Annual Report 2011 Max Planck Institute for Astronomy

78 IV. Instrumental Developments and Projects
Credit: MPIA
2011 and is awaiting its final adoption in mid 2012, with
the implementation phase scheduled to start immediately
thereafter. Overall, Germany is mostly involved with
NISP – the optical assembly is provided by the MPE –
and the German eucLid national data center with contributions
by the Universities in Bonn, LMU Munich, MPE
and MPIA. Part of the institute's involvement is being
funded through the DLR. This includes four positions for
instrument scientist, image simulations, calibrations, and
hardware, as well as in-house contributions concentrated
on the science side.
MPIA hardware contributions: Near infrared filters and
calibration source
While we are not responsible for mechanisms, the NIR
filters provide specific challenges with a diameter of
140mm, necessitated by the 0.730.7-wide field of
view of eucLid. These diameters are larger by a factor
of three compared to any of the WFC3/IR filters on HST
and by a factor of two compared to JWST’s NIRcam.
Aside from the mere material challenge of a pound of
glass being homogeneously coated to very high accuracy,
the three filter bandpasses (Y, J, H) have rather stringent
requirements on throughput, out-of-band-blocking,
and shape.
Fig. IV.4.2: Current mechano-optical design of the Near Infrared
Spectrophotometer (NISP) onboard eucLid. MPIA’s contribution
lies in the supervision of the scientific performance of
NISP, the internal Calibration Source, needed to calibrate the
instrument's detectors, as well as the three infrared science
filters for NISP.
The NISP calibration source is being designed to
provide the photometric accuracy levels required by the
mission. An overall 1.5 % accuracy for all positions and
epochs of the survey is the basis for the photometric redshifts
to be computed for all of the faint galaxies to be
used in the weak lensing diagnostic. This leaves little
margin for the characterization of the detector array (16
Hawaii 2RG chips). The calibration source therefore has
to provide flat-field and non-linearity characteristics of
the arrays in flight and monitor their radiation-induced
degradation with increasing mission duration.
The demands of the filter and calibration source design
combined with the overall development of the mission
will make for very interesting years ahead of us.
Legacy science: A place to participate
Scientifically, eucLid offers endless opportunities beyond
the core cosmology science. 15 000 square degrees
of imaging data of a 5000–9000 Å band at 0.1
sampling, complemented with somewhat undersampled
NIR photometry at 0.3 pixel scale, as well as slit-less
spectroscopy will provide data input to topics ranging
from AGN and galaxy evolution to Milky Way science,
and from supernovae to planet searches. eucLid’s extensive
Science Working Groups are starting to plan projects
and opportunities in these legacy science areas, to
exploit imaging data of billions of objects and spectroscopy
of several tens of millions.
Knud Jahnke, Rory Holmes, Gregor Seidel,
Felix Hormuth, Stefanie Wachter