Information on Service 'Photometric redshifts in Stripe 82'

Further access options are discussed below

This is a catalogue of photometric redshifts of galaxies in the Stripe 82 obtained when morphology (galaxy size, ellipticity, Sérsic index, and surface brightness) are included in training on galaxy samples from the SDSS and the CFHT Stripe-82 Survey (CS82). Our redshifts yield a 68th percentile error of 0.058(1 + z), and a outlier fraction of 5.2 per cent.

For a list of all services and tables belonging to this service's resource, see Information on resource 'Photometric redshifts in Stripe 82'

Service Documentation

The distributions P(z) used to estimate z_phot and z_morph are available as FITS binary tables from pz_phot (1.4 GB) and pz_morph (0.8 GB), respectively.

The data in the cs82morphoz.main table is also available as a FITS binary table: phz.fits (0.7 GB).

Overview

You can access this service using:

form -- an interface for web browsers through an HTML form
scs.xml -- a standard SCS interface as defined by the IVOA to access catalog-type data; SCS clients use http://dc.zah.uni-heidelberg.de/cs82morphoz/q/cone/scs.xml? to access the service
static -- static (i.e. prepared) data or custom client-side code; probably used to access ancillary files here

This service is published as follows:

Within the set(s) ivo_managed with the renderer dali
Within the set(s) local,ivo_managed with the renderer form
Within the set(s) ivo_managed with the renderer scs.xml

local means it is listed on our front page, ivo_managed means it has a record in the VO registry.

Input Fields

The following fields are available to provide input to the service (with some renderers, some of these fields may be unavailable):

Name	Table Head	Description	Unit	UCD
DEC	Delta (ICRS)	Declination (ICRS decimal)	deg	pos.eq.dec
hscs_pos	Position/Name	Coordinates (as h m s, d m s or decimal degrees), or SIMBAD-resolvable object	N/A	N/A
hscs_sr	Search radius	Search radius in arcminutes	N/A	N/A
mag_auto	i Kron	CS82 Kron i-band magnitude	mag	phot.mag;em.opt.i
maxrec	Match limit	Maximum number of records returned. Pass 0 to retrieve service parameters.	N/A	N/A
RA	Alpha (ICRS)	Right Ascension (ICRS decimal)	deg	pos.eq.ra
responseformat	Output Format	File format requested for output.	N/A	meta.code.mime
SR	Search Radius	Search radius	deg	N/A
verb	Verbosity	Exhaustiveness of column selection. VERB=1 only returns the most important columns, VERB=2 selects the columns deemed useful to the average user, VERB=3 returns a table with all available columns.	N/A	N/A
zbest	z best	Best redshift for this object, in order of priority: zspec, zphot, zmorph	N/A	src.redshift

Default Output Fields

The following fields are contained in the output by default. More fields may be available for selection; these would be given below in the VOTable output fields.

Name	Table Head	Description	Unit	UCD
aspect_exp	Ax. Ratio	Exponential fit axis-ratio	N/A	src.morph.param
class_spec	Class	Class of object based on spectral fit: GALAXY or QSO	N/A	meta.code.class
dec	Dec	ICRS Declination	deg	pos.eq.dec;meta.main
fitclass	Fit class	lensFit star-galaxy classifier: 1=stars; 0=galaxies; -1=no usable data; -2=blended objects; -3=miscellaneous reasons; -4=chi-square exceeded critical value	N/A	meta.code;src.class
flags	Ex. Qual	Source extraction quality flag (ranges from 0 to 3, with 0 being the best)	N/A	meta.code
lens	lens?	Lensing tag. Objects with lens=1 are objects from the lensing subsample (fitclass=0, weight>0)	N/A	meta.code
mag_auto	i Kron	CS82 Kron i-band magnitude	mag	phot.mag;em.opt.i
mag_dered_g	g dered	SDSS dereddened g-band magnitude	mag	phot.mag;em.opt.V
mag_dered_i	i dered	SDSS dereddened i-band magnitude	mag	phot.mag;em.opt.I
mag_dered_r	r dered	SDSS dereddened r-band magnitude	mag	phot.mag;em.opt.R
mag_dered_u	u dered	SDSS dereddened u-band magnitude	mag	phot.mag;em.opt.U
mag_dered_z	z dered	SDSS dereddened z-band magnitude	mag	phot.mag;em.opt.I
mag_exp	i fit	CS82 exponential fit i-band magnitude	mag	phot.mag;em.opt.i
mag_psf	i psf	CS82 PSF i-band magnitude	mag	phot.mag;em.opt.i
magerr_auto	Err. i Kron	CS82 Kron i-band magnitude error. Signal-to-noise ratio is 1.086/MAGERR_AUTO	mag	stat.error;phot.mag;em.opt.i
mu_mean_exp	SB	Exponential fit mean surface brightness	mag/arcsec**2	phot.mag.sb;em.opt.i
n_ser	Sérsic	Sersic index	N/A	stat.fit.param
objid_cs82	CS82 id	Identifier built as im_num*1000000+se_id	N/A	meta.id;meta.main
objid_sdss	SDSS id	SDSS object ID for objects with matched ugriz broadband magnitudes (if available)	N/A	meta.id.cross
odds_best	Odds(z best)	Odds value for zbest (=1 if zspec is used)	N/A	stat.fit.goodness
odds_morph	Odds(z morph)	Odds value for zmorph	N/A	stat.fit.goodness
odds_phot	Odds(z best)	Odds value for zphot	N/A	stat.fit.goodness
p_exp	S/E?	Exponential shape probability: ~1 -> disc galaxy; ~0 -> elliptical galaxy	N/A	stat.fit.goodness
ra	RA	ICRS Right Ascension	deg	pos.eq.ra;meta.main
reff_exp	R	Exponential fit effective radius	arcsec	phys.angsize;src
spread_model_ser	Spread model	Sersic spread model, the star-galaxy separator we used for this study. All objects in this catalogue have SPREAD_MODEL_SER>0.008, which are considered extended objects (galaxies).	N/A	stat.fit.param
weight	lensFit	lensFit shape measurement confidence. weight>0 indicates good shape measurement	N/A	stat.weight
zbest	z best	Best redshift for this object, in order of priority: zspec, zphot, zmorph	N/A	src.redshift
zmorph	z morph	Photometric redshift estimated using inputs i+morphology	N/A	src.redshift
zphot	z phot	Photometric redshift estimated using inputs ugriz+morphology	N/A	src.redshift
zspec	z spec	Spectroscopic redshift from source given in source_spec	N/A	src.redshift

VOTable Output Fields

The following fields are available in VOTable output. The verbosity level is a number intended to represent the relative importance of the field on a scale of 1 to 30. The services take a VERB argument. A field is included in the output if their verbosity level is less or equal VERB*10.

Name	Table Head	Description	Unit	UCD	Verb. Level
objid_cs82	CS82 id	Identifier built as im_num*1000000+se_id	N/A	meta.id;meta.main	1
ra	RA	ICRS Right Ascension	deg	pos.eq.ra;meta.main	1
dec	Dec	ICRS Declination	deg	pos.eq.dec;meta.main	1
fitclass	Fit class	lensFit star-galaxy classifier: 1=stars; 0=galaxies; -1=no usable data; -2=blended objects; -3=miscellaneous reasons; -4=chi-square exceeded critical value	N/A	meta.code;src.class	1
mag_auto	i Kron	CS82 Kron i-band magnitude	mag	phot.mag;em.opt.i	1
reff_exp	R	Exponential fit effective radius	arcsec	phys.angsize;src	1
n_ser	Sérsic	Sersic index	N/A	stat.fit.param	1
spread_model_ser	Spread model	Sersic spread model, the star-galaxy separator we used for this study. All objects in this catalogue have SPREAD_MODEL_SER>0.008, which are considered extended objects (galaxies).	N/A	stat.fit.param	1
lens	lens?	Lensing tag. Objects with lens=1 are objects from the lensing subsample (fitclass=0, weight>0)	N/A	meta.code	1
zphot	z phot	Photometric redshift estimated using inputs ugriz+morphology	N/A	src.redshift	1
zmorph	z morph	Photometric redshift estimated using inputs i+morphology	N/A	src.redshift	1
zbest	z best	Best redshift for this object, in order of priority: zspec, zphot, zmorph	N/A	src.redshift	1
flags	Ex. Qual	Source extraction quality flag (ranges from 0 to 3, with 0 being the best)	N/A	meta.code	15
weight	lensFit	lensFit shape measurement confidence. weight>0 indicates good shape measurement	N/A	stat.weight	15
magerr_auto	Err. i Kron	CS82 Kron i-band magnitude error. Signal-to-noise ratio is 1.086/MAGERR_AUTO	mag	stat.error;phot.mag;em.opt.i	15
mag_exp	i fit	CS82 exponential fit i-band magnitude	mag	phot.mag;em.opt.i	15
mag_psf	i psf	CS82 PSF i-band magnitude	mag	phot.mag;em.opt.i	15
aspect_exp	Ax. Ratio	Exponential fit axis-ratio	N/A	src.morph.param	15
mu_mean_exp	SB	Exponential fit mean surface brightness	mag/arcsec**2	phot.mag.sb;em.opt.i	15
p_exp	S/E?	Exponential shape probability: ~1 -> disc galaxy; ~0 -> elliptical galaxy	N/A	stat.fit.goodness	15
objid_sdss	SDSS id	SDSS object ID for objects with matched ugriz broadband magnitudes (if available)	N/A	meta.id.cross	15
mag_dered_u	u dered	SDSS dereddened u-band magnitude	mag	phot.mag;em.opt.U	15
mag_dered_g	g dered	SDSS dereddened g-band magnitude	mag	phot.mag;em.opt.V	15
mag_dered_r	r dered	SDSS dereddened r-band magnitude	mag	phot.mag;em.opt.R	15
mag_dered_i	i dered	SDSS dereddened i-band magnitude	mag	phot.mag;em.opt.I	15
mag_dered_z	z dered	SDSS dereddened z-band magnitude	mag	phot.mag;em.opt.I	15
zspec	z spec	Spectroscopic redshift from source given in source_spec	N/A	src.redshift	15
odds_phot	Odds(z best)	Odds value for zphot	N/A	stat.fit.goodness	15
odds_morph	Odds(z morph)	Odds value for zmorph	N/A	stat.fit.goodness	15
odds_best	Odds(z best)	Odds value for zbest (=1 if zspec is used)	N/A	stat.fit.goodness	15
class_spec	Class	Class of object based on spectral fit: GALAXY or QSO	N/A	meta.code.class	15
source_spec	Src	Source of spectroscopy: SDSS, BOSS, DEEP2, WIGGLEZ or VVDS	N/A	meta.bib	25

VOResource XML (that's something exclusively for VO nerds)

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