J/other/PASA/18.232 FLAIR II spectroscopy of DENIS samples (Mamon+, 2001)
FLAIR II spectroscopy of two DENIS J band galaxy samples.
Mamon G.A., Parker Q.A., Proust D.
<Publ. Astron. Soc. Australia, 18, 232 (2001)>
=2001PASA...18..232M 2001PASA...18..232M
ADC_Keywords: Galaxies, IR ; Radial velocities ; Magnitudes
Keywords: infrared: galaxies - cosmology: observations - surveys -
galaxies: luminosity function
Abstract:
As a pilot survey for the forthcoming 6dF Galaxy Redshift Survey,
spectroscopy of galaxies selected in the 1.2 micron J waveband with
the DENIS imaging survey was performed at the UKST using the FLAIR II
multi-object spectroscope. Sixty-nine galaxy redshifts were obtained
in a high galactic latitude field and an additional 12 redshifts in a
low galactic latitude (b=-17°), obscured field. This spectroscopic
follow-up of NIR selected galaxies illustrates the feasibility of
obtaining redshifts with optical spectra on galaxies selected at much
longer wavelengths. It validated a very preliminary algorithm for
star/galaxy separation for high galactic latitude DENIS objects, with
99% reliability for J<13.9. The FLAIR II redshifts are in excellent
agreement with those, previously published, of 20 common galaxies.
However, the FLAIR II redshift determinations presented here required
substantially longer integration times to achieve 90% completeness
than expected from previous optical surveys at comparable depth. This
is mainly due to a degradation in overall fibre throughput due to
known problems with ageing of the prism- cement-fibre interface with
exposure to UV light. In comparison to our high galactic latitude
field, our low latitude (high extinction) field required 2.5 times
more exposure time for less than 50% of successful redshift
measurements.
Among the J≤13.9 galaxies with measured redshifts, only 37±6%
display emission lines, in comparison with 60% of emission line
galaxies in optical samples of comparable depth. These galaxies are,
on average, half a magnitude bluer in B-J than galaxies of the same
luminosity without emission fines. We confirm a previous
optically-based result that the fraction of galaxies with emission
lines increases rapidly with decreasing galaxy luminosity. The J band
luminosity function is estimated. Our high latitude field displays a
concentration of galaxies at cz~=38000km/s suggesting a possible
supercluster. A radial velocity is reported for a galaxy lying near
the projected centre of the Abell 1434 cluster of galaxies, for which
no cluster redshift is currently available.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 76 69 Galaxy redshifts in field F787
table3.dat 76 12 Galaxy redshifts in field F20
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See also:
B/denis : The DENIS database (Epchtein+, 1999)
http://msowww.anu.edu.au/~colless/6dF/ : 6dF Galaxy Survey Home Page
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- [MPP2001] Name
8 A1 --- n_[MPP2001] Individual note (1)
10- 11 I2 h RAh Right ascension (J2000), from COSMOS
13- 14 I2 min RAm Right ascension (J2000), from COSMOS
16- 19 F4.1 s RAs Right ascension (J2000), from COSMOS
22 A1 --- DE- Declination sign (J2000), from COSMOS
23- 24 I2 deg DEd Declination (J2000), from COSMOS
26- 27 I2 arcmin DEm Declination (J2000), from COSMOS
29- 32 F4.1 arcsec DEs Declination (J2000), from COSMOS
35 A1 --- Type [GS] COSMOS type (G: galaxy, S: star)
37- 41 F5.2 mag bjmag bJ magnitude
43- 46 I4 --- Strip DENIS strip number
48- 52 F5.2 mag Jmag J magnitude
54- 58 I5 km/s cz Measured radial velocity
60- 62 I3 km/s e_cz rms uncertainty on cz
64- 67 F4.1 --- R Tonry & Davis (1979AJ.....84.1511T 1979AJ.....84.1511T)
correlation parameter
69- 72 I4 --- Cont Maximum continuum, typically reached around
5500Å, in arbitrary units
74- 76 A3 --- Lines "em" for presence of emission lines,
"abs" for absorption lines only
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Note (1): Visual inspection of the photographic UKST plates and
cross-identification with NED indicated the following:
F787-05 = VV 457
F787-09 = NGC 3952
F787-14 = is a binary galaxy
F787-16 = NGC 3967
F787-35 = has a star superposed on the galaxy
F787-37 = is within 42" of the cluster Abell 1434
F787-49 = is a low surface brightness galaxy
F787-61 = is a galaxy triplet
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History:
Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 20-Jun-2002