J/AJ/127/2455 Gemini Deep Deep Survey (GDDS) (Abraham+, 2004)
The Gemini Deep Deep Survey.
I. Introduction to the survey, catalogs, and composite spectra.
Abraham R.G., Glazebrook K., Mccarthy P.J., Crampton D., Murowinski R.,
Jorgensen I., Roth K., Hook I.M., Savaglio S., Chen H.-W., Marzke R.O.,
Carlberg R.G.
<Astron. J., 127, 2455-2483 (2004)>
=2004AJ....127.2455A 2004AJ....127.2455A
ADC_Keywords: Galaxies, photometry ; Redshifts ; Photometry, infrared
Keywords: galaxies: evolution
Abstract:
The Gemini Deep Deep Survey (GDDS) is an ultradeep (K<20.6mag,
I<24.5mag) redshift survey targeting galaxies in the "redshift desert"
between z=1 and z=2. The primary goal of the survey is to constrain
the space density at high redshift of evolved high-mass galaxies. We
obtained 309 spectra in four widely separated 30-arcmin2 fields
using the Gemini North telescope and the Gemini Multi-Object
Spectrograph (GMOS). The spectra define a one-in-two sparse sample of
the reddest and most luminous galaxies near the I-K versus I
color-magnitude track mapped out by passively evolving galaxies in the
redshift interval 0.8<z<1.8. This sample is augmented by a
one-in-seven sparse sample of the remaining high-redshift galaxy
population. The GMOS spectrograph was operating in a nod-and-shuffle
mode, which enabled us to remove sky contamination with high
precision, even for typical exposures times of 20-30hr per field. The
resulting spectra are the deepest ever obtained. In this paper we
present our sample of 309 spectra, along with redshifts,
identifications of spectral features, and photometry. This makes the
GDDS the largest and most complete infrared-selected survey probing
the redshift desert. The seven-band (VRIz'JHKs) photometry is taken
from the Las Campanas Infrared Survey (Cat. VII/228).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 140 309 Master data table
table5.dat 49 273 Spectral Features and Classifications
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See also:
VII/228 : Las Campanas Infrared Survey (Chen+, 2001-2002)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [SA]
3- 9 A7 --- GDDS GDDS object identification (HH-NNNN)
11- 16 F6.4 --- z ? Redshift
18- 19 I2 h RAh Hour of right ascension (J2000)
21- 22 I2 min RAm Minute of right ascension (J2000)
24- 28 F5.2 s RAs Second of right ascension (J2000)
30 A1 --- DE- Sign of the declination (J2000)
31- 32 I2 deg DEd Degree of declination (J2000)
34- 35 I2 arcmin DEm Arcminute of declination (J2000)
37- 41 F5.2 arcsec DEs Arcsecond of declination (J2000)
43- 44 I2 --- Conf Redshift confidence (G1)
46- 48 A3 --- Ovlap Slit geometry/collision class (1)
50- 56 F7.5 --- Weight Sampling weight (2)
58- 62 F5.2 mag Bmag ? B-band magnitude (3)
63 A1 --- n_Bmag [s] s for 2σ detection limit in Bmag
64- 68 F5.2 mag e_Bmag ? Uncertainty in Bmag (3)
70- 74 F5.2 mag Vmag V-band magnitude (3)
75 A1 --- n_Vmag [s] s for 2σ detection limit in Vmag
76- 80 F5.2 mag e_Vmag ? Uncertainty in Vmag (3)
82- 86 F5.2 mag Rmag ? Cousins R-band magnitude (3)
87 A1 --- n_Rmag [s] s for 2σ detection limit in Rmag
88- 92 F5.2 mag e_Rmag ? Uncertainty in Rmag (3)
94- 98 F5.2 mag Icmag Cousins I-band magnitude (3)
99 A1 --- n_Icmag [s] s for 2σ detection limit in Icmag
100-103 F4.2 mag e_Icmag Uncertainty in Icmag (3)
105-109 F5.2 mag z'mag z'-band magnitude (3)
110 A1 --- n_z'mag [s] s for 2σ detection limit in z'mag
111-115 F5.2 mag e_z'mag ? Uncertainty in z'mag (3)
117-121 F5.2 mag Hmag ? H-band magnitude (3)
122 A1 --- n_Hmag [s] s for 2σ detection limit in Hmag
123-127 F5.2 mag e_Hmag ? Uncertainty in Hmag (3)
129-133 F5.2 mag Ksmag Ks-band magnitude (3)
134 A1 --- n_Ksmag [s] s for 2σ detection limit in Ksmag
135-139 F5.2 mag e_Ksmag ? Uncertainty in Ksmag (3)
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Note (1): Classification of spectrum overlaps take the following numbers:
0 = Both A and B channels uncontaminated (at most very minor masking
needed).
1 = Single channel overlap. Offending channel not used (at most very
minor masking needed).
2 = A contaminating zeroth-order line has been masked. Remaining
continuum is trustworthy.
3 = Two channel collision. Major masking used in extraction.
Continuum in blue should not be trusted.
4 = Two channel collision. Major masking used in extraction.
Continuum in red should not be trusted.
5 = Extreme measures needed to try to recover a spectrum.
Continuum should not be trusted.
Note (2): The practical upshot of our general mask design strategy is
graphically summarized in the bottom left panel of Figure 6. This
panel is a two-dimensional histogram showing the number of independent
slits assigned each cell of color-magnitude space. For the reasons
just described heavy emphasis is given to the (22<I<24.5, 3<I-Ks<5)
region of color-magnitude space. The relative number of slits as a
function of the average population in each cell expected in a
wide-area survey can be computed by dividing the bottom left panel of
the figure by the top left panel. The values computed using this
procedure are shown in the bottom right panel and correspond to
sampling weights. These weights will prove important in the
computation of the luminosity and mass functions in future papers in
this series.
Note (3): Non-detections have been placed at the formal 2σ detection
limit of the filter and magnitude error set to blank.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [SA]
3- 9 A7 --- GDDS GDDS object identification (HH-NNNN)
11 I1 --- AGN [0/1] Indicative of AGN activity (1)
13 I1 --- [OII] [0/2] Is [O II] (3727 Å) present? (1)
15 I1 --- [OIII] [0/2] Is [O III] (5007 Å) present? (1)
17 I1 --- HiBal [0/2] Are Balmer lines bluer than Hβ
present? (1)
19 I1 --- LoBal [0/2] Is Hα and/or Hβ present? (1)
21 I1 --- Fe2375 [0/2] Is Fe II (2375 Å) present? (1)
23 I1 --- Fe2600 [0/2] Is Fe II (2600 Å) present? (1)
25 I1 --- Mg2800 [0/2] Is Mg II (2800 Å) present? (1)
27 I1 --- Mg2852 [0/2] Is Mg II (2852 Å) present? (1)
29 I1 --- HandK [0/2] Are Ca II H & K lines present? (1)
31 I1 --- Balmer [0/2] Is the Balmer decrement present? (1)
33 I1 --- D4000 [0/2] Is the D4000 feature present? (1)
35 I1 --- Temp Redshift template code (2)
37- 39 I3 --- Class Spectral class (3)
41- 42 I2 --- Conf Confidence code (G1)
44- 48 F5.3 --- z Redshift
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Note (1): Flag is: 0=No, 1=Yes
2=Feature did not fall within the wavelength range of our spectra
Note (2): Redshift template code as follows:
1 = Comparison against a reference template was used to obtain the
redshift
2 = No template needed to obtain the redshift
Note (3): Classes use the following numbers:
001 = Objects showing pure, or nearly pure, signatures of an evolved
stellar population (e.g., D4000, H&K, or template matches)
100 = Objects that are dominated by the flat-UV continuum and strong
emission-lines characteristic of star- forming systems
010 = those showing signatures of intermediate ages (e.g., strong
Balmer absorption).
Many objects show characteristics of more than one type and so are
assigned classes that are the sum of old (001), intermediates (010),
and young (100) populations. Example:
Objects listed as "101" may show strong H&K absorption and 4000Å
breaks and yet have a flat-UV continuum tail indicative of a low level
of ongoing star formation.
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Global notes:
Note (G1): Redshift confidence classes as follows:
0 = Failures. No redshift determined. If a redshift is given in
table4.dat it should be taken as an educated guess.
1 = Failures. Confidence <50%. Very insecure
2 = Redshift Inferred from Multiple Features. Confidence >75%.
Reasonably secure. Two or more matching lines/features.
3 = Redshift Inferred from Multiple Features. Confidence = 95%.
Secure. Two or more matching lines/features + supporting continuum.
4 = Redshift Inferred from Multiple Features. Confidence: Certain.
Unquestionably correct.
8 = Single-Line Redshift. Single emission line. Continuum suggests
line is [O II] λ3727.
9 = Single-Line Redshift. Single emission line.
14 = AGN Redshift. Class 4 as above, but with AGN characteristics.
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History:
From electronic version of the journal
References:
Savaglio et al., Paper II 2004ApJ...602...51S 2004ApJ...602...51S
Glazebrook et al., Paper III 2004Natur.430..181G 2004Natur.430..181G
McCarthy et al., Paper IV 2004ApJ...614L...9M 2004ApJ...614L...9M
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 08-Jul-2004