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The present paper focuses on the high-mass star-forming region G23.01-0.41. Methods: Using the VLBA and the EVN arrays, we conducted phase-referenced observations of the three most powerful maser species in G23.01-0.41: H2O at 22.2 GHz (4…
In 2010/3, the Large Area Telescope on board Fermi revealed a transient gamma-ray source, positionally coincident with the optical nova in the symbiotic binary, V407Cyg. This event marked the first discovery of gamma-ray emission from a…
We report a serendipitous detection of rapid, large amplitude flux density variations in the highly core-dominated, flat-spectrum radio quasar 1156+295 during an observing session at the Very Long Baseline Array (VLBA). The source was…
Studies of 22GHz H2O maser emission from the merging galaxy NGC 6240 with double nuclei are presented. Two epochs of Very Large Array (VLA) observations in the A-configuration in spectral-line mode were carried out at 0.1 arcsec resolution…
PKS 1510-089 is one of the most variable blazars in the third Fermi-LAT source catalog. During 2015, this source has shown four flares identified as flare A, B, C, and D in between three quiescent states Q1, Q2, and Q3. The multi-wavelength…
Following up on our discovery of terahertz water masers, reported in 2017, we report two further detections of water maser emission at frequencies above 1 THz. Using the GREAT instrument on SOFIA, we have detected emission in the 1.296411…
Observations of the masers in the course of RadioAstron mission yielded detections of fringes for a number of sources in both water and hydroxyl maser transitions. Several sources display numerous ultra-compact details. This proves that…
We present five epochs of VLBI water maser observations around the massive protostar Cepheus A HW2 with 0.4 mas (0.3 AU) resolution. The main goal of these observations was to follow the evolution of the remarkable water maser…
Abridged. Methods. We made use of the Karl G. Jansky Very Large Array (VLA) in the B configuration at K band, and in the A configuration at both Ku and C bands, in order to image the radio continuum emission towards 25 H$_2$O maser sites…
We obtained K-band spectro-interferometric observations of the Miras R Cnc, X Hya, W Vel, and RW Vel with a spectral resolution of 1500 using the VLTI/AMBER instrument. We obtained concurrent JHKL photometry using the the Mk II instrument…
The aim of this study is to investigate the physical properties of molecular envelopes of planetary nebulae in their earliest stages of evolution. Using the 100m telescope at Effelsberg, we have undertaken a high sensitivity discrete source…
We present Very Large Array (VLA) observations of H2O and OH masers, as well as radio continuum emission at 1.3 and 18 cm toward three sources previously cataloged as planetary nebulae (PNe) and in which single-dish detections of H2O masers…
The planned Laser Interferometer Space Antenna (LISA) will detect gravitational wave signals from a wide range of sources. However, disentangling individual signals from the source-dominated data stream is a challenging problem and the…
Results of a ground-based optical monitoring campaign on NGC5548 in June 1998 are presented. The broad-band fluxes (U,B,V), and the spectrophotometric optical continuum flux F_lambda(5100 A) monotonically decreased in flux while the…
Aims: We investigated the possible relationship between the evolutionary stage of post-AGB stars and planetary nebulae (PNe) and the presence of water masers in their envelopes. Methods: We have used NASA's 70-m antenna in Robledo de…
We report multiwavelength observations of the gravitationally lensed blazar QSO B0218+357 in 2016-2020. Optical, X-ray and GeV flares were detected. The contemporaneous MAGIC observations do not show significant very-high-energy (VHE, >=…
Spectroscopic measurements of Mira variable stars, as a function of phase, probe the stellar atmospheres and underlying pulsation mechanisms. For example, measuring variations in TiO, VO, and ZrO with phase can be used to help determine…
Recently, a relationship between the water maser detection rate and far infrared (FIR) flux densities has been established as a result of two 22 GHz maser surveys in a complete sample of galaxies (Dec>-30 degree) with 100 micron flux…
The FRI/FRII dichotomy is a much debated issue in the astrophysics of extragalactic radio sources. Study of the properties of HYbrid MOrphology Radio Sources (HYMORS) may bring crucial information and lead to a step forward in understanding…
We present the data and analysis of VLBI observations at 1.6, 5 and 15 GHz of a sample of faint Gigahertz Peaked Spectrum (GPS) sources selected from the Westerbork Northern Sky Survey (WENSS). The 5 GHz observations involved a global array…