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NGC 7725



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Ultraviolet and Far-Infrared-selected Star-forming Galaxies at z=0: Differences and Overlaps
We study two samples of local galaxies, one UV (GALEX) selected and theother FIR (IRAS) selected, to address the question of whether UV and FIRsurveys see two sides (``bright'' and ``dark'') of the star formation ofthe same population of galaxies or two different populations ofstar-forming galaxies. No significant difference between theLtot (=L60+LFUV) luminosity functionsof the UV and FIR samples is found. In addition, after the correctionfor the ``Malmquist bias'' (bias for flux-limited samples), theFIR-to-UV ratio versus Ltot relations of the two samples areconsistent with each other. In the range of9<~log(Ltot/Lsolar)<~12, both can beapproximated by a simple linear relation oflog(L60/LFUV)=log(Ltot/Lsolar)-9.66.These are consistent with the hypothesis that the two samples representthe same population of star-forming galaxies, and their well-documenteddifferences in Ltot and in FIR-to-UV ratio are due only tothe selection effect. A comparison between the UV luminosity functionsshows marginal evidence for a population of faint UV galaxies missing inthe FIR-selected sample. The contribution from these ``FIR-quiet''galaxies to the overall UV population is insignificant, given that theK-band luminosity functions (i.e., the stellar mass functions) of thetwo samples do not show any significant difference.

The ISOPHOT 170 μm Serendipity Survey II. The catalog of optically identified galaxies%
The ISOPHOT Serendipity Sky Survey strip-scanning measurements covering≈15% of the far-infrared (FIR) sky at 170 μm were searched forcompact sources associated with optically identified galaxies. CompactSerendipity Survey sources with a high signal-to-noise ratio in at leasttwo ISOPHOT C200 detector pixels were selected that have a positionalassociation with a galaxy identification in the NED and/or Simbaddatabases and a galaxy counterpart visible on the Digitized Sky Surveyplates. A catalog with 170 μm fluxes for more than 1900 galaxies hasbeen established, 200 of which were measured several times. The faintest170 μm fluxes reach values just below 0.5 Jy, while the brightest,already somewhat extended galaxies have fluxes up to ≈600 Jy. For thevast majority of listed galaxies, the 170 μm fluxes were measured forthe first time. While most of the galaxies are spirals, about 70 of thesources are classified as ellipticals or lenticulars. This is the onlycurrently available large-scale galaxy catalog containing a sufficientnumber of sources with 170 μm fluxes to allow further statisticalstudies of various FIR properties.Based on observations with ISO, an ESA project with instruments fundedby ESA Member States (especially the PI countries: France, Germany, TheNetherlands and the UK) and with the participation of ISAS and NASA.Members of the Consortium on the ISOPHOT Serendipity Survey (CISS) areMPIA Heidelberg, ESA ISO SOC Villafranca, AIP Potsdam, IPAC Pasadena,Imperial College London.Full Table 4 and Table 6 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr ( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/39

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Observation and Astrometry data

Right ascension:23h39m14.70s
Aparent dimensions:0.871′ × 0.759′

Catalogs and designations:
Proper Names   (Edit)
NGC 2000.0NGC 7725

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