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EUROPEAN SOUTHERN OBSERVATORY
Organisation Europ’eenne pour des Recherches Astronomiques dans l'H’emisph‘ere Austral
Europ˜aische Organisation f˜ur astronomische Forschung in der s˜udlichen Hemisph˜are
171.A­3045
VISITING ASTRONOMERS SECTION . Karl­Schwarzschild­Straúe 2 . D­85748 Garching bei M˜unchen . e­mail: visas@eso.org . Tel. : +49­89­32 00 62 23
APPLICATION FOR OBSERVING TIME LARGE PROGRAMME PERIOD: 71A
To be submitted only to: proposal@eso.org
Important Notice:
By submitting this proposal, the PI takes full responsibility for the content of the proposal, in particular with regard to the
names of COIs and the agreement to act according to the ESO policy and regulations, should observing time be granted
1. Title Panel: A--1
The Great Observatories Origins Deep Survey: ESO Public Observations of the SIRTF Legacy/HST Trea­
sury/Chandra Deep Field South
2. Abstract / Total Time Requested
TotalAmountOfTime: 125h TotalNumberOfSemesters: 3
This proposal represents the continuation with VIMOS of the ESO campaign to secure essential ground­based
data for the Great Observatories Origins Deep Survey (GOODS). Through ESO, the European astronomy is
playing a major role in this public survey program, with raw and reduced data products to be rapidly released
to the community. GOODS combines observations with three NASA Great Observatories (HST, SIRTF, and
Chandra), ESA's XMM--Newton and ground--based telescopes to carry out an intensive study of galaxy evolution
and cosmology. GOODS is designed to measure the evolution of stellar mass content and star formation activity
in galaxies from z # 5 to z # 0.5; to map the emergence of the Hubble Sequence; to take a census of energetics
from massive central black holes in galaxies and study their role in galaxy evolution; and to secure a large sample
of SNe Ia at 1.2 < z < 1.8 to confirm or rule out the accelerated cosmic expansion. This specific program
with VIMOS will provide low­resolution spectra for redshift determination for all # 6000 objects
in the 160 arcmin 2 area of the GOODS field in the Southern hemisphere, down to mag=25. This
public data set will allow the ESO community to start cutting--edge research with GOODS data alone, as well
as to most e#ciently plan for further follow--up studies with the VLT.
3. Run Telescope Instrument Time Month Moon Seeing Sky Trans. Obs.Mode
A UT3 VIMOS 1h aug d # 0.8 ## CLR s
B UT3 VIMOS 10h sep d # 0.8 ## CLR s
C UT3 VIMOS 10h sep d # 0.8 ## CLR s
4. Principal Investigator: C. Cesarsky (ESO, ESO, ccesarsk@eso.org)
CoI(s): J. Bergeron (IAP, F), S. Cristiani (INAF, I), L. da Costa (ESO, ESO), E. Daddi (ESO, ESO),
M. Dickinson (STScI, USA), D. Elbaz (CEA, F), S. Ettori (ESO, ESO), R. Fosbury (ST­ECF, ESA), M.
Giavalisco (STScI, USA), R. Hook (ST­ECF, ESO), H. Kuntschner (ST­ECF, ESO), B. Leibundgut (ESO,
ESO), M. Nonino (INAF, I), A. Renzini (ESO, ESO), P. Rosati (ESO, ESO)
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5. Description of the proposed programme
A) Scientific Rationale: The first part of this section replicates the basic information on the GOODS project,
as from the GOODS Large Programme proposal submitted for P70, approved by OPC, and and currently being
carried out. Updates, whre needed, are in italic. The P70 proposal had illustrated the integrated strategy for a
complete, low­resolution spectroscopic follow­up first with FORS2 (in P70) and then with VIMOS (in P71 and
following periods). VIMOS is now being o#ered, and the current proposal describes the GOODS strategy with
this instrument. Quotation from P70 proposal begins here.
GOODS in Context: The Great Observatories Origins Deep Survey (GOODS) is a public, multi--facility
project that aims to answer some of the most profound questions in cosmology: How did galaxies form and
assemble their stellar mass? When was the morphological di#erentiation of galaxies established and how did the
Hubble Sequence form? How did AGN form and evolve, and what role do they play in galaxy evolution? How
much do galaxies and AGN contribute to the extragalactic background light? Is the expansion of the universe
dominated by a cosmological constant?
A project of this scope requires large and coordinated e#orts from many facilities, pushed to their limits, to
collect a database of su#cient quality and size for the task at hand. It also requires that the data be readily
available to the worldwide community for independent analysis, verification, and follow--up. To accomplish
this, NASA proposed a new concept for large--scale investigations: the Legacy/Treasury programs. These are
defined as (1) large, coherent science investigations, not reproducible by any reasonable number or combination
of smaller General Observer programs; (2) programs whose archived scientific data are of general and lasting
importance to the broad community; and (3) programs for which all raw and pipeline--processed data must
enter the public domain immediately, enabling timely and e#ective opportunities for follow--on observations
and archival research.
Among the approved Legacy/Treasury projects, GOODS (http://www.stsci.edu/science/goods) is a deep, high
latitude survey to study cosmology and galaxy evolution. The program targets two carefully selected fields,
the Hubble Deep Field North (HDF--N) and the Chandra Deep Field South (CDF--S), with the three NASA
Great Observatories (HST, SIRTF and Chandra), ESA's XMM--Newton, and a wide variety of ground--based
facilities (see Table 1). The area common to all the observing programs is 320 arcmin 2 , equally divided between
the N and S fields. For an overview of GOODS, see Dickinson et al. (astro­ph/0204213) and Renzini et al.
(astro­ph/0204214).
European collaboration was established in all major components of GOODS since its inception, including the
SIRTF Legacy Program (P.I. M. Dickinson; 647 hours of observing time), and the HST Treasury Program
(P.I. M. Giavalisco; 398 orbits). Given the public nature of the survey and the importance of wide community
involvement, European participation at large was also stimulated through an Open Letter, emphasizing the
importance of coverage from the observatories at La Silla and Paranal for Legacy programs with substantial
involvement from the ESO community (http://http.hq.eso.org/observing/misc/20000824.sirtf.html).
Ground--based observations are an integral part of GOODS. The Legacy project was allocated multi--year blocks
of NOAO time for deep optical and infrared imaging, including critical U--band imaging, which cannot be done
with ACS. ESO allocated 298h of near--IR imaging of the CDF--S with ISAAC in P68­70­72, and 40h of optical
imaging with WFI to reach deeper flux limits compared to the EIS data on the same field (see Table 1). With
this proposal, we seek to secure one of the most important parts of the whole project, namely spectroscopic
observations for redshift identification in the CDF--S.
Science with GOODS: Each segment of the GOODS project aims at major scientific goals. Here we review
some of these, with emphasis on the data from the CDF--S.
. SIRTF/IRAC data from 3.6 to 8.0µm will sample the rest--frame near--IR light (e.g., K--band at z # 3) of
# L # galaxies out to z # 5, providing the best measure of stellar mass to reconstruct the mass assembly history
of galaxies from z # 5 to z # 0.5. SIRTF CDF--S observations are planned for Aug 2003 -- Feb 2004.
. 24µm SIRTF/MIPS data will detect dust--obscured star forming galaxies and AGN with a 6 ## FWHM beam,
locating them to # 1 ## accuracy and enabling the identification of optical/near­IR/X­ray/radio counterparts.
ISOCAM 15 µm surveys studied obscured star formation at z # 1; GOODS 24 µm data will extend this work
to z # 2.5 by probing the rest--frame 7.7 µm PAH emission from relatively ``ordinary'' starburst galaxies.
. HST/ACS is now imaging the GOODS field in the F435W (B), F606W (V ), F775W (i), and F850LP (z) bands
with ``near--HDF'' sensitivity. The observations (see Fig. 2) are phased in 5 epochs (with the CDF--S in the
period Aug 2002 -- Feb 2003) to allow detection of type Ia supernovae at 1.2 < z < 1.8 to test the transition from
decelerated to accelerated expansion predicted in ``dark energy'' cosmological models. Deep, high--resolution
imaging will trace the emergence of the Hubble Sequence, gather a census of Lyman break galaxies (LBGs)
out to z # 6.5 (i.e. approaching the reionization epoch), and provide a rich resource for studying the cosmic
mass distribution via weak gravitational lensing. At the time of submitting this proposal complete data for the
first three epochs have been successfully completed, and the reduced data for the first epoch have been publicly
released.
. Deep JHK s imaging with ISAAC over the GOODS/CDF--S bridges the wavelength gap between ACS and
SIRTF, providing optical rest--frame photometry for high redshift galaxies. Data for about 1/3 of the field have
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5. Description of the proposed programme (continued)
already been taken in P68 and have been made immediately publicly available from the ESO/GOODS URL
(www.eso.org/science/goods). The preliminary (V0.5) version of the coadded and reduced frames have been
released in March 2002. These include JK s data for part of the field from another program (PI E. Giallongo),
whose PI kindly waived his proprietary rights.
Besides the above data taken explicitly for the GOODS project, other complementary data on the two GOODS
fields are publicly available or are now being collected. These include:
. The deepest Chandra (1--2 Msec) and XMM--Newton (225--500 ksec) X--ray observations. Using these X­ray
data, the sample of SIRTF 24 µm­selected sources will be ``sorted'' among starburst galaxies and AGN, enabling
a census of energetic output from both types of objects, and a determination of the relative abundance of type
2 (obscured) vs. type 1 (unobscured) AGN at the ``quasar epoch'' (z # 2--3).
. Far­UV (135­180 nm) and Near­UV (180­300 nm) imaging of the GOODS fields will be secured by GALEX,
to be launched by NASA in February 2003.
. Radio observations, including data from the VLA and new CDF--S observations from the ATCA.
. The SIRTF/SWIRE Legacy Project. While shallower than GOODS, it includes a much larger (7.2 deg 2 ) field
around the CDF--S, with ESO supporting optical imaging from WFI (PI A. Franceschini).
. The COMBO­17 project, having imaged a 30 # â30 # region around CDF--S through 17 broad and intermediate­
band filters, will observe this area with HST/ACS through F606W and F850LP as a Large Program (GEMS,
PIs K. Meisenheimer & H.­W. Rix).
From this list it is clear that GOODS o#ers an absolutely unique combination of area, depth, angular resolution
and wavelength coverage for studying the distant universe. GOODS is arguably the most ambitious, complete
and coherent attempt to understand fundamental cosmology and galaxy formation and evolution for many years
to come. The GOODS data base will set the ground for a variety of follow--up programs from future facilities
such as NGST and ALMA.
Clearly, imaging alone is not su#cient to reach GOODS scientific goals. Spectroscopy is essential to get reliable
redshifts, which provide the time coordinate needed to delineate the evolution of galaxy masses, morphologies,
and star formation. It will also calibrate the photometric redshifts that can be derived from the 13--band imaging
data at 0.36--8µm. Spectroscopy will measure physical diagnostics for galaxies in the GOODS field (e.g., emission
line strengths and ratios to trace star formation, AGN activity, ionization, and chemical abundance; absorption
lines and break amplitudes that reflect stellar population ages). Precise redshifts are also indispensable to
properly plan for future follow--up at higher dispersion, e.g., to study galaxy kinematics or detailed spectral line
properties.
Among southern hemisphere observatories, ESO has unparalleled spectroscopic multiplex. It is therefore pro­
posed that ESO will lead the southern campaign with an e#ort proportional to the unique capabilities of its
VLT. In the same spirit as the multiwavelength GOODS imaging programs, we aim to collect and disseminate a
public data resource of low resolution spectra for all the objects in the GOODS/CDF--S field which can feasibly
be observed. As demonstrated below, this can be achieved with a rather modest investment of VLT time. Given
the size of the GOODS/CDF--S field, the field of view of the VLT multiobject spectrographs, and the number
of feasible targets, we argue that this campaign is most e#ciently done as a single project, as opposed to a
set of several smaller projects each selecting targets according to di#erent criteria. For a project of the scien­
tific importance of GOODS, we argue that completeness and uniformity of the low--resolution spectroscopic
database is mandatory.
The ESO/GOODS spectroscopic program is a complete, magnitude--limited survey, observing all galaxies for
which VLT optical spectroscopy is likely to yield useful data (i.e. redshifts). The program will make full
use of the VLT instrument capabilities (FORS2 and VIMOS), matching targets to instrument and disperser
combinations in order to maximize the e#ectiveness of the observations. The magnitude limits and selection
bandpasses depend to some degree on the instrumental setup being used. The aim is to reach mag = 25 with
adequate S/N, with this limiting magnitude being in the B band for objects observed with the VIMOS LR­Blue
grism, in the V band for those observed in the LR­Red grism, and in the z band for the objects being now
observed with FORS2. This is not only a practical limit, however, but is also well matched to the scientific
aims of the GOODS program. The ACS i­band imaging will sample rest--frame optical (B--band) light out to
z = 1.2, where i AB = 25 reaches 1.5 to 2 magnitudes past L # B . This is also the practical limit for high--quality,
quantitative morphological measurements from the ACS images (cf. Abraham et al. 1996). Similarly, i AB = 25
is # 1 mag fainter than the measured L # UV for z = 3 LBGs, and 0.5 mag fainter than that at z = 4 (Steidel et
al. 1999). These are the limits to which GOODS/SIRTF IRAC data will robustly measure rest--frame near--IR
light, and hence constrain the stellar mass. The proposed ESO spectroscopy will therefore target galaxies to
luminosities where the HST and SIRTF data will be most valuable.
Certainly, low­resolution spectroscopy alone will not answer all the scientific questions that will arise by studying
the GOODS database. Spectroscopy at higher resolution than that proposed here will be necessary to derive
dynamical masses for high redshift galaxies (from rotation curves of spirals and velocity dispersion of spheroids),
chemical compositions of passively evolving and star­forming galaxies, detailed stellar population indices, etc.
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5. Description of the proposed programme (continued)
However, such projects are su#ciently diverse and self--contained that they may be carried out more e#ectively
with dedicated follow--up programs. As a public survey, GOODS will concentrate on low--resolution spectroscopy
for the purpose of redshift identification. These data, together with the multiwavelength imaging from ground--
and space--based observatories, will then promote both archival research and dedicated programs of follow--
up observations. ESO will make every e#ort to promote e#ective coordination among those teams from the
community that aim to submit such proposals, and hence a more e#cient use of the VLT.
End of quote from P70 proposal.
B) Immediate Objective:
Two spectrographs are needed to carry out the GOODS observing program, namely 1) VIMOS, the workhorse
instrument due to its uniquely large multiplexing power, which will be used every time that extreme red
sensitivity is not key to the success of the observations; and 2) the newly refurbished FORS2, when its unique
sensitivity at red wavelengths is required. While the observing time has already been allocated on FORS2 in
P70, and the observations are under way (data can already be retrived from
www.eso.org/science/goods/products.html#spectroscopy, see also Fig. 3 &4, here we provide a description of
the overall observing program with both instruments, as currently envisaged.
To the limits of VIMOS spectroscopic capability (say, VAB = 25), there are # 6000 objects over the 160
arcmin 2 of the GOODS field, or # 37 arcmin -2 . This is # 10â higher than the surface density of VIMOS
slits (# 800/224 = 3.6 arcmin -2 ). Hence, more than 10 masks per pointing are necessary to ensure virtual
completeness in the spectroscopic survey. Moreover, the VIMOS field of view (16 # â 18 # , with a cross gap of
2 # between the quadrants) is such that only 50% of it can overlap with the 10 # â 16 # GOODS field. So, up to
400 objects at a time could be observed. We calculate that # 24 VIMOS masks, 6 for each of 4 pointings are
necessary to ensure # 90% completeness in the spectroscopic coverage of # 6000 targets in the GOODS field,
with the extra bonus of longer--than--average integration times on sources located in 45% of the field (Renzini
et al. 2002, astro­ph/0204214). With an average integration time of 4h per pointing, and # 30% overhead, this
makes a total of 125h, or # 13 nights.
As mentioned above, there are three possible instrument/disperser combinations to carry out the GOODS low­
resolution spectroscopic survey: VIMOS/LR­Blue, VIMOS/LR­Red, and FORS2, and in order to maximize the
e#ciency of the survey a strategy is needed to identify the setup of choice for each target. Figure 1 shows the
total instrument+telescope throughput for these three options, and Table 2 summarizes the situation. It shows
that # 60% of the objects are best observed with VIMOS/LR­Red, # 30% with VIMOS/LR­Blue, and # 10%
with FORS2. The P70 GOODS proposal was focused on the FORS2 observations dedicated to objects best
observed with this instrument, i.e. those with (R - I) AB > 1 and I AB < 25. In practice, for the observations
being carried out in P70 it was decided to use the superior GOODS/ACS data already publicly available, hence
the actual selection has been (i-z)AB > 0.6 and z AB < 24.5 with # 450 galaxies fulfilling this criterion. Also for
the GOODS/VIMOS spectroscopic observations the targets will be selected from the GOODS/ACS catalogs.
For the observation with VIMOS a simple color criterion would not ensure the best target­to­setup assignement,
and a more refined, two step strategy will be applied. Step 1: On the basis of photometric redshifts (from
GOODS publicly available UBV izJHK data) the #­range in which the key spectral features are expected will
be identified, and following Table 2 # 2/3 of the objects will be observed first with VIMOS red and # 1/3 with
VIMOS blue, primarily in P71+P72. Step 2: Objects which fail to yield redshifts in P70­72 will be re­observed
in P74 with the complementary grism. No observations are planned for P73. It is also planned to reach down
to B < 25 for objects observed with the blue grism and to V < 25 for those with the red grism.
C) Telescope Justification: Spectroscopy of so many objects down to the stated limiting magnitudes requires
VLT+VIMOS.
D) Observing Mode Justification (visitor or service): Service mode is preferable, given that the S/N of
faint object spectra will critically depend on the seeing. However, visitor mode will also be acceptable.
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5. Attachments (Figures)
Table 1: GOODS Observations and Complementary Data Sets.
Wavelength Facility Sensitivity (S/N=5)
0.36µm KPNO+CTIO 4m AB = 27.3 (U)
0.4­0.9µm HST/ACS AB = 27.9, 28.2, 27.5, 27.4 a (BV iz)
1.2­2.2µm VLT, KPNO 4m AB = 25.2, 24.7, 24.4 (JHK s )
3.6­8.0µm SIRTF/IRAC AB = 24.5, 24.5, 23.8, 23.7 (0.6--1.2 µJy) b
24µm SIRTF/MIPS 20­80 µJy c
Type Facility Notes
Spectroscopy VLT, Gemini, Keck Various PIs; GOODS programs & collabs.
X­ray Chandra, XMM Public Chandra data and XMM GTO progs.
70, 160µm SIRTF/MIPS SIRTF GTO program; SWIRE Legacy program
Sub­mm SCUBA, SEST Various PI programs
Radio VLA, ATCA Various PIs; CDF--S observs. in progress
a For 0.5 arcsec diameter aperture
b For ``handbook'' IRAC PSF; 3.6 and 4.5µm performance may be better
c Uncertain sensitivity; depends on instrument performance and source confusion
Table 2: Most E#ective Instrument Setups vs Redshift
Redshift Fraction Key Features Instrument/grism
z < 0.5 24% [OII], H#, [OIII], (H#), CaII H&K VIMOS blue
0.5 < z < 1.3 56% [OII], H#, CaII H&K VIMOS red/FORS2
1.3 < z < 2.3 12% [OII], CaII H&K; CIV, AlII FORS2/FORS1­UV(?) a
2.3 < z < 3.5 6% Ly#, SiII, CII, CIV, OI, SiIV VIMOS blue
z > 3.5 1% Ly#, SiII, CII, CIV, OI, SiIV VIMOS red/FORS2
This table shows for the various redshift intervals the fraction of galaxies in a R = 25 limited sample (from
photometric redshifts), the features most useful for redshift determination, and the most appropriate instru­
ment/grism combination for detecting such features.
a In this range the lack of a near­IR spectrograph and of a UV­optimized spectrograph will limit somewhat the
capability of measuring the redshift of intrinsically red and blue galaxies, respectively.
Fig. 1 ­ The VIMOS and FORS2 throughput for the grisms adopded for the GOODS survey.
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5. Attachments (Figures)
Fig. 2 ­ The VIMOS field of View and its 4­pointing imprint over the GOODS field.
Left: The geometry of the VIMOS field of view, for either imaging or multiobject spectroscopy. Right: The
CDFS/GOODS 10 # â 16 # field, in the same scale as the VIMOS FoV. The VIMOS 4­pointing imprinting on the
GOODS field is rendered with di#erent shadings. Dark areas: areas common to all 4 VIMOS basic pointings
(A set of subfields). Shaded areas: areas common to 2 VIMOS pointings (B set of subfields). Lightly shaded
areas: areas covered by only one VIMOS pointing (C set of subfields). Subfields A will be covered by all the
24 planned masks, subfields B by 12 masks, and subfields C by 6 masks only. Correspondingly, spectra will be
obtained for # 100% of targets down to mag# 25 in area A, for # 85% in area B, and for <
# 60% in area C.
The actual e#ciency may be somewhat reduced in area B when using the blue grism, as for each pointing there
will relatively few objects to observe, i.e. # 3 times the maximum number of slits.
Fig. 3 ­ A sample of GOODS/FORS2 spectra.
These spectra have been obtained during the October 2002 run of the GOODS program with FORS2, and have
been retrived from the ESO public archive. The sky­subtracted spectra shown here come from only one of the
two FORS2 CCDs.
Fig. 4 ­ An example of an extracted emission line galaxy at a redshift of one.
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6. Experience of the applicants with telescopes, instruments and data reduction
Many of the proposers have extensive experience with deep multiobject spectroscopy of faint targets with the
VLT and other facilities, and are well versed in the reduction of these sorts of data. Moreover, many have lead
or contributed to major surveys with rapid public data releases, such as the HDF and EIS programs.
7. Resources available to the team, such as: computing facilities, research assistants, etc.
ESO shall take responsibility for the whole data taking, reduction, and prompt dissemination world--wide,
both in the spirit of Legacy/Treasury Programs and as a firm commitment to its own community. The list
of targets, maps, etc. will be posted on the ESO/GOODS web well in advance of the observations. The
immediate public release of the raw data will be made using the standard resources of the ESO archive. For the
processing and prompt dissemination of the spectroscopic data, a dedicated team is being established including
-- besides the proposers -- a suitable number of scientists from the ESO community. This opportunity will also
be widely advertised through the web and The Messenger, and it is ESO commitment to achieve the widest
possible involvement of the community in the data production process. Data products will include reduced,
coadded, calibrated and extracted spectra. The Team will be committed to exploit VIMOS/FORS pipeline
tools, experiencing an in­house scientific validation of such tools and provide feedback to the pipeline producers.
Besides working as an early testbed for pipelines, the GOODS project is already o#ering to the AVO project
data to start built ``bottom­up'' Virtual Observatory tools using top quality data in wide demand. Funding will
be requested from the EC for Fellowships associated with the exploitation of GOODS data.
8. Special remarks
Two other major European programs are underway on the CDF­S field and are submitting VIMOS proposals:
the follow­up of XMM X­ray sources and optically selected AGNs (PI J. Bergeron) and the VIMOS follow­up of
the COMBO17/GEMS project (PI M. Barden). To avoid overlap with GOODS, the PIs of these two projects
have decided to refrain from submitting a proposal for VIMOS low­resolution spectroscopy, and will concentrate
on intermediate­ and high­resolution spectroscopy, expecting su#cient low­resolution data will be made publicly
available from GOODS. GOODS is a community­service project, and it is very important that the community is
widely involved. ESO resources will be used to attract young scientists to ESO to participate in the preparation
of the observations and data reduction e#orts. Information for and from the community is organized through
the Web, as well as through focused ESO workshops, the first one on ``The Mass of Galaxies at Low and High
Redshift,'' was held in the fall of 2001. A second such workshop is now planned for 2003 on ``Multiwavelength
Mapping of Galaxy Formation & Evolution''.
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9. Justification of requested observing time and lunar phase
Lunar Phase Justification: For the deep optical spectroscopy of the faint galaxies in the field dark time is
mandatory.
Time Justification: The telescope time is set by two requirements: completeness down to the limiting
magnitude, and adequate S/N. The target sample consists of # 6000 galaxies down to B (or V )=25. The layout
of the VIMOS FoV is shown in Fig. 2: a minimum of 4 VIMOS pointings is necessary to ensure that all parts of
the GOODS field are covered by at least one of the pointings. The chosen pattern consist of 4 VIMOS pointings
in which in turn each of the 4 outer corners of the VIMOS FoV coincides with each of the 4 GOODS field corners.
For each pointing, the central cross gaps of VIMOS separate 4 sub­fields over GOODS, for a total coverage of
112 arcmin 2 . Hence, for each pointing, the fraction of the VIMOS low resolution multiplex expendable on
GOODS is 112/224 (50%,), i.e., with an e#ective multiplex 0.5 â 800 = 400. These 4 pointings imprint on the
GOODS field a set of subfields, with some being common to all 4 pointings (set A, 45% of GOODS), some
only to 2 pointings (set B, also 45% of GOODS), and 2 subfields are covered by only one pointing (set C, 10%
of GOODS). This is also shown in Fig. 2. For a set of 6 masks for each of the 4 pointings, all targets in A
subfields can be observed at least once, and some twice, i.e. for a total 8h integration; we estimate that # 85%
of all targets in B subfields can be observed once, while only <
# 60% of targets in subfields C could be observed.
Hence, with a total of 6 â 4 = 24 sets of masks one can ensure # 90% completeness over the whole field. In
any case, priority in slit assignement will be given to observe objects with z phot >
# 0.5, including LBGs, EROs,
AGN candidates, and few objects with special characteristics.
The current exposure VIMOS time calculator has been used under default assumptions (i.e., new moon, 1.2
airmass, 0 ## .8 seeing, 1 ## slit, point sources) using elliptical, Sb, and starburst galaxy templates redshifted to
z > 1. For both B = 25 objects with the LR­Blue grism and V = 25 objects with the LR­Red grism one reaches
S/N> 10 per resolution element (3­4 pixels). The overhead is 17m per observation (from VIMOS web). To
reach 4h integration per mask 4 OBs, 1h each, are necessary, hence the overhead is 68m per mask. The total
telescope time is therefore 24 â (240 + 68) min = 7392 min = 123h, or # 13 nights. For the pre­imaging, 4
exposures 15m each are necessary, or 22m including 7m overhead, for a total of 68m, i.e. # 1h. NB: for the
targets lying inside the VIMOS FoV but outside the GOODS field the same selection criteria as
for the GOODS field will be followed. ACS COMBO17/GEMS data are publicly available, and
the COMBO17/GEMS team will provide the astrometric catalogs for mask preparation.
Calibration Request: We need wavelength calibration for each science frame.
10.Applicant's publications related to the subject of this application during the past two years
Cristiani, S., Appenzeller, I., Arnouts, S., et al. 2000, A&A, 359, 489: ``The first VLT FORS1 spectra of
Lyman­break candidates in the HDF­S and AXAF Deep Field.''
Daddi, E., Cimatti, A., & Renzini, A., 2000, A&A, 362, L45: ``EROs and the formation epoch of field
ellipticals.''
Elbaz, D., Cesarsky, C., Fadda, D, et al. 1999, A&A, 351, L37: ``Source counts from the 15 µm ISOCAM Deep
Surveys.''
Ferguson, H.C., Dickinson, M., Williams, R., 2000, ARA&A, 38, 667: ``The Hubble Deep Fields.''
Genzel, R., & Casarsky, C. J., 2000, ARA&A, 38, 761: ``Extragalactic Results from the Infrared Space Obser­
vatory.''
Giacconi, R., Rosati, P., Tozzi, P., et al. 2001, ApJ, 551, 624: ``First Results from the X­ray and Optical Survey
of the Chandra Deep Field South.''
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11.List of targets proposed in this programme
Run Target/Field # # Eq. Mag. Diam. Additional info Reference star
A CDF­S 03 32 28 ­27 48 30 J2000
B CDF­S 03 32 28 ­27 48 30 J2000
C CDF­S 03 32 28 ­27 48 30 J2000
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12.Scheduling requirements
13.Instrument configuration
Telescope Instrument Run ID Parameter Value or list
UT3 VIMOS A PRE­IMG R
UT3 VIMOS B MOS­grisms LR­Red
UT3 VIMOS C MOS­grisms LR­Blue
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