- ID:
- ivo://nasa.heasarc/hubbleudf
- Title:
- Hubble Ultra Deep Field Catalog
- Short Name:
- UDF
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Hubble Ultra Deep Field (UDF, Principle Investigator: Steven V. W. Beckwith) is a 400-orbit Hubble Space Telescope (HST) Cycle 12 program to image a single field of the Wide Field Camera (WFC) of the Advanced Camera for Surveys (ACS) in four filters: F435W (B), F606W (V), F775W (i), and F850LP (z). The observations took place over 4 months from September 2003 to January 2004 under two program IDs: 9978 and 10086. The observations consist of half-orbit exposures, cycling through each of the filters in a 4-point dither pattern to provide sub-pixel sampling, as well as a larger-scale 3-point line pattern to cover the 2 second of arc gap between the two ACS/WFC chips. The total exposure times are summarized below, with typical exposure times of 1200s for individual images. The AB magnitude zero-points for ACS are current as of March 2004. <pre> Number of Number of Total Exp. AB mag. Orbits Exposures Time (s) zero-point B (F435W): 56 112 134880 25.673 V (F606W): 56 112 135320 26.486 i (F775W): 144 288 347110 25.654 z (F850LP): 144 288 346620 24.862 </pre> This HEASARC Browse table contains the list of sources found in the deepest UDF image, the i-band image. The formal i-band catalog contains a total of 10,040 sources. A visual inspection of all the sources revealed an additional 5 spurious sources (which do not form part of the catalog). Moreover, the deblending algorithms in SExtractor caused an additional 100 sources to be missed, owing to their proximity to brighter sources. These sources were identified manually, and formally added by doing another SExtractor run with considerably different deblending parameters, in order to detect them all. An initial list of 208 sources was produced, which was then reduced to a total of 100 sources after visual inspection and rejection of sources that were clearly part of previously identified sources. These additional sources are denoted by ID numbers 20001 - 20208. Although the i-band image is the deepest image, there remain additional sources that were not detected in i-band, even though they may be detected in one of the other bands. Therefore, the authors produced a second catalog based on detection in the z-band image (not part of the present table), and an additional 39 sources are included from this catalog that were detected at > 10 sigma in the z-band image, but were not in the catalog that was run using the i-band image for detection. These additional sources are denoted by ID numbers above 30000. More details are found in the file <a href="https://cdsarc.cds.unistra.fr/ftp/cats/II/258/intro.txt">https://cdsarc.cds.unistra.fr/ftp/cats/II/258/intro.txt</a> or from the UDF home page at <a href="http://www.stsci.edu/hst/udf/">http://www.stsci.edu/hst/udf/</a>. This table was created by the HEASARC in May 2005 based on CDS table II/258/udf-i.dat. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/m31phatsfh
- Title:
- M 31 Disk Chandra PHAT Survey: HST-Derived Star Formation History
- Short Name:
- M31PHATSFH
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The X-ray source populations within galaxies are typically difficult to identify and classify with X-ray data alone. The authors break through this barrier by combining deep new Chandra ACIS-I observations with extensive Hubble Space Telescope (HST) imaging from the Panchromatic Hubble Andromeda Treasury (PHAT) of the M 31 disk. They detect 373 X-ray sources down to 0.35-8.0keV flux of 10<sup>-15</sup>erg/cm<sup>-2</sup>/s over 0.4deg<sup>2</sup>, 170 of which are reported for the first time. The authors identify optical counterpart candidates for 188 of the 373 sources, after using the HST data to correct the absolute astrometry of our Chandra imaging to 0.1". These data are available at <a href="/W3Browse/chandra/m31phatcxo.html">M31PHATCXO</a>. For point-like counterparts, the authors examine the star formation history of the surrounding stellar populations to look for a young component that could be associated with a high-mass X-ray binary. This table presents the star formation histories for a subset of sources in the <a href="/W3Browse/chandra/m31phatcxo.html">M31PHATCXO catalog</a>. About one-third of the point sources are not physically associated with a young population, and are therefore more likely to be background galaxies. For the 40 point-like counterpart candidates associated with young populations, the authors find that their age distribution has two peaks at 15-20Myr and 40-50Myr. Considering only the 8 counterpart candidates with typical high-mass main-sequence optical star colors, their age distribution peaks mimic those of the sample of 40. Finally, the authors find that intrinsic faintness, and not extinction, is the main limitation for finding further counterpart candidates. In 2015 October, the authors observed the Panchromatic Hubble Andromeda Treasury (PHAT) footprint with Chandra with 7 pointings. The footprints are overlaid on a GALEX NUV image of M 31, along with the corresponding HST coverage, in Figure 1 of the reference paper. At each pointing they observed for about 50 ks in VF mode (Chandra ObsID 17008 to 17014 spanning 2015 Oct 06 to 2015 Oct 26). This table was created by the HEASARC in April 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/239/13">CDS Catalog J/ApJS/239/13</a> file table7.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m31phatcxo
- Title:
- M 31 Disk Chandra PHAT Survey: X-Ray Source Catalog
- Short Name:
- M31PHATCXO
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The X-ray source populations within galaxies are typically difficult to identify and classify with X-ray data alone. The authors break through this barrier by combining deep new Chandra ACIS-I observations with extensive Hubble Space Telescope (HST) imaging from the Panchromatic Hubble Andromeda Treasury (PHAT) of the M 31 disk. They detect 373 X-ray sources down to 0.35-8.0keV flux of 10<sup>-15</sup>erg/cm<sup>-2</sup>/s over 0.4deg<sup>2</sup>, 170 of which are reported for the first time. The authors identify optical counterpart candidates for 188 of the 373 sources, after using the HST data to correct the absolute astrometry of our Chandra imaging to 0.1". While 58 of these 188 are associated with point sources potentially in M 31, over half (107) of the counterpart candidates are extended background galaxies, 5 are star clusters, 12 are foreground stars, and 6 are supernova remnants. Sources with no clear counterpart candidate are most likely to be undetected background galaxies and low-mass X-ray binaries in M 31. The hardest sources in the 1-8keV band tend to be matched to background galaxies. The 58 point sources that are not consistent with foreground stars are bright enough that they could be high-mass stars in M 31; however, all but 8 have optical colors inconsistent with single stars, suggesting that many could be background galaxies or binary counterparts. For point-like counterparts, the authors examine the star formation history of the surrounding stellar populations to look for a young component that could be associated with a high-mass X-ray binary. The associated star formation histories for sources in the catalog are available in the linked table <a href="/W3Browse/chandra/m31phatsfh.html">M31PHATSFH</a>. In 2015 October, the authors observed the Panchromatic Hubble Andromeda Treasury (PHAT) footprint with Chandra with 7 pointings. The footprints are overlaid on a GALEX NUV image of M 31, along with the corresponding HST coverage, in Figure 1 of the reference paper. At each pointing they observed for about 50ks in VF mode (Chandra ObsID 17008 to 17014 spanning 2015 Oct 06 to 2015 Oct 26). This table was created by the HEASARC in April 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/239/13">CDS Catalog J/ApJS/239/13</a> file table4.dat and table6.dat. This is a service provided by NASA HEASARC .
