The Great Easter Egg Hunt: The Void's Incredible Richness (Forwarded)

ESO Education and Public Relations Dept.

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Text with all links and the photos are available on the ESO
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http://www.eso.org/outreach/press-re.../pr-14-06.html
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For immediate release: 14 April 2006

ESO Press Photo 14/06

The Great Easter Egg Hunt: The Void's Incredible Richness

Huge Astronomical Image of 'Empty Space' Obtained with ESO Telescope

An image made of more than 300 million pixels is being released by
ESO, based on more than 64 hours of observations with the Wide-Field
Camera on the 2.2m telescope at La Silla (Chile). The image covers
an 'empty' region of the sky five times the size of the full moon,
opening an exceptionally clear view towards the most distant part
of our universe. It reveals objects that are 100 million times
fainter than what the unaided eye can see.

Easter is in many countries a time of great excitement for children
who are on the big hunt for chocolate eggs, hidden all about the
places. Astronomers, however, do not need to wait this special day
to get such an excitement: it is indeed daily that they look for
faraway objects concealed in deep images of the sky. And as with
chocolate eggs, deep sky objects, such as galaxies, quasars or
gravitational lenses, come in the wildest variety of colours and
shapes.

The image presented here is one of such very deep image of the sky.
It is the combination of 714 frames for a total exposure time of
64.5 hours obtained through four different filters (B, V, R, and I)!
It consists of four adjacent Wide-Field Camera pointings (each
33x34 arcmin), covering a total area larger than one square degree.

Yet, if you were to look at this large portion of the firmament
with the unaided eye, you would just see ... nothing. The area,
named Deep 3, was indeed chosen to be a random but empty, high
galactic latitude field, positioned in such a way that it can
be observed from the La Silla observatory all over the year.

Together with two other regions, Deep 1 and Deep 2, Deep 3 is part
of the Deep Public Survey (DPS), based on ideas submitted by the
ESO community and covering a total sky area of 3 square degrees.
Deep 1 and Deep 2 were selected because they overlapped with
regions of other scientific interest. For instance, Deep 1 was
chosen to complement the deep ATESP radio survey carried out with
the Australia Telescope Compact Array (ATCA) covering the region
surveyed by the ESO Slice Project, while Deep 2 included the CDF-S
field. Each region is observed in the optical, with the WFI, and
in the near-infrared, with SOFI on the 3.5-m New Technology
Telescope also at La Silla.

Deep 3 is located in the Crater (The Cup), a southern constellation
with very little interest (the brightest star is of fourth magnitude,
i.e. only a factor six brighter than what a keen observer can see
with the unaided eye), in between the Virgo, Corvus and Hydra
constellations. Such comparatively empty fields provide an unusually
clear view towards the distant regions in the Universe and thus open
a window towards the earliest cosmic times. The deep imaging data
can for example be used to pre-select objects by colour for follow-
up spectroscopy with ESO's Very Large Telescope instruments.

But being empty is only a relative notion. True, on the whole image,
the SIMBAD Astronomical database references less than 50 objects,
clearly a tiny number compared to the myriad of anonymous stars and
galaxies that can be seen in the deep image obtained by the Survey!

Among the objects catalogued is the galaxy visible in the top middle
right (see also PR Photo 14b/06) and named ESO 570-19. Located 60
million light-years away, this spiral galaxy is the largest in the
image. It is located not so far -- on the image! -- from the
brightest star in the field, UW Crateris. This red giant is a
variable star that is about 8 times fainter than what the unaided
eye can see. The second and third brightest stars in this image
are visible in the lower far right and in the lower middle left.
The first is a star slightly more massive than the Sun, HD 98081,
while the other is another red giant, HD 98507.

In the image, a vast number of stars and galaxies are to be studied
and compared. They come in a variety of colours and the stars form
amazing asterisms (a group of stars forming a pattern), while the
galaxies, which are to be counted by the tens of thousands come in
different shapes and some even interact or form part of a cluster.

The image and the other associated data will certainly provide a
plethora of new results in the years to come. In the meantime, why
don't you explore the image with the zoom-in facility, and start
your own journey into infinity? Just be careful not to get lost.
And remember: don't eat too many of these chocolate eggs!

High resolution images and their captions are available at
http://www.eso.org/outreach/press-re...hot-14-06.html

Notes

The ESO Deep-Public-Survey (DPS) is a multi-colour imaging survey
carried out by the ESO Imaging Survey (EIS) team and consists of
data taken in UBVRI-bands taken with the Wide Field Imager (WFI)
at the 2.2m telescope at La Silla and infrared data in the J- and
Ks-bands observed with SOFI at the New Technology Telescope, also
at La Silla. The main scientific drivers for the ESO DPS are
searches for high-redshift galaxies, distant clusters, high-
redshift quasars, low surface-brightness galaxies, and
gravitational lensing studies. The survey was designed in a way
to deliver a unique dataset also for studies on Galactic structure,
very low-metallicity stars, white dwarfs, M-dwarfs, and field
brown dwarfs.

The image is based on data processed by the GaBoDS team, a German
collaboration, using a specific reduction pipeline, THELI. The
team released 63 reduced, photometrically and astrometrically
fully calibrated, and stacked images of the optical part. Some of
these, covering the Deep 3 field in the B, V, R, and I-bands, were
combined in a colour image by Hännes Heyer and Olivia Blanchemain
(ESO).

National contacts for the media:

Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Riitta Tirronen, +358 9 7748 8369
Denmark: Dr. Michael Linden-Vørnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Dr. Leopoldo Benacchio, benacchio @ inaf.it
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25

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