scholarly journals Radio light-curve for WR 146 (HM19-3, WC6+O8.5), a colliding wind binary

1999 ◽  
Vol 193 ◽  
pp. 390-391
Author(s):  
Diah Y.A. Setia Gunawan ◽  
A. Ger de Bruyn ◽  
Karel A. van der Hucht ◽  
Peredur M. Williams
Keyword(s):  
Light Curve ◽  
Flux Density ◽  
Radio Telescope ◽  
Time Scale ◽  
Preliminary Results ◽  
Average Flux

We report preliminary results of monitoring the flux from the Wolf-Rayet object WR 146 with the Westerbork Synthesis Radio Telescope at 21 cm since 1989. We find the average flux density slowly rising in the period 1989–1997, with evidence of shorter time-scale variability.

scholarly journals Low radio frequency spectrum of Sgr-A*

2016 ◽  
Vol 11 (S322) ◽  
pp. 54-55
Author(s):  
Subhashis Roy
Keyword(s):  
Radio Frequency ◽  
Flux Density ◽  
Frequency Spectrum ◽  
Spectral Index ◽  
Radio Telescope ◽  
Major Axis ◽  
Galactic Centre ◽  
Preliminary Results ◽  
Radio Frequency Spectrum ◽  
Sgr A

AbstractWe observed the Galactic centre (GC) region with the partially upgraded Giant Metrewave Radio Telescope (GMRT) using a wideband system in frequency ranges of 300– 500 MHz with 16 antennas. Preliminary results are presented here. Sgr-A* is clearly detected down to 450 MHz. Sgr-A West slowly disappears at lower frequencies across the band. By taking cross-cuts across the known major-axis of Sgr-A*, we measure its total flux density across the band to be 0.4 Jy consistent with what is expected from earlier results. It clearly indicates lack of absorption from Sgr-A West. Its spectral index is consistent with its higher frequency value of +0.3.

scholarly journals A Very Rapid Extreme Scattering Event in the IDV Source 0954+658

2002 ◽  
Vol 19 (1) ◽  
pp. 10-13 ◽  
Author(s):  
Giuseppe Cimò ◽  
T. Beckert ◽  
T. P. Krichbaum ◽  
L. Fuhrmann ◽  
A. Kraus ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Light Curve ◽  
Frequency Dependence ◽  
Flux Density ◽  
Time Scales ◽  
Time Scale ◽  
Variable Light ◽  
Ray Path ◽  
Intraday Variability ◽  
Scattering Events

AbstractExtreme scattering events (ESEs) are dramatic variations of the flux density at gigahertz frequencies caused by ray path distortions within an isolated inhomogeneity (‘plasma lens’) in the interstellar medium. These events are characterised by a deep flux density minimum in the light curve with, in some cases, surrounding maxima. The variability time scales range from weeks to months. These phenomena show a strong frequency dependence, in which the variability amplitudes increase with wavelength. During an intraday variability (IDV) monitoring project (March 2000), a feature resembling an ESE-like event appeared in the variable light curve of 0954+658, however with a time scale of less than two days. We will discuss this effect and its implications for a better description of the interstellar medium.

scholarly journals Study of mutual occultation phenomena of the Galilean satellites at radio wavelengths

2010 ◽  
Vol 6 (S269) ◽  
pp. 245-249 ◽  
Author(s):  
S. Pluchino ◽  
E. Salerno ◽  
G. Pupillo ◽  
F. Schillirò ◽  
A. Kraus ◽  
...  
Keyword(s):  
Flux Density ◽  
Radio Telescope ◽  
Density Variation ◽  
Radio Flux ◽  
Max Planck ◽  
Galilean Satellites ◽  
Preliminary Results ◽  
Mutual Occultation

AbstractWe present preliminary results for our study of mutual phenomena of the Galilean satellites performed at radio wavelengths with the Medicina and Noto antennas of the Istituto di Radioastronomia - INAF, and with the Effelsberg 100-m radio telescope of the Max-Planck-Institute for Radioastronomy, Bonn. Measurements of the radio flux density variation during the mutual occultations of Io by Europa and Ganymede were carried out during the PHEMU09 campaign at 22 GHz and 43 GHz. Flux density variations observed at radio wavelengths are consistent with the typical optical patterns measured when partial occultations occur.

scholarly journals Variability Observations of a Complete Sample of Flat-Spectrum Radio Sources: Preliminary Results

2001 ◽  
Vol 182 ◽  
pp. 93-96
Author(s):  
A.G. Gorshkov ◽  
V.K. Konnikova ◽  
M.G. Mingaliev
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
Time Scale ◽  
Radio Sources ◽  
Complete Sample ◽  
Limited Sample ◽  
Preliminary Results ◽  
Spectrum Radio ◽  
Intrinsic Mechanism ◽  
Short Time

AbstractThis report presents preliminary results of daily observations, over 60 and 100 days, of a complete, flux-limited sample of radio sources with flat spectra. The existence of flicker up to 21.7 GHz was confirmed, for sources with flat spectra, on a time-scale of 4 days. A model explaining the flux density variations of the unique radio source 0524+034, on long and short time-scales, by an intrinsic mechanism is proposed.

scholarly journals Simultaneous X-ray and radio observations of the transitional millisecond pulsar candidate CXOU J110926.4–650224

2021 ◽  
Vol 655 ◽  
pp. A52
Author(s):  
F. Coti Zelati ◽  
B. Hugo ◽  
D. F. Torres ◽  
D. de Martino ◽  
A. Papitto ◽  
...  
Keyword(s):  
Radio Emission ◽  
Flux Density ◽  
Millisecond Pulsar ◽  
Radio Emissions ◽  
X Ray ◽  
Link Type ◽  
Upper Limit ◽  
Variability Pattern ◽  
Average Flux ◽  
Compact Array

We present the results of simultaneous observations of the transitional millisecond pulsar (tMSP) candidate CXOU J110926.4–650224 with the XMM-Newton satellite and the MeerKAT telescope. The source was found at an average X-ray luminosity of LX ≃ 7 × 1033 erg s−1 over the 0.3−10 keV band (assuming a distance of 4 kpc) and displayed a peculiar variability pattern in the X-ray emission, switching between high, low and flaring modes on timescales of tens of seconds. A radio counterpart was detected at a significance of 7.9σ with an average flux density of ≃33 μJy at 1.28 GHz. It showed variability over the course of hours and emitted a ≃10-min long flare just a few minutes after a brief sequence of multiple X-ray flares. No clear evidence for a significant correlated or anticorrelated variability pattern was found between the X-ray and radio emissions over timescales of tens of minutes and longer. CXOU J110926.4–650224 was undetected at higher radio frequencies in subsequent observations performed with the Australia Telescope Compact Array, when the source was still in the same X-ray sub-luminous state observed before, down to a flux density upper limit of 15 μJy at 7.25 GHz (at 3σ). We compare the radio emission properties of CXOU J110926.4–650224 with those observed in known and candidate tMSPs and discuss physical scenarios that may account for its persistent and flaring radio emissions.

scholarly journals IPS Observations at Miyun Station, BAO

2001 ◽  
Vol 203 ◽  
pp. 580-582
Author(s):  
X.Z. Zhang ◽  
J.H. Wu
Keyword(s):  
Radio Telescope ◽  
Data Reduction ◽  
Astronomical Observatory ◽  
Paper Briefly ◽  
Preliminary Results

IPS observations have recently begun at Miyun Station, Beijing Astronomical Observatory. This paper briefly describes the radio telescope at Miyun Station, discusses the observation and the data reduction procedures and presents the preliminary results of observations on IPS source 3C48.

scholarly journals On the Photometric Variations of the Irregular Variable Red Giant HD 65750 in the Reflection Nebula IC 2220

1977 ◽  
Vol 42 ◽  
pp. 601-605
Author(s):  
J. Dachs ◽  
J. Isserstedt ◽  
J. Rahe
Keyword(s):  
Light Curve ◽  
Time Scale ◽  
Reflection Nebula ◽  
Irregular Variable ◽  
Red Giant

AbstractThe light-curve between 1964 and 1977 for the variable M2II giant HD 65750 = V341 Car is derived from 77 photographic and 83 photoelectric UBV measurements and analyzed. It is concluded that the light variations of the star are irregular and due to variable extinction in the circumstellar nebula. The appearence of the visible reflection nebula IC 2220 into which HD 65750 is embedded, has been found to vary on a time scale of four years.

scholarly journals A short-lived flare of EV Lacertae

1990 ◽  
Vol 137 ◽  
pp. 35-36
Author(s):  
B. E. Zhilyaev ◽  
Ya. O. Romanjuk ◽  
O. A. Svyatogorov
Keyword(s):  
Fine Structure ◽  
Light Curve ◽  
Time Resolution ◽  
Time Scale ◽  
High Time ◽  
High Time Resolution ◽  
Decay Times ◽  
Ev Lac

Flare events on a time scale of the order of one second were observed on EV Lac by Gershberg and Petrov [1], Zalinian and Tovmassian [2], Tsvetkov, Antov and Tsvetkova [3]. The nature of such phenomena is very mysterious. We hope that monitoring of EV Lac with high time resolution will yield the information about growing and decay times as well as fine structure of the light curve and color one. A short-lived flare of EV Lac was recorded in U and V bands in 1989, September 3 2h 14m 30s UT. The duration of the event was about 150 milliseconds.

scholarly journals Statistics of the 6.7 GHz methanol maser variability from the Toruń survey

2002 ◽  
Vol 206 ◽  
pp. 135-138
Author(s):  
Anna Niezurawska ◽  
Marian Szymczak ◽  
Grzegorz Hrynek ◽  
Andrzej J. Kus
Keyword(s):  
Flux Density ◽  
Time Scales ◽  
Radio Telescope ◽  
Methanol Maser ◽  
Maser Line

A sample of 174 methanol sources has been observed with the 32 m Toruń radio telescope at four or five epochs separated by 3-7 months. Observations of the 6.7 GHz maser line revealed that about 80% of sources are variable. 20% of sources showed strong variations of the integrated flux density usually on time-scales of 5-12 months. These variations were associated with strong changes in the relative intensities of maser features. Methanol emission from five sources disappeared. The time-scales of variability were longer than 12 months for only 23% of variable sources. It is suggested that the variability of methanol emission is related to the dynamics of the maser regions.

scholarly journals IPS Observations at Miyun Station, BAO

2001 ◽  
Vol 182 ◽  
pp. 189-192 ◽  
Author(s):  
J. Wu ◽  
X. Zhang ◽  
Y. Zheng
Keyword(s):  
Radio Telescope ◽  
Data Reduction ◽  
Astronomical Observatory ◽  
Paper Briefly ◽  
Preliminary Results

AbstractIPS observations have recently begun at Miyun Station, Beijing Astronomical Observatory. This paper briefly describes the radio telescope at Miyun Station, discusses the observation and the data reduction procedures, and presents the preliminary results of observations on IPS source 3C48.

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