Related papers: Photometric observations of selected, optically br…

We present preliminary source counts at 6.7um and 15um from the Preliminary Analysis of the European Large Area ISO survey, with limiting flux densities of \~2mJy at 15um & ~1mJy at 6.7um. We separate the stellar contribution from the…

We present the results of a massive variability search based on a photometric survey of a six square degree region along the Galactic plane at ($l = 305^\circ$, $b = -0.8^\circ$) and ($l = 330^\circ$, $b = -2.5^\circ$). This survey was…

We present a sample of 40 Ultra Steep Spectrum (USS, $\alpha \leq -1.3$, $S_{\nu}\propto \nu^{\alpha}$) radio sources selected from the Westerbork in the Southern Hemisphere (WISH) catalog. The USS sources have been imaged in K--band at the…

The Red MSX Source (RMS) survey is a multi-wavelength programme of follow-up observations designed to distinguish between genuine massive young stellar objects (MYSOs) and other embedded or dusty objects, such as ultra compact (UC) HII…

We present multiwavelength data for twelve blazars observed from 2008-2010 as part of an ongoing optical-infrared photometric monitoring project. Sources were selected to be bright, southern (dec < 20 deg) blazars observed by the Fermi…

We describe an ongoing optical spectrophotometric monitoring program of a sample of Fermi/LAT bright sources showing prominent and variable {\gamma}-ray emission, with the 2.1m telescope at Observatorio Astrof\'isico Guillermo Haro (OAGH)…

Using photometric variability information from the new Gaia DR3 release, I show for the first time that photometric variability is inversely correlated with the prevalence of optical-radio position offsets in the active galactic nuclei…

We present JHK near-infrared (NIR) spectroscopy of 25 candidate Type II quasars selected from the Sloan Digital Sky Survey, using Triplespec on the Apache Point Observatory 3.5m telescope, FIRE at the Magellan/Baade 6.5m telescope, and…

In this Letter, we present the initial characterization of extragalactic 24um sources in the Spitzer First Look Survey (FLS) by examining their counterparts at 8um and R-band. The color-color diagram of 24-to-8 vs. 24-to-0.7um is populated…

We describe a program to identify optical counterparts to radio sources from the VLA FIRST survey using the Cambridge APM scans of the POSS-I plates. We use radio observations covering 4150 square degrees of the north Galactic cap to a 20…

The detection of rapid variability on a time-scale of hours in radio-quiet quasars (RQQSOs) could be a powerful discriminator between starburst, accretion disc and relativistic jet models of these sources. This paper contains an account of…

We present a crossmatch between a combined catalog of X-ray sources and the Vera C. Rubin Observatory Data Preview 1 (DP1) to identify optical counterparts. The six fields targeted as part of DP1 include the Extended Chandra Deep Field…

The cross-correlation between the ROSAT all-sky survey (~150000 sources) and the Tycho mission (~1000000 stars) catalogs has selected about 14000 stellar X-ray sources (RasTyc sample, Guillout et al. 1999). About 200-300 stars have been…

Studies of young stellar objects (YSOs) in the Galaxy have found that a significant fraction exhibit photometric variability. However, no systematic investigation has been conducted on the variability of extragalactic YSOs. Here we present…

The third iteration of the International Celestial Reference Frame (ICRF3) is made up of 4536 quasars observed at S/X bands using Very Long baseline Interferometry (VLBI). These sources are high redshift quasars, typically between $1<z<2$,…

We present results from the photometric and spectroscopic identification of 122 X-ray sources discovered by XMM-Newton in the 2-10 keV band (the HELLAS2XMM 1dF sample). One of the most interesting results (which is found also in deeper…

We present a catalog of 792 DR5 SDSS quasars with optical spectra that have been observed serendipitously in the X-rays with the \emph{XMM-Newton}. These quasars cover a redshift range of z = 0.11 - 5.41 and a magnitude range of i =…

We present observational results for extragalactic radio sources with milliarcsecond components, obtained with the 600 meter ring radio telescope RATAN-600 from 1st to 22nd December, 1997. For each source, a six frequency broad band radio…

This paper presents the first results of a survey for bright quasars (V < 14.5 and R<15.4) covering the North Hemisphere at galactic latitudes |b|>30. The photometric database is derived from the GSC and USNO catalogs. Quasars are…

(Abridged) Photometry of archival Spitzer observations of the Large Magellanic Cloud (LMC) are used to search for young stellar objects (YSOs). Simple mid-infrared selection criteria were used to exclude most normal and evolved stars and…