ACDS V10.0 - Detailed Description of II/321

ACDS V10.0 - Mon Jan 20 15:32:55 CET 2025

| # Detailed Description of II/321 : IPHAS DR2 Source Catalogue (Barentsen+, 2014) |

Note : this is the description file of the original catalog. This HTML page corresponds well to the original description, but some minor changes in the format may have been introduced in the FITS output files in order to allow for arithmetic operations on quantities such as coordinates and times. h:m:s and d:m:s units are normally converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the units; the value given in the HTML files supersedes the value indicated in the ReadMe file for this catalogue.

    II/321              IPHAS DR2 Source Catalogue                (Barentsen+, 2014)
    ================================================================================
    The Second Data Release of the INT Photometric H-Alpha Survey of the Northern
    Galactic Plane (IPHAS DR2)
         Barentsen G., Farnhill H.J., Drew J.E., Gonzalez-Solares E.A., Greimel R.,
         Irwin M.J., Miszalski B., Ruhland C., Groot P., Mampaso A., Sale S.E.,
         Henden A.A., Aungwerojwit A., Barlow M.J., Carter P.J., Corradi R.L.M.,
         Drake J.J., Eisloffel J., Fabregat J., Gansicke B.T., Gentile Fusillo N.P.,
         Greiss S., Hales A.S., Hodgkin S., Huckvale L., Irwin J., King R.,
         Knigge C., Kupfer T., Lagadec E., Lennon D.J., Lewis J.R., Mohr-Smith M.,
         Morris R.A.H., Naylor T., Parker Q.A., Phillipps S., Pyrzas S., Raddi R.,
         Roelofs G.H.A., Rodriguez-Gil P., Sabin L., Scaringi S., Steeghs D.,
         Suso J., Tata R., Unruh Y.C., Roestel J.VAN , Viironen K., Vink J.S.,
         Walton N.A., Wright N.J., Zijlstra A.A.
        <Mon. Not. R. Astron. Soc., 444, 3220--3257 (2014)>
        =2014yCat.2321....0B
        =2014MNRAS.444.3230B
    ================================================================================
    ADC_Keywords: Photometry, H-alpha ; Stars, emission ; Galactic plane ; Surveys

    Keywords: catalogues, surveys - stars: emission-line - Galaxy: stellar content

    Description:
        The INT/WFC Photometric H-Alpha Survey of the Northern Galactic Plane
        (IPHAS) is a 1860 deg2 imaging survey of the Northern Milky Way at red
        visible wavelengths. It covers Galactic latitudes |b|<5° and
        longitudes l=30 to 215° in the broad-band r, i and narrow-band
        H-alpha filters using the Wide Field Camera (WFC) on the 2.5-m Isaac
        Newton Telescope (INT) in La Palma.

        IPHAS Data Release 2 (DR2) is the first quality-controlled and globally
        calibrated source catalogue derived from the survey, providing single-epoch
        photometry for 219 million unique sources across 92% of the footprint.  The
        observations were carried out between 2003 and 2012 at a median seeing of
        1.1 arcsec (sampled at 0.33 arcsec/pixel) and to a mean 5-sigma depth of
        21.2 (r), 20.0 (i) and 20.3 (H-alpha). The photometric calibration is in
        the Vega magnitude system and carries an external precision of 0.03mag
        (root-mean-square error).

        The catalogue includes all the sources which have been detected at a
        signal-to-noise ratio of 5 or better in at least one band. Many
        applications will require a combination of quality criteria to be applied
        to avoid faint stars or confused sources.  The choice of quality criteria
        tensions completeness against reliability, and hence depends on the
        requirements of a project. To aid users, the data release paper
        (arXiv:1406.4862) recommends two sets of quality criteria, named "a10"
        and "a10point", which should satisfy most projects. As a minimum, the
        "a10" criteria select objects which have been detected at the minimum
        level of 10-sigma in all bands, without being saturated. Additional
        constraints are provided by the "a10point" criteria, which require objects
        to be point sources free of blending, unaffected by nearby bright stars,
        as well as being unsaturated >10-sigma detections in all bands. Sources in
        both categories are flagged in the catalogue using the boolean columns a10
        and a10point.

        Imaging and auxiliary data are available from the project website
        (www.iphas.org).

    Acknowledging IPHAS in publications:
        The survey is defined in Drew et al. (2005MNRAS.362..753D) and the DR2
        catalogue is presented in Barentsen et al. (arXiv:1406.4862).  Users are
        requested to cite these papers as appropriate in journal articles and
        similar.
        Please include the following in any published material that makes use of
        the IPHAS data products:
        "This paper makes use of data obtained as part of the INT Photometric
        H-alpha Survey of the Northern Galactic Plane (IPHAS, www.iphas.org)
        carried out at the Isaac Newton Telescope (INT). The INT is operated on
        the island of La Palma by the Isaac Newton Group in the Spanish
        Observatorio del Roque de los Muchachos of the Instituto de Astrofisica
        de Canarias. All IPHAS data are processed by the Cambridge Astronomical
        Survey Unit, at the Institute of Astronomy in Cambridge. The bandmerged
        DR2 catalogue was assembled at the Centre for Astrophysics Research,
        University of Hertfordshire, supported by STFC grant ST/J001333/1."
    File Summary:

    File Summary:

           FileName      Lrecl  Records   Explanations

    ×                   80        .   This file
    × ReadMe            80        .   This file
    × iphas2.sam       659     1000   Sample of the IPHAS DR2 release

    Byte-by-byte Description of file:  iphas2.sam

       Bytes Format Units   Label     Explanations

       1- 19  A19   ---     IPHAS     IPHAS name, based on J2000 position
      21- 29  F9.5  deg     RAdeg     Right ascension (J2000) from r-band
      31- 38  F8.5  deg     DEdeg     Declination (J2000) from r-band
      40- 53  A14   ---     sourceID  Unique identification number
      55- 58  F4.2  arcsec  posErr    RMS residual against 2MASS across the CCD
      60- 61  I2    ---  mergedClass  Image classification flag (1)
      63- 69  F7.2  --- mergedClassStat  Merge stellarness-of-profile statistic
      71- 74  F4.2  ---     pStar     Point source probability
      76- 79  F4.2  ---     pGalaxy   Extended source probability
      81- 84  F4.2  ---     pNoise    Noise source probability
      86- 90  F5.2  mag     rmi       ? r-i colour
      92- 96  F5.2  mag     rmha      ? r-Halpha colour
      98-102  F5.2  mag     r         ? r mag using 2.3 arcsec diameter aperture
                                            (Vega scale)
     104-107  F4.2  mag     rErr      ? Uncertainty for r (2)
     109-113  F5.2  mag     rPeakMag  ? Alternative r mag derived from the peak
                                            pixel height (Vega scale)
     115-118  F4.2  mag  rPeakMagErr  ? Uncertainty in rPeakMag (2)
     120-124  F5.2  mag    rAperMag1  ? Alternative r mag using the 1.2 arcsec
                                            diameter aperture (Vega scale)
     126-133  F8.2  mag rAperMag1Err  ? Uncertainty in rAperMag1 (2)
     135-139  F5.2  mag    rAperMag3  ? Alternative r mag using the 3.3 arcsec
                                            diameter aperture (Vega scale)
     141-150  F10.3 mag rAperMag3Err  ? Uncertainty in rAperMag3 (2)
     152-158  F7.2  pix     rGauSig   ? RMS of axes of ellipse fit in r-band
     160-163  F4.2  ---     rEll      ? Ellipticity in the r-band
     165-170  F6.2  deg     rPA       ? Position angle in the r-band
     172-173  I2    ---     rClass    Discrete image classification flag (3)
     175-181  F7.2  ---   rClassStat  ? N(0,1) stellarness-of-profile statistic
         183  I1    ---     rDeblend  [0,1] Blend flag for r-band.
         185  I1    ---   rSaturated  [0,1] Saturation flag for r-band
     187-197  F11.5 d       rMJD      ? Modified Julian Date for the r exposure
     199-202  F4.2  arcsec  rSeeing   ? Average FWHM in the same CCD frame
     204-217  A14   --- rDetectionID  ? Unique identifier of the r detection (4)
     219-225  F7.2  pix     rX        ? Pixel position in the r-band exposure
     227-233  F7.2  pix     rY        ? Pixel position in the r-band exposure
     235-239  F5.2  mag     i         ? i mag using 2.3 arcsec diameter aperture
                                            (Vega scale)
     241-244  F4.2  mag     iErr      ? Uncertainty for i (2)
     246-250  F5.2  mag     iPeakMag  ? Alternative i mag derived from the peak
                                            pixel height (Vega scale)
     252-255  F4.2  mag  iPeakMagErr  ? Uncertainty in iPeakMag (2)
     257-261  F5.2  mag    iAperMag1  ? Alternative i mag using the 1.2 arcsec
                                            diameter aperture (Vega scale)
     263-270  F8.2  mag iAperMag1Err  ? Uncertainty in iAperMag1 (2)
     272-276  F5.2  mag    iAperMag3  ? Alternative i mag using the 3.3 arcsec
                                            diameter aperture (Vega scale)
     278-286  F9.2  mag iAperMag3Err  ? Uncertainty in iAperMag3 (2)
     288-294  F7.2  pix     iGauSig   ? RMS of axes of ellipse fit in i-band
     296-299  F4.2  ---     iEll      ? Ellipticity in the i-band
     301-306  F6.2  deg     iPA       ? Position angle in the i-band
     308-309  I2    ---     iClass    Discrete image classification flag (3)
     311-317  F7.2  ---   iClassStat  ? N(0,1) stellarness-of-profile statistic
         319  I1    ---     iDeblend  [0,1] Blend flag for i-band.
         321  I1    ---   iSaturated  [0,1] Saturation flag for i-band
     323-333  F11.5 d       iMJD      ? Modified Julian Date for the i exposure
     335-338  F4.2  arcsec  iSeeing   ? Average FWHM in the same CCD frame
     340-353  A14   --- iDetectionID  ? Unique identifier of the i detection (4)
     355-361  F7.2  pix     iX        ? Pixel position in the i-band exposure
     363-369  F7.2  pix     iY        ? Pixel position in the i-band exposure
     371-381  F11.2 arcsec  iXi       ? offset of the i-band position relative
                                            to the ra column
     383-387  F5.2  arcsec  iEta      ? offset of the i-band position relative
                                            to the dec column
     389-393  F5.2  mag     ha        ? H-alpha mag using 2.3" diameter aperture
                                            (Vega scale)
     395-398  F4.2  mag     haErr     ? Uncertainty for H-alpha (2)
     400-404  F5.2  mag    haPeakMag  ? Alternative H-alpha mag derived from
                                            the peak pixel height (Vega scale)
     406-409  F4.2  mag haPeakMagErr  ? Uncertainty in haPeakMag (2)
     411-415  F5.2  mag   haAperMag1  ? Alternative H-alpha mag using the
                                           1.2 arcsec diameter aperture (Vega scale)
     417-423  F7.2  mag haAperMag1Err  ? Uncertainty in haAperMag1 (2)
     425-429  F5.2  mag   haAperMag3  ? Alternative H-alpha mag using the
                                           3.3 arcsec diameter aperture (Vega scale)
     431-440  F10.2 mag haAperMag3Err  ? Uncertainty in iAperMag3 (2)
     442-448  F7.2  pix     haGauSig  ? RMS of axes of ellipse fit in H-alpha
     450-453  F4.2  ---     haEll     ? Ellipticity in H-alpha
     455-460  F6.2  deg     haPA      ? Position angle in H-alpha
     462-463  I2    ---     haClass   Discrete image classification flag (3)
     465-471  F7.2  ---  haClassStat  ? N(0,1) stellarness-of-profile statistic
         473  I1    ---    haDeblend  [0,1] Blend flag for H-alpha
         475  I1    ---  haSaturated  [0,1] Saturation flag for H-alpha
     477-487  F11.5 d       haMJD     ? Modified Julian Date for the Ha exposure
     489-492  F4.2  arcsec  haSeeing  ? Average FWHM in the same CCD frame
     494-507  A14   --- haDetectionID  ? Unique ID of the H-alpha detection (4)
     509-515  F7.2  pix     haX       ? Pixel position in the H-alpha exposure
     517-523  F7.2  pix     haY       ? Pixel position in the H-alpha exposure
     525-535  F11.2 arcsec  haXi      ? offset of the H-alpha position relative
                                            to the ra column
     537-541  F5.2  arcsec  haEta     ? offset of the H-alpha position relative
                                            to the dec column
         543  I1    --- brightNeighb  [0,1] Nearby very bright star flag (5)
         545  I1    ---     deblend   [0,1] Blend flag
         547  I1    ---    saturated  [0,1] Saturation flag
         549  I1    ---     nBands    Number of bands for source detection
         551  I1    ---     a10       [0,1] signal-to-noise >10 flag (6)
         553  I1    ---     a10point  [0,1] quality criteria flag (7)
     555-568  A14   ---     fieldID   Survey field identifier
     570-572  A3    ---   fieldGrade  Internal quality control score
     574-581  I8    ---     night     UT date at the start of the night
     583-586  F4.2  arcsec  seeing    Maximum of rSeeing, iSeeing or HaSeeing
         588  I1    ---     ccd       [1-4] CCD chip number
         590  I1    ---     nObs      [1-9] Number of observations of the source
     592-605  A14   ---    sourceID2  ? SourceID of the alternative detection
                                            of the object in the partner exposure
     607-620  A14   ---     fieldID2  ? Field identifier of the partner
                                             detection
     622-626  F5.2  mag     r2        ? r mag in the dithered partner field
                                            (Vega scale)
     628-631  F4.2  mag     rErr2     ? Uncertainty for r2
     633-637  F5.2  mag     i2        ? i mag in the dithered partner field
                                            (Vega scale)
     639-642  F4.2  mag     iErr2     ? Uncertainty for i2
     644-648  F5.2  mag     ha2       ? Ha mag in the dithered partner field
                                            (Vega scale)
     650-653  F4.2  mag     haErr2    ? Uncertainty for ha2
     655-659  I5    ---     errBits2  ? Error bitmask for the partner
                                            detection (8)

    Note (1): Based on all bands: 1=galaxy, 0=noise, -1=star, -2=probableStar.

    Note (2): Does not include systematics. For example, the uncertainty in the
              photometric calibration, estimated to equal 0.03 mag
              (root-mean-square error), is not included.
    Note (3): Discrete image classification flag as follows:
                1 = galaxy
                0 = noise
               -1 = star
               -2 = probableStar
    Note (4): Unique identifier of the band detection in the format
        "#run-#ccd-#number", i.e. composed of the INT telescope run number, the
        CCD number and a sequential source detection number.
    Note (5): True if a very bright star is nearby (defined as brighter than
        V<4 within 10 arcmin, or brighter than V<7 within 5 arcmin). Such very
        bright stars cause scattered light and diffraction spikes, which may add
        systematic errors to the photometry or even trigger spurious detections.
    Note (6): True if the source is detected at S/N>10 in all bands without being
        saturated, and if the photometric measurements are consistent across
        different aperture diameters. Algebraic condition:
        (rErr<0.1 & iErr<0.1 & haErr<0.1 & NOT saturated &
        (abs(r-rAperMag1)<3*hypot(rErr,rAperMag1Err)+0.03) &
        (abs(i-iAperMag1)<3*hypot(iErr,iAperMag1Err)+0.03) &
        (abs(ha-haAperMag1)<3*hypot(haErr,haAperMag1Err)+0.03).
    Note (7): True if both the a10 quality criteria above are satisfied, and if
        the object looks like a single, unconfused point source. Algebraic
        condition: a10 & pStar>0.9 & NOT deblend & NOT brightNeighb.
    Note (8): flag a bright neighbour (1), source blending (2), saturation (8),
        vignetting (64), truncation (128) and bad pixels (32768). Be careful
        if errBits2>0.

    Acknowledgements:
        Geert Barentsen (University of Hertfordshire)
    ================================================================================
    (End)                 Laurent Cambresy, Thomas Boch [CDS]            09-Sep-2014