ISO observations of ELAIS-S1
ELAIS overview
The European Large Area ISO Survey (ELAIS) has covered a total of 12 square
degrees. The entire area has been surveyed at 15 microns using the CAM
instrument and at 90 microns using PHOT. 7 square degrees has also been
observed at 6.7 microns and 1 square degree at 175 microns. The ISO observations
for the ELAIS programme were executed from 12th March 1996 (revolution
116) until 8th April 1998 (revolution 875).
The choice of ELAIS fields was governed by a number of factors. Firstly,
in order to reduce the impact of cosmic variance on the survey, they were
distributed on completely independent not-contiguos regions of the sky.
Cirrus confusion is a particular problem, so the sky areas to be observed
were selected within regions with low IRAS 100 microns intensities (I100<1.5MJy/sr),
using the maps of Rowan-Robinson et al. 1991).
In recognition of the large amount of time required, minimization
of scheduling conflict with other ISO observations was adopted, by restricting
ELAIS to regions of high visibility (>25 %) over the mission lifetime.
To reduce the impact of the Zodiacal background only regions with high
Ecliptic latitudes (>40 deg.) were selected. Finally, it was essential
to avoid saturation of the ISO-CAM detectors, so any bright IRAS 12 micron
source (S[12microns]>0.6Jy) was avoided.
Futher informations on the ELAIS survey are available at the ELAIS
official web-page.
ELAIS-S1
The figure on the right shows the Schlegel et al. (1998) 100
microns IRAS map of the sky emissivity in the ELAIS-S1 region (see also
the SWIRE homepage).
(right click for full-size view)
Sources and boxes are drawn according to the following scheme:
| green ellipse + circle |
galaxies < 13.5 mag |
| yellow ellipse + circle |
galaxies > 3 arcmin |
| blue * |
SAO stars < 6 mag |
| red * |
SAO stars 6 to 7 mag |
| yellow + |
25um IRAS sources < 0.5 Jy |
| red + |
25um IRAS sources 0.5 to 1.0 Jy |
| blue + |
25um IRAS sources 1.0 to 2.0 Jy |
| blue O |
Chandra Pointing |
| red O |
NVSS > 0.5 Jy |
| cyan * |
UV(Galex) stars > 0.03PHU |
| yellow/pink
triangle |
MIPS/IRAC
GTO Target |
| pink square |
ISO ELAIS-S1 Field |
| cyan circle/square |
15 sq deg FOV centered at RA=0h 38m 30s
Dec=-44° 00' 00'' (30'S of nominal ES1 center. |
|
 |
The ISOCAM detector was stepped across the sky in a grid pattern, with
about half detector width steps in one direction and the whole detector
width steps in the other. In this way, the reliability was improved as
each sky position was observed twice in successive pointings, and the overheads
were reduced because each raster covered a relatively large area (40X40
sq. arcmin). At each raster pointing (i.e., grid position of the raster)
the 32X32 ISOCAM detector was read out several times.
Details on ELAIS-S1 ISOCAM 15 microns observations and data reduction
can be found at the
Elais 15 microns final
analysis page.
Optical Identification of ELAIS
15 Micron and Radio Sources and the ELAIS
Final Band-Merged Catalogue are also available.
Click here to access ISO contouring on WFI field.