Terapix Star Formation Region IC 1396, © 2002 CFHT
CFHTLS T0005 wide and deep summary
Last content update November 12th, 2008

TERAPIX T0005 release : overview of deep and wide data
Release reference identification : T0005 : Pre-Release date: August 28, 2008 - Official Release date : November 14, 2008.


Terapix T0005 pages

Important :

-  Get the CFHTLS T0005 Release: explanatory document

-  CFHTLS users restricted access to T0005 data at CADC

1. T0005 quick summary table : Exposure time, Seeing, Effective area, Star/Disk Completeness

2. T0005 Synoptic Table : explanatory table

3. T0005 astrometric and photometric calibration

4. T0005 CFHTLS / SDSS comparisons

5. T0005 file naming convention

6. T0005 catalogue parameters

7. The CFHTLS Data Access Policy

9. Acknowledgement


Improvements compared to T0004

-  All flat-fields have been re-generated at CFHT. This means that all weight-maps have been recreated. Also CFHT have recomputed the photometric calibrations for all data (new PHOT_C values in all headers).

-  Deep stacks have longer integration times

-  Significant increase in coverage in five filter area for the wide fields.

CFHTLS T0005 target lists:

-  Deep fields with 25% best seeing images: D1-25, D2-25, D3-25 and D4-25
-  Deep fields with 85% best seeing images: D1-85, D2-85, D3-85 and D4-85
-  Wide fields: W1, W2, W3 and W4

-  Positions of Deep and Wide fields in the sky.

Image selection criteria for the stacking process:
-  Data obtained between: May 26, 2003 and February 16, 2008.
-  Terapix Class : A or B
-  Exp. time: > 60 sec.
-  Seeing : < 1.3" , except for u* (<1.4")
-  Airmass: < 1.7
-  Skyprobe value: <2.0 Mag. (security limit)

Overview of T0005 stacks and status of the CFHTLS-T0005 sky coverage

-  Number of Deep stacks: 48 (24 D25+24 D85: filter i.9701 (i.2003) and i.9702 (i.2007) not staked together)
-  Number of Wide stacks: 804 (129 u, 176 g, 178 r, 173 i, 148 z)
-  Filter distribution of wides:

Wide field gri onlygriz onlyall ugrizall gri (=chi2) Total u/g/r/i/ or z
W1230497272
W250253030
W3019304949
W400202525
Total2819124176176

W1-ugriz -T0005 sky coverage W2-ugriz -T0005 sky coverage W3-ugriz -T0005 sky coverage W4-ugriz -T0005 sky coverage

Quick T0005 stack summary table and printable table The Synopic T0005 Table

Overview photometry:

-  Magnitudes: AB Megacam instrumental system
-  Magnitude zero points : The zero points of all images are set to 30 AB magnitudes. The images have an effective exposure time of one second.
-  SDSS/CFHTLS transformations resulting from the SNLS group (Regnault et al. ):

. uCFHTLS - uSDSS = -0.214 * (u-g)SDSS

. gCFHTLS - gSDSS = -0.156 * (g-r)SDSS

. rCFHTLS - rSDSS = -0.000 * (g-r)SDSS

. iCFHTLS - iSDSS = -0.094 * (r-i)SDSS for the i.9701 filter

. iCFHTLS - iSDSS = -0.003 * (r-i)SDSS for the i.9702 filter

. zCFHTLS - zSDSS = +0.050 * (i-z)SDSS

-  Mean rms external errors with respect to SDSS (when available): 0.02 mag. , but depends on the field and the filter.

-  Fields in common between T0004 and T0005 have the same magnitude zero points as demonstrated from the stellar color-color plots and past SDSS comparisons.

WARNING: there are several fields with an offset in u*-band of around 0.1 magnitudes.

A detailed CFHTLS/SDSS comparison.

Overview of astrometric solutions

-  Calibration catalogue: 2MASS. For each patch (D1, D2, D3, D4, W1, W2, W3, W4), all CFHTLS images located in the field with exp. time >180s. , airmass <1.7 and seeing<1.5" have been used to set the astrometric calibration of each field used later for the stacks.

-  Mean rms external error with respect to 2MASS: 0.24"+/-0.02" in both directions (instead of 0.42" in previous releases using USNO-B, with significant anisotropy)).

-  Mean rms internal error is 0.017"+/-0.002" in both directions (instead of 0.035" before).

-  Mean systematic offset of stacks with respect to 2MASS astrometric positions: 0.017"

More detailed information can be found here

Catalogue parameters

All fields having at least rgi image stacks have an associated chi2 images and catalogues centered on the i-band stack. Otherwise, simple single-band ldac catalogues are delivered. The catalogues contain the following Sextractor parameters.

Catalogue parameters and filenames are described in data and parameter description, except for the 'merged ugriz' that contain less information (see the item 'merged catalogue' in the T0005 explanatory table).

Data products and filenames

Terapix products relating to T0005 stacks available at CADC to CFHTLS registered users are:

Data File Name Type Nb Files
Wide stacks CFHTLS_W_filter_RA-DEC_T0005.fits FITS image 806
Wide weights CFHTLS_W_filter_RA-DEC_T0005_weight.fits FITS image 806
Wide chi2 CFHTLS_W_gri_RA-DEC_T0005.fits FITS image (only stacks with at least gri) 176
Wide chi2 weight CFHTLS_W_gri_RA-DEC_T0005_weight.fits FITS image (only stacks with at least gri) 176
Wide masks CFHTLS_W_RA-DEC_T0005.reg ASCII DS9 compliant in WCS 198
Wide chi2 catalogue CFHTLS_W_filter_RA-DEC_T0005.cat ASCII table (only stacks with at least gri) 800
Wide individual catalogue CFHTLS_W_filter_RA-DEC_T0005.ldac LDAC FITS table 804
Wide merged ugriz catalogue CFHTLS_W_ugriz_RA-DEC_T0005.cat ASCII table (only stacks with at least gri) 171
Deep stacks 25% CFHTLS_D-25_filter_RA-DEC_T0005.fits FITS image 24
Deep weight 25% CFHTLS_D-25_filter_RA-DEC_T0005_weight.fits FITS image 24
Deep chi2 25% CFHTLS_D-25_gri_RA-DEC_T0005.fits FITS image 4
Deep chi2 weight 25% CFHTLS_D-25_gri_RA-DEC_T0005_weight.fits FITS image 4
Deep masks 25% CFHTLS_D_RA-DEC_T0005.reg ASCII DS9 compliant in WCS 4
Deep 25% chi2 catalogue CFHTLS_D-25_filter_RA-DEC_T0005.cat ASCII table 24
Deep 25% individual catalogue CFHTLS_D-25_filter_RA-DEC_T0005.ldac LDAC FITS table 24
Deep 25% merged ugriz catalogue CFHTLS_D-25_ugriz_RA-DEC_T0005.cat ASCII table 4
Deep stacks 85% CFHTLS_D-85_filter_RA-DEC_T0005.fits FITS image 24
Deep weight 85% CFHTLS_D-85_filter_RA-DEC_T0005_weight.fits FITS image 24
Deep chi2 85% CFHTLS_D-85_gri_RA-DEC_T0005.fits FITS image 4
Deep chi2 weight 85% CFHTLS_D-85_gri_RA-DEC_T0005_weight.fits FITS image 4
Deep masks 85% CFHTLS_D_RA-DEC-T0005.reg ASCII DS9 compliant in WCS 4 (same as D-25)
Deep 85% chi2 catalogue CFHTLS_D-85_filter_RA-DEC_T0005.cat ASCII table 24
Deep 85% individual catalogue CFHTLS_D-85_filter_RA-DEC_T0005.ldac LDAC FITS table 24
Deep 85% merged ugriz catalogue CFHTLS_D-85_ugriz_RA-DEC_T0005.cat ASCII table 4

Individual weight map images have been generated for each CFHT FITS image, their QFITs-in, as well as the QFITS-out quality assessment outputs of each stack are available at CADC.

Important note about the catalogues at CADC

Catalogues with names like 'CFHTLS_D*/W*_z_RA-DEC_T0005.cat' are chisquared catalogues. They are only produced when at least the g,r and i data are available. All catalogues of the kind 'CFHTLS_D*/W*_u,g,r,i,z_RA-DEC_T0005.cat' are extracted with the same chisquared detection image and contain the same objects (i.e., they are all aperture-matched). Columns of catalogs with '.cat' and 'ldac' extentions are defined in the '.param' files. They are listed in the CFHTLS catalogue parameter list. The '.cat' file contains also the E(b-v) in the last column.

Access to T0005 release products (restricted to CFHTLS users):

-  Reminder: CADC is the ONLY access point to CFHTLS release. Please read the data access policy as defined by the CFHT Board of Directors.

-  The deep and wide T0005 release at CADC (link not active yet).

Annex:

Overview of CFHTLS Data Products.

Articles
article
Stack T0005: list of CFHT included in each D1 stacks
article
Stack T0005: list of CFHT included in each D2 stacks
article
Stack T0005: list of CFHT included in each D3 stack
article
Stack T0005: list of CFHT included in each D4 stack
article
Stack T0005: list of CFHT included in each W1 stack
article
Stack T0005: list of CFHT included in each W2 stack
article
Stack T0005: list of CFHT included in each W3 stack
article
Stack T0005: list of CFHT included in each W4 stack
article
T0005 quick summary table : exposure time, effective area
article
T0005 quick summary table : exposure time, effective area for the W3 field
article
T0005 quick summary table : exposure time, effective area for the W2 field
article
T0005 quick summary table : exposure time, effective area for the W1 field
article
T0005 quick summary table : exposure time, effective area for the W4 field
article
T0005 Synopic Table : explanatory table
article
T0005 Synoptic Table : short description and access point
article
T0005 astrometric and photometric calibration
article
CFHTLS / SDSS comparisons
article
T0005 file naming convention
article
T0005 catalogue parameters

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