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A Search for H 2O Maser Emission toward Active Galactic Nuclei: Discovery of a Nuclear Maser Source in NGC 3735
We report the results of a survey for H2O maser emission in the 616--523transition at 1.35 cm wavelength in 29 active galactic nuclei (AGNs).One new maser was detected. The detection rate among objects withrecessional velocities <7000 km s-1 is consistent with rates reportedelsewhere for similarly nearby objects (about one in 15). The new maserlies in the edge-on Seyfert 2 galaxy NGC 3735 (inclination 77 deg)within 10 km s-1 of the systemic velocity. No other emission has beenidentified at velocities within +/-500 km s-1 of the systemic velocity.The maser is coincident with the radio continuum peak of the nucleus at6 and 3.6 cm wavelengths to within the estimated 1 sigma astrometricuncertainty of 0."1 (15 pc at a distance of 30 Mpc).
| A Multiwavelength Catalog of Seyfert 2 Galaxies Observed in the 2--10 keV Energy Band
This paper is a catalog of Seyfert 2 galaxies observed in the 2-10 keVband (339 flux entries). In total, it contains data on 150 objects; for76 objects, a positive detection is reported, while for the remainingsources, 2 σ upper limits to the X-ray emission are given. Most ofthe data have been collected from the literature over a period startingfrom 1974 up to the middle of 1995. Accurate searches of literature anddatabases were performed for all objects, and frequently spectral fitswere reevaluated in order to make the data in the catalog uniform andcomplete. Some unpublished data are also included. For six objects,EXOSAT/ME date have been extracted from the satellite database andanalyzed; the 13 fluxes obtained have been added to the present catalog.The compilation of hard X-ray data has been complemented with data inthe soft (0.1-3 keV) X-ray band, as well as in ultraviolet (1450 A),optical (5500 A), infrared (3.5, 12, 25, 60, 100 micron), and radio (6cm) bands. Fluxes of the [O II] λ5007 and Hβ emission linesas well as the Balmer decrement Hα/Hβ, and axial ratio a/bare also given. The present database is meant to be a useful tool forthe study of the Seyfert 2 phenomenon in its various aspects.
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| X-ray and infrared selected AGN. II - Optical spectroscopy
In a search for obscured active galactic nuclei, 144 X-ray/IR emittinggalaxies were selected. Optical spectroscopy of this sample ispresented. A classification according to the nuclear activity shows that28 are AGN, 39 are transition-type objects, and 44 are H II region-likegalaxies. Three of the 28 AGN are Seyfert 1 galaxies and the others areof Type 2. It is suggested that the objects identified as narrow lineAGN are obscured Seyfert 1. Most of the observed galaxies are seenedge-on, indicating that dust may have a flattened distribution coplanarto the disk of the parent galaxy. With the inclusion of the newlyidentified AGN, the sample of the X-ray emitting Seyfert 2 galaxies isfairly complete above a flux limit of log F(Hx) = -10.8.
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