 Top level directory for web access:
 Top level directory local to NERSC computers (for collaborators):

/global/cfs/cdirs/cosmo/data/legacysurvey/dr6/
Summary Files
surveybricks.fits.gz
FITS binary table with the RA, DEC bounds of each geometrical "brick" on the sky. This includes all bricks on the sky, not just the ones in our footprint or with coverage in DR6. For that information, see the next file description.
Column 
Type 
Description 


char[8] 
Name of the brick. 

int32 
A unique integer with 1to1 mapping to 

int16 
A "priority" factor used for processing. 

int32 
Dec row number. 

int32 
Number of the brick within a Dec row. 

float64 
RA of the center of the brick. 

float64 
Dec of the center of the brick. 

float64 
Lower RA boundary. 

float64 
Upper RA boundary. 

float64 
Lower Dec boundary. 

float64 
Upper Dec boundary. 
surveybricksdr6.fits.gz
A FITS binary table with information that summarizes the contents of each brick for DR6.
Column 
Type 
Description 


char[8] 
Name of the brick 

float64 
RA of the center of the brick 

float64 
Dec of the center of the brick 

int16 
Median number of exposures in the unique area (i.e. 

int16 
Median number of exposures in the unique area of the brick in rband 

int16 
Median number of exposures in the unique area of the brick in zband 

int32[6] 
Histogram of number of pixels in the unique brick area with 0, 1, 2, 3, 4, or > 5 exposures in g 

int32[6] 
Histogram of number of pixels in the unique brick area with 0, 1, 2, 3, 4, or > 5 exposures in r 

int32[6] 
Histogram of number of pixels in the unique brick area with 0, 1, 2, 3, 4, or > 5 exposures in z 

int16 
Total number of 

int16 
Total number of 

int16 
Total number of 

int16 
Total number of 

int16 
Total number of 

int16 
Total number of 

int16 
Total number of 

float32 
Median PSF size, in arcsec, evaluated at the 

float32 
Median PSF size, in arcsec, evaluated at the 

float32 
Median PSF size, in arcsec, evaluated at the 

float32 
5sigma PSF detection depth in \(g\)band (AB mag), using PsfEx PSF model 

float32 
5sigma PSF detection depth in \(r\)band (AB mag), using PsfEx PSF model 

float32 
5sigma PSF detection depth in \(z\)band (AB mag), using PsfEx PSF model 

float32 
5sigma galaxy (0.45" round exp) detection depth in \(g\)band (AB) mag 

float32 
5sigma galaxy (0.45" round exp) detection depth in \(r\)band (AB) mag 

float32 
5sigma galaxy (0.45" round exp) detection depth in \(z\)band (AB) mag 

float32 
Median SFD dust map E(BV) extinction, in magnitudes, evaluated at 

float32 
Median Milky Way dust transparency in \(g\)band, based on 

float32 
Median Milky Way dust transparency in \(g\)band, based on 

float32 
Median Milky Way dust transparency in \(z\)band, based on 

float32 
Extinction in \(g\)band 

float32 
Extinction in \(r\)band 

float32 
Extinction in \(z\)band 

int16[4] 
Number of images that contributed to WISE calculations in each filter (not profileweighted) 

float32[4] 
Median Milky Way dust transparency in WISE bands, based on 

float32 
Extinction in \(W1\)band 

float32 
Extinction in \(W2\)band 

float32 
Extinction in \(W3\)band 

float32 
Extinction in \(W4\)band 
Note that, for the nexphist
rows, pixels that are masked by the NOIRLab Community Pipeline as, e.g., cosmic rays or saturation, do
NOT count toward the number of exposures. More information about the morphological types and MW_TRANSMISSION
can be found on
the catalogs page.
surveyccds*fits.gz
FITS binary table with almanac information about each individual CCD image in each band. There is one file for each of:
90primeg: BASS \(g\)band
90primer: BASS \(r\)band
mosaicz: MzLS \(z\)band
dr6plus: Additional MzLS CCDs
These files contain information regarding the photometric and astrometric zero points for each CCD of every image that is part of the DR6 data release. Photometric zero points for each CCD are computed by identifying stars and comparing their instrumental magnitudes to colorselected stars in the PanSTARRS "qz" catalog.
The photometric zeropoints (zpt
, ccdzpt
, etc) are magnitudelike numbers (e.g. 25.04), and
indicate the magnitude of a source that would contribute one count per second to the image. For example, in an image with
zeropoint of 25.04 and exposure time of 30 seconds, a source of magnitude 22.5 would
contribute
\(30 * 10^{((25.04  22.5) / 2.5)} = 311.3\)
counts.
Column 
Type 
Description 


char[55] 
Path to FITS image, eg "decam/CP20140810_g_v2/c4d_140815_235218_ooi_g_v2.fits.fz" 

int16 
FITS HDU number in the 

char[7] 
The camera that took this image 

int32 
Exposure number, eg 348224 

char[4] 
CCD name (see Legacy Survey camera layout), eg "N10", "S7" 

char[24] 
Name listed in the object tag from the CCD header 

char[10] 
Proposal ID of the program that took this image, eg "2014B0404" 

char[1] 
Filter used for observation, eg "\(g\)", "\(r\)", "\(z\)" 

float32 
Exposure time in seconds, eg 30 

float64 
Date of observation in MJD (in UTC system), eg 56884.99373389 

float32 
FWHM of observation 

int16 
Width in pixels of this image, eg 2046 

int16 
Height in pixels of this image, eg 4096 

float64 
Telescope boresight RA of this exposure (deg) 

float64 
Telescope boresight Dec of this exposure (deg) 

float32 
Astrometric header value: X reference pixel 

float32 
Astrometric header value: Y reference pixel 

float64 
Astrometric header value: RA of reference pixel 

float64 
Astrometric header value: Dec of reference pixel 

float32 
Astrometric header value: transformation matrix 

float32 
Astrometric header value: transformation matrix 

float32 
Astrometric header value: transformation matrix 

float32 
Astrometric header value: transformation matrix 

float64 
Approximate RA center of this CCD (deg) 

float64 
Approximate Dec center of this CCD (deg) 

float32 
Sky rms for the entire image (in counts) 

float32 
Median perpixel error standard deviation, in nanomaggies 

float32 
Zeropoint for the CCD (AB mag) 

float32 
Median zero point for the entire image (median of all CCDs of the image), eg 25.0927 

float32 
Median astrometric offset for the CCD <GaiaLegacy Survey> in arcsec 

float32 
Median astrometric offset for the CCD <GaiaLegacy Survey> in arcsec 

float32 
Mean sky count level per pixel in the CPprocessed frames measured (with iterative rejection) for each CCD in the image section [500:1500,1500:2500] 

float32 
rms in astrometric offset for the CCD <GaiaLegacy Survey> in arcsec 

float32 
rms in astrometric offset for the CCD <GaiaLegacy Survey> in arcsec 

float32 
Photometric rms for the CCD (in mag) 

int32 
(ignore) 
surveyccdsdr6plus.kd.fits
As for the surveyccds*.fits.gz files but limited by the depth of each observation. This file contains all of the CCDs actually used for the DR6 reductions. Columns are the same as for surveyccds*.fits.gz files.
ccdsannotated*.fits.gz
Versions of each of the surveyccds*.fits.gz file with additional information gathered during calibration preprocessing before running the Tractor reductions. One each for
90primeg: BASS \(g\)band
90primer: BASS \(r\)band
mosaicz: MzLS \(z\)band
mosaicdr6plus: Additional MzLS images
Includes all of the columns in the surveyccds*.fits.gz file plus the following:
Column 
Type 
Description 


boolean 
(ignore) 

int16[4] 
If only a subset of the CCD images was used, this array of x0,x1,y0,y1 values gives the coordinates that were used, [x0,x1), [y0,y1). 1 for no cut (most CCDs) 

float64 
RA coordinate of pixel (1,1)...Note that the ordering of the CCD corners is detailed here 

float64 
Dec coordinate of pixel (1,1) 

float64 
RA coordinate of pixel (1,H) 

float64 
Dec coordinate of pixel (1,H) 

float64 
RA coordinate of pixel (W,H) 

float64 
Dec coordinate of pixel (W,H) 

float64 
RA coordinate of pixel (W,1) 

float64 
Dec coordinate of pixel (W,1) 

float32 
Maximum distance from RA,Dec center to the edge midpoints, in RA 

float32 
Maximum distance from RA,Dec center to the edge midpoints, in Dec 

float64 
RA coordinate of CCD center 

float64 
Dec coordinate of CCD center 

float32 
Our pipeline (not the CP) estimate of the sky level, average over the image, in ADU. 

float32 
Standard deviation of our sky level 

float32 
Max of our sky level 

float32 
Min of our sky level 

float32 
Pixel scale (via sqrt of area of a 10x10 pixel patch evaluated in a 5x5 grid across the image), in arcsec/pixel. 

float32 
Standard deviation of pixel scale 

float32 
Max of pixel scale 

float32 
Min of pixel scale 

float32 
PSF norm = 1/sqrt of N_eff = sqrt(sum(psf_i^2)) for normalized PSF pixels i; mean of the PSF model evaluated on a 5x5 grid of points across the image. Pointsource detection standard deviation is 

float32 
Standard deviation of PSF norm 

float32 
Norm of the PSF model convolved by a 0.45" exponential galaxy. 

float32 
Standard deviation of galaxy norm. 

float32 
PSF model second moment in x (pixels^2) 

float32 
PSF model second moment in y (pixels^2) 

float32 
PSF model second moment in xy (pixels^2) 

float32 
PSF model major axis (pixels) 

float32 
PSF model minor axis (pixels) 

float32 
PSF position angle (deg) 

float32 
PSF ellipticity 1  minor/major 

float32 
Percent humidity outside 

float32 
Outside temperate (deg C). 

int32 
tile number, 0 for data from programs other than MzLS or DECaLS 

uint8 
tile pass number, 1, 2 or 3, if this was an MzLS or DECaLS observation, or 0 for data from other programs. Set by the observers (the meaning of 

float32 
Mean SFD E(BV) extinction in the tile, 0 for data from programs other than BASS, MzLS or DECaLS 

char[6] 
Community Pipeline (CP) PLVER version string 

float32 
SFD E(BV) extinction for CCD center 

float32[6] 
Extinction for optical filters \(ugrizY\) 

float32[4] 
Extinction for WISE bands W1,W2,W3,W4 

float32 
5sigma PSF detection depth in AB mag, using PsfEx PSF model 

float32 
5sigma galaxy (0.45" round exp) detection depth in AB mag 

float32 
5sigma PSF detection depth in AB mag, using Gaussian PSF approximation (using 

float32 
5sigma galaxy detection depth in AB mag, using Gaussian PSF approximation 
Note that two columns have different formats between the surveyccds*.fits.gz and ccdsannotated*.fits.gz files.
The camera
column is char[6] and the object
column is char[37].
dr6depth.fits.gz
A concatenation of the depth histograms for each brick, from the
coadd/*/*/*depth.fits
tables. HDU1 contains histograms that describe the
number of pixels in each brick with a 5sigma AB depth in the given magnitude
bin. HDU2 contains the bin edges of the histograms.
HDU1
Column 
Type 
Description 


int32[50] 
Histogram of pixels for point source depth in \(g\) band 

int32[50] 
Histogram of pixels for canonical galaxy depth in \(g\) band 

int32[50] 
Histogram of pixels for point source depth in \(r\) band 

int32[50] 
Histogram of pixels for canonical galaxy depth in \(r\) band 

int32[50] 
Histogram of pixels for point source depth in \(z\) band 

int32[50] 
Histogram of pixels for canonical galaxy depth in \(z\) band 

char[8] 
Name of the brick 
HDU2
Column 
Type 
Description 


float32 
Lower bin edge for each histogram in HDU1 (5sigma AB depth) 

float32 
Upper bin edge for each histogram in HDU1 (5sigma AB depth) 
dr6depthsummary.fits.gz
A summary of the depth histogram of the whole DR6 survey. FITS table with the following columns:
Column 
Type 
Description 


float32 
Lower limit of the depth bin 

float32 
Upper limit of the depth bin 

int64 
Number of pixels in histogram for point source depth in \(g\) band 

int64 
Number of pixels in histogram for canonical galaxy depth in \(g\) band 

int64 
Number of pixels in histogram for point source depth in \(r\) band 

int64 
Number of pixels in histogram for canonical galaxy depth in \(r\) band 

int64 
Number of pixels in histogram for point source depth in \(z\) band 

int64 
Number of pixels in histogram for canonical galaxy depth in \(z\) band 
The depth histogram goes from magnitude of 20.1 to 24.9 in steps of 0.1 mag. The first and last bins are "catchall" bins: 0 to 20.1 and 24.9 to 100, respectively. The histograms count the number of pixels in each brick's unique area with the given depth. These numbers can be turned into values in square degrees using the brick pixel area of 0.262 arcseconds square. These depth estimates take into account the smallscale masking (cosmic rays, edges, saturated pixels) and detailed PSF model.
External Files
 The Legacy Survey photometric catalogs have been matched to the following external spectroscopic files from the SDSS, which can be accessed through the web at:

https://portal.nersc.gov/cfs/cosmo/data/legacysurvey/dr6/external/
 Or on the NERSC computers (for collaborators) at:

/global/cfs/cdirs/cosmo/data/legacysurvey/dr6/external/
Each row of each externalmatch file contains the full record of the nearest object in our Tractored survey
imaging catalogs, matched at a radius of 1.0 arcsec. The structure of the imaging catalog files
is documented on the catalogs page. If no match is found, then OBJID
is set to 1.
In addition to the columns from the Tractor catalogs, we have added columns from the SDSS files that can be used to track objects uniquely. These are typically some combination of PLATE
, FIBER
, MJD
(or SMJD
) and, in some cases, RERUN
.
surveydr6specObjdr14.fits
HDU1 (the only HDU) contains Tractored survey photometry that is rowbyrowmatched to the SDSS DR14 spectrosopic pipeline file such that the photometric parameters in row "N" of surveydr6specObjdr14.fits matches the spectroscopic parameters in row "N" of specObjdr14.fits. The spectroscopic file is documented in the SDSS DR14 data model for specObjdr14.fits.
surveydr6dr14Q_v4_4.fits
HDU1 (the only HDU) contains Tractored survey photometry that is rowbyrowmatched to the SDSS DR14 (partially) visually inspected quasar catalog (Paris et al. 2018) such that the photometric parameters in row "N" of surveydr6dr14Q_v4_4.fits matches the spectroscopic parameters in row "N" of DR14Q_v4_4.fits. The spectroscopic file is documented in the SDSS DR14 data model for DR14Q_v4_4.fits.
surveydr6dr12Q.fits
HDU1 (the only HDU) contains Tractored survey photometry that is rowbyrowmatched to the SDSS DR12 visually inspected quasar catalog (Paris et al. 2017) such that the photometric parameters in row "N" of surveydr6dr12Q.fits matches the spectroscopic parameters in row "N" of DR12Q.fits. The spectroscopic file is documented in the SDSS DR12 data model for DR12Q.fits.
surveydr6supersetdr12Q.fits
HDU1 (the only HDU) contains Tractored survey photometry that is rowbyrowmatched to the superset of all SDSS DR12 spectroscopically confirmed objects that were visually inspected as possible quasars (Paris et al. 2017) such that the photometric parameters in row "N" of surveydr6Superset_dr12Q.fits matches the spectroscopic parameters in row "N" of Superset_DR12Q.fits. The spectroscopic file is documented in the SDSS DR12 data model for Superset_DR12Q.fits.
surveydr6dr7Q.fits
HDU1 (the only HDU) contains Tractored survey photometry that is rowbyrowmatched to the SDSS DR7 visually inspected quasar catalog (Schneider et al. 2010) such that the photometric parameters in row "N" of surveydr6dr7Q.fits matches the spectroscopic parameters in row "N" of DR7qso.fit. The spectroscopic file is documented on the DR7 quasar catalog description page.
Tractor Catalogs
In the file listings outlined below:
brick names (<brick>) have the format <AAAa>c<BBB> where A, a and B are digits and c is either the letter m or p (e.g. 1126p222). The names are derived from the (RA, Dec) center of the brick. The first four digits are \(int(RA \times 10)\), followed by p to denote positive Dec or m to denote negative Dec ("plus"/"minus"), followed by three digits of \(int(Dec \times 10)\). For example the case 1126p222 corresponds to (RA, Dec) = (112.6°, +22.2°).
<brickmin> and <brickmax> denote the corners of a rectangle in (RA, Dec). Explicitly, <brickmin> has the format <AAA>c<BBB> where <AAA> denotes three digits of the minimum \(int(RA)\) in degrees, <BBB> denotes three digits of the minimum \(int(Dec)\) in degrees, and c uses the p/m ("plus"/"minus") format outlined in the previous bullet point. The convention is similar for <brickmax> and the maximum RA and Dec. For example 000m010010m005 would correspond to a survey region limited by \(0^\circ \leq RA < 10^\circ\) and \(10^\circ \leq Dec < 5^\circ\).
subdirectories are listed by the RA of the brick center, and subdirectory names (<AAA>) correspond to RA. For example 002 corresponds to brick centers between an RA of 2° and an RA of 3°.
<filter> denotes the \(g\), \(r\) or \(z\) band, using the corresponding letter.
Note that it is not possible to go from a brick name back to an exact (RA, Dec) center (the bricks are not on 0.1° grid
lines). The exact brick center for a given brick name can be derived from columns in the
surveybricks.fits.gz file (i.e. brickname
, ra
, dec
).
tractor/<AAA>/tractor<brick>.fits
FITS binary table containing Tractor photometry, documented on the catalogs page.
Users interested in database access to the Tractor Catalogs can contact the Astro Data Lab [1] at datalab@noirlab.edu.
Sweep Catalogs
sweep/6.0/sweep<brickmin><brickmax>.fits
The sweeps are lightweight FITS binary tables (containing a subset of the most commonly used
Tractor measurements) of all the Tractor catalogs for which BRICK_PRIMARY==T
in rectangles of RA, Dec. In addition to the columns listed below, the columns pertaining to optical data
also have \(U\), \(I\) and \(Y\)band entries (e.g. FLUX_U
, FLUX_I
, FLUX_Y
), but, in DR6, these extra columns contain only zeros.
Name 
Type 
Units 
Description 


int32 
Unique integer denoting the camera and filter set used (RELEASE is documented here) 


int32 
Brick ID [1,662174] 


char[8] 
Name of brick, encoding the brick sky position, eg "1126p222" near RA=112.6, Dec=+22.2 


int32 
Catalog object number within this brick; a unique identifier hash is 


char[4] 
Morphological model: "PSF"=stellar, "REX"="round exponential galaxy" = round EXP galaxy with a variable radius, "EXP"=exponential, "DEV"=deVauc, "COMP"=composite. Note that in some FITS readers, a trailing space may be appended for "PSF ", "EXP " and "DEV " since the column data type is a 4character string 


float64 
deg 
Right ascension at equinox J2000 

float64 
deg 
Declination at equinox J2000 

float32 
1/deg² 
Inverse variance of 

float32 
1/deg² 
Inverse variance of 

float32[5] 
Difference in χ² between successively morecomplex model fits: PSF, REX, DEV, EXP, COMP. The difference is versus no source. 


float32 
mag 
Galactic extinction E(BV) reddening from SFD98, used to compute 

float32 
nanomaggies 
model flux in \(g\) 

float32 
nanomaggies 
model flux in \(r\) 

float32 
nanomaggies 
model flux in \(z\) 

float32 
nanomaggies 
WISE model flux in \(W1\) 

float32 
nanomaggies 
WISE model flux in \(W2\) 

float32 
nanomaggies 
WISE model flux in \(W3\) 

float32 
nanomaggies 
WISE model flux in \(W4\) 

float32 
1/nanomaggies² 
Inverse variance of 

float32 
1/nanomaggies² 
Inverse variance of 

float32 
1/nanomaggies² 
Inverse variance of 

float32 
1/nanomaggies² 
Inverse variance of 

float32 
1/nanomaggies² 
Inverse variance of 

float32 
1/nanomaggies² 
Inverse variance of 

float32 
1/nanomaggies² 
Inverse variance of 

float32 
Galactic transmission in \(g\) filter in linear units [0,1] 


float32 
Galactic transmission in \(r\) filter in linear units [0,1] 


float32 
Galactic transmission in \(z\) filter in linear units [0,1] 


float32 
Galactic transmission in \(W1\) filter in linear units [0,1] 


float32 
Galactic transmission in \(W2\) filter in linear units [0,1] 


float32 
Galactic transmission in \(W3\) filter in linear units [0,1] 


float32 
Galactic transmission in \(W4\) filter in linear units [0,1] 


int16 
Number of images that contribute to the central pixel in \(g\): filter for this object (not profileweighted) 


int16 
Number of images that contribute to the central pixel in \(r\): filter for this object (not profileweighted) 


int16 
Number of images that contribute to the central pixel in \(z\): filter for this object (not profileweighted) 


int16 
Number of images that contribute to the central pixel in \(W1\): filter for this object (not profileweighted) 


int16 
Number of images that contribute to the central pixel in \(W2\): filter for this object (not profileweighted) 


int16 
Number of images that contribute to the central pixel in \(W3\): filter for this object (not profileweighted) 


int16 
Number of images that contribute to the central pixel in \(W4\): filter for this object (not profileweighted) 


float32 
Profileweighted χ² of model fit normalized by the number of pixels in \(g\) 


float32 
Profileweighted χ² of model fit normalized by the number of pixels in \(r\) 


float32 
Profileweighted χ² of model fit normalized by the number of pixels in \(z\) 


float32 
Profileweighted χ² of model fit normalized by the number of pixels in \(W1\) 


float32 
Profileweighted χ² of model fit normalized by the number of pixels in \(W2\) 


float32 
Profileweighted χ² of model fit normalized by the number of pixels in \(W3\) 


float32 
Profileweighted χ² of model fit normalized by the number of pixels in \(W4\) 


float32 
Profileweighted fraction of the flux from other sources divided by the total flux in \(g\) (typically [0,1]) 


float32 
Profileweighted fraction of the flux from other sources divided by the total flux in \(r\) (typically [0,1]) 


float32 
Profileweighted fraction of the flux from other sources divided by the total flux in \(z\) (typically [0,1]) 


float32 
Profileweighted fraction of the flux from other sources divided by the total flux in \(W1\) (typically [0,1]) 


float32 
Profileweighted fraction of the flux from other sources divided by the total flux in \(W2\) (typically [0,1]) 


float32 
Profileweighted fraction of the flux from other sources divided by the total flux in \(W3\) (typically [0,1]) 


float32 
Profileweighted fraction of the flux from other sources divided by the total flux in \(W4\) (typically [0,1]) 


float32 
Profileweighted fraction of pixels masked from all observations of this object in \(g\), strictly between [0,1] 


float32 
Profileweighted fraction of pixels masked from all observations of this object in \(r\), strictly between [0,1] 


float32 
Profileweighted fraction of pixels masked from all observations of this object in \(z\), strictly between [0,1] 


float32 
Fraction of a source's flux within the blob in \(g\), near unity for real sources 


float32 
Fraction of a source's flux within the blob in \(r\), near unity for real sources 


float32 
Fraction of a source's flux within the blob in \(z\), near unity for real sources 


int16 
Bitwise mask set if the central pixel from any image satisfies each condition in \(g\) 


int16 
Bitwise mask set if the central pixel from any image satisfies each condition in \(r\) 


int16 
Bitwise mask set if the central pixel from any image satisfies each condition in \(z\) 


int16 
Bitwise mask set if the central pixel from all images satisfy each condition in \(g\) 


int16 
Bitwise mask set if the central pixel from all images satisfy each condition in \(r\) 


int16 
Bitwise mask set if the central pixel from all images satisfy each condition in \(z\) 


uint8 
W1 bright star bitmask, \(2^0\) \((2^1)\) for southward (northward) scans 


uint8 
W2 bright star bitmask, \(2^0\) \((2^1)\) for southward (northward) scans 


float32 
arcsec 
Weighted average PSF FWHM in the \(g\) band 

float32 
arcsec 
Weighted average PSF FWHM in the \(r\) band 

float32 
arcsec 
Weighted average PSF FWHM in the \(z\) band 

float32 
1/nanomaggies² 
For a \(5\sigma\) point source detection limit in \(g\), \(5/\sqrt(\mathrm{PSFDEPTH\_G})\) gives flux in nanomaggies and \(2.5[\log_{10}(5 / \sqrt(\mathrm{PSFDEPTH\_G}))  9]\) gives corresponding magnitude 

float32 
1/nanomaggies² 
For a \(5\sigma\) point source detection limit in \(g\), \(5/\sqrt(\mathrm{PSFDEPTH\_R})\) gives flux in nanomaggies and \(2.5[\log_{10}(5 / \sqrt(\mathrm{PSFDEPTH\_R}))  9]\) gives corresponding magnitude 

float32 
1/nanomaggies² 
For a \(5\sigma\) point source detection limit in \(g\), \(5/\sqrt(\mathrm{PSFDEPTH\_Z})\) gives flux in nanomaggies and \(2.5[\log_{10}(5 / \sqrt(\mathrm{PSFDEPTH\_Z}))  9]\) gives corresponding magnitude 

float32 
1/nanomaggies² 
As for 

float32 
1/nanomaggies² 
As for 

float32 
1/nanomaggies² 
As for 

char[8] 
unWISE coadd file name for the center of each object 


float32 
Fraction of model in deVauc [0,1] 


float32 
Inverse variance of 


float32 
arcsec 
Halflight radius of deVaucouleurs model (>0) 

float32 
1/arcsec 
Inverse variance of 

float32 
Ellipticity component 1 


float32 
Inverse variance of 


float32 
Ellipticity component 2 


float32 
Inverse variance of 


float32 
arcsec 
Halflight radius of exponential model (>0) 

float32 
1/arcsec2 
Inverse variance of 

float32 
Ellipticity component 1 


float32 
Inverse variance of 


float32 
Ellipticity component 2 


float32 
Inverse variance of 
Image Stacks
Image stacks are on tangentplane (WCS TAN) projections, 3600 × 3600 pixels, at 0.262 arcseconds per pixel.
 coadd/<AAA>/<brick>/legacysurvey<brick>ccds.fits

FITS binary table with the list of CCD images that were used in this brick. Contains the same columns as surveyccdsdr6plus.kd.fits, and also contains the additional columns:
Column
Type
Description
ccd_cuts
int32
(ignore)
ccd_x0
int16
Minimum x image coordinate overlapping this brick
ccd_y0
int16
Minimum y image coordinate overlapping this brick
ccd_x1
int16
Maximum x image coordinate overlapping this brick
ccd_y1
int16
Maximum y image coordinate overlapping this brick
brick_x0
int16
Minimum x brick image coordinate overlapped by this image
brick_x1
int16
Maximum x brick image coordinate overlapped by this image
brick_y0
int16
Minimum y brick image coordinate overlapped by this image
brick_y1
int16
Maximum y brick image coordinate overlapped by this image
psfnorm
float32
Same as
psfnorm
in the ccdsannotated filegalnorm
float32
Same as
galnorm
in the ccdsannotated fileplver
char[4]
Community Pipeline (CP) version
skyver
char[19]
Git version of the sky calibration code
wcsver
char[1]
Git version of the WCS calibration code
psfver
char[12]
Git version of the PSF calibration code
skyplver
char[4]
CP version of the input to sky calibration
wcsplver
char[4]
CP version of the input to WCS calibration
psfplver
char[4]
CP version of the input to PSF calibration
 coadd/<AAA>/<brick>/legacysurvey<brick>image<filter>.fits

Stacked image centered on a brick location covering 0.25° × 0.25°. The primary HDU contains the coadded image (inversevariance weighted coadd), in units of nanomaggies per pixel.
NOTE: These are not the images used by Tractor, which operates on the singleepoch images.
NOTE: that these images are resampled using Lanczos3 resampling.
 coadd/<AAA>/<brick>/legacysurvey<brick>invvar<filter>.fits

Corresponding stacked inverse variance image based on the sum of the inversevariances of the individual input images in units of 1/(nanomaggies)² per pixel.
NOTE: These are not the inverse variance maps used by Tractor, which operates on the singleepoch images.
 coadd/<AAA>/<brick>/legacysurvey<brick>model<filter>.fits.gz

Stacked model image centered on a brick location covering 0.25° × 0.25°.
The Tractor's idea of what the coadded images should look like; the Tractor's model prediction.
 coadd/<AAA>/<brick>/legacysurvey<brick>chi2<filter>.fits

Stacked χ² image, which is approximately the summed χ² values from the singleepoch images.
 coadd/<AAA>/<brick>/legacysurvey<brick>depth<filter>.fits.gz

Stacked depth map in units of the pointsource flux inversevariance at each pixel.
The 5σ pointsource depth can be computed as \(5 / \sqrt(\mathrm{depth\_ivar})\) .
 coadd/<AAA>/<brick>/legacysurvey<brick>galdepth<filter>.fits.gz

Stacked depth map in units of the canonical galaxy flux inversevariance at each pixel. The canonical galaxy is an exponential profile with effective radius 0.45" and round shape.
The 5σ galaxy depth can be computed as \(5 / \sqrt(\mathrm{galdepth\_ivar})\) .
 coadd/<AAA>/<brick>/legacysurvey<brick>nexp<filter>.fits.gz

Number of exposures contributing to each pixel of the stacked images.
 coadd/<AAA>/<brick>/legacysurvey<brick>image.jpg

JPEG image of calibrated image using the \(g,r,z\) filters as the colors.
 coadd/<AAA>/<brick>/legacysurvey<brick>model.jpg

JPEG image of the Tractor's model image using the \(g,r,z\) filters as the colors.
 coadd/<AAA>/<brick>/legacysurvey<brick>resid.jpg

JPEG image of the residual image (data minus model) using the \(g,r,z\) filters as the colors.
Raw Data
See the raw data page.
Footnotes