7C

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1990MNRAS.246..110McGilchrist+
1995A&AS..110..419Visser+
1995MNRAS.276..614Lacy+
1996MNRAS.282..779Waldram+
1999MNRAS.306...31Riley+

The 7C survey covers most of the northern hemisphere above a declination of 20d, but generally away from the Galactic plane, at 151 MHz, with a resolution of 70x70cosec(declination) arcsec**2 (EWxNS) (i.e., about four times better resolution than the 6C survey).

The published portions of this survey are:

regions centred at 10h28m, 41d and 6h28m, 45d
McGilchrist et al. 1990 MNRAS, 246, 110;
a region centred at 17h, 65d
Visser et al. 1995, A&AS, 110, 419;
a region centred at 18h, 66d
Lacy et al. 1995, MNRAS, 276, 614;
a region covering 9h to 16h, 20d to 36d,
Waldram et al. 1996, MNRAS, 282, 779 (erratum 284, 1007);
a region covering 9h to 16h, 20d to 36d,
Waldram et al. 1996, MNRAS, 282, 779 (erratum 284, 1007);
33 regions in the range 7h<RA<17h,30d<DE<58d
1999MNRAS.306...31Riley, Waldram & Riley:

The published paper contains source lists on microfiche. Versions of this papers with the lists on paper are available on request from MRAO.

Some source lists are available in computer readable form by ftp, or from NSSDC's Online Data and Information Service (NODIS), and are searchable on line via the Einstein On-Line Service (Einline) of the Smithsonian Astrophysical Observatory, and the DIRA2 service at Bologna. Other source lists (and images) of other regions, although not yet published, may be available on request.

1990MNRAS..246..110McGilchrist+

The 7C survey at 151 MHz: Two fields at 1028+41 and 0628+45

McGilchrist, M.M., Baldwin, J.E., Riley, J.M., Titterington, D.J., Waldram, E.M., and Warner, P.J.

Table of Contents .

 1 Description  Description of catalog 
 2 Field List   A general listing of all the fields in the catalog
 3 Example      Example SQL query to the catalog with expected results
 4 References
 5 Additional Information
 6 Further Acknowledgements
 7 Appendix
 8 Filename     Document URL
 9 Origin       Origin of catalog
10 Date         Catalog creation date
11 Revised      Last revision date
12 Columns      Number of columns or fields in the catalog
13 Rows         Number of rows or entries in the catalog
14 Time Period  Time period for which catalog data are available
15 Other        Any additional information concerning the physical attributes of the catalog
16 Contact      Addresses for further information
17 Keywords      Keywords

Description

The 7C survey of radio sources is being made with the Cambridge Low Frequency Synthesis Telescope at 151 MHz, with an angular resolution of 70"x70"xcosec(decl). This catalogue contains the first part of the survey with 4723 sources covering 0.144 sr in two areas of sky centered at RA=10h28m, Dec=+41d and RA=06h28m, Dec=+45d (B1950). It reaches a limiting flux density of 80 mJy and is complete for sources with flux densities greater than 350 mJy in the 06h field, and for sources with flux densities greater than 250 mJy in the 10h field. The data were originally presented in McGilchrist et al. 1990, MNRAS 246, 110

Field List - Short Descriptions

The values in parenthesis include (units, datatype, example).

1 ra_rad      radians Right ascension of source in radians (B1950) (real, example: 1.747184)
2 dec_rad     radians Declination of source in radians (B1950) (real, example: 0.789712)
3 ra_deg      degrees Right ascension of source in degrees (B1950) (real, example: 100.106293)
4 dec_deg     degrees Declination of source in degrees (B1950) (real, example: 45.247169)
5 s_151       Jy      Flux density of source at 151 MHz (real, example: 0.555)
6 size        arcsec  Angular size (real, example: 144.95)
7 pa          degrees Position angle (int, example: 204)
8 num_pix             No. of pixels used to calculate integrated flux density (int, example: 40)
9 class               Source classification - Morphological type (char3, example: 'PT' or 'E')
10 class_flg          Quality of source classification (char1, example: '.' or '*' or '?' etc.)
11 field              Code as to which field contains source (int, example: 1)
12 atten              Primary beam attenuation (real, example: 0.979)
13 aberr              Depression in height of beam due to aberration (real, example: 0.953)
14 hi_pix     Jy/beam Value of highest pixel in source in Jy/beam (real, example: 0.341)
15 pos_mthd           Method used to determine position (char2, example: 'Pr' or 'Us')
16 flx_mthd           Method used to determine flux density (char2, example: 'Cn' or 'Dy')
17 siz_mthd           Method used to determine angular size and PA (char2, example: 'Us' or 'a')

Field List - Detailed Descriptions

1. COLUMNS ra_rad dec_rad ra_deg dec_deg

These columns contain the B1950 coordinates of the source, in radians and in degrees. The method used to determine the position is given in the pos_mthd column below. Combining the random and systematic errors, the position errors in RA vary from approximately

sqrt [1^2 + (1/S)^2] arcsec for sources near the calibrator to approx.

sqrt [3^2 + (1/S)^2] arcsec at the greatest distance from it.

The corresponding errors in Dec are
sqrt [1^2 + (cosec dec/S)^2] arcsec to approx.
sqrt [3^2 + (cosec dec/S)^2] arcsec
where S is the flux density in Jy.
Example (ra_rad) (real): 1.747184
Example (dec_rad) (real): 0.789712
Example (ra_deg) (real): 100.106293
Example (dec_deg) (real): 45.247169

2. COLUMN s_151

This column gives the flux density in Jy at 151 MHz. The method used to determine the flux density is given in the flx_mthd column below. Flux density errors are typically 18 mJy. See the paper for details.
Example (s_151) (real): 0.555

3. COLUMNS size pa

These columns contain the angular size, in arcseconds and the position angle, in degrees. If the source is significantly resolved, the method used to determine the size is given in the siz_mthd column below. The position angle is given only if the source is significantly resolved.
Example (size) (real): 144.95
Example (pa) (int): 204

4. COLUMN num_pix hi_pix

These columns give the number of pixels used when calculating the flux density, and the value of the highest pixel in the source (in Jy/beam). The highest pixel value is taken before correction for primary beam and without allowing for the depression of the peak value of the synthesized beam. If there is more than one peak in the source, the average of the highest pixel is given.
Example (num_pix) (int): 40
Example (hi_pix) (real): 0.341

5. COLUMNS class class_flg

These columns give information about the source classification. The class column gives the morphological type, as follows:

PT point
E extended
EC extended complex
DE equal double
DUn unequal double, the flux densities of the components being in the ratio n:1
DC double complex
HT head tail.

The class_flg column gives an indication of the quality of the morphological classification, as follows:

. firm classification
? uncertain classification
% slightly confused but firm classification
# slightly confused, uncertain classification
+ confused but firm classification
* confused, uncertain classification

Example (class) (char3): 'PT' or 'E' Example (class_flg) (char1): '.' or '*' or '?' etc.

6. COLUMN field

This column gives the number of the field that the source was in, as follows:

See the paper for details on field centers and calibrator positions.
Example (field) (int): 1

7. COLUMNS atten aberr

These columns give the primary beam attenuation and the depression in the height of the beam due to geometric and chromatic aberration.
Example (atten) (real): 0.979
Example (aberr) (real): 0.953

8. COLUMN pos_mthd

This column gives the method used to calculate the position. The following abbreviations are used:

Dy The position was found from an iterative least-squares fit to the synthesized beam. The algorithm runs automatically and is used for point sources; it is not suitable for complex sources.
Pr The data around the peak are interpolated on to a much finer grid, and the position of the maximum on this fine grid is taken; if a source has more than one peak, the position adopted is the unweighted mean of all the peak positions.
Us For a very complex source, the position given is that at which the optical identification is most likely to be found.

Example (pos_mthd) (char2): 'Pr' or 'Us'

9. COLUMN flx_mthd

This column gives the method used to calculate the flux density. The following abbreviations are used:

Dy The flux density was found from an iterative least-squares fit to the synthesized beam. The algorithm runs automatically and is used for point sources; it is not suitable for complex sources.
I The pixels above a certain level are summed; in addition, the sum is converted to a flux density using an appropriate normalization factor.
P The pixels above a certain level are summed; in addition the immediate neighbors of the outermost points are included. The sum is converted to a flux density using an appropriate normalization factor.
Sf A rotationally symmetric representation of the synthesized beam is fitted to the source profile with height and zero-level as the only parameters; pixels with values substantially different from those expected are not included in the fitting procedure.
Cn The area covered by the source is CLEANed down to the noise level, using the local synthesized beam as the dirty beam; the flux density is the sum of the clean components.

Example (flx_mthd) (char2): 'Cn' or 'Dy'

10. COLUMN siz_mthd

This column gives the method used to calculate the angular size. The following abbreviations are used:

Us The user selects two points on a contour map of the source. The angular size is the angular separation of these points and the position angle is that of the line joining them. For complex sources the size is generally the largest angular size; for those with only one peak it is typically the full width at half maximum in the direction of maximum extension, corrected for beam broadening.
a This is only used for sources with two or more peaks. The angular size is the angular distance between the two most widely separated peaks; the position angle is that of the line joining them.

Example (siz_mthd) (char2): 'Us' or 'a'

References

McGilchrist, M.M., Baldwin, J.E., Riley, J.M., Titterington, D.J., Waldram, E.M., and Warner, P.J. 1990, MNRAS, 246, 110.

1995A&AS..110..419V

The 7C survey of radio sources at 151 MHz - a 418-square-degree region centred at RA 17h, Dec. 65deg.

Visser, A.E., Riley J.M., Rottgering H.J.A. & Waldram E.M.

Astronomy and Astrophysics Supplement, v.110, p.419

05/1995

Abstract

The Cambridge Low Frequency Synthesis Telescope has been used at 151MHz to survey a region of 418 square degrees centred at RA 17h, Dec 65deg, which includes the North Ecliptic Cap. The resolution is 70x70''cosec {delta} and the rms noise on the maps is 25mJy.beam^-1^. We present positions and flux densities for 2702 sources which have a signal to noise ratio >5.5 and radio maps of 37 selected extended sources.

1995MNRAS.276..614L
from ADS Astronomy Abstract Service

A radio-optical survey of the North Ecliptic Cap

Lacy M., Riley J.M., Waldram E.M., McMahon R.G., Warner P.J.

Monthly Notices RAS, v. 276, Issue 2, pp. 614-626.

Abstract

The Cambridge Low Frequency Synthesis Telescope has been used to survey a region ~=7x7 deg^2 about the North Ecliptic Cap at 151 MHz with a resolution of 70x77 arcsec^2. The resulting radio source catalogue of 400 sources is complete to a peak flux density limit of 120 mJy beam^-1. Using the Cambridge APM we have searched for identifications on the Palomar Sky Survey plate 550 which covers much of the survey area, and we list the 157 sources with one or more optical objects within 15 arcsec of the radio position.

1996MNRAS.282..779W

The 7C survey of radio sources at 151 MHz - a region covering RA 9^h to 16^h and Dec. 20 deg to 35 deg

E.M. Waldram, J.A. Yates, J.M. Riley & P.J. Warner

Abstract

The Cambridge Low Frequency Synthesis Telescope has been used at 151 MHz to survey a region of 1393 deg^2, in the range RA 9^h-16^h, Dec. 20 deg-35 deg, with an angular resolution of 108x108 cosec delta arcsec^2. The rms noise on the maps is, in general, ~35-55 mJy beam^-1, but varies considerably and exceeds this in some areas. We have extracted sources with a signal-to-noise ratio <~5.5, totalling 5526, and present a catalogue of their positions and flux densities.


VIII/XXXX 7C 151-MHz surveys at 1005+53, 1042+57, 1332+38 (Pooley+ 1998)
===========================================================================
The 7C Survey of Radio Sources at 151 MHz: three regions centred at
RA 10h 05m, Dec 53deg 54m; RA 10h 42m, Dec 57deg 36m; RA 13h 32m, Dec 38deg 10m
     Pooley D.M., Waldram E.M., Riley J.M.
    
    =1998MNRAS,298..637P       (SIMBAD/NED BIBCODE)
===========================================================================
ADC_Keywords: Radio sources ; Surveys

Keywords: catalogues -  surveys - radio continuum: general

Description:
   The Cambridge Low Frequency Synthesis Telescope has been used at 151 MHz
   to survey three regions centred at RA 10h 05m,Dec 53deg 54m, 
   RA 10h 42m,Dec 57deg 36m and RA 13h 32m,Dec 38deg 10m, each of area 
   7.3 x 7.3cosec(dec) deg^2^. The resolution is 70 x 70cosec(dec) arcsec^2^,
   and the rms noise on the maps is typically 15mJy beam^-1^. We present
   positions and flux densities for 2381 sources which have signal-to-noise
   ratios > 5.5. The RAxDec coverage, average rms noise, flux density of the 
   faintest source listed and completeness limit for each region catalogued 
   are given in the table below. All coordinates are equinox B1950.
   --------------------------------------------------------------------------
   Region    Coverage RA x Dec (see notes*)    av.rms noise  Sfaint    Scomp
   --------------------------------------------------------------------------
   1005+53   09h40m-10h30m;49deg05m-58deg20m   15mJy         50mJy     170mJy
   1042+57   10h10m-11h10m;53deg00m-61deg45m   13mJy         50mJy     150mJy
   1332+38   13h15m-13h50m;31deg40m-43deg45m   14mJy         50mJy     200mJy 
   --------------------------------------------------------------------------
   *Note: RA coverage is indicated by approx RA range at Dec of field centre
   *Note: Dec coverage is indicated by approx Dec range at RA of field centre
   --------------------------------------------------------------------------

   1-sigma errors on the listed source positions may be approximated by:
   Right Ascension error(arcsec) = SQRT(1.0**2 + (32/SNR)**2)
   Declination error(arcsec) = 1.3cosec(dec) x (RA error)
   and
   1-sigma errors on the listed flux densities may be approximated by:
   Error on S beam-fitted(Jy)  =  SQRT(0.03**2 + SNR**-2) x S(Jy)
   Error on Sint(Jy) = 1.5 x SQRT(0.03**2 + SNR**-2) x Sint(Jy)
  
   where SNR, S and Sint correspond to the columns denoted by those names
   in the byte-by-byte description below. For multi-component sources
   the SNR for the brightest component is used to estimate the Sint error.
     
   For further details of the surveys and data analysis procedures please
   refer to the published paper referenced at the head of this file.
   
File Summary:
----------------------------------------------------------------------------
FileName   Lrecl  Records     Explanations
----------------------------------------------------------------------------
ReadMe        80        .     This file
100553.dat    74      743     7C sourcelist of 743 sources
104257.dat    74      757     7C sourcelist of 757 sources
133238.dat    74      881     7C sourcelist of 881 sources
7C_Pooley.dat 74     2281     Sum 7C sourcelist of 2281 sources (CATS)
-----------------------------------------------------------------------------

Byte-by-byte Description of file: *.dat
-----------------------------------------------------------------------------
   Bytes   Format  Units   Label     Explanations
--------------------------------------------------------------------------------
   1-  2   I2      h       RAh       Beam-fitted position right ascension B1950
   4-  5   I2      min     RAm       Beam-fitted position right ascension B1950
   7- 10   F4.1    s       RAs       Beam-fitted position right ascension B1950
      12   A1      -       DE-       Beam-fitted position declination (sign)
  13- 14   I2      deg     DEd       Beam-fitted position declination B1950
  16- 17   I2      arcmin  DEm       Beam-fitted position declination B1950
  19- 20   I2      arcsec  DEs       Beam-fitted position declination B1950
  24- 25   I2      h       RACh      Centroid position right ascension B1950
  27- 28   I2      min     RACm      Centroid position right ascension B1950
  30- 33   F4.1    s       RACs      Centroid position right ascension B1950
      35   A1      -       DEC-      Centroid position declination (sign)
  36- 37   I2      deg     DECd      Centroid position declination B1950
  39- 40   I2      arcmin  DECm      Centroid position declination B1950
  42- 43   I2      arcsec  DECs      Centroid position declination B1950
  47- 52   F6.2    Jy/beam S         Beam-fitted flux density
  54- 59   F6.2    Jy      Sint      Integrated flux density
  61- 65   F5.1    ---     SNR       Signal-to-noise ratio
  67- 70   F4.1    ---     Extent    Extent of the source 
                                      in units of local beam area
      74   I1      ---     Nmax      Number of local maxima within the 
                                      integrated region
--------------------------------------------------------------------------------

================================================================================
(End)                                Sally Hales [MRAO]          20-Oct-1998


================================================================================


1999MNRAS.306...31Riley, Waldram & Riley: The 7C survey of radio sources
at 151 MHz: 33 regions in the range 7h<RA<17h,30d<DE<58d (ctsy. S.Hales 5/99)

33 files merged and marked with the field name in the first column (H.Andernach 5/99)
   total of  19226 entries; S151_bf_max=85206 mJy;  S151_int=84716 mJy

Fieldnam RADEC_bf_B1950 RADEC_cen_B1950 S151_bf _int/mJy S/N Ext Nmax
----+----1----+----2----+----3----+----4----+----5----+----6----
0722+45 070011.1+482817 070011.1+482819   825   891  23.2  1.1 1
0722+45 070021.3+480907 070021.7+480909   274   311  10.1  1.3 1

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