THE KIDS project web
Intro: what is KIDS
To be written
The proposal to ESO
|Complete proposal text||(PDF)|
|ESOFORM template pt. 1||(PDF)|
|ESOFORM template pt. 2||(PDF)|
|ESOFORM template pt. 3||(PDF)|
|Management plan v.2006/4/15||(PDF)|
The time allocation
Here's what has been approved (in hours):
|P77|| 60|| 60||119|| 143|| 51|| 43
|P78|| 60|| 60||119|| 143|| 51|| 43
|P79|| 60|| 60||119|| 143|| 51|| 21
|P80|| 60|| 60||119|| 143|| 51|| 21
|P81|| 60|| 60||119|| 143|| 51|| 21
|P82|| 60|| 60||119|| 143|| 51|| 21
|P83|| 60|| 60||119|| 143|| 51||
|P84|| 60|| 60||119|| 143|| 51||
|P85|| ||120|| || || ||
|P86|| ||120|| || || ||
|P87|| ||120|| || || ||
|P88|| ||120|| || || ||
|GRAND TOT INC REPEAT||4114|
KIDS will target two patches, KIDS-N and KIDS-S. The total area is
KIDS-N runs along the equator in the NGC, from RA 10:00 to 15:52 (150
to 238 deg), and between declination -5 and +3 (with the exception of
RA> 15, dec< -3). In addition it includes the area RA 8:40 to
9:08, dec -3 to -1.
KIDS-S is a single rectangular patch around the SGP, between RA=22:00
and 3:30, and dec -35 to -25.
The location of the fields, plotted on top of the Schlegel,
Finkbeiner, & Davis 1998, ApJ, 500, 525 reddening maps, is shown
below. The areas are outlined in green; B-V extinction is contoured at
intervals of 0.05.
Click on the images for a larger version.
Order in which fields are to be observed
To increase the science return from the survey before it is completed,
we have considered the best order in which to build up the
survey. Relevant considerations are
The following proposal emerged from this (discussions KK, Wilman,
Phleps, Schuecker). It is illustrated here for KIDS-N. (Click for a
larger PS version).
- a desire to get a useful angular power spectrum on large scales
- a wish to maximize coverage of the GAMA AAO spectroscopic
survey patch contained in KIDS-N
- not compromise schedulability
- build in some overlaps of adjacent fields to allow calibration
to be checked and improved
The KIDS-N patch is divided into square blocks, 9x9 degrees. A half-hour
integration, plus 25% overheads, takes about 38 minutes, and in this
time the sky rotates 9 degrees on the equator.
So on a good night one field can be
observed from each block in r, or two fields in g (or u), etc.
The blocks come in two varieties, 'inc' and 'dec' (increasing and
decreasing RA coverage). They alternate along the KIDS patch.
Within a block the sequence of observation is as shown in the lower
panels of the figures. The first two declination strips are observed
in opposite directions in the two blocks, so that where the blocks
meet contiguous areas build up rather quickly. After about 1/4 of the
patch is observed we will have a complete 2 degree-wide strip. From
this point on, the remaining strips can be built up in order of
increasing RA, and the distinction between Inc and Dec is no longer
The first fours strips to be completed are those between declinations
-2 and +2, where the spectroscopic AAO survey will take place.
In the KIDS-S patch (declination -30) the sky rotates a factor 0.87
so here the natural width of a block in RA is 8, not 9
To avoid holes in the KIDS images, observations will be dithered with
offsets sufficiently large to bridge the inter-CCD gaps of
OmegaCAM. We will use 5 dithered exposures per field, which results in
an exposure map that looks like
where white indicates the area covered in all 5 exposures, and
progressively darker shades indicate lower and lower total exposure time.
At the edges of the fields, the exposure level decreases from 5 to 0,
in a staircase pattern with step width equal to the dither steps (25
arcsec in X, 85 arcsec in Y).
The adjacent fields should mesh with each other in a nice way. Two
possibilities are illustrated below (click on figure for postscript
These panels show the exposure levels at the edges of two adjacent
dithered images. The top panels show the exposure
versus X, the lower panels versus Y (which has bigger steps). The
horizontal axes are labelled in pixels (below) and arcminutes (above),
and the center of the field is at (0,0).
Option A is illustrated on the left. The field
centers are separated by the full extent of the mosaic, so that the
combined exposure level in the overlap area,
obtained by summing the exposures from both
dither sets, is everywhere nicely equal to 5. This
minimizes the number of exposures but leaves no redundancy. It also
means that in the data analysis results from different OBs need to be
processed together, otherwise every pointing is surrounded by a rim
where the total exposure is only 60% of
The field centers are separated by 3645arcsec = 60.76arcmin in X, and
3672arcsec=61.2arcmin in Y. (for a 0.2134arcsec/pix scale)
Option B is shown on the right. The field centers are closer
together than in option A (2 offset steps=50arcsec in X, 170 arcsec in
Y closer). 80% exposure can now
be achieved without having to add up observations from different
fields, which simplifies the analysis. Moreover, there is now some
redundancy: around each OB we have a strip that is 2 steps
(50-170arcsec) wide, one degree long,
that has received 4 exposures in one OB and 3 in another.
The price for the overlap is (obviously) an increased number of field
The field centers are separated by 3595arcsec = 59.9arcmin in X, and
3502arcsec=58.4arcmin in Y. (for a 0.2134arcsec/pix scale)
Because of the redundancy and operational simplicity, option B
is preferred. The resulting exposure pattern from a 2x2 set of fields is
then as illustrated below. The darkest shade of grey represents 3/5 of
the total exposure time. The grey horizontal and vertical strips
marked with a + are the overlap regions where 4 exposures from one
field overlap with three exposures from the adjacent one.|
A list of field centers that is compatible with these considerations,
and that can tile the whole sky, can then be calculated. The result
can be seen here.
Last modified: Wed Mar 26 10:15:42 2008