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J/MNRAS/278/1025 The APM Bright Galaxy Catalogue (Loveday 1996)
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The APM Bright Galaxy Catalogue
Loveday J.
<Mon. Not. R. Astron. Soc. 278, 1025 (1996)>
=1996MNRAS.278.1025L
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ADC_Keywords: Galaxy catalogs ; Photometry
Abstract:
The APM Bright Galaxy Catalogue lists positions, magnitudes, shapes
and morphological types for 14,681 galaxies brighter than b(J)
magnitude 16.44 over a 4,180 square degree area of the southern sky.
Galaxy and stellar images have been located from glass copy plates of
the United Kingdom Schmidt Telescope (UKST) IIIaJ sky survey using the
Automated Photographic Measuring (APM) facility in Cambridge, England.
The majority of stellar images are rejected by the regularity of their
image surface brightness profiles. Remaining images are inspected by
eye on film copies of the survey material and classed as stellar,
multiple stellar, galaxy, merger or noise. Galaxies are further
classified as elliptical, lenticular, spiral, irregular or uncertain.
The 180 survey fields are put onto a uniform photometric system by
comparing the magnitudes of galaxies in the overlap regions between
neighbouring plates. The magnitude zero-point, photometric uniformity
and photographic saturation are checked with CCD photometry. Finally,
the completeness and reliability of the catalogue is assessed using
various internal tests and by comparing with several independently
constructed galaxy catalogues.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
galaxy.dat 64 14681 Galaxies in APM-BGC
fields.dat 23 180 *Field centres
holes.dat 75 1456 *Holes drilled around big bright objects
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Note on fields.dat:
This table lists SERC field centres in 1950 decimal degrees.
The column labeled RAextent gives the half-size of the Right Ascension
of the field in degrees. The DEextent is 2.5 degrees for every field.
This list of fields may be used for example to generate a random catalogue
with the same boundaries as the survey data as follows.
A point with coordinates (RAp, DEp) is inside a field with coordinates
(RAf, DEf) if (abs(RAp - RAf) < RAextent) and (abs(DEp - DEf) < DEextent).
An additional test should be made to allow for the extra overlap between
fields at RA = 0. If RAf is not zero then abs(RAp) must be greater
than RAextent.
Note on holes.dat:
This table lists the coordinates of parallelogram shaped holes drilled
out around big bright objects in the survey. The following FORTRAN code
will test if a point with coordinates (xr,yr) lies in a hole:
c
c *** Set drilled = .true. if point (xr,yr) lies in a given hole
c
c Method: Express displacement vector to (xr,yr) in terms of basis
c vectors of parallelogram
c
c Vr = a1*V1 + a2*V2
c - - -
c
c Then (xr,yr) is drilled if 0 <= a1,a2 <= 1
c
drilled = .false.
dx = xr - HOLX1
dy = yr - HOLY1
dx1 = HOLX2 - HOLX1
dy1 = HOLY2 - HOLY1
dx2 = HOLX3 - HOLX1
dy2 = HOLY3 - HOLY1
if (abs(dx2).gt.0) then
a1 = (dx*dy2 - dy*dx2)/(dx1*dy2 - dy1*dx2)
a2 = (dx - a1*dx1)/dx2
if (0.le.a1.and.a1.le.1.and.0.le.a2.and.a2.le.1) drilled = .true.
endif
Byte-by-byte Description of file: galaxy.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Galaxy name (1)
14- 15 I2 h RAh Right Ascension 1950 (hours)
17- 18 I2 min RAm Right Ascension 1950 (minutes)
20- 24 F5.2 s RAs Right Ascension 1950 (seconds)
27 A1 --- DE- Declination 1950 (sign)
28- 29 I2 deg DEd [17,72] Declination 1950 (degrees)
31- 32 I2 arcmin DEm Declination 1950 (arcminutes)
34- 37 F4.1 arcsec DEs Declination 1950 (arcseconds)
40- 44 F5.2 mag Bj Bj magnitude
47- 49 I3 arcsec MajDiam Major diameter
52- 54 I3 arcsec MinDiam Minor diameter
57- 59 I3 deg PA [0,360[ Position angle (degrees) (2)
63- 64 I2 --- MType Morphological type (3)
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Note (1):
Each galaxy name is composed of the survey field number and the x, y
position of the galaxy on the plate---this should ease location of any
particular galaxy on the plate material. The first 3 digits are the
SERC field number. The second set of digits are the x-position in
millimetres from the centre of the plate (actually the APM scan
centre). These are preceded by a `+' sign for galaxies to the right
(west) of the plate centre or by a `-' sign for galaxies to the left
(east) of centre. The final 3 digits are the y position, again in
mm from the plate centre. A preceding `-' indicates galaxies above
(north) of the plate centre, `+' indicates galaxies below (south) of
the centre.
Note (2):
PA is measured clockwise from south-north line.
Note (3):
The morphological type is given by mod(Mtype,10)
1 = Elliptical
2 = Lenticular
3 = Spiral
4 = Irr/Pec
5 = Uncertain
8 = Merged with star
9 = Multile galaxy
Galaxies from the ESO catalogue have 10 added.
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Byte-by-byte Description of file: fields.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Field [53,605] SERC field number
5- 10 F6.2 deg RAdeg RA of field centre 1950 (degrees)
12- 17 F6.2 deg DEdeg Dec of field centre 1950 (degrees)
19- 23 F5.3 deg RAextent RA extent of field (degrees)
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Byte-by-byte Description of file: holes.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Field [53,605] SERC field number
5- 15 F11.7 deg HOLX1 RA of 1st corner of hole (degrees)
17- 27 F11.7 deg HOLY1 Dec of 1st corner of hole (degrees)
29- 39 F11.7 deg HOLX2 RA of 2nd corner of hole (degrees)
41- 51 F11.7 deg HOLY2 Dec of 2nd corner of hole (degrees)
53- 63 F11.7 deg HOLX3 RA of 3rd corner of hole (degrees)
65- 75 F11.7 deg HOLY3 Dec of 3rd corner of hole (degrees)
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(End) Jon Loveday [Fermilab] 21-Feb-1996