arXiv subjects

D. Lemke

Publications and source records attributed to D. Lemke.

44 records · Page 3Linked to original sources

arXiv1999

The European Large Area ISO Survey: ELAIS

The European Large Area ISO Survey (ELAIS) has surveyed 12 square degrees of the sky at 15 and 90 microns, and subsets of this area at 6.75 and 175 microns, using the Infrared Space Observatory (ISO). This project was the largest single open time programme executed by ISO, taking 375 hours of data. A preliminary catalogue of more than 1000 galaxies has been produced. In this talk we describe the goals of the project, describe the follow-up programmes that are in progress, and present some first scientific results including a provisional number count analysis at 15 and 90 microns.

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arXiv1999

FIRBACK Far Infrared Survey with ISO: Data Reduction, Analysis and First Results

FIRBACK is one of the deepest cosmological surveys performed in the far infrared, using ISOPHOT. We describe this survey, its data reduction and analysis. We present the maps of fields at 175 microns. We point out some first results: source identifications with radio and mid infrared, and source counts at 175 microns. These two results suggest that half of the FIRBACK sources are probably at redshifts greater than 1. We also present briefly the large follow-up program.

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arXiv1998

Detection of widely distributed UIR band emission in the disk of NGC 891

The spectrum of the unidentified infrared (UIR) emission bands between 5.9 and 11.7 [micro]m has been observed for the first time in the disk of an external galaxy. We have used the low-resolution spectrometer of the ISOPHOT instrument aboard ISO. The UIR bands at 6.2, 7.7 and 11.3 [micro]m have absolute intensities which are similar to the values observed for the diffuse emission of our own Galaxy. The UIR bands between 5.9 and 11.7 [micro]m contribute ~9% of the total IR radiation of NGC 891. The intensity ratios and band widths in the NGC 891 disk emissions are similar to the diffuse emission of the Milky Way, pointing to a common carrier for the UIR bands in the two galaxies. However, there are some notable variations of the band ratios along the major axis of the galaxy.

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arXiv1998

A 1.4 GHz Survey of the Southern ELAIS Region

A deep survey of the European Large Area ISO Survey (ELAIS) field in the southern celestial hemisphere (hereinafter S1) has been carried out with the Australia Telescope Compact Array (ATCA) at 1.4 GHz. The S1 region, covering about 4 square degrees, has been also surveyed in the mid- and far-infrared (5-200 micron) with the Infrared Space Observatory (ISO). The radio survey provides uniform coverage of the entire S1 region, with a sensitivity (5 sigma) of 0.4 mJy over the whole area and 0.2 mJy in the center. To this sensitivity, virtually all the radio counterparts of the far-infrared extragalactic ISO sources should be detected. This paper presents a radio sample - complete at the 5 sigma level - consisting of 581 sources detected at 1.4 GHz. Of these radio sources, 349 have peak flux density in the range 0.2-1 mJy, forming a new homogeneous sample of sub-mJy radio sources. Due to its size, depth and multi-waveband coverage, the sample will allow us to study in greater detail the sub-mJy radio source population. The full catalogue will be available from http://athena.ph.ac.uk/

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arXiv1998

Isophot Observations of Comet Hale-Bopp: Initial Data Reduction

Comet Hale-Bopp was observed five times with ISOPHOT, the photometer on board the Infrared Space Observatory (ISO). Each time broadband photometry was performed using 4 different detectors, 5 apertures and, 10 filters covering the range between 3.6 to 175 $μ$m. Calibration measurements using the internal Fine Calibration Source were done together with each individual measurement. Background observations were performed with identical instrument settings at the same positions on the sky several days after the comet observations. The observation strategy and the initial data reduction steps are described in some detail and the resulting in-band power values of the Hale-Bopp observations and their uncertainties are derived. Initial reduction of these measurements was performed in 3 steps: (1) processing of raw data by removing instrumental and energetic particle effects, (2) averaging of the individual signals, and (3) determination of the detector responsivities and their uncertainties. The detector signal is determined by two different methods and the best value is chosen. At the present level of processing uncertainties range from 10% to a factor of 3 for the low power levels at short wavelengths. The in-band power levels at different wavelengths varied over 3 orders of magnitude.

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arXiv1998

The European Large Area ISO Survey - ISOPHOT results using the MPIA-pipeline

The European Large Area ISO Survey (ELAIS) will provide Infrared observations of 4 regions in the sky with ISO. Around 2000 Infrared sources have been detected at 7 and 15 microns (with ISOCAM), 90 and 175 microns (with ISOPHOT)) over 13 square degrees of the sky. We present the source extraction pipeline of the 90 microns ISOPHOT observations, describe and discuss the results obtained and derive the limits of the ELAIS observational strategy.

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arXiv1998

The FIRBACK 175 micron Survey

The FIRBACK project is a collaboration of eight institutes aimed at using long wavelength surveys with ISO to uncover the nature of the Cosmic Far-Infrared Background. We have surveyed nearly 4 sq. deg. in three regions in the northern and southern hemispheres with the ISOPHOT instrument on ISO, using the 175 micron filter. As reported by Puget et al. (1998) and Reach et al. (these proceedings), the first 0.25 sq. deg. region studied in this programme contains many more 175 micron sources than expected. Initial reduction of the remaining survey areas appears to confirm this result. The area surveyed by FIRBACK represents the largest and deepest long wavelength far-IR survey available before the launch of SIRTF.

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arXiv1998

A Deep VLA survey at 20cm of the ISO ELAIS survey regions

We have used the Very Large Array(VLA) in C configuration to carry out a sensitive 20cm radio survey of regions of sky that have been surveyed in the Far Infra-Red over the wavelength range 5-200 microns with ISO as part of the European Large Area ISO Survey(ELAIS). As usual in surveys based on a relatively small number of overlapping VLA pointings the flux limit varies over the area surveyed. The survey has a flux limit that varies from a 5$σ$ limit of 0.135mJy over an area of 0.12deg$^2$ to a 5$σ$ limit of 1.15mJy or better over the whole region covered of 4.22 deg$^2$. In this paper we present the radio catalogue of 867 sources. These regions of sky have previously been surveyed to shallow flux limits at 20cm with the VLA as part of the VLA D configuration NVSS(FWHM=45 arcsec) and VLA B configuration FIRST(FWHM=5 arcsec) surveys. We have carried out a a detailed comparison of the reliability of our own survey and these two independent surveys in order to assess the reliability and completeness of each survey.

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