J/MNRAS/521/3127 CAFOS DR1 point photometric catalog (Cortes-Contreras+, 2023)
The Calar Alto CAFOS direct imaging first data release.
Cortes-Contreras M., Solano E., Alonso-Hernandez J., Cardiel N., Cruz P.,
Rodrigo C.
<Mon. Not. R. Astron. Soc. 521, 3127-3149 (2023)>
=2023MNRAS.521.3127C 2023MNRAS.521.3127C (SIMBAD/NED BibCode)
ADC_Keywords: Photometry, SDSS ; Fundamental catalog ; Surveys ; Optical ;
Stars, variable ; Stars, dwarfs ; Stars, normal ;
Positional data ; Observatory log
Keywords: techniques: image processing - catalogues - virtual observatory tools
Abstract:
We present the first release of the Calar Alto CAFOS direct imaging
data, a project led by the Spanish Virtual Observatory with the goal
of enhancing the use of the Calar Alto archive by the astrophysics
community. Data Release 1 contains 23903 reduced and astrometrically
calibrated images taken from 2008 March to 2019 July with a median of
the mean uncertainties in the astrometric calibration of 0.04 arcsec.
The catalogue associated to 6132 images in the Sloan griz filters
provides accurate astrometry and PSF calibrated photometry for 139 337
point-like detections corresponding to 21 985 different sources
extracted from a selection of 2338 good-quality images. The mean
internal astrometric and photometric accuracies are 0.05 arcsec and
0.04 mag, respectively. In this work we describe the approach followed
to process and calibrate the images, and the construction of the
associated catalogue, together with the validation quality tests
carried out. Finally, we present three cases to prove the science
capabilities of the catalogue: discovery and identification of
asteroids, identification of potential transients, and identification
of cool and ultracool dwarfs.
Description:
The large amount of data obtained from ground and space based
telescopes make astronomical archives and catalogues prime assets for
astrophysics research. They provide raw and reduced data, but also
high-level data products highly demanded by thescientific community.
Projects like SDSS , 2MASS or WISE are good examples of extensively
used science-ready data products. The Calar Alto Observatory
is the largest astronomical observatory located in continental Europe.
Its 2.2 m telescope hosts the Calar Alto Faint Object Spectrograph
(CAFOS), a versatile instrument that allows four modes of observation:
direct imaging, spectroscopy, polarimetry, and narrow band imaging
using a Fabry Perot etalon. In its standard configuration, CAFOS is
equipped with a 2048 * 2048 pixel blue sensitive CCD with an image
scale of 0.53 arcsec pixel-1. This paper presents the first
release of the CAFOS direct imaging data, which includes reduced and
astrometrically calibrated images and its associated catalogue of
point-like sources. The point-like catalogue of sources and validation
exercises carried out with SDSS DR12 data are introduced in Section 7.
We report two science cases carried out with the catalogue aiming at
showing its potential for science exploitation in Section 8
(i.e. Identification of asteroids as SSOs, Transient candidates,
Identification of cool dwarfs).
The sample of images to be processed is constituted by 42173 exposures
observed with CAFOS between 2008 March and 2019 July that can be
accessed from the Calar Alto archive.For the first data release of the
astrometric and photometric catalogue and to simplify, we will focus
only on broad-band images observed in the Sloan system of filters g
(λ 4750 Å), r (λ 6300 Å), i (λ
7800 Å), and z (λ 9250 Å). There were a total of 6616
such images observed in the Sloan's griz bands between 2012 September
and 2019 June, with most of them (∼ 75 per cent) taken between 2017
and 2018. Next, astrometric calibration are carried out by Filabres as
described in section 3. Also, we developped a CAFOS Photometry
Calibrator to measure, to select sources and to calibrate. Extractions
is performed with both sextractor and psfex model as explained in
section 4. Hereafter for flux calibrators as presented in section 5,
we cross-matched our sources with SDSS DR12 and APASS dr9.
Additionnally (i.e. section 6), a selection on images quality is done.
For the first data release, our main purpose is to provide a
point-like photometric catalogue from the CAFOS images with SDSS
filters available at the CAHA archive, i.e. a collection of images
taken for different science cases and therefore, showing different
observational parameters. The choice of a point-like catalogue alone
in this first data release is made by simplicity and motivated by the
shallower depth compared for instance to the GTC Osiris DR1 catalogue
previously published by this group following a similar procedure
(Cortes-Contreras et al. 2020MNRAS.491..129C 2020MNRAS.491..129C, Cat. J/MNRAS/491/129).
The table.dat concatenates all astrometric and photemetric quantities
acquired during this work for 139337 detections grouped in 21985
different sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 452 139337 The first data release of our point-like
photometric catalogue from the CAFOS images
with SDSS filters
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See also:
J/MNRAS/491/129 : The GTC OSIRIS broad-band DR1 (Cortes-Contreras+, 2020)
J/MNRAS/476/5253 : Light curves for 5 LMEBs in WFCAM Transit Survey
(Cruz+, 2018)
J/A+A/642/A115 : CARMENES input catalogue of M dwarfs. V. (Cifuentes+, 2020)
J/A+A/619/L8 : Ultra-cool dwarfs candidates in Gaia DR2 (Reyle, 2018)
J/A+A/597/A47 : CARMENES input catalogue of M dwarfs II
(Cortes-Contreras+ 2017)
J/A+A/492/277 : Analysis of Collinder 69 stars with VOSA (Bayo+, 2008)
J/ApJ/867/105 : ATLAS all-sky stellar ref. catalog, ATLAS-REFCAT2
(Tonry+, 2018)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/AJ/141/97 : SDSS DR7 M dwarfs (West+, 2011)
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006)
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001)
VII/233 : 2MASS All-Sky Extended Source Catalog (XSC)
(IPAC-UMass, 2003-2006)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+,2016)
II/336 : AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)
II/335 : Revised catalog of GALEX UV sources (GUVcat_AIS GR6+7)
(Bianchi+ 2017)
II/314 : UKIDSS-DR8 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/297 : AKARI/IRC mid-IR all-sky Survey (ISAS/JAXA, 2010)
II/240 : The DENIS database first release (Epchtein+, 1999)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Source Numerical ID of sources detected
more than once within 0.5 arcsec
(SourceNID)
7- 17 F11.7 deg RAdeg Celestial Right Ascension (J2000)
(RAJ2000)
19- 29 E11.7 deg DEdeg Celestial Declination (J2000)
(DEJ2000)
31- 42 E12.10 arcsec e_RAdeg Right ascension error (e_RAJ2000)
44- 55 E12.10 arcsec e_DEdeg Declination error (e_DEJ2000)
57- 86 A30 --- DetID Detection identifier (Detection_ID)
88-112 A25 --- ImgID Image identifier (Image_identifier)
114-193 A80 --- ImgURL URL to access the reduced image
(Image_url)
195-202 F8.3 mag gmag ?=9999.99 PSF calibrated magnitude
in the g band (gmag)
204-211 F8.3 mag e_gmag ?=9999.99 PSF calibrated magnitude
error in the g band (e_gmag)
213-232 F20.15 mag rmag ?=9999.99 PSF calibrated magnitude
in the r band (rmag)
234-257 F24.19 mag e_rmag ?=9999.99 PSF calibrated magnitude
error in the r band (e_rmag)
259-278 F20.15 mag imag ?=9999.99 PSF calibrated magnitude
in the i band (imag)
280-302 F23.18 mag e_imag ?=9999.99 PSF calibrated magnitude
error in the i band (e_imag)
304-323 F20.15 mag zmag ?=9999.99 PSF calibrated magnitude
in the z band (zmag)
325-347 F23.18 mag e_zmag ?=9999.99 PSF calibrated magnitude
error in the z band (e_zmag)
349 A1 --- Flagph Calibration flag (Flag_phot) (1)
351-355 A5 --- Filter Filter of observation as SDSSi,r,g,z
(Filter)
357-361 A5 --- RefCal Reference catalogue used for the
photometric calibration as APASS dr9
or SDSS dr12 (Refcat)
363-366 F4.2 deg Elon Elongation of the detection
(Elongation)
368-371 F4.2 --- Ell Ellipticity of the detection
(Ellipticity)
373-376 F4.2 arcsec FWHM Full width half maximum of the
detection (FWHM)
378-386 F9.3 --- SNR Signal to noise ratio (SNR_WIN)
388-397 E10.7 --- Spread Spread parameter from model-fitting
(SPREAD_MODEL) (2)
399-408 F10.4 d MJD Modified Julian Date (MJD)
410-413 I4 yr Obs.Y The iso-8601 observing epoch
(DATE-OBS)
414 A1 --- --- [-]
415-416 I2 "month" Obs.M The iso-8601 observing epoch
(DATE-OBS)
417 A1 --- --- [-]
418-419 I2 d Obs.D The iso-8601 observing epoch
(DATE-OBS)
420 A1 --- --- [T]
421-422 I2 h Obs.h The iso-8601 observing epoch
(DATE-OBS)
423 A1 --- --- [:]
424-425 I2 min Obs.m The iso-8601 observing epoch
(DATE-OBS)
426 A1 --- --- [:]
427-428 I2 s Obs.s The iso-8601 observing epoch
(DATE-OBS)
430-432 I3 --- SrcSize Number of detections for each source
in GroupID (SourceSize) (3)
434-452 A19 --- Notes Notes on sources stellar parameters
as Teff (Notes)
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Note (1): Flags from calibration are as follows:
A = For calibrated magnitudes within the interval of magnitudes
used for the photometric calibration
B = For calibrated magnitudes fainter than the faintest magnitudes,
C = For calibrated magnitudes brighter magnitudes than the brightest
magnitude used for the photometric calibration
Note (2): It takes values close to zero for point sources, positive for
extended sources galaxies and negative for detections smaller than
the PSF, such as cosmic ray hits.
Note (3): Detections were grouped into sources by carrying out with STILTS
an internal match of the whole catalogue (this is, regardless the
photometric band) within 0.5 arcsec. This value is a good compromise
between completeness and reliability. Larger values may produce
associations among unrelated detections. Smaller values could miss
faint detections, which typically show large centroiding errors or
sources with high proper motions. This way, the 139337 detections
were grouped in 21985 different sources, each of which presents a
numerical identifier in the catalogue. Note that the absence of a
source in the catalogue does not imply that it has not been detected
by CAFOS but that it might not has passed the quality tests.
We thus address him/her to the Calar Alto archive to obtain its
photometry from the ready-to-use science images.
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Luc Trabelsi [CDS] 03-Jun-2026