Vis Calibrated Catalogue Product¶
Metadata¶
Data product name |
DpdVisCalibratedFrameCatalog |
Data product custodian |
VIS |
Name of the Schema file |
|
Processing Element(s) creating/using the data product |
VIS_science_xml_out |
Processing function using the data product |
SHE processing functions. |
Proposed for inclusion in EAS/SAS¶
Yes
Data product elements¶
Header |
object of type sys:genericHeader |
Data |
object of type vis:visCalibratedFrameCatalogData |
QualityFlags |
object of type dqc:sqfPlaceHolder |
Parameters |
object of type ppr:genericKeyValueParameters |
Detailed description of the data product¶
The VIS processing function provides a series of catalogues delivered in FITS “LDAC” format. These catalogues are produced using SExtractor (Bertin & Arnouts 1996).
The Vis PSF Model Product is given as input to the VIS pipeline for fitting a spread model. The spread model is then used to calculate a zero point by comparing to Gaia data and for data selection.
This calibrated catalogue contains 2 types of tables:
The LDAC_IMHEAD table, a 1-column catalogue containing the header and some information (like SE parameters) of the original image.
The LDAC_OBJECTS table, an 84-column catalogue. These columns are described below.
We calculate the magnitude in 4 apertures: 7, 13, 26, and 50 pixels.
An aperture correction (APERCORR) is calculated from the mean differences between the magnitude measured in the 50-pixel aperture (\(MAG\_APER_{50}\)) and the 13-pixel aperture (\(MAG\_APER_{13}\)).
This correction is saved as a keyword in the FITS header.
Then the relevant aperture to use is \(MAG\_APER_{13}\) with this aperture correction.
In the catalogues flux and magnitude are available as calibrated measurements and raw measurements. The available column are:
MAG_[…]_RAW: raw magnitude (units: mag)
FLUX_[…]: raw flux (units: count)
MAG_[…]: calibrated magnitude (units: mag)
FLUX_[…]_CAL: calibrated flux (units: uJy)
The Gaia to VIS magnitude conversion is computed using the conversion table BP-RP_G-VIS_GAIA_DR3_sim-obs-combined_function.fits
stored in the mission data base (MDB) SpaceSegment.Instrument.VIS.GaiaVISColorTransformation.
Name of file:
EUC_VIS_SWL_CAT-[ObsId]-[Dither]-[exposure]-0000000__[YYYYMMDDThhmmss.s]Z.fits.gz
where the date is the production date.
User case¶
Selection of Stars: You can use the spread model to select all the stars of the catalogue (i.e. abs(SPREAD_MODEL) \(< 0.003\)). However this can also select cosmic rays that are not correctly detected. We recommend to also use a selection in magnitude and FLUX_RADIUS for better results. If you want no saturated star, you need also to select object with Flags=0.
Changes introduced by the PF version¶
PF 17.0¶
MAG_AUTO is now a calibrated magnitude, and the raw value is stored in the new column MAG_AUTO_RAW
MAG_APER[0] (7-pixel aperture), MAG_APER[1] (13-pixel aperture), MAG_APER[2] (26-pixel aperture), MAG_APER[3] (50-pixel aperture) are now calibrated magnitudes
Raw values of 7, 13, 26, 50-pixel aperture magnitudes are stored in new columns MAG_APER_RAW[0-3]
Calibrated fluxes and associated errors are stored in new columns FLUX_AUTO_CAL / FLUX_APER_CAL and FLUXERR_AUTO_CAL / FLUXERR_APER_CAL
PF 18.0¶
New Gaia-VIS conversion
Add new column related to model fitting
PF 18.1¶
Use NoiseChisel background substraction to performe photometry
Column descriptions¶
Name |
Units |
Description |
|---|---|---|
FLAGS |
NA |
SExtractor extraction flags, basic warnings about the source extraction process, in order of increasing concern. |
FLAGS_WIN |
NA |
SExtractor flag for various issues which may happen with windowed measurements. |
FLAGS_MODEL |
NA |
SExtractor flag for various issues which may happen during the fitting process. |
IMAFLAGS_ISO |
NA |
Flags from the flag map maid during the processing. See Vis Flag Map Product for flags details. |
NIMAFLAGS_ISO |
NA |
Number(s) of relevant flag map pixels. |
SPREAD_MODEL |
NA |
Spread parameter from model-fitting. Stars are object with: abs(SPREAD_MODEL) \(< 0.003\). |
FLUX_AUTO |
Count |
Flux within a Kron-like elliptical aperture. This flux is not calibrated. |
FLUX_APER |
Count |
Flux in an aperture. This flux is not calibrated. |
FLUXERR_APER |
Count |
RMS error of flux aper |
FLUXERR_AUTO |
Count |
RMS error for AUTO flux. |
MAG_AUTO |
mag |
Kron-like elliptical aperture magnitude. This magnitude is calibrated. |
MAGERR_AUTO |
mag |
RMS error for AUTO magnitude. |
FLUX_RADIUS |
Count |
Fraction-of-light radii (pixels). |
MAG_APER |
mag |
Magnitude calibrated in a defined aperture. |
MAGERR_APER |
mag |
Error of the calibrated magnitude in aperture. |
MAG_APER_RAW |
mag |
Raw values of mag aper, i.e without the zero point. It is the instrumental magnitude. |
MAG_AUTO_RAW |
mag |
Raw values of MAG_AUTO. |
FLUX_AUTO_CAL |
uJy |
Flux calibrated by applying the zero-point. |
FLUXERR_AUTO_CAL |
uJy |
Error in calibrated flux auto. |
FLUX_APER_CAL |
uJy |
Flux in aperture calibrated. |
FLUXERR_APER_CAL |
uJy |
Errors in flux aperture calibrated. |
NUMBER |
NA |
Running object number |
X_IMAGE |
pixel |
Object position along x |
Y_IMAGE |
pixel |
Object position along y |
XPSF_IMAGE |
pixel |
X coordinate from PSF-fitting |
YPSF_IMAGE |
pixel |
Y coordinate from PSF-fitting |
X_WORLD |
deg |
Barycenter position along world x axis |
Y_WORLD |
deg |
Barycenter position along world y axis |
ERRA_WORLD |
deg |
Major axis of the isophotal image centroid error ellipse |
ERRB_WORLD |
deg |
Minor axis of the isophotal image centroid error ellipse |
ERRTHETA_WORLD |
deg |
Position angle of the isophotal image centroid ellipse |
XPSF_WORLD |
deg |
PSF position along world x axis |
YPSF_WORLD |
deg |
PSF position along world y axis |
ERRAPSF_WORLD |
pixel |
Major axis of the PSF |
ERRBPSF_WORLD |
pixel |
Minor axis of the PSF |
ERRTHETAPSF_WORLD |
deg |
Position angle of the PSF |
A_WORLD |
deg |
Profile RMS along major axis (world units) |
B_WORLD |
deg |
Profile RMS along minor axis (world units) |
THETA_WORLD |
deg |
Position angle (CCW/world-x) |
ERRX2_WORLD |
deg**2 |
Estimated variance of isophotal image centroid x coordinate |
ERRY2_WORLD |
deg**2 |
Estimated variance of isophotal image centroid y coordinate |
ALPHA_J2000 |
deg |
J2000 right ascension of the isophotal image centroid |
DELTA_J2000 |
deg |
J2000 declination of the isophotal image centroid |
ERRTHETA_J2000 |
deg |
J2000 Position angle of the isophotal image centroid ellipse |
THETA_J2000 |
deg |
Isophotal image position angle |
XWIN_WORLD |
deg |
x coordinate of windowed image centroid |
YWIN_WORLD |
deg |
y coordinate of windowed image centroid |
ALPHAPSF_J2000 |
deg |
Right ascension of the fitted PSF (J2000) |
DELTAPSF_J2000 |
deg |
Declination of the fitted PSF (J2000) |
ERRTHETAPSF_J2000 |
deg |
Position angle of the fitted PSF (J2000) |
ALPHAWIN_J2000 |
deg |
Right ascension of the windowed image |
DELTAWIN_J2000 |
deg |
Declinaison of of the windowed image |
ERRAWIN_WORLD |
deg |
Major axis of the windowed image centroid error ellipse |
ERRBWIN_WORLD |
deg |
Minor axis of the windowed image centroid error ellipse |
ERRTHETAWIN_WORLD |
deg |
Position angle of the windowed image centroid ellipse |
AWIN_WORLD |
deg |
Windowed image major axis |
BWIN_WORLD |
deg |
Windowed image minor axis |
THETAWIN_WORLD |
deg |
Windowed image position angle |
ERRX2WIN_WORLD |
deg**2 |
Estimated variance of windowed image centroid x coordinate |
ERRY2WIN_WORLD |
deg**2 |
Estimated variance of windowed image centroid y coordinate |
MU_THRESHOLD |
\(mag*arcsec^{-2}\) |
The surface brightness corresponding to the threshold |
MU_MAX |
\(mag*arcsec^{-2}\) |
The surface brightness of the brightest pixel |
MU_MAX_MODEL |
\(mag*arcsec^{-2}\) |
Peak model surface brightness above the background |
MU_EFF_MODEL |
\(mag*arcsec^{-2}\) |
Effective model surface brightness above the background |
MU_MEAN_MODEL |
\(mag*arcsec^{-2}\) |
Mean effective model surface brightness above the background |
MU_MAX_SPHEROID |
\(mag*arcsec^{-2}\) |
Peak model surface brightness above the background using Sérsic (\(R^{1/n}\)) spheroid model |
MU_EFF_SPHEROID |
\(mag*arcsec^{-2}\) |
Effective model surface brightness above the background using Sérsic (\(R^{1/n}\)) spheroid model |
MU_MEAN_SPHEROID |
\(mag*arcsec^{-2}\) |
Mean effective model surface brightness above the background using Sérsic (\(R^{1/n}\)) spheroid model |
MU_MAX_DISK |
\(mag*arcsec^{-2}\) |
Peak model surface brightness above the background using exponential disk model |
MU_EFF_DISK |
\(mag*arcsec^{-2}\) |
Effective model surface brightness above the background using exponential disk model |
MU_MEAN_DISK |
\(mag*arcsec^{-2}\) |
Mean effective model surface brightness above the background using exponential disk model |
BACKGROUND |
count |
Background at centroid position |
MAG_PSF |
mag |
Magnitude from PSF-fitting |
MAGERR_PSF |
mag |
RMS magnitude error from PSF-fitting |
ELLIPTICITY |
NA |
1 - B IMAGE/A IMAGE |
ELONGATION |
NA |
A IMAGE/B IMAGE |
FWHM_IMAGE |
pixel |
FWHM assuming a Gaussian core |
SNR_WIN |
NA |
Signal to noise ratio of the windowed image |
ERRAWIN_IMAGE |
pixel |
Major axis of the windowed image centroid error ellipse |
ERRBWIN_IMAGE |
pixel |
Minor axis of the windowed image centroid error ellipse |
ERRTHETAWIN_IMAGE |
pixel |
Position angle of the windowed image centroid ellipse |
VECTOR_MODEL |
NA |
Model-fitting coefficients |
VECTOR_MODELERR |
NA |
Model-fitting coefficient uncertainties |
MATRIX_MODELERR |
NA |
Model-fitting covariance matrix |
CHI2_MODEL |
NA |
Reduced Chi2 of the fit |
FLAGS_MODEL |
NA |
Model-fitting flags |
NITER_MODEL |
NA |
Number of iterations for model-fitting |
FLUX_MODEL |
Count |
Flux from model-fitting |
FLUXERR_MODEL |
Count |
RMS error on model-fitting flux |
MAG_MODEL |
mag |
Magnitude from model-fitting |
MAGERR_MODEL |
mag |
RMS error on model-fitting magnitude |
XMODEL_IMAGE |
pixel |
X coordinate from model-fitting |
YMODEL_IMAGE |
pixel |
Y coordinate from model-fitting |
XMODEL_WORLD |
deg |
Fitted position along world x axis |
YMODEL_WORLD |
deg |
Fitted position along world y axis |
ELLIP1MODEL_IMAGE |
NA |
Ellipticity component from model-fitting |
ELLIP2MODEL_IMAGE |
NA |
Ellipticity component from model-fitting |
ELLIP1ERRMODEL_IMAGE |
NA |
Ellipticity component std.error from model-fitting |
ELLIP2ERRMODEL_IMAGE |
NA |
Ellipticity component std.error from model-fitting |
ELLIPCORRMODEL_IMAGE |
NA |
Corr.coeff between ellip.components from model-fitting |
ELLIP1MODEL_WORLD |
NA |
Ellipticity component from model-fitting |
ELLIP2MODEL_WORLD |
NA |
Ellipticity component from model-fitting |
ELLIP1ERRMODEL_WORLD |
NA |
Ellipticity component std.error from model-fitting |
ELLIP2ERRMODEL_WORLD |
NA |
Ellipticity component std.error from model-fitting |
ELLIPCORRMODEL_WORLD |
NA |
Corr.coeff between ellip.components from model-fitting |
XWIN_IMAGE |
pixel |
x coordinate of windowed image centroid |
YWIN_IMAGE |
pixel |
y coordinate of windowed image centroid |
SNR |
NA |
Signal to noise ratio define as FLUX_APER/FLUXERR_APER in the 50 pixel aperture |
Header¶
Primary Header |
|
|---|---|
SIMPLE |
This is a FITS file |
BITPIX |
|
NAXIS |
|
EXTEND |
This file may contain FITS extensions |