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Telescopes and Instrumentation

ESO Public Sur veys with the VST and VISTA

The ESO Sur vey team: Magda A rnaboldi, Mark J. Neeser, L aura C. Parker, Piero Rosati, Marco Lombardi, JЖrg P. Dietrich, Wolfgang Hummel A n e w c h a p te r f o r E u r o p e a n a s t r o n o m y w i l l s o o n b e g i n w i t h d e d i c a t e d s u r ve y telescopes in the optical and near-infrar e d . T h e i n te n t o f t h i s a r t i c l e i s to i l l u s t r a te t h e E S O p o l i c i e s f o r m a n a g i n g P u b l i c S u r ve y s ( P S ) a n d v a l i d a t i n g t h e i r a d v a n c e d d a t a p r o d u c t s , to i n t r o duce the VST and VISTA telescopes along with their wide -field instruments, a n d t o p r ov i d e a b r i e f s u m m a r y o f t h e p l a n n e d p u b l i c s u r ve y s . ES O p o l i c i e s f o r P u b l i c S u r v e y s a n d t h e i r i m p l e m e nt ati o n The large collaborative sur veys selected for VST and VISTA within Europe target m a ny of t h e f u n d a m e n t a l q u e s t i o n s i n a s trophysics today, ranging from the nature of dark energy to the universalit y of the stellar initial mass function (see ht tp: // w w w.eso.org /obse r ving /we bone.html for more details of ESO Public Sur veys). In the following, we illustrate briefly the mechanisms that ESO has set in place to manage the sur vey projects, to ensure t h e i r l e g a c y va l u e a n d t h e i r u s e f u l n e s s fo r the astronomical communit y at large. T h e S u r ve y M a n a g e m e n t P l a n The Principal Investigators (PIs) whose p u b l i c s u r ve y p r o p o s a l s h ave b e e n r e v i e w e d by t h e P u b l i c S u r v e y Pa n e l ( P S P ) a n d r e c o m m e n d e d by t h e O b s e r v i n g Programme Commit tee (OPC) are then asked to submit a Sur vey Management Plan (SMP). The ESO Guidelines for t h e p r e p a r a t i o n of t h e S M P a r e av a i l a b l e at ht tp: //w w w.eso.org/obse r ving/ps / Guide lines_ SMP.pdf T h e S M P re p re s e n t s a n a d d i t i o n a l fo r m requested from the PIs and it is an integral par t of ESO's appraisal of the prop o s a l. T h e S M P a i m s a t c o l l e c t i n g t h e necessar y information to carr y out PS in Ser vice Mode (SM), and allows for an efficient and timely planning of Phase 2 and telescope operations. The SMP must il-

lustrate the obser ving strategy, the sur vey d a t a c a l i b r a t i o n n e e d s, t h e d a t a re d u c t i o n p ro c e s s, t h e m a n p owe r a n d h a rd wa re c a p a b i l i t i e s, t h e d a t a q u a l i t y a s s e s s m e n t p ro c e s s, a n d t h e d a t a p ro d u c t deliver y to the Vir tual Obser vator y. During the SMP process, the iterations with the Sur vey Consor tia for the definition of the obser ving strategy will ensure that at no t i m e a r e t h e r e e ve r m o r e t h a n t wo a c t i ve P S c ove r i n g t h e s a m e R A r a n g e o r s i m i l a r obser ving conditions (dark time, excellent seeing, etc.). The ESO sur vey team The ESO sur vey team (EST ) follows the implementation of the ESO policies for PS. T h e ES T m e m b e r s a r e M a g d a A r n a b o l d i (team leader), JЖrg Dietrich, Wolfgang Hummel, Mark Neeser, L aura Parker, and P i e r o R o s a t i. I n t h e f r a m e w o r k s e t b y t h e c u r r e n t p o l i c i e s , t h e ES T h a s a r o l e w h i c h is similar to that of an audit group. We will suppor t the teams during their observa t i o n s w i t h t h e s u r ve y i n s t r u m e n t s a n d telescopes ( VST and VISTA), monitor the p ro g r e s s of t h e s u r ve y s, a n d r e f e r e e t h e data qualit y of the PS products submit ted for ingestion into the ESO archive, based on the qualit y control parameters and technical repor ts provided by the sur vey c o n s o r ti a . Monitoring of the sur vey progress The PSP is asked to ser ve as independe n t r e f e r e e of t h e p ro g r e s s a n d a c h i e ve m e n t s of t h e P S . T h e C h a i r of t h e P S P w i l l r e c e i v e a y e a r l y r e p o r t b y t h e ES T with the information on the basic monitoring of the progress for each PS. The first p ro g re s s re v i e w w i l l b e c a r r i e d o u t o n e year af ter the sur veys have star ted, and then once per year, until the completion of each sur vey. The EST leader, af ter consultation with the PSP Chair, will repor t to the OPC on the status and progress of each PS. Fur thermore, any time required for additional sur vey related obser vations (e. g. spectroscopic follow-up) at other ESO telescopes must be applied for.

S u r ve y d a t a p ro d u c t s What makes these sur veys par ticularly unique is that while they are facilitated and archived by ESO, the Principal Investigator (PI) of each sur vey is ultimately r e s p o n s i b l e fo r t h e h i g h e r l e ve l d a t a p ro d ucts. The sur veys are simply too large and diverse to all be carried out by ESO and having PIs with a vested interest in t h e d a t a w i l l e n s u re t h e b e s t d a t a p ro d ucts for the communit y at large. R aw d a t a I n F i g u r e 1 we s h ow a c o m p a r i s o n of the total monthly output of the current VLT instruments, and that expected from O m e g a CA M a n d V I R CA M . T h e v a l u e s fo r t h e s u r ve y i n s t r u m e n t s a r e b a s e d o n image sizes and the data rates expected f r o m t h e P S , a n d t h i s p l ot c l e a r l y s h o w s the challenge and ef for ts to carr y out PS! T h e r aw d a t a f ro m t h e P S w i t h O m e g aCAM and VIRCAM will be immediately made public worldwide from the ESO archive, with public users being able to download limited volumes. Ad va n c e d d a t a p ro d u c t s A d v a n c e d d a t a p r o d u c t s f r o m t h e ES O PS (instrumentally corrected-stacked f r a m e s, we i g h t m a p s a n d o b j e c t s c a t alogues) will be available from the ESO archive. For the VISTA PS, a copy of the a d v a n c e d d a t a p r o d u c t s w i l l b e av a i l a b l e a l s o f ro m t h e W i d e F i e l d A s t ro n o my Unit at the Royal Obser vator y Edinburgh (ht tp: //w w w.roe.ac.uk /ifa /w fau / ). The accuracy/uniformit y of the advanced data products from the PS must be validated b e f o r e t h e i r a c c e pt a n c e a n d i n g e s t i o n into the ESO archive, and the EST has iss u e d g u i d e l i n e s w h i c h d e s c r i b e th e re quired repor ts and tests supplied by the sur vey consor tia in order to verif y the declared data qualit y. They also include i n fo r m a t i o n o n d a t a fo r m a t s a n d m e t a data to be delivered to ESO which will p u b l i s h t h e m i n t h e a rc h i ve i n c o m p l i a n c e with Vir tual Obser vator y standards. These guidelines are available at ht tp://w w w. eso.org/obse r ving/ps/ VOS-RRD.pdf. Nonetheless, the ultimate responsibilit y fo r t h e q u a l i t y of t h e d e l i ve r e d d a t a

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products rests on the teams proposing a n d p ro c e s s i n g t h e s u r ve y s. The VLT Sur vey Telescope ( VST ) The VLT Sur vey Telescope ( VST ) is a 2.6 -m optical telescope that will be fit ted w i t h a l a r g e c a m e r a ( O m e g a CA M ) c o m prised of 32 separate CCD chips (280 Megapixels). This enormous camera has a field of view of one square degree with a pixel scale of 0.2 arcseconds: in F i g u r e 2 we s h ow a r e a l i m a g e f ro m t h e OmegaCAM laborator y tests. The large field of view is ideally suited for sur veying l a r g e a re a s. T h e c a m e r a w i l l b e e q u i p p e d with five broadband filters (u;, g;, r;, i;, z;) as well as an Ha filter, StrЖmgren v, Johnson B and V and a four-segment u;g;r;i;filter for photometric monitoring. More i n fo r m a t i o n c a n b e fo u n d a t t h e re l e va n t web sites: for the VST telescope at ht tp: // t wg.na.astro.it /vst /vst_ homepage_ t wg. h t m l a n d f o r t h e O m e g a CA M c a m e r a a t ht tp://w w w.astro.rug.nl/~omegacam/ T h e r e a r e t h r e e VST P S i n t h e p ro c e s s of final approval by the ESO Director General, and they are described below. In F i g u r e 3 we s h ow t h e s k y c ove r a g e of t h e t h r e e V S T P S , o v e r l a i d o n a 2M A S S image of the southern hemisphere. It is anticipated that the sur veys will take approximately five years to carr y out and they are scheduled to begin data acquis i t i o n i n 20 0 8 . T h e V S T s u r v e y d e t a i l s are summarised in Table 1. The VST and O m e g a CA M h a v e b e e n d i s c u s s e d i n p r e v i o u s M e s s e n g e r a r t i c l e s (C a p a c c i o l i et al. 20 05; Cappellaro 20 05). 1. KIDS ­ The K ilo-Degree Sur vey PI Konrad Kuijken (Leiden Obser vator y) This sur vey aims to image 1 50 0 square degrees in four bands (to be complemented in the near-infrared with data from the VISTA VIKING sur vey). The survey aims to cover this large area to a depth 2.5 magnitudes deeper than the Sloan Digital Sk y Sur vey (SDSS), with considerably bet ter image qualit y. The p r i m a r y s c i e n c e d r i ve r fo r t h e d e s i g n of t h i s p r o j e c t h a s b e e n we a k g r av i t a t i o n a l l e n s i n g. T h e s c i e n c e g o a l s o f t h e K I D S p ro j e c t a re n u m e ro u s, i n c l u d i n g s t u d y i n g dark mat ter halos and dark energy with
O me g aCA M 24 % (~ 2 50 0 G B)

A l l c u r re nt Pa r a n a l I n s t r u m e n t s 4 % (433.2 G B)

Figu re 1: A c o mpa r iso n of th e tota l m o n t h l y o u t p u t (r a w c a l i b r a t i o n a n d raw scie nc e f ra me s) of th e V LT ins t r u m e n t s , a n d t h a t e x p e c te d f r o m O m e g a CA M a n d V I R CA M . T h e s t a t i s t i c s fo r t h e c u r r e n t Pa r a n a l i n s t r u m e nts a re b a s e d o n th e m o nth l y ave r a g e fo r a l l 20 0 6, w h i l e t h e va l u e s fo r t h e s u r vey i n s tr u m e n ts a re b a s e d o n i m a g e s i z e s a n d t h e d a t a r a te s e x p e c te d f r o m t h e P u b l i c S e r v e y s .

VIRCA M 72 % (~ 7 50 0 G B)

FORS1 F O R S2 G IR A FFE I S A AC MIDI N AC O SIN FO NI U V ES VIMOS VISIR V I R CA M O m e g a CA M Figu re 2: A re a l imag e f O m e g a C A M l a b o r a to r y fi e ld of v iew is d e mo nst by s u p e r p o s i t i o n of a n i M o o n. ro m th e te s t s . T h e r a te d m a g e of t h e

w e a k l e n s i n g, i n v e s t i g a t i n g g a l a x y e v o lution, searching for gala x y clusters, a n d l o o k i n g fo r h i g h - re d s h i f t q u a s a r s. T h e KIDS project fills an impor tant niche in lensing sur veys bet ween smaller, slightly d e e p e r s u r ve y s, s u c h a s t h e C F H T L e g acy Sur vey, and larger, shallower sur veys like the SDSS.

2. The VST ATL AS PI Tom Shanks (Universit y of Durham) T h i s s u r ve y i s t a r g e t i n g 4 5 0 0 s q u a r e d e grees of the Southern Sk y in five filters to depths comparable to the SDSS. This sur vey will also be complemented with near-infrared data from the VHS VISTA sur vey. The primar y science driver is to determine the dark energy equation of state by examining the `bar yon wiggles' in the mat ter power spectrum, via sur veys

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Telescopes and Instrumentation

Arnaboldi M. et al., ESO Public Sur veys with the VST and VISTA

o f l u m i n o u s r e d g a l a x i e s u s i n g b ot h p h o tometric and spectroscopic redshif ts. T h i s s u r ve y w i l l a l s o p r ov i d e t h e i m a g i n g b a s e f o r m a ny ot h e r f u t u r e s p e c t r o s c o p ic sur veys, both at the VLT and also via wide-field fibre spectrographs such as the new A AOmega instrument at the A ngloAustralian Obser vator y. For example, the VST ATL AS will be valuable in the hunt for h i g h - re d s h i f t g a l a x i e s a n d q u a s a r s. 3. VPHAS+ ­ The VST Photometric H a S u r ve y of t h e S o u t h e r n G a l a c t i c P l a n e PI Janet Drew (Imperial College London) T h i s s u r ve y w i l l c o m b i n e H a a n d b ro a d band u;g;r;i; imaging over an area of 1 8 0 0 s q u a r e d e g r e e s c a pt u r i n g t h e w h o l e of t h e S o u t h e r n G a l a c t i c P l a n e w i t h i n t h e l a t i t u d e r a n g e |b| < 5 d e g re e s. VPHAS+ will facilitate detailed ex tinct i o n m a p p i n g o f t h e G a l a c t i c P l a n e, a n d can be used to map the structure of the Galactic disc and its star-formation histor y. The sur vey will yield a catalogue of a ro u n d 5 0 0 m i l l i o n o b j e c t s, w h i c h w i l l i n c l u d e g r e a t l y e n h a n c e d s a m p l e s of r a r e e vo l ve d m a s s i ve s t a r s , B e s t a r s , H e r b i g and T Tau stars, post-AGB stars, compact nebulae, white dwar fs and interacti n g b i n a r i e s. T h i s s u r ve y i s c o m p l e m e n tar y to IPHAS, a sur vey of the Nor thern G a l a c t i c P l a n e n e a r i n g c o m p l e t i o n, b u t VPHAS+ will include more filters and will achieve bet ter image qualit y. VISTA The Visible and Infrared Sur vey Telescope for Astronomy ( VISTA) is a 4-m near-infrared optimised telescope that will be equipped with a large array of 16 infrared detectors that will fill a 1.5 square degree field (af ter stepping to fill in the gaps bet ween the detectors). In Figure 4 we show the VIRCAM field of view, with the moon superimposed for scale. The VISTA filter set includes Z, Y, J, H, Ks and a narrowband filter at 1.18 microns. Each exposure will contain 67 Megapixe l s, a n d a t y p i c a l o b s e r v i n g n i g h t w i l l s e e t h e c o l l e c t i o n of 3 0 0 G B of d a t a . T h i s e n o r m o u s d a t a vo l u m e w i l l r e q u i r e ve r y ef ficient processing and considerable re s o u rc e s.

KIDS-N

AT L A S - N

K I D S -W 2

V PH A S +

AT L A S - S KIDS-S F i g u r e 3: T h e s k y c o v e r a g e o f t h e t h r e e V S T P u b l i c S u r v e y s , ov e r l a i d o n a 2M A S S i m a g e o f t h e s o u t h e r n h e m i s p h e r e.

S u r ve y K IDS

A r e a [d e g 2] 1 50 0

F i l te r u; g; r; i; u; g; r; i; z; u; g; Ha r; i;

M a g ni tu d e li mi t 24.1 24.6 24.4 2 3 .4 22.0 22.2 22.2 21,3 2 0. 5 21.8 22.5 21.6 22.5 21.8

D e pth M e a s u re 10 s (A B)

Ta b le 1: Summa r y of th e VST P u b l i c S u r vey s b a s e d o n t h e i r S u r vey M a n a g e m e nt Pl a n s.

AT L AS

4 50 0

10 s (A B)

VPHAS+

1 80 0

10 s (A B)

At present there are six VISTA PS that have been recommended by the VISTA P u b l i c S u r v e y Pa n e l a n d e n d o r s e d by the OPC. They are currently in the process of submission of their SMP, and their final approval awaits acceptance of the SMPs (planned for early 20 07). They are listed below according to the priorit y for their implementation given by the VISTA P u b l i c S u r v e y P a n e l, a n d i n F i g u r e 5 we show their sk y coverage. The VISTA PS are scheduled to begin data acquisition sometime in late 20 07 and to have a duration of five years. The basic VISTA sur vey proper ties are summarised in Table 2. The progress of the VISTA project wa s r e c e n t l y r e v i e we d i n T h e M e s s e n g e r (Emerson et al. 20 0 6), and more information is available from the VISTA web page (ht tp: //w w w.vista.ac.uk ).
Figu re 4: T he VIRCA M d ete cto r pla ne, w i th th e M o o n s u p e r i m p o s e d f o r s c a l e.

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1. Ultra-VISTA PI s J i m D u n l o p ( U n i v e r s i t y o f E d i n burgh); Marijn Franx (Leiden Obser vator y); Johan Fynbo (Universit y of Copenhagen); Olivier LeFХvre (L aboratoire d'Astrophysique de Marseille) Ultra-VISTA aims to image one patch of the sk y (the COSMOS field) over and over again to unprecedented depths. The survey will use the Y, J, H, and Ks broadband filters along with one narrowband filter specifically designed to study Lyman-a emit ters at redshif t 8.8, of which ~ 30 are expected to be found with this sur vey. The science goals of Ultra-VISTA include studying the first gala xies, the stellar m a s s b u i l d - u p d u r i n g t h e p e a k e p o c h of star-formation activit y, and dust obscured s t a r f o r m a t i o n. 2. VHS ­ VISTA Hemisphere Sur vey PI R i c h a r d M c M a h o n ( U n i v e r s i t y o f Cambridge) T h e V H S w i l l i m a g e th e e nti re S o u th e r n Sk y, with the exception of the areas alr e a d y c o v e r e d by t h e V I K I N G a n d V V V sur veys, in J and Ks. The resulting data w i l l b e a b o u t fo u r m a g n i t u d e s d e e p e r than 2MASS and DENIS. The 5 000 square d e g r e e s c o v e r e d by t h e D a r k E n e r g y Sur vey (DES), another imaging sur vey scheduled to begin in 2010 at the CTIO 4-m Blanco telescope, will also be obs e r v e d i n H - b a n d. T h e a r e a a r o u n d b o t h of t h e G a l a c t i c C a p s w i l l a l s o b e o b ser ved in Y- and H-band by the VHS, to b e c o m b i n e d w i t h t h e d a t a f ro m t h e VST ATL AS sur vey. The main science drivers of the VHS include examining lowm a s s a n d n e a r by s t a r s , s t u d y i n g t h e merger histor y of the Gala x y, measuring t h e p ro p e r t i e s of D a r k E n e r g y t h ro u g h t h e ex a m i n a t i o n of l a r g e - s c a l e s t r u c t u r e to a redshif t of ~ 1, and searches for highre d s h i f t q u a s a r s. 3. VIDEO ­ VISTA Deep E x tragalactic O b s e r va t i o n s S u r ve y PI M a t t J a r v i s ( U n i v e r s i t y o f H e r t f o r d shire) VIDEO is a 15 square degree, Z, Y, J, H, Ks sur vey of AGN, gala x y cluster evolution and ver y massive gala xies to study g a l a x y e vo l u t i o n a s a f u n c t i o n of e p o c h

V I D EO

VIKING U l t r a-V I STA VHS VVV

VMC V I D EO V I D EO VIKING Figu re 5: S k y C ove rag e of VISTA sur veys, ove r la id o n a 2M A S S i m a g e o f t h e s o u t h e r n h e m i s p h e r e.

V I D EO

S u r ve y U l tra-V ISTA

A r e a [d e g 2] 0.73 (ul tra-d e e p)

F i l te r Y J H Ks NB Y J H Ks Z Y J H Ks Z Y J H Ks Z Y J H Ks Y J K

M a g ni tu d e li mi t 26.7 26 .6 26.1 25.6 24.1 21.2 21.1 2 0.6 2 0 .0 25.7 24.6 24.5 24.0 23. 5 21.9 21.2 2 0. 2 18.2 18.1 23.1 22.3 22.1 21.5 21.2 21.9 21.4 2 0. 3

Limit Measure 5 s ( A B)

Ta b le 2: S u mma r y of VISTA Pu blic S u r veys a s d e scr ib e d in th e su bmi tte d p r o p o s a l s .

VHS

20 0 0 0

5 s ( A B)

V ID EO

15

5 s ( A B)

VVV

52 0

5 s ( Ve ga)

VIKING

1 50 0

5 s ( A B)

VMC

18 4

10 s ( Ve ga)

s

and environment to a redshif t of ~ 4. Three fields of the original four described i n t h e p r o p o s a l h ave b e e n r e c o m m e n d e d by the VISTA PSP: the Chandra Deep Field South; 4.5 square degrees of the XMM-New ton L arge-Scale Structure Survey; and a field of the European L argeArea ISO Sur vey. The width and area of VIDEO are intermediate bet ween the wide, but relatively shallow, VIKING survey and the small, but ver y deep, UltraVISTA .

4. V V V ­ VISTA Variables in the Via L actea PI Dante Minniti (Universidad CatСlica) T h e V V V s u r ve y w i l l t a r g e t t h e G a l a c t i c B u l g e a n d a r e g i o n of t h e a d j a c e n t p l a n e in Z, Y, J, H, and Ks. The total area of this sur vey is 520 square degrees and contains 355 open and 33 globular clusters. The V V V is multi-epoch in nature in order to detect a large number of variable objects and will provide > 10 0 carefully

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spaced obser vations for each tile. A catalogue with ~ 109 point sources including 10 6 variable objects is expected. These will be used to create a three-dimensional map of the Bulge using well-understood distance indicators such as RR Lyrae stars. High-proper-motion objects will be detected and other science drivers include the ages of stellar populations, globular cluster evolution, as well as the stellar initial mass function. 5. VIKING ­ VISTA K ilo-Degree I n f r a r e d G a l a x y S u r ve y PI W i l l S u t h e r l a n d ( U n i v e r s i t y o f Cambridge) T h e V I K I N G s u r ve y p r ov i d e s a n i m p o r t a n t complement to the optical KIDS project. The VISTA PSP has recommended that V I K I N G s h a l l c ove r t h e K I D S 1 5 0 0 s q u a r e

degrees of the sk y in Z, and few hundreds square degrees in Y, J, H, and Ks at a limiting magnitude 2 to 2.4 mag deeper th a n th e n o r th e r n h e m i s p h e re U K I D S S L arge Area Sur vey. The near-infrared data will be used in the determination of ver y accurate photometric redshif ts, especially at z > 1, and is crucial for the weak lensing analysis and the obser vation of bar yo n a c o u s t i c o s c i l l a t i o n s. O t h e r s c i e n c e d r i ve r s i n c l u d e t h e h u n t fo r h i g h - r e d s h i f t quasars, gala x y clusters, and the study of gala x y stellar masses. 6. VMC ­ VISTA Magellanic Sur vey PI M a r i a - R o s a C i o n i ( U n i v e r s i t y o f Edinburgh) This sur vey will image 184 square degrees of the Magellanic System, i.e., t h e L a r g e M a g e l l a n i c C l o u d, t h e S m a l l

M a g e l l a n i c C l o u d , t h e B r i d g e, a n d t h e Magellanic Stream in the Y, J, and Ks w ave b a n d s . M u l t i - e p o c h o b s e r v a t i o n s w i l l c o n s t r a i n t h e m e a n m a g n i t u d e of shor t-period variables. The sur vey will be used to study resolved stellar populations, the star-formation histor y of the system as well as to trace its threedimensional structure.
R efe re n c e s Ca pac cio li M., M a ncini D. a nd Se dma k G. 20 0 5, T he M e s se ng e r 120, 10 Ca pp e lla ro E. 20 0 5, T he M e s se ng e r 120, 13 Eme r so n J., Mc Phe r so n A . a nd Su the r la nd W. 20 0 6, T he M e s se ng e r 126, 41

Ph oto: H. H. H eye r, ESO

C o m et M c N au g ht i ma g e d f r o m Pa r a n a l. I n th e fo re g ro u n d a re o n e of the V LT U ni t Te l e s c o p e d o m e s a n d t wo Au x ilia r y Te l e sc o p e s. Picture ta ke n o n 18 Ja nu a r y 20 07 (se e ESO PR 0 5/07 fo r mo re imag e s).

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T he Me s se ng e r 127 ­ M a rc h 20 07