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The Canadian Galactic Plane Survey - Phase 2
Journal of the Royal Astronomical Society of Canada, 1999
The Dominion Radio Astrophysical Observatory (DRAO) is carrying out a survey as part of an international collaboration to image the northern Milky Way, at a common resolution, in emission from all major constituents of the interstellar medium; the neutral atomic gas, the molecular gas, the ionised gas, dust and relativistic plasma. For many of these constituents the angular resolution of the images (1 arcmin) will be more than a factor of 10 better than any previous studies. The aim is to produce a publicly-available database of high resolution, high-dynamic range images of the Galaxy for multi-phase studies of the physical states and processes in the interstellar medium. We will sketch the main scientific motivations as well as describe some preliminary results from the Canadian Galactic Plane Survey/Releve Canadien du Plan Galactique (CGPS/RCPG).
The UKIDSS Galactic Plane Survey
Monthly Notices of the Royal Astronomical Society, 2008
The UKIDSS Galactic Plane Survey (GPS) is one of the five near infrared Public Legacy Surveys that are being undertaken by the UKIDSS consortium, using the Wide Field Camera on the United Kingdom Infrared Telescope. It is surveying 1868 deg 2 of the northern and equatorial Galactic plane at Galactic latitudes −5 • < b < 5 • in the J, H and K filters and a ∼ 200 deg 2 area of the Taurus-Auriga-Perseus molecular cloud complex in these three filters and the 2.12 µm (1-0) H 2 filter. It will provide data on ∼ 2 × 10 9 sources. Here we describe the properties of the dataset and provide a user's guide for its exploitation. We also present brief Demonstration Science results from DR2 and from the Science Verification programme. These results illustrate how GPS data will frequently be combined with data taken in other wavebands to produce scientific results. The Demonstration Science comprises six studies. (1) A GPS-Spitzer-GLIMPSE cross match for the star formation region G28.983-0.603 to identify YSOs. This increases the number of YSOs identified by a factor of ten compared to GLIMPSE alone. (2) A wide field study of the M17 nebula, in which an extinction map of the field is presented and the effect of source confusion on luminosity functions in different sub-regions is noted. (3) H 2 emission in the ρ Ophiuchi dark cloud. All the molecular jets are traced back to a single active clump containing only a few protostars, which suggests that the duration of strong jet activity and associated rapid accretion in low mass protostars is brief. (4) X-ray sources in the Nuclear Bulge. The GPS data distinguishes local main sequence counterparts with soft X-ray spectra from Nuclear Bulge giant counterparts with hard X-ray spectra. (5) External galaxies in the Zone of Avoidance. The galaxies are clearly distinguished from stars in fields at longitudes l>90 • . (6) IPHAS-GPS optical-infrared spectrophotometric typing. The (i'-J) vs.(J-H) diagram is used to distinguish A-F type dwarfs, G dwarfs, K dwarfs and red clump giants in a field with high reddening.
The Southern Galactic Plane Survey: H i Observations and Analysis
The Astrophysical Journal Supplement Series, 2005
We describe the H i component of the Southern Galactic Plane Survey (SGPS). The SGPS is a large-scale project to image at arcminute resolution the H i spectral line and 21 cm continuum emission in parts of the plane of the Milky Way. The survey covers Galactic longitudes 253 • ≤ l ≤ 358 • and latitudes |b| ≤ 1. • 5 (SGPS I), plus a first quadrant extension covering 5 • ≤ l ≤ 20 • and |b| ≤ 1. • 5 (SGPS II). The survey combines data from the Australia Telescope Compact Array and the Parkes Radio Telescope for sensitivity to angular scales ranging from 2 arcminutes to several degrees. The combined data cover 325 deg 2 and have an rms sensitivity of 1.6 K. Here we describe the H i observations and data reduction in detail, and present examples from the final data products. The complete dataset is publicly available through the Australia Telescope National Facility's H i Surveys archive. This dataset provides an unprecedented view of the neutral component of interstellar hydrogen in the inner Milky Way.
Hi-GAL: The Herschel Infrared Galactic Plane Survey
Publications of the Astronomical Society of the Pacific, 2010
Aims. We present the first public release of high-quality data products (DR1) from Hi-GAL, the Herschel infrared Galactic Plane Survey. Hi-GAL is the keystone of a suite of continuum Galactic plane surveys from the near-IR to the radio and covers five wavebands at 70, 160, 250, 350 and 500 µm, encompassing the peak of the spectral energy distribution of cold dust for 8 < ∼ T < ∼ 50 K. This first Hi-GAL data release covers the inner Milky Way in the longitude range 68 • > ∼ > ∼ −70 • in a |b| ≤ 1 • latitude strip. Methods. Photometric maps have been produced with the ROMAGAL pipeline, which optimally capitalizes on the excellent sensitivity and stability of the bolometer arrays of the Herschel PACS and SPIRE photometric cameras. It delivers images of exquisite quality and dynamical range, absolutely calibrated with Planck and IRAS, and recovers extended emission at all wavelengths and all spatial scales, from the point-spread function to the size of an entire 2 • × 2 • "tile" that is the unit observing block of the survey. The compact source catalogues were generated with the CuTEx algorithm, which was specifically developed to optimise source detection and extraction in the extreme conditions of intense and spatially varying background that are found in the Galactic plane in the thermal infrared. Results. Hi-GAL DR1 images are cirrus noise limited and reach the 1σ-rms predicted by the Herschel Time Estimators for parallel-mode observations at 60 s −1 scanning speed in relatively low cirrus emission regions. Hi-GAL DR1 images will be accessible through a dedicated web-based image cutout service. The DR1 Compact Source Catalogues are delivered as single-band photometric lists containing, in addition to source position, peak, and integrated flux and source sizes, a variety of parameters useful to assess the quality and reliability of the extracted sources. Caveats and hints to help in this assessment are provided. Flux completeness limits in all bands are determined from extensive synthetic source experiments and greatly depend on the specific line of sight along the Galactic plane because the background strongly varies as a function of Galactic longitude. Hi-GAL DR1 catalogues contain 123210, 308509, 280685, 160972, and 85460 compact sources in the five bands.
Far‐Infrared [C ii ] Line Survey Observations of the Galactic Plane
The Astrophysical Journal Supplement Series, 1998
We present results of our survey observations of the [C II] 158 µm line emission from the Galactic plane using the Balloon-borne Infrared Carbon Explorer (BICE). Our survey covers a wide area (350 • ∼ < l ∼ < 25 • , |b| ∼ < 3 •) with a spatial resolution of 15 ′. We employed a new observing method called the "fast spectral scanning" to make large-scale observations efficiently. Strong [C II] line emission was detected from almost all areas we observed. In the general Galactic plane, the spatial distribution of the [C II] line emission correlates very well with that of far-infrared continuum emission, but diffuse components are more prominent in the [C II] line emission; the I [CII] /I FIR ratio is ∼ 0.6 % for diffuse components but is ∼ 0.2 % for compact sources such as active star-forming regions. In the Galactic center region, on the other hand, the distribution of the [C II] line emission is quite different from that of the far-infrared continuum emission, and the I [CII] /I FIR ratio is systematically lower there. The FWHM velocity resolution of our instrument is 175 km s −1 , but we determined the central velocity of the line at each observed point very precisely with statistical
The Southern Galactic Plane Survey: The Test Region
The Astrophysical Journal, 2001
The Southern Galactic Plane Survey (SGPS) is a project to image the H i line emission and 1.4 GHz continuum in the fourth quadrant of the Milky Way at high resolution using the Australia Telescope Compact Array (ATCA) and the Parkes Radio Telescope. In this paper we describe the survey details and goals, present λ21-cm continuum data, and discuss H i absorption and emission characteristics of the SGPS Test Region (325. • 5 ≤ l ≤ 333. • 5; −0. • 5 ≤ b ≤ +3. • 5). We explore the effects of massive stars on the interstellar medium (ISM) through a study of H i shells and the H i environments of H ii regions and supernova remnants. We find an H i shell surrounding the H ii region RCW 94 which indicates that the region is embedded in a molecular cloud. We give lower limits for the kinematic distances to SNRs G327.4+0.4 and G330.2+1.0 of 4.3 kpc and 4.9 kpc, respectively. We find evidence of interaction with the surrounding H i for both of these remnants. We also present images of a possible new SNR G328.6-0.0. Additionally, we have discovered two small H i shells with no counterparts in continuum emission.
The Astronomical Journal, 2006
The VLA Galactic Plane Survey (VGPS) is a survey of H i and 21-cm continuum emission in the Galactic plane between longitude 18 • and 67 • with latitude coverage from |b| < 1. • 3 to |b| < 2. • 3. The survey area was observed with the Very Large Array (VLA) in 990 pointings. Short-spacing information for the H i line emission was obtained by additional observations with the Green Bank Telescope (GBT). H i spectral line images are presented with a resolution of 1 ′ × 1 ′ × 1.56 km s −1 (FWHM) and rms noise of 2 K per 0.824 km s −1 channel. Continuum images made from channels without H i line emission have 1 ′ (FWHM) resolution. The VGPS images reveal structures of atomic hydrogen and 21-cm continuum as large as several degrees with unprecedented resolution in this part of the Galaxy. With the completion of the VGPS, it is now possible for the first time to assess the consistency between arcminute-resolution
Astronomy & Astrophysics, 2010
We present a detailed analysis of high resolution observations of the three lowest CO transitions in two nearby active galaxies, NGC 4569 and NGC 4826. The CO(1-0) and (2-1) lines were observed with the Plateau de Bure Interferometer and the CO(3-2) line with the Submillimeter Array. Combining these data allows us to compare the emission in the three lines and to map the line ratios, R 21 = I CO(2−1) /I CO(1−0) and R 32 = I CO(3−2) /I CO(1−0) at a resolution of ∼2 , i.e., a linear resolution of 160 pc for NGC 4569 and 40 pc for NGC 4826. In both galaxies the emission in the three lines is similarly distributed spatially and in velocity, and CO is less excited (R 32 < 0.6) than in the Galactic Center or the centers of other active galaxies studied so far. According to a pseudo-LTE model the molecular gas in NGC 4569 is cold and mainly optically thick in the CO(1-0) and (2-1) lines; less than 50% of the gas is optically thin in the CO(3-2) line. LVG modeling suggests the presence of an elongated ring of cold and dense gas coinciding with the inner Lindblad resonance (ILR) of the stellar bar in agreement with a previous analysis of the kinematics. More excited gas is resolved in the circumnuclear disk of NGC 4826. According to our pseudo-LTE model this corresponds to warmer gas with a ∼20% of the CO(3-2) emission being optically thin. LVG modeling indicates the presence of a semicircular arc of dense and cold gas centered on the dynamical center and ∼70 pc in radius. The gas temperature increases and its density decreases toward the center. A near side/far side asymmetry noticeable in the CO, R 32 and Paα maps suggests that opacity effects play a role. Examining published CO maps of nearby active galaxies we find similar asymmetries suggesting that this could be a common phenomenon in active galaxies. These mainly qualitative results open new perspectives for the study of active galaxies with the future Atacama Large Millimeter/submillimeter Array.
The Low-Resolution DRAO Survey of H [CSC]i[/CSC] Emission from the Galactic Plane
The Astronomical Journal, 2000
A survey of H I line emission in the Galactic plane from Galactic longitude to 0, and l \ 72¡ .2 149¡ . latitude to has been made using the 26-m Telescope at the Dominion Radio Astrob \ [5¡ .4 7¡ .2, physical Observatory. Spectra were observed at intervals of longitude and latitude, providing a 0¡ .2 survey which is fully sampled in the spatial domain. A detailed study of the antenna characteristics of the telescope allowed the correction of the spectra for stray radiation. The spectral resolution is 1.32 km s~1, and the LSR velocity range is [260 to 161 km s~1. The Ðnal spectra have an estimated scaling T b accuracy of 1% and an estimated rms noise in one channel (0.8245 km s~1) of 0.25 K. A region of suspected strong H I self-absorption at l D 92¡, b D 3¡, has been identiÐed. Comparison with spectra from the Leiden/Dwingeloo Survey is used to estimate the overall accuracy of the stray radiation corrections. This comparison also shows that a small percentage (D1%) of the spectra in the latter survey su †er from calibration errors exceeding 10%. A table of positions of the more discordant spectra is given.