The following table contains brief descriptions of all metadata information characterizing Atlas image data. The table also contains some processing-specific information as well as image statistics derived from the atlas images.
The columns in the following table are:
| Column Name | Format | Units | nulls | Description | |
|---|---|---|---|---|---|
| coadd_id | %20s | ---- | no | Atlas Tile identifier from which source was extracted. The identifier
has the general form: RRRRsDDd_[trev], where
For example, the identifier of the AllWISE Atlas Tile with center at (α,δ = 304.13896,-13.63000) is 3041m137_ac51. |
|
| band | %1d | ---- | no | WISE band number for the image. | |
| naxis | %1d | ---- | no | Number of data axes; it is always '2' for two-dimensional images. | |
| naxis1 | %4d | pixels | no | Length of data axis 1 or number of columns in the image. | |
| naxis2 | %4d | pixels | no | Length of data axis 2 or number of rows in the image. | |
| wrelease | %20s | ---- | no | The version number of the WISE multiframe pipeline used for this current data release. | |
| crpix1 | %9.1f | pixel | no | Axis 1 reference pixel at position crval1,crval2: 0.5*(naxis1+1) | |
| crpix2 | %9.1f | pixel | no | Axis 2 reference pixel at position crval1,crval2: 0.5*(naxis2+1) | |
| crval1 | %16.12f | degree | no | Reference Right Ascension at crpix1,crpix2 for EQUINOX. | |
| crval2 | %16.12f | degree | no | Reference Declination at crpix1,crpix2 for EQUINOX. | |
| ctype1 | %13s | ---- | no | Projection type for axis 1. It is always set to use the SIN (orthographic) projection; for the definition, see Calabretta & Greisen, 2002. | |
| ctype2 | %13s | ---- | no | Projection type for axis 2. It is always set to use the SIN (orthographic) projection; for the definition, see Calabretta & Greisen, 2002. | |
| equinox | %6.1f | year | no | Equinox of the World Coordinate System (WCS). | |
| bunit | %20s | ---- | no | Image pixel units: Data Number (DN) for intensity and uncertainty filetypes; "effective pixels" for the coverage filetype. Image filetypes are described in section II.3. | |
| elon | %16.12f | degrees | no | Ecliptic longitude of the reference pixel. CAUTION: This coordinate should not be used as an astrometric reference. | |
| elat | %16.12f | degrees | no | Ecliptic latitude of the reference pixel. CAUTION: This coordinate should not be used as an astrometric reference. | |
| glon | %16.12f | degrees | no | Galactic longitude of the reference pixel. CAUTION: This coordinate should not be used as an astrometric reference. | |
| glat | %16.12f | degrees | no | Galactic latitude of the reference pixel. CAUTION: This coordinate should not be used as an astrometric reference. | |
| ra1 | %16.12f | degrees | no | Right ascension (J2000) at corner #1 (crpix1,crpix2 = -0.5,-0.5) | |
| dec1 | %16.12f | degrees | no | Declination (J2000) at corner #1 (crpix1,crpix2 = -0.5,-0.5) | |
| ra2 | %16.12f | degrees | no | Right ascension (J2000) at corner #2 (crpix1,crpix2 = naxis1+0.5,-0.5) | |
| dec2 | %16.12f | degrees | no | Declination (J2000) at corner #2 (crpix1,crpix2 = naxis1+0.5,-0.5) | |
| ra3 | %16.12f | degrees | no | Right ascension (J2000) at corner #3 (crpix1,crpix2 = naxis1+0.5,naxis2+0.5) | |
| dec3 | %16.12f | degrees | no | Declination (J2000) at corner #3 (crpix1,crpix2 = naxis1+0.5,naxis2+0.5) | |
| ra4 | %16.12f | degrees | no | Right ascension (J2000) at corner #4 (crpix1,crpix2 = -0.5,naxis2+0.5) | |
| dec4 | %16.12f | degrees | no | Declination (J2000) at corner #4 (crpix1,crpix2 = -0.5,naxis2+0.5) | |
| magzp | %9.5f | mag | no | Relative photometric zero-point magnitude for the image. | |
| magzpunc | %8.6f | mag | no | 1-sigma uncertainty in the photometric zero-point magnitude for the image. | |
| fcdate | %20s | datetimeZ | no | Date and time of the intensity image file creation, in Coordinated Universal Time (UTC). | |
| date_obs1 | %24s | datetimeZ | no | The date and time (UTC) of the observation for the earliest frame in the Atlas Image stack. | |
| mid_obs | %24s | datetimeZ | no | The date and time (UTC) of the observation for the middle frame in the Atlas Image stack. | |
| date_obs2 | %24s | datetimeZ | no | The date and time (UTC) of the observation for the latest frame in the Atlas Image stack. | |
| sizex | %9.6f | degrees | no | Linear dimension of the coadd image along axis 1 (x). | |
| sizey | %9.6f | degrees | no | Linear dimension of the coadd image along axis 2 (y). | |
| pxscal1 | %9.6f | arcsec/pixel | no | Arcsec per pixel scale at the reference position of the image (crpix1,crpix2) for axis 1 (x). See cdelt1 for the degree equivalent. | |
| pxscal2 | %9.6f | arcsec/pixel | no | Arcsec per pixel scale at the reference position of the image (crpix1,crpix2) for axis 2 (y). See cdelt2 for the degree equivalent. | |
| moonrej | %6d | ---- | no | The number of single-exposure frames rejected due to moon glow when constructing the Atlas Image. See section IV.4.f.iv on moon-affected frames. | |
| mooninp | %6d | ---- | no | The number of single-exposure frames in the Atlas Image footprint with suspected moon-glow as determined by the moon-mask prior to any filtering by the moon-rejection algorithm. See section IV.4.f.iv on moon-affected frames. | |
| medint | %10.3f | DN | no | Median intensity pixel value calculated over the full Atlas Image. | |
| medcov | %10.3f | pixel | no | The median depth-of-coverage per pixel for the full Atlas Image footprint. | |
| mincov | %10.3f | pixel | no | The minimum depth of coverage of the Atlas Image. | |
| maxcov | %10.3f | pixel | no | The maxmimum depth of coverage of the Atlas image. | |
| lowcovpc1 | %10.6f | ---- | no | The percentage of the area within the Atlas Image footprint which has the depth of coverage ≤ 4 pixels. See also the cautionary note in section I.4.c.ii. | |
| lowcovpc2 | %10.6f | ---- | no | The percentage of the area within the Atlas Image footprint which has the depth of coverage ≤ 6 pixels. | |
| nomcovpc | %10.6f | ---- | no | The percentage of the area within the Atlas Image footprint which has the depth of coverage ≤ 8 pixels. | |
| mincovpc | %10.6f | ---- | no | The percentage of the area of the internal working image tile used for outlier-detection which has the depth of coverage ≤ 4 pixels. | |
| robsig | %14.6f | DN | no | The robust estimate of the spatial sigma for pixels with depth-of-coverage values within the interval: median ± 0.25. (e.g. If the median depth-of-coverage is 8.0, it uses pixels with depth-of-coverages from 7.75 to 8.25.) The sigma is computed from a trimmed standard-deviation from the mode using only the lower-tail of the intensity pixel distribution. | |
| pixchis1 | %11.6f | ---- | no | The ratio between the robust spatial sigma and the median uncertainty for pixels with depth-of-coverage values within the interval: median ± 0.25. (e.g. If the median depth-of-coverage is 8.0, it uses pixels with depth-of-coverages from 7.75 to 8.25.) See also section II.3.e.i. | |
| pixchis2 | %11.6f | ---- | no | The ratio between the robust spatial sigma and the modal uncertainty for pixels with depth-of-coverage values within the interval: median ± 0.25. (e.g. If the median depth-of-coverage is 8.0, it uses pixels with depth-of-coverages from 7.75 to 8.25.) See also section II.3.e.i. | |
| mednmsk | %10.1f | ---- | no | The median number of masked pixels per frame in the frames used in the Atlas Image. | |
| cdelt1 | %21.18f | degrees/pixel | no | Degree per pixel scale at the reference position of the image (crpix1,crpix2) for axis 1 (x). See pxscal1 for the arcsec equivalent. | |
| cdelt2 | %21.18f | degrees/pixel | no | Degree per pixel scale at the reference position of the image (crpix1,crpix2) for axis 2 (y). See pxscal2 for the arcsec equivalent. | |
| crota2 | %18.13f | degrees | no | Image twist: the position of the image positive y-axis West of North at the EQUINOX in the opposite direction of the conventional Position Angle, where position angle (P.A.) = -CROTA for J2000. | |
| bitmask | %9d | ---- | no | Fatal bitstring mask template used to signal rejected input frame pixels. The bits are defined here. | |
| numfrms | %5d | ---- | no | The final number of single-exposure frames touching the Atlas Image footprint after all filtering is performed. | |
| qual_coadd | %2d | ---- | no | This integer indicates the quality score value for the Tile, with values of 0 (poor quality) or 10 (high quality). All Atlas Tiles have received quality scores of 10. The value is determined by the minimum of the quality factors qc_fact, qa_fact, and qi_fact, multiplied by ten. | |
| qc_fact | %3.1f | ---- | no | This quality factor gauges the quality of completion. If the status value from the Multiframe pipeline was equal to 0 (indicating a problem-free completion), then qc=1.0. Otherwise, qc=0.0 because the coadd failed to complete processing. All Atlas Tiles have received qc values of 1.0. | |
| qi_fact | %3.1f | ---- | no | This quality factor gauges the image shape quality. It checks for potential image smearing by using the axial ratio of the PSF calculated from a subset of sources in the Tile. The value of qi is 1.0 if the axial ratio b/a > 0.60; otherwise it is 0.0. All Atlas Tiles have received qi values of 1.0. | |
| qa_fact | %3.1f | ---- | no | This factor gauges the astrometric quality. If the standard deviation of WISE positions with respect to the 2MASS Point Source Catalog positions is < 0.5 arcsec on each axis (or 0.71 arcsec RSS), for sources having SNR > 20 in at least one band, then qa=1.0. Otherwise, qa=0.0. All Atlas Tiles have received qa values of 1.0. | |
| date_imgprep | %20s | datetimeZ | no | The date and time when the data was prepared by the WISE archive software DBPREP for the archive loading, in UTC. | load_id | %5i | --- | no | Unique integer which identifies the data load ingested into the IRSA database |
| cntr | %12d | ---- | no | Unique sequential identification number for the image metadata table entry. | |
| x | %19.16f | ---- | no | The x value of the reference pixel in a unit sphere coordinate system (x,y,z). | |
| y | %19.16f | ---- | no | The y value of the reference pixel in a unit sphere coordinate system (x,y,z). | |
| z | %19.16f | ---- | no | The z value of the reference pixel in a unit sphere coordinate system (x,y,z). | |
| spt_ind | %9d | ---- | no | The HTM spatial index key. |
Last Update: 15 November 2013