Event in the Seyfert Galaxy NGC 3516

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Product

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First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6

First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6