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PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5 m optical/infrared telescope to be located at Dome C on the Antarctic plateau. Conditions at Dome C are known to be exceptional for astronomy. The seeing (above ~30 m height), coherence time, and isoplanatic angle are all twice s good as at typical mid-latitude sites, while the water-vapour column, and the atmosphere and telescope thermal emission are all an order of magnitude better. These conditions enable a unique scientific capability for PILOT, which is addressed in this series of papers. The current paper presents an overview of the optical and instrumentation suite for PILO and its expected performance, a summary of the key science goals and observational approach for the facility, a discussion of the synergies between the science goals for PILOT and other telescopes, and a discussion of the future of Antarctic astronomy. Paper II and Paper III present details of the science projects divided, respectively, between the distant Universe (i.e., studies of first light, and the assembly and evolution of structure) and the nearby Universe (i.e., studies of Local Group galaxies, the Milky Way, and the Solar System)., Comment: 19 pages, 8 figures, accepted for publication in PASA more...

PILOT (the Pathfinder for an International Large Optical Telescope is a proposed 2.5 m optical/infrared telescope to be located at DomeC on the Antarctic plateau. The atmospheric conditions at Dome C deliver a high sensitivity, high photometric precision, wide-field, high spatial resolution, and high-cadence imaging capability to the PILOT telescope. These capabilities enable a unique scientific potential for PILOT, which is addressed in this series of papers. The current paper presents a series of projects dealing with the nearby Universe that have been identified as key science drivers for the PILOT facility. Several projects are proposed that examine stellar populations in nearby galaxies and stellar clusters in order to gain insight into the formation and evolution processes of galaxies and stars. A series of projects will investigate the molecular phase of the Galaxy and explore the ecology of star formation, and investigate the formation processes of stellar and planetary systems. Three projects in the field of exoplanet science are proposed: a search for free-floating low-mass planets and dwarfs, a program of follow-up observations of gravitational microlensing events, and a study of infrared light-curves for previously discovered exoplanets. Three projects are also proposed in the field of planetary and space science: optical and near-infrared studies aimed at characterising planetary atmospheres, a study of coronal mass ejections from the Sun, and a monitoring program searching for small-scale Low Earth Orbit satellite debris items., Comment: 27 pages, 16 figures (degraded quality), accepted for publication in PASA more...

PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5 m optical/infrared telescope to be located at Dome C on the Antarctic plateau. Conditions at Dome C are known to be exceptional for astronomy. The seeing (above ~30 m height), coherence time, and isoplanatic angle are all twice s good as at typical mid-latitude sites, while the water-vapour column, and the atmosphere and telescope thermal emission are all an order of magnitude better. These conditions enable a unique scientific capability for PILOT, which is addressed in this series of papers. The current paper presents an overview of the optical and instrumentation suite for PILO and its expected performance, a summary of the key science goals and observational approach for the facility, a discussion of the synergies between the science goals for PILOT and other telescopes, and a discussion of the future of Antarctic astronomy. Paper II and Paper III present details of the science projects divided, respectively, between the distant Universe (i.e., studies of first light, and the assembly and evolution of structure) and the nearby Universe (i.e., studies of Local Group galaxies, the Milky Way, and the Solar System)., Comment: 19 pages, 8 figures, accepted for publication in PASA more...

PILOT (the Pathfinder for an International Large Optical Telescope is a proposed 2.5 m optical/infrared telescope to be located at DomeC on the Antarctic plateau. The atmospheric conditions at Dome C deliver a high sensitivity, high photometric precision, wide-field, high spatial resolution, and high-cadence imaging capability to the PILOT telescope. These capabilities enable a unique scientific potential for PILOT, which is addressed in this series of papers. The current paper presents a series of projects dealing with the nearby Universe that have been identified as key science drivers for the PILOT facility. Several projects are proposed that examine stellar populations in nearby galaxies and stellar clusters in order to gain insight into the formation and evolution processes of galaxies and stars. A series of projects will investigate the molecular phase of the Galaxy and explore the ecology of star formation, and investigate the formation processes of stellar and planetary systems. Three projects in the field of exoplanet science are proposed: a search for free-floating low-mass planets and dwarfs, a program of follow-up observations of gravitational microlensing events, and a study of infrared light-curves for previously discovered exoplanets. Three projects are also proposed in the field of planetary and space science: optical and near-infrared studies aimed at characterising planetary atmospheres, a study of coronal mass ejections from the Sun, and a monitoring program searching for small-scale Low Earth Orbit satellite debris items., Comment: 27 pages, 16 figures (degraded quality), accepted for publication in PASA more...

The Gattini cameras are two site testing instruments for the measurement of optical sky brightness, large area cloud cover and auroral detection of the night sky above the high altitude Dome C site in Antarctica. The cameras have been operating since installation in January 2006 and are currently at the end of the first Antarctic winter season. The cameras are transit in nature and are virtually identical both adopting Apogee Alta CCD detectors. By taking frequent images of the night sky we obtain long term cloud cover statistics, measure the sky background intensity as a function of solar and lunar altitude and phase and directly measure the spatial extent of bright aurora if present and when they occur. The full data set will return in December 2006 however a limited amount of data has been transferred via the Iridium network enabling preliminary data reduction and system evaluation. An update of the project is presented together with preliminary results from data taken since commencement of the winter season. more...

We report the discovery of a new M9.0 dwarf at only 8.2 pc, which we identified in our search for nearby ultracool dwarf (I - J ≥ 3.0, later than M8.0) in the DENIS data base. We measure a very high proper motion of 2.5 arcsec yr-1. The PC3 index measur more...

We report the discovery of a new M9.0 dwarf at only 8.2 pc, which we identified in our search for nearby ultracool dwarf (I-J >= 3.0, later than M8.0) in the DENIS database. We measure a very high proper motion of 2.5 arc-sec/yr. The PC3 index measured from its low-resolution spectrum gives a spectrophotometric distance of 8.2 pc. This makes it the third closest M9.0 dwarf., Comment: revised version, accepted by MNRAS Letters more...

We report the discovery of a new M9.0 dwarf at only 8.2 pc, which we identified in our search for nearby ultracool dwarf (I-J >= 3.0, later than M8.0) in the DENIS database. We measure a very high proper motion of 2.5 arc-sec/yr. The PC3 index measured from its low-resolution spectrum gives a spectrophotometric distance of 8.2 pc. This makes it the third closest M9.0 dwarf., Comment: revised version, accepted by MNRAS Letters more...

The ISOGAL project is an infrared survey of specific regions sampling the Galactic Plane selected to provide information on Galactic structure,stellar populations,stellar mass-loss and the recent star formation history of the inner disk and Bulge of the Galaxy. ISOGAL combines 7 and 15 micron ISOCAM observations - with a resolution of 6'' at worst - with DENIS IJKs data to determine the nature of the sources and theinterstellar extinction. We have observed about 16 square degrees with a sensitivity approaching 10-20mJy, detecting ~10^5 sources,mostly AGB stars,red giants and young stars. The main features of the ISOGAL survey and the observations are summarized in this paper,together with a brief discussion of data processing and quality. The primary ISOGAL products are described briefly (a full description is given in Schuller et al. 2003, astro-ph/0304309): viz. the images and theISOGAL-DENIS five-wavelength point source catalogue. The main scientific results already derived or in progress are summarized. These include astrometrically calibrated 7 and 15um images,determining structures of resolved sources; identification and properties of interstellar dark clouds; quantification of the infrared extinction law and source dereddening; analysis of red giant and (especially) AGB stellar populations in the central Bulge,determining luminosity,presence of circumstellar dust and mass--loss rate,and source classification,supplemented in some cases by ISO/CVF spectroscopy; detection of young stellar objects of diverse types,especially in the inner Bulge with information about the present and recent star formation rate; identification of foreground sources with mid-IR excess. These results are the subject of about 25 refereed papers published or in preparation., Comment: A&A in press. 19 pages,10 Ps figures; problems with figures fixed more...

This paper reports updated results on our systematic mining of the DENIS database for nearby very cool M-dwarfs (M6V-M8V, 2.0ate="" the="" denis="" (m_i,="" i-j)="" colour-luminosity="" relationship="" from="" m="" dwarfs="" with="" well="" measured="" parallaxes="" (hip,="" gctp,...),="" obtaining="" errors="" for="" single="" of="" 25%.="" using="" proper="" motions="" on="" archive="" schmidt="" plates="" stars="" that="" meet="" selection="" criteria,="" eliminate="" giants="" by="" a="" reduced="" motion="" cutoff,="" which="" is="" significantly="" more="" selective="" than="" simple="" cutoff.="" here="" present="" new="" data="" 62="" red="" dwarf="" candidates="" selected="" over="" 5700="" square="" degrees="" in="" database.="" 26="" those="" originate="" 2100="" analysed="" paper="" i,="" improved="" parameters="" here,="" and="" 36="" were="" found="" 3600="" additional="" degrees.="" 25="" are="" nearby="" dwarfs.="" determine="" sample="" stellar="" density="" 12.0 more...

The ISOGAL project is an infrared survey of specific regions sampling the Galactic Plane selected to provide information on Galactic structure,stellar populations,stellar mass-loss and the recent star formation history of the inner disk and Bulge of the Galaxy. ISOGAL combines 7 and 15 micron ISOCAM observations - with a resolution of 6'' at worst - with DENIS IJKs data to determine the nature of the sources and theinterstellar extinction. We have observed about 16 square degrees with a sensitivity approaching 10-20mJy, detecting ~10^5 sources,mostly AGB stars,red giants and young stars. The main features of the ISOGAL survey and the observations are summarized in this paper,together with a brief discussion of data processing and quality. The primary ISOGAL products are described briefly (a full description is given in Schuller et al. 2003, astro-ph/0304309): viz. the images and theISOGAL-DENIS five-wavelength point source catalogue. The main scientific results already derived or in progress are summarized. These include astrometrically calibrated 7 and 15um images,determining structures of resolved sources; identification and properties of interstellar dark clouds; quantification of the infrared extinction law and source dereddening; analysis of red giant and (especially) AGB stellar populations in the central Bulge,determining luminosity,presence of circumstellar dust and mass--loss rate,and source classification,supplemented in some cases by ISO/CVF spectroscopy; detection of young stellar objects of diverse types,especially in the inner Bulge with information about the present and recent star formation rate; identification of foreground sources with mid-IR excess. These results are the subject of about 25 refereed papers published or in preparation., Comment: A&A in press. 19 pages,10 Ps figures; problems with figures fixed more...

This paper reports updated results on our systematic mining of the DENIS database for nearby very cool M-dwarfs (M6V-M8V, 2.0ate="" the="" denis="" (m_i,="" i-j)="" colour-luminosity="" relationship="" from="" m="" dwarfs="" with="" well="" measured="" parallaxes="" (hip,="" gctp,...),="" obtaining="" errors="" for="" single="" of="" 25%.="" using="" proper="" motions="" on="" archive="" schmidt="" plates="" stars="" that="" meet="" selection="" criteria,="" eliminate="" giants="" by="" a="" reduced="" motion="" cutoff,="" which="" is="" significantly="" more="" selective="" than="" simple="" cutoff.="" here="" present="" new="" data="" 62="" red="" dwarf="" candidates="" selected="" over="" 5700="" square="" degrees="" in="" database.="" 26="" those="" originate="" 2100="" analysed="" paper="" i,="" improved="" parameters="" here,="" and="" 36="" were="" found="" 3600="" additional="" degrees.="" 25="" are="" nearby="" dwarfs.="" determine="" sample="" stellar="" density="" 12.0 more...

We present 30 new nearby (d<30 pc) red dwarf candidates, with estimated spectral types M6 to M8. 26 were directly selected from the DENIS database, and another 4 were first extracted from the LHS catalogue and cross-identified with a DENIS counterpart. Their proper motions were measured on the MAMA measuring machine from plates spanning 13 to 48 years, and are larger than 0.1 arcsec/yr, ruling out the possibility that they are giants. Their distances were estimated from the DENIS colours and IR colour-magnitude relations and range between 15 and 30 pc., Comment: Accepted in Astronomy and Astrophysics more...

By cross-correlating the results of two recent large-scale surveys, the general properties of a well defined sample of semi-regular variable stars have been determined. ISOGAL mid-infrared photometry and MACHO lightcurves are assembled for approximately 300 stars in the Baade's Windows of low extinction towards the Galactic bulge. These stars are mainly giants of late M spectral type, evolving along the asymptotic giant branch (AGB). They are found to possess a wide and continuous distribution of pulsation periods and to obey an approximate log~period -- bolometric magnitude relation or set of such relations. Approximate mass-loss rates in the range of 1e-8 to 5e-7 M_sun per year are derived from ISOGAL mid-infrared photometry and models of stellar spectra adjusted for the presence of optically-thin circumstellar silicate dust. Mass-loss rates depend on luminosity and pulsation period. Some stars lose mass as rapidly as short-period Miras but do not show Mira-like amplitudes. A period of 70 days or longer is a necessary but not a sufficient condition for mass loss to occur. For AGB stars in the mass-loss ranges that we observe, the functional dependence of mass-loss rate on temperature and luminosity is found to be in agreement with recent theoretical predictions. If we include our mass-loss rates with a sample of extreme mass-losing AGB stars in the Large Magellanic Cloud, we get the general result for AGB stars that mass-loss rate is proportional to luminosity^{2.7}, valid for AGB stars with 10^{-8} to 10^{-4} M_sun per year (Abridged)., Comment: to appear in The Astrophysical Journal, 51 pages, 9 figures, 3 tables; table 1 will be available in machine-readable format at the electronic ApJ more...

We present 30 new nearby (d<30 pc) red dwarf candidates, with estimated spectral types M6 to M8. 26 were directly selected from the DENIS database, and another 4 were first extracted from the LHS catalogue and cross-identified with a DENIS counterpart. Their proper motions were measured on the MAMA measuring machine from plates spanning 13 to 48 years, and are larger than 0.1 arcsec/yr, ruling out the possibility that they are giants. Their distances were estimated from the DENIS colours and IR colour-magnitude relations and range between 15 and 30 pc., Comment: Accepted in Astronomy and Astrophysics more...

By cross-correlating the results of two recent large-scale surveys, the general properties of a well defined sample of semi-regular variable stars have been determined. ISOGAL mid-infrared photometry and MACHO lightcurves are assembled for approximately 300 stars in the Baade's Windows of low extinction towards the Galactic bulge. These stars are mainly giants of late M spectral type, evolving along the asymptotic giant branch (AGB). They are found to possess a wide and continuous distribution of pulsation periods and to obey an approximate log~period -- bolometric magnitude relation or set of such relations. Approximate mass-loss rates in the range of 1e-8 to 5e-7 M_sun per year are derived from ISOGAL mid-infrared photometry and models of stellar spectra adjusted for the presence of optically-thin circumstellar silicate dust. Mass-loss rates depend on luminosity and pulsation period. Some stars lose mass as rapidly as short-period Miras but do not show Mira-like amplitudes. A period of 70 days or longer is a necessary but not a sufficient condition for mass loss to occur. For AGB stars in the mass-loss ranges that we observe, the functional dependence of mass-loss rate on temperature and luminosity is found to be in agreement with recent theoretical predictions. If we include our mass-loss rates with a sample of extreme mass-losing AGB stars in the Large Magellanic Cloud, we get the general result for AGB stars that mass-loss rate is proportional to luminosity^{2.7}, valid for AGB stars with 10^{-8} to 10^{-4} M_sun per year (Abridged)., Comment: to appear in The Astrophysical Journal, 51 pages, 9 figures, 3 tables; table 1 will be available in machine-readable format at the electronic ApJ more...

We present the discovery of a previously unknown member of the immediate solar neighbourhood, DENIS-P J104814.7-395606.1 (hereafter DENIS 1048-39), identified while mining the DENIS database for new nearby stars. A HIRES echelle spectrum obtained with the 10-m Keck telescope shows that it is an M9 dwarf. DENIS 1048-39 has a very bright apparent magnitude (I=12.67) for its spectral type and colour (I-J=3.07), and is therefore very nearby. If it is single its distance is only 4.1 +- 0.6pc, ranking it as between our twelfth and fortyth closest neighbour. It is also the closest star or brown dwarf with a spectral type later than M7V. Its proper motion was determined through comparison of Sky atlas Schmidt plates, scanned by the MAMA microdensitometer, with the DENIS images. At 1.53"/yr it further attests the closeness of DENIS 1048-39, and hence its dwarf status. These characteristics make it an obvious target for further detailed studies., Comment: In press in A&A Letters more...

We have compiled the near infrared Point Source Catalogue (PSC) towards the Magellanic Clouds (MCs) extracted from the data obtained with the Deep Near Infrared Survey of the Southern Sky - DENIS (Epchtein et al. 1997). The catalogue covers an area of of 19.87* 16 square degrees centered on (RA, DEC)=(5h27m20s, -69o00'00'') for the Large Magellanic Cloud (LMC) and 14.7* 10 square degrees centered on (RA, DEC)=(h02m40s, -73o00'00'' for the Small Magellanic Cloud (SMC) at the epoch J2000. It contains about 1300000 sources towards the LMC and 300000 sources towards the SMC each detected in at least 2 of the 3 photometric bands involved in the survey (I, J, Ks). 70% of the detected sources are true members of the Magellanic Clouds, respectively and consist mainly of red giants, asymptotic giant branch stars and super-giants. The observations have all been made with the same instrument and the data have been calibrated and reduced uniformly. The catalogue provides a homogeneous set of photometric data., Comment: 1 figure changed, published more...

We present the discovery of a previously unknown member of the immediate solar neighbourhood, DENIS-P J104814.7-395606.1 (hereafter DENIS 1048-39), identified while mining the DENIS database for new nearby stars. A HIRES echelle spectrum obtained with the 10-m Keck telescope shows that it is an M9 dwarf. DENIS 1048-39 has a very bright apparent magnitude (I=12.67) for its spectral type and colour (I-J=3.07), and is therefore very nearby. If it is single its distance is only 4.1 +- 0.6pc, ranking it as between our twelfth and fortyth closest neighbour. It is also the closest star or brown dwarf with a spectral type later than M7V. Its proper motion was determined through comparison of Sky atlas Schmidt plates, scanned by the MAMA microdensitometer, with the DENIS images. At 1.53"/yr it further attests the closeness of DENIS 1048-39, and hence its dwarf status. These characteristics make it an obvious target for further detailed studies., Comment: In press in A&A Letters more...

We have compiled the near infrared Point Source Catalogue (PSC) towards the Magellanic Clouds (MCs) extracted from the data obtained with the Deep Near Infrared Survey of the Southern Sky - DENIS (Epchtein et al. 1997). The catalogue covers an area of of 19.87* 16 square degrees centered on (RA, DEC)=(5h27m20s, -69o00'00'') for the Large Magellanic Cloud (LMC) and 14.7* 10 square degrees centered on (RA, DEC)=(h02m40s, -73o00'00'' for the Small Magellanic Cloud (SMC) at the epoch J2000. It contains about 1300000 sources towards the LMC and 300000 sources towards the SMC each detected in at least 2 of the 3 photometric bands involved in the survey (I, J, Ks). 70% of the detected sources are true members of the Magellanic Clouds, respectively and consist mainly of red giants, asymptotic giant branch stars and super-giants. The observations have all been made with the same instrument and the data have been calibrated and reduced uniformly. The catalogue provides a homogeneous set of photometric data., Comment: 1 figure changed, published more...

DENIS observations in the J (1.2 micron) and K_S (2.15 micron) bands together with isochrones calculated for the RGB and AGB phase are used to draw an extinction map of the inner Galactic Bulge. The uncertainty in this method is mainly limited by the optical depth of the Bulge itself. A comparison with fields of known extinction shows a very good agreement. We present an extinction map for the inner Galactic Bulge (approx. 20 sq. deg.), Comment: 4 pages, 4 figures, accepted for publication in A&A as a letter, see also http://www-denis.iap.fr/articles/extinction more...

This paper presents the first I-band photometric catalog of the brightest galaxies extracted from the Deep Near Infrared Survey of the Southern Sky (DENIS) An automatic galaxy recognition program has been developed to build this provisional catalog. The method is based on a discriminating analysis. The most discriminant parameter to separate galaxies from stars is proved to be the peak intensity of an object divided by its array. Its efficiency is better than 99%. The nominal accuracy for galaxy coordinates calculated with the Guide Star Catalog is about 6 arcseconds. The cross-identification with galaxies available in the Lyon-Meudon Extragalactic DAtabase (LEDA) allows a calibraton of the I-band photometry with the sample of Mathewson et Al. Thus, the catalog contains total I-band magnitude, isophotal diameter, axis ratio, position angle and a rough estimate of the morphological type code for 20260 galaxies. The internal completeness of this catalog reaches magnitude $I_{lim}=14.5$, with a photometric accuracy of $\sim 0.18m$. 25% of the Southern sky has been processed in this study. This quick look analysis allows us to start a radio and spectrographic follow-up long before the end of the survey., Comment: 13 pages, 17 figures, to appear A&A Supl. S more...

DENIS observations in the J (1.2 micron) and K_S (2.15 micron) bands together with isochrones calculated for the RGB and AGB phase are used to draw an extinction map of the inner Galactic Bulge. The uncertainty in this method is mainly limited by the optical depth of the Bulge itself. A comparison with fields of known extinction shows a very good agreement. We present an extinction map for the inner Galactic Bulge (approx. 20 sq. deg.), Comment: 4 pages, 4 figures, accepted for publication in A&A as a letter, see also http://www-denis.iap.fr/articles/extinction more...

The ISOGAL project is a survey of the stellar populations, structure, and recent star formation history of the inner disk and bulge of the Galaxy. ISOGAL combines 15 and 7micron ISOCAM observations with DENIS IJKs data to determine the nature of a source and the interstellar extinction. In this paper we report an ISOGAL study of a small field in the inner Galactic Bulge (l=0deg, b=1.0deg, area=0.035 sq. deg) as a prototype of the larger area ISOGAL survey of the inner Galaxy. The five wavelengths of ISOGAL+DENIS, together with the relatively low and constant extinction in front of this specific field, allow reliable determination of the nature of the sources. The primary scientific result of this paper is evidence that the most numerous class of ISOGAL 15micron sources are Red Giants in the Galactic bulge and central disk, with luminosities just above or close to the RGB tip and weak mass-loss rates. They form loose sequences in the magnitude-colour diagrams [15]/Ks-[15] and [15]/[7]-[15]. Their large excesses at 15micron with respect to 2micron and 7micron is due to circumstellar dust produced by mass-loss at low rates. These ISOGAL results are the first systematic evidence and study of dust emission at this early stage (''Intermediate'' AGB), before the onset of the large mass-loss phase. It is thus well established that efficient dust formation is already associated with such low mass-loss rates during this early phase., Comment: 15 pages, 9 figures, accepted for publication in Astronomy and Astrophysics Journal more...

This paper presents the first I-band photometric catalog of the brightest galaxies extracted from the Deep Near Infrared Survey of the Southern Sky (DENIS) An automatic galaxy recognition program has been developed to build this provisional catalog. The method is based on a discriminating analysis. The most discriminant parameter to separate galaxies from stars is proved to be the peak intensity of an object divided by its array. Its efficiency is better than 99%. The nominal accuracy for galaxy coordinates calculated with the Guide Star Catalog is about 6 arcseconds. The cross-identification with galaxies available in the Lyon-Meudon Extragalactic DAtabase (LEDA) allows a calibraton of the I-band photometry with the sample of Mathewson et Al. Thus, the catalog contains total I-band magnitude, isophotal diameter, axis ratio, position angle and a rough estimate of the morphological type code for 20260 galaxies. The internal completeness of this catalog reaches magnitude $I_{lim}=14.5$, with a photometric accuracy of $\sim 0.18m$. 25% of the Southern sky has been processed in this study. This quick look analysis allows us to start a radio and spectrographic follow-up long before the end of the survey., Comment: 13 pages, 17 figures, to appear A&A Supl. S more...

This paper presents an analysis of the nature of point sources discovered by DENIS in an area of 1.5 x 3 degrees around the Chamaeleon I molecular cloud. Most of the 30000 objects detected in the J band are background stars that were previously used to derive an accurate extinction map of the full area (Cambresy et al., 1997) using star count method. In the present work, we investigate the young stellar population of the cloud using the IJK photometric DENIS data. The whole sample of 126 already known YSOs, which are mainly T Tauri stars, are identified in the DENIS catalogue. Besides, we propose 54 sources as new candidates of YSOs. These new faint objects are selected according to their extremely red near infrared colour, that cannot be explained only by the reddening of the cloud. Moreover they are concentrated near to the most obscured areas of the cloud. Although spectroscopic confirmation is badly requested, they are interpreted as probable classical T Tauri stars that have escaped previous spectroscopic, IRAS or X-ray observations and pertaining to the low-end of the luminosity function. Assuming that they are reliable YSOs with massive accretion disks, and using theoretical pre-main-sequence tracks we estimate the age of this sample to be ranging from 5 10^5 to 4 10^6 years, an elapse of time that spans the range between the end of the star formation in the cloud and the maximum life time of the circumstellar disk., Comment: 12 pages, 8 figures, accepted in A&A more...

We have begun to look for low-mass stars and brown dwarfs using data from the 2MASS Prototype Cameras. Reported here are some very early, yet very encouraging, results which demonstrate the ease with which 2MASS will uncover missing, very cool members of the solar neighborhood. more...

This paper presents an analysis of the nature of point sources discovered by DENIS in an area of 1.5 x 3 degrees around the Chamaeleon I molecular cloud. Most of the 30000 objects detected in the J band are background stars that were previously used to derive an accurate extinction map of the full area (Cambresy et al., 1997) using star count method. In the present work, we investigate the young stellar population of the cloud using the IJK photometric DENIS data. The whole sample of 126 already known YSOs, which are mainly T Tauri stars, are identified in the DENIS catalogue. Besides, we propose 54 sources as new candidates of YSOs. These new faint objects are selected according to their extremely red near infrared colour, that cannot be explained only by the reddening of the cloud. Moreover they are concentrated near to the most obscured areas of the cloud. Although spectroscopic confirmation is badly requested, they are interpreted as probable classical T Tauri stars that have escaped previous spectroscopic, IRAS or X-ray observations and pertaining to the low-end of the luminosity function. Assuming that they are reliable YSOs with massive accretion disks, and using theoretical pre-main-sequence tracks we estimate the age of this sample to be ranging from 5 10^5 to 4 10^6 years, an elapse of time that spans the range between the end of the star formation in the cloud and the maximum life time of the circumstellar disk., Comment: 12 pages, 8 figures, accepted in A&A more...

We present the analysis of three colour optical/near-infrared images, in IJK, taken for the DENIS project. The region considered covers 17.4 square deg and lies within |l|<5 deg, |b|<1.5 deg. The adopted methods for deriving photometry and astrometry in these crowded images, together with an analysis of the deficiencies nevertheless remaining, are presented. The numbers of objects extracted in I,J and K are 748000, 851000 and 659000 respectively, to magnitude limits of 17,15 and 13. 80% completeness levels typically fall at magnitudes 16, 13 and 10 respectively, fainter by about 2 magnitudes than the usual DENIS limits due to the crowded nature of these fields. A simple model to describe the disk contribution to the number counts is constructed, and parameters for the dust layer derived. We find that a formal fit of parameters for the dust plane, from these data in limited directions, gives a scalelength and scaleheight of 3.4+-1.0 kpc and 40+-5 pc respectively, and a solar position 14.0+-2.5 pc below the plane. This latter value is likely to be affected by localised dust asymmetries. We convolve a detailed model of the systematic and random errors in the photometry with a simple model of the Galactic disk and dust distribution, to simulate expected colour-magnitude diagrams. These are in good agreement with the observed diagrams, allowing us to isolate those stars from the inner disk and bulge. After correcting for local dust-induced asymmetries, we find evidence for longitude-dependent asymmetries in the distant J and K sources, consistent with the general predictions of some Galactic bar models. We consider complementary L-band observations in a second paper., Comment: 14 pages, 33 figures, LaTeX, MNRAS accepted more...

Massive, large scale star counts in the J band provided by the Deep Near Infrared Survey of the Southern Sky (DENIS) are used for the first time to draw out an extinction map of the Chamaeleon I dark cloud. We derived a 2 arcminutes resolution map of the cloud from J star counts within an area of 1.5 x 3 degres around the centre of the cloud using an adaptive grid method and applying a wavelet decomposition. A comparison of our extinction map with the cold contribution of the IRAS 100 microns emission shows an almost perfect matching. It is shown that J star counts supersede optical counts on Schmidt plate where Av > 4., Comment: 4 pages, accepted for publication in Astronomy & Astrophysics Letters more...

The Two Micron All Sky Survey (2MASS) will begin operations in the spring of 1997 (Skrutskie et al., this volume). The Infrared Processing and Analysis Center (IPAC) is tasked with processing ~30 GB of data that will be obtained each night by the northern and southern telescopes during the survey. The goal of this processing is to produce three primary data products: 1) the 2MASS Image Atlas that will contain ~ 10⁶ 512 x 1024 (1″/pix) images in J,H and K_s, 2) the 2MASS Point Source Catalog containing accurate astrometry and photometry for ~ 10⁸ point sources, and 3) the 2MASS Extended Source Catalog that will contain accurate positions, photometry and morphological information for ~ 10⁶ small extended sources. more...

We present the analysis of three colour optical/near-infrared images, in IJK, taken for the DENIS project. The region considered covers 17.4 square deg and lies within |l|<5 deg, |b|<1.5 deg. The adopted methods for deriving photometry and astrometry in these crowded images, together with an analysis of the deficiencies nevertheless remaining, are presented. The numbers of objects extracted in I,J and K are 748000, 851000 and 659000 respectively, to magnitude limits of 17,15 and 13. 80% completeness levels typically fall at magnitudes 16, 13 and 10 respectively, fainter by about 2 magnitudes than the usual DENIS limits due to the crowded nature of these fields. A simple model to describe the disk contribution to the number counts is constructed, and parameters for the dust layer derived. We find that a formal fit of parameters for the dust plane, from these data in limited directions, gives a scalelength and scaleheight of 3.4+-1.0 kpc and 40+-5 pc respectively, and a solar position 14.0+-2.5 pc below the plane. This latter value is likely to be affected by localised dust asymmetries. We convolve a detailed model of the systematic and random errors in the photometry with a simple model of the Galactic disk and dust distribution, to simulate expected colour-magnitude diagrams. These are in good agreement with the observed diagrams, allowing us to isolate those stars from the inner disk and bulge. After correcting for local dust-induced asymmetries, we find evidence for longitude-dependent asymmetries in the distant J and K sources, consistent with the general predictions of some Galactic bar models. We consider complementary L-band observations in a second paper., Comment: 14 pages, 33 figures, LaTeX, MNRAS accepted more...

Massive, large scale star counts in the J band provided by the Deep Near Infrared Survey of the Southern Sky (DENIS) are used for the first time to draw out an extinction map of the Chamaeleon I dark cloud. We derived a 2 arcminutes resolution map of the cloud from J star counts within an area of 1.5 x 3 degres around the centre of the cloud using an adaptive grid method and applying a wavelet decomposition. A comparison of our extinction map with the cold contribution of the IRAS 100 microns emission shows an almost perfect matching. It is shown that J star counts supersede optical counts on Schmidt plate where Av > 4., Comment: 4 pages, accepted for publication in Astronomy & Astrophysics Letters more...

Cosmic Microwave Background observations became the tool to probe the the first events of cosmic history. After WMAP data releases, galactic and extragalactic foregrounds are perceived as the main limiting uncertainity for the near-future search for the B-mode polarization inprints from the inflationary era, either through satellites or ground-based experiments like Brain at Dome-C. A combination of technology, scanning strategy and above all, accurate knowledge of polarized foregrounds will be necessary for an optimal mapping of B-mode CMB Polarization. In addition, the search for a better understanding of the galactic foregrounds will provide unprecedented knowledge on the Milky Way structure and star formation. more...

We summarize the results of the Cosmic Microwave Background (CMB) working group of the ARENA project. The focus has been on precision measurements of CMB polarization (looking for the echoes of cosmological inflation) and high angular resolution CMB measurements (looking for Sunyaev Zeldovich effect in distant clusters of Galaxies, to probe the evolution of the Universe, Dark Matter and Dark Energy). For both projects the Dome C site represents the best choice worldwide. more...