The intra-day optical monitoring of BL Lacerate object 1ES 1218+304 at its highest X-ray flux level

In order to compare X-ray-selected BL Lac objects with radio-selected BL Lac objects, we have carried out optical monitoring of some of these objects for about three years at Yunnan Observatory in China. All observations have been made with a CCD-image system at the f/13.3 Cassegrain focus of the 102-cm RCC telescope. The CCD-image system was developed by Ye et al. in Kitt Peak National Observatory of USA (Ye et al., 1985). The filters used were as follows: B-GG385(2mm)+BG12(1mm)+BG18(1mm), V-GG495(2mm)+BG18(2mm). After observing many times, more complete light curves have obtained for the X-ray-selected BL Lac object IE 0317+186 and the radio-selected BL Lac object ON 231, respectively(Fig 1 and Fig 2). Fig 1 shows that IE 0317+186 has a characteristic timescale of about 4.5hours with an amplitudes of ΔV≃0.65 mag. Fig 2 indicates that a timescale of short-term variability in ON 231 is about 70 min with an amplitudes of ΔB≃0.8 mag.

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X-Rays from Wolf-Rayet Stars Observed by the Einstein Observatory

Symposium - International Astronomical Union ◽

10.1017/s0074180900029430 ◽

1982 ◽

Vol 99 ◽

pp. 589-595

Author(s):

W. T. Sanders ◽

J. P. Cassinelli ◽

K. A. van der Hucht

Keyword(s):

Mean Value ◽

Spectral Energy ◽

X Rays ◽

X Ray ◽

Total Luminosity ◽

Hydrogen Emission Lines ◽

Flux Level ◽

The Mean ◽

Einstein Observatory ◽

Thin Source

Preliminary results of three X-ray surveys are presented. Out of a sample of 20 stars, X-rays were detected from four Wolf-Rayet stars and two 08f+ stars. The detected stars have about the same mean value as 0 stars for the X-ray to total luminosity ratio, LX/L = 10−7, but exhibit a much larger variation about the mean. The spectral energy distributions are also found to be like that of 0 stars in that they do not exhibit large attenuation of X-rays softer than 1 keV. This indicates that for both the 0 stars and WR stars much of the X-ray emission is coming from hot wisps or shocks in the outer regions of the winds and not from a thin source at the base of the wind. The general spectral shape and flux level place severe restrictions on models that attribute the lack of hydrogen emission lines to extremely high temperatures of the gas in the wind.

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On the Long-Term Light Curve Behaviour of the Intermediate Polar TX Col

International Astronomical Union Colloquium ◽

10.1017/s0252921100038598 ◽

1996 ◽

Vol 158 ◽

pp. 185-186

Author(s):

D. A. H. Buckley

Keyword(s):

Light Curve ◽

High Flux ◽

X Rays ◽

X Ray ◽

Beat Period ◽

Spin Period ◽

Flux Level

TX Col (1H0547–407; Porb = 5.72 h) is an intermediate polar (IP) with spin and synodic (beat) periods of 1911s and 2106 s respectively (Buckley & Tuohy 1989). EXOSAT observations (Tuohy et al. 1986) showed the beat period dominated at higher energies (ME; 1… 9keV), while the spin period was stronger in softer X-rays (LE1; 0.1… IkeV). The high flux level, and pulse fraction (>70%), of the soft X-rays were unique in an IP at that time. Now three other IPs, recently discovered from the ROSAT survey, have been found to show a true separate soft X-ray component, similar to the polars (Motch & Haberl 1994).The strength of the synodic X-ray period in TX Col was, until the recent discovery of the variable polarised IP, RX J1712.6–2414 (Buckley et al. 1995), unique. This was taken as evidence for direct accretion onto the magnetosphere (e.g. Mason, Rosen & Hellier 1988), through a component of the accretion stream overflowing the disc (Hellier 1992).

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Results of Optical Monitoring of the Dwarf Nova SS Cyg During the 1993 Campaign of co-ordinated Observations with the Asca Satellite

International Astronomical Union Colloquium ◽

10.1017/s0252921100038252 ◽

1996 ◽

Vol 158 ◽

pp. 73-74

Author(s):

Irina Voloshina

Keyword(s):

Cataclysmic Variable ◽

Optical Monitoring ◽

X Ray ◽

Dwarf Nova ◽

Spectroscopic Observations ◽

Photometric And Spectroscopic Observations ◽

Wide Range

SS Cyg is the brightest known and therefore best studied classical dwarf nova and it was the first one from which X-ray radiation was discovered. SS Cyg is unique because it has been detected at very wide range of energies, from a few eV up to ~ 10 keV (Jones & Watson 1992). It was chosen as the first cataclysmic variable for X-ray observations with the Japanese satellite ASCA. Simultaneous optical photometric and spectroscopic observations were also provided for completeness of the study.

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X-Ray and Optical Monitoring of a Gamma-Ray-Emitting Radio Galaxy, NGC 1275

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/65.2.30 ◽

2013 ◽

Vol 65 (2) ◽

pp. 30 ◽

Cited By ~ 11

Author(s):

Syoko Yamazaki ◽

Yasushi Fukazawa ◽

Mahito Sasada ◽

Ryosuke Itoh ◽

Sho Nishino ◽

...

Keyword(s):

Gamma Ray ◽

Radio Galaxy ◽

Optical Monitoring ◽

X Ray ◽

Ngc 1275

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RESULTS FROM LONG-TERM OPTICAL MONITORING OF THE SOFT X-RAY TRANSIENT SAX J1810.8–2609

The Astrophysical Journal ◽

10.1088/0004-637x/761/2/118 ◽

2012 ◽

Vol 761 (2) ◽

pp. 118 ◽

Cited By ~ 1

Author(s):

Ling Zhu ◽

Rosanne Di Stefano ◽

Lukasz Wyrzykowski

Keyword(s):

Optical Monitoring ◽

X Ray

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Intriguing X-ray and optical variations of the γ Cassiopeiae analog HD 45314

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731782 ◽

2018 ◽

Vol 615 ◽

pp. A44 ◽

Cited By ~ 6

Author(s):

G. Rauw ◽

Y. Nazé ◽

M. A. Smith ◽

A. S. Miroshnichenko ◽

J. Guarro Fló ◽

...

Keyword(s):

Optical Spectrum ◽

Optical Emission ◽

Magnetic Interaction ◽

Emission Lines ◽

Magnetic Star ◽

Optical Monitoring ◽

X Ray ◽

Direct Association ◽

Intensity Changes ◽

Observed Behaviour

Context. A growing number of Be and Oe stars, named the γ Cas stars, are known for their unusually hard and intense X-ray emission. This emission could either trace accretion by a compact companion or magnetic interaction between the star and its decretion disk. Aims. To test these scenarios, we carried out a detailed optical monitoring of HD 45314, the hottest member of the class of γ Cas stars, along with dedicated X-ray observations on specific dates. Methods. High-resolution optical spectra were taken to monitor the emission lines formed in the disk, while X-ray spectroscopy was obtained at epochs when the optical spectrum of the Oe star was displaying peculiar properties. Results. Over the last four years, HD 45314 has entered a phase of spectacular variations. The optical emission lines have undergone important morphology and intensity changes including transitions between single- and multiple-peaked emission lines as well as shell events, and phases of (partial) disk dissipation. Photometric variations are found to be anti-correlated with the equivalent width of the Hα emission. Whilst the star preserved its hard and bright X-ray emission during the shell phase, the X-ray spectrum during the phase of (partial) disk dissipation was significantly softer and weaker. Conclusions. The observed behaviour of HD 45314 suggests a direct association between the level of X-ray emission and the amount of material simultaneously present in the Oe disk as expected in the magnetic star-disk interaction scenario.

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Late‐Time X‐Ray, UV, and Optical Monitoring of Supernova 1979C

The Astrophysical Journal ◽

10.1086/432869 ◽

2005 ◽

Vol 632 (1) ◽

pp. 283-293 ◽

Cited By ~ 20

Author(s):

Stefan Immler ◽

Robert A. Fesen ◽

Schuyler D. Van Dyk ◽

Kurt W. Weiler ◽

Robert Petre ◽

...

Keyword(s):

Late Time ◽

Optical Monitoring ◽

X Ray

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Discovery of new changing look in NGC 1566

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002720 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 127-131

Author(s):

Victor L. Oknyansky ◽

Sergey S. Tsygankov ◽

Vladimir M. Lipunov ◽

Evgeny S. Gorbovskoy ◽

Nataly V. Tyurina

Keyword(s):

South African ◽

Astronomical Observatory ◽

Emission Lines ◽

Optical Monitoring ◽

X Ray ◽

Broad Emission ◽

High Ionization ◽

The Galaxy ◽

Multi Wavelength ◽

Bright Phase

AbstractWe present continuation of the multi-wavelength (from X-ray to optical) monitoring of the nearby changing look (CL) active galactic nucleus in the galaxy NGC 1566 performed with the Neil Gehrels Swift Observatory,the MASTER Global Robotic Network over the period 2007–2019. We also present continuation of optical spectroscopy using the South African Astronomical Observatory 1.9-m telescope between Aug. 2018 and Mar. 2019. We investigate remarkable re-brightenings in of the light curve following the decline from the bright phase observed at Dec. 2018 and at the end of May 2019. For the last optical spectra (31 Nov. 2018–28 Mar. 2019) we see dramatic changes compared to 2 Aug. 2018, accompanied by the fading of broad emission lines and high-ionization [FeX]6374Å line. Effectively, one more CL was observed for this object: changing from Sy1.2 to the low state as Sy 1.8–Sy1.9 type. Some possible explanations of the observed CL are discussed.

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