The UKIDSS Early Data Release
UKIDSS is the next
generation near-IR sky survey, the successor to 2MASS. UKIDSS began in
May 2005 and will survey 7500 square degrees of the northern sky,
extending over both high and low Galactic latitudes, in JHK to K=18.3
(three magnitudes deeper than 2MASS). UKIDSS will be the true
near-infrared counterpart to the Sloan survey. UKIDSS is made up of
five surveys, including two deep extra-Galactic elements and a
panoramic atlas of the Galactic plane. See the main UKIDSS web site for full details.
The first ESO-wide release of UKIDSS data took place on 10 February
2006. The data are available at the WFCAM Science Archive (WSA)
surveys.roe.ac.uk/wsa. All
UKIDSS data are proprietary to ESO astronomers for 18 months, before
world release. Users need to be registered to be able to log in. The
registration process is described at
www.ukidss.org/archive/archive.html.
In broad outline the contents of the EDR are summarised in Table
1. This lists the area covered in each survey with the full filter
complement of the survey. In the EDR, the data summarised in Table 1
correspond to the `EDR database'. This is a subset of the larger `EDR+
database', which contains all data that have passed quality control,
and includes fields observed where the full filter complement has not
yet been completed. The total area of the EDR+ database, i.e. sky
coverage in any filter, is 220 sq. degs.
|
| Survey | Area sq. degs | Filters |
K-band depth
(5sigma Vega) |
| Large Area Survey | 27 | YJHK | 18.1 |
| Galactic Clusters Survey | 7 | ZYJHK | 18.1 |
| Galactic Plane Survey | 15 | JHK | 17.7 |
| Deep ExtraGalactic Survey | 2.4 | JK | 20.6 |
| Ultra Deep Survey | 0.8 | JK | 21.1 |
|
Table 1: Summary of area covered and depth for each survey in the EDR
database.
|
By way of introduction, users of EDR data should refer to the
following three very useful UKIDSS papers:
-
Lawrence et al. (astroph/0604426) `The UKIRT Infrared Deep Sky Survey', MNRAS,
submitted (astro-ph/0603nnn). This paper describes the design and
implementation of the surveys, and the final (7-year) goals.
-
Dye et al. (astroph/0603608), `The UKIRT Infrared Deep Sky Survey Early Data
Release', MNRAS, submitted (astro-ph/0603nnn). The purpose of this
paper is to provide a self-contained guide to the EDR.
-
Hewett et al. (astroph/0601592), `The UKIRT Infrared Deep Sky Survey ZYJHK
Photometric System: Passbands and Synthetic Colours', MNRAS, in
press (astro-ph/0601592). This paper was described in the previous
edition of the UKIRT newsletter. It provides response curves for
the five broadband filters, and synthetic colours of a wide range
of stars, galaxies, and quasars.
The first paper provides important background material, and the
third paper will be helpful for interpreting scientific results. But
for beginners, we strongly recommend a careful reading of the second
paper, which is designed to be a self-contained guide to the contents
of the EDR, and the structure of the data and its quirks. The second
paper also includes a summary of the observing protocols followed for
each survey. It explains the different data structures used in the
five surveys, e.g. whether data are interlaced, and whether data are
rebinned. A brief overview of the pipeline is provided. There is also
an important section describing data artefacts and UKIDSS quality
control (QC). The final section of the paper describes how to use the
WSA, with some worked examples.
The EDR is a small fraction of UKIDSS, about 1% of the seven year
plan, but rather impressively is similar in scope to 2MASS in terms of
numbers of photons collected. The next release, called Data Release 1,
is set for 1 July 2006, and will be several times larger.
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