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J/A+AS/58/39     1412 MHz catalogue of Westerbork survey. II (Windhorst+, 1984)

A deep Westerbork survey of areas with multicolor Mayall 4 m plates. II. Optical identifications. Windhorst R.A., Kron R.G., Koo D.C. <Astron. Astrophys. Suppl. Ser. 58, 39 (1984)> =1984A&AS...58...39W
ADC_Keywords: Radio sources ; Surveys ; Cross identifications Keywords: radio sources: general - astrometry - galaxies: radio - cosmology Abstract: A deep multicolor optical identification program is presented for a complete sample of 302 radio sources that were observed with the Westerbork Synthesis Radio Telescope within 5.52°2 down to S1.4GHz≳0.6mJy (5σ). Optical identifications are made from multicolor prime focus plates taken with the Kitt Peak 4 meter telescope in the passbands U,J,F and N with approximate respective limiting magnitudes of ∼23.3, 23.7, 22.7 and 21.1. The astrometry has systematic errors smaller than 0.2"-0.3", while the random errors are of order 0.4". The agreement between the radio and optical coordinate frames is on average better than 0.25". Identifications are based on positional coincidence using the likelihood ratio method. For 171 out of the 302 radio sources likely identifications are proposed with an a posteriori identification percentage of 53%, 14 expected spurious objects (or 5% of all radio sources), while not more than 4 identifications have been missed. The sample reliability is 92% and its completeness 98%. About 20% of the identifications are stellar objects, the remaining have extended images or are too faint to be classified. About 15% of the identifications appear in possible clusters. The identification statistics are roughly constant from field to field, except for the Hercules 2 field which has an unusually high identification fraction (74%). The identification fraction is presented as a function of 21 cm flux density and limiting magnitude, and amounts to 15% for 1≲S1.4GHz≲100mJy down to the Palomar Sky Survey limit and 29% down to the effective 48" Schmidt limit. For S1.4≲100mJy the identification fraction remains roughly constant with flux density, contrary to the prediction of higher fractions by some models for cosmological evolution. The magnitude distributions for galaxies plus objects of unknown type generally increase towards fainter magnitudes; the quasar magnitude distributions are also increasing but not as steeply as for the radio galaxies. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 76 46 List of Mayall prime focus plates used table4a.dat 80 171 List of optical identifications in the complete sample table4b.dat 80 41 List of identifications NOT in a complete sample notes.dat 80 119 Individual notes
See also: VIII/62 : The Westerbork Northern Sky Survey (Leiden, 1998) J/A+AS/58/1 : 1412 MHz catalogue of Westerbork survey (Windhorst+, 1984) J/A+A/35/393 : Westerbork Second Deep Survey (Katgert, 1974) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 6 A6 --- Field Field designation 8- 9 I2 h RAh Right ascension (1950) 11- 12 I2 min RAm Right ascension (1950) 14- 15 I2 s RAs Right ascension (1950) 17 A1 --- DE- Declination sign (1950) 18- 19 I2 deg DEd Declination (1950) 21- 22 I2 arcmin DEm Declination (1950) 24- 25 I2 arcsec DEs Declination (1950) 27- 30 I4 --- MPF Mayall prime focus plate number 32- 37 A6 --- Emuls Emulsion 39- 43 A5 --- Filter Filter 45- 47 I3 min Texp Exposition time 49- 52 A4 --- HA Hour angle (end exposure) 54- 57 F4.2 --- Airmass Airmass (mid-exposure) 59- 62 F4.2 arcsec Seeing Seeing (in σ/") 64- 76 A13 --- Com Comments/observers (1)
Note (1): Observers are R. Kron or K. Koo unless stated otherwise
Byte-by-byte Description of file: table4a.dat table4b.dat
Bytes Format Units Label Explanations
1- 6 A6 --- WSTB Westerbork designation (1) 7 A1 --- m_WSTB [*ABC] Multiplicity index on Name (2) 9- 10 I2 h RAh Right ascension (1950.0) 12- 13 I2 min RAm Right ascension (1950.0) 15- 19 F5.2 s RAs Right ascension (1950.0) 22 A1 --- DE- Declination sign (1950.0) 23- 24 I2 deg DEd Declination (1950.0) 26- 27 I2 arcmin DEm Declination (1950.0) 29- 32 F4.1 arcsec DEs Declination (1950.0) 34- 38 F5.1 arcsec oRA Average offset in right ascension (3) 40- 44 F5.1 arcsec oDE Average offset in declination (3) 47- 51 F5.2 --- R Normalized position difference 54- 59 F6.2 --- LR Likelihood ratio 64- 65 A2 --- ID Identification type (4) 67- 68 A2 --- Morph Morphology (5) 71- 72 A2 --- Env Environment (6) 75- 76 A2 --- Note Notes (7) 79- 80 I2 --- q_ID Identification code (8)
Note (1): Westerbork designation that consist of the Westerbork Survey number, which is 52 for SA57, 53 for Hercules, 54 for SA68 and 55 for Lynx, and a sequence number, in order of increasing RA. WSTB 52W NNA, WSTB 53W NNA, WSTB 54W NNA and WSTB 55W NNA in Simbad. Note (2): An * indicates that for this source multiple components were found, which are listed directly below, and are labelled A, B, C, etc. A detectable central component is always labelled "C". Generally, A and B are the western and easternmost components Note (3): the offsets are defined as: oRA = RArad - RAopt - <RArad - RAopt>field oDE = DErad - DEopt - <DErad - DEopt>field Note (4): Identification type: G: galaxy (extended image) Q: stellar object (not necessarily a quasar) S: spectroscopically confirmed star ?: object, but too faint to classify Note (5): For objects ≳4.0mag above the plate limits we consider: CD: first ranked galaxy in a cluster or group EL: elliptical or lenticular galaxy SP: spiral galaxy PC: peculiar (explained in the notes) For fainter objects we use: CM: compact, high surface brightness FZ: low surface brightness, fuzzy galaxy Note (6): Environment: CL: possible cluster, with ≥5 apparently associated galaxies GR: group of galaxies, with fewer apparently associated objects. DB: double galaxy. Another galaxy within one magnitude and one diameter. Note (7): Number refers to notes on the optical identification: 1: object in stellar, but not blue 2: blue object is of (unusually) high surface brightness, or sometimes a red object is of (unusually) low surface brightness. 3: the identification has a very close companion or an optical jet. 4: the identification is optically variable 5: two or more possible identifications were found in the various radio components of this double or complex radio source. Table4a.dat lists the identification that we believe to be correct one from all available data: table4b.dat gives the other possible identifications. These cases are discussed individually in the notes. 6: other notes on the optical object listed in the notes.dat file 7: detected s X-ray source (Katgert et al., 1983ApJ...275....1K) Capitals refers to notes on the radio source morphology, if relevant for the optical identification. Here the additional 25 objects are classified, for which the likelihood ratio analysis did not give an identification, while still a very likely optical candidate was found. A: Very extended radio sources (doubles with angular sizes ≳30") B: Head-tail and asymmetrical or complex radio sources C: Sources evidently misaligned with the centre of the optical image D: Diffuse radio sources with a spectroscopically confirmed candidate E: Very low surface brightness radio sources without spectroscopy *: indicates a note detailed in "notes.dat" file Note (8): Identification code: 0: reliable identification in the conservative sample of 146 objects -1: likely identification in the additional sample of 25 objects. Reason is given in column note and in the notes of notes.dat file 1: reliable identification but not in the complete optical sample 2: reliable identification but not in the complete radio sample
Byte-by-byte Description of file: notes.dat
Bytes Format Units Label Explanations
1- 6 A6 --- WSTB Westerbork designation 8- 80 A73 --- Note Text of the Note (1)
Note (1): Individual notes are given for optical objects that could not be adequately described in notes 5-8. Notes are also given for the 25 extended or complex radio sources for which the identification was not straightforward. For this latter subsample we classify the suggested identification as solid, very likely, likely or possible. The 21cm information is taken from Paper I, (Windhorst et al., Cat. J/A+AS/58/1) where contours of extended and complex radio sources are given, in which the positions of the optical objects from the current paper are marked with crosses. The surface brightness of the radio sources was noted from these contour plots or from a comparison between the contour plots of the high resolution and the low resolution 21cm maps of Paper I and the 50cm maps of Windhorst and Oppe (1984; Paper IV, submitted). For extended sources the western- and eastern-most components are referred to as A and B respectively, while any detectable central component is called C. All 50cm radio information (including spectral index α=-logSv/logv) is taken from Paper IV. For a few sources that were asymmetrically resolved at 21cm a better position was obtained at 50cm, which in a few doubtful cases clarified the situation. All additional optical information (photometry, spectra) is taken from Paper III (Kron et al., 1985A&A...146...38K), unless stated otherwise.
History: OCR'ed by H. Andernach (), proofread at CDS. Errors in table4a and table4b corrected on 28-Jul-2001 1 error in table4b corrected on 02-Aug-2001 1 further error in table4b corrected on 02-Jun-2004 References: Windhorst et al., Paper I 1984A&AS...58...39W, Cat. J/A+A/58/1 Windhorst et al., Paper III 1985A&A...146...38K
(End) Patricia Bauer [CDS] 10-May-2001
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