HST Daily Report #3340 (Part 1)
HUBBLE SPACE TELESCOPE
DAILY REPORT #3340
PERIOD COVERED: DOYS 101-103
OBSERVATIONS SCHEDULED
ACS 9468
ACS Grism Parallel Survey of Emission- line Galaxies at Redshift z pl 7
We propose an ACS grism parallel survey to search for emission-line
galaxies toward 50 random lines of sight over the redshift interval 0 <
zpl 7. We request ACS parallel observations of duration more than one
orbit at high galactic latitude to identify ~ 300 HAlpha emission-line
galaxies at 0.2pl zpl 0.5, ~ 720 O IILambda3727 emission-line galaxies
at 0.3pl zpl 1.68, and pg 1000 Ly-alpha emission-line galaxies at
3pl zpl 7 with total emission line flux fpg 2* 10^-17 ergs s^-1 cm^-2
over 578 arcmin^2. We will obtain direct images with the F814W and F606W
filters and dispersed images with the WFC/G800L grism at each position.
The direct images will serve to provide a zeroth order model both for
wavelength calibration of the extracted 1D spectra and for determining
extraction apertures of the corresponding dispersed images. The primary
scientific objectives are as follows: {1} We will establish a uniform
sample of HAlpha and O II emission-line galaxies at z<1.7 in order to
obtain accurate measurements of co-moving star formation rate density
versus redshift over this redshift range. {2} We will study the spatial
and statistical distribution of star formation rate intensity in
individual galaxies using the spatially resolved emission-line
morphology in the grism images. And {3} we will study high-redshift
universe using Ly-alpha emitting galaxies identified at z pl 7 in the
survey. The data will be available to the community immediately as they
are obtained.
ACS 9649
ACS internal CTE monitor
The charge transfer efficiency {CTE} of the ACS CCD detectors will
decline as damage due to on-orbit radiation exposure accumulates. This
degradation will be closely monitored at regular intervals, because it
is likely to determine the useful lifetime of the CCDs. All the data for
this program is acquired using internal targets {lamps} only, so all of
the exposures should be taken during Earth occultation time {but not
during SAA passages}. This program emulates the ACS pre-flight ground
calibration and post-launch SMOV testing {program 8948}, so that results
from each epoch can be directly compared. Extended Pixel Edge Response
{EPER} and First Pixel Response {FPR} data will be obtained over a range
of signal levels for both the Wide Field Channel {WFC}, and the High
Resolution Channel {HRC}.
ACS 9673
CCD Daily Monitor
This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS
ACS 9480
Cosmic Shear With ACS Pure Parallels
Small distortions in the shapes of background galaxies by foreground
mass provide a powerful method of directly measuring the amount and
distribution of dark matter. Several groups have recently detected this
weak lensing by large-scale structure, also called cosmic shear. The
high resolution and sensitivity of HST/ACS provide a unique opportunity
to measure cosmic shear accurately on small scales. Using 260 parallel
orbits in Sloan textiti {F775W} we will measure for the first time:
beginlistosetlength sep0cm setlengthemsep0cm setlength opsep0cm em the
cosmic shear variance on scales <0.7 arcmin, em the skewness of the
shear distribution, and em the magnification effect. endlist Our
measurements will determine the amplitude of the mass power spectrum
sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20, and the mass
density Omega_m with s/n=4. They will be done at small angular scales
where non-linear effects dominate the power spectrum, providing a test
of the gravitational instability paradigm for structure formation.
Measurements on these scales are not possible from the ground, because
of the systematic effects induced by PSF smearing from seeing. Having
many independent lines of sight reduces the uncertainty due to cosmic
variance, making parallel observations ideal.
ACS 9476
Galaxy Evolution in the Richest Clusters at z=0.8: the EDisCS Cluster
Sample
The study of distant cluster galaxies requires two key ingredients: {1}
deep high-resolution imaging, to constrain galaxy structure; and {2}
8m-class spectroscopy, to measure stellar content, star-formation rates,
dynamics, and cluster membership. We will reach both conditions with the
addition of HST/ACS imaging to our suite of VLT {36 nights} and NTT {20
nights} observations of 10 confirmed clusters at z~0.8, drawn from the
ESO Distant Cluster Survey {EDisCS}. The proposed HST/ACS data will
complement our existing optical/IR imaging and spectroscopy with
quantitative measures of cluster galaxy morphologies {i.e. sizes and
shapes, bulge-disk decompositions, asymmetry parameters}, and with
measurements of cluster masses via weak lensing. Major advantages unique
to the EDisCS project include: {i} uniform selection of clusters; {ii}
large enough sample sizes to characterize the substantial
cluster-to-cluster variation in galaxy populations; {iii} large
quantities of high quality data from 8m telescopes; {iv} uniform
measurements of morphologies, spectroscopic and photometric redshifts,
SEDs, star-formation/AGN activities, and internal kinematics; {v}
optical selection of clusters to complement the X-ray selection of
almost all high-z clusters in the ACS GTO programs; {vi} forefront
numerical simulations designed specifically to allow physical
interpretation of observed differences between the high-z and local
clusters.
ACS 9293
Massive Black Holes in Early Type Galaxies
Recently, a nearly perfect relation has been recognized between the
masses of the black holes {for 3×10^6 Msun < M_BH < 3×10^9 Msun} at the
centers of galaxies and the velocity dispersions of their bulges.
However, uncertainties over the exact slope of the correlation still
remain, and it is not known if such a relation extends to black holes of
lower and higher masses. The discovery of small {r ~ a few hundred pc},
well defined, dust and gas disks in the nuclei of some active elliptical
galaxies opened a new avenue for measuring central mass distributions.
When ionized gas is present, a small number of high spatial resolution
{e.g. STIS} spectra are sufficient to characterize the disk dynamics and
the galaxy’s central mass {e.g., M87, M81, NGC 4374}. We propose to use
STIS spectroscopy to measure black hole masses, using gas dynamics, in
the centers of several brightest cluster galaxies {BCGs}, 2 nearby
galaxies with low velocity dispersions, and a number of elliptical
galaxies known to harbor small nuclear dust disks. The proposed targets
encompass a wide range of black hole masses, allowing us to fully
examine the M_BH — sigma relationship. We will also obtain H-alpha and
continuum images to fully characterize the gaseous and dust morphology
as well as stellar surface profile in the central regions.
ACS 9294
Observations of the Host Galaxy of 3C 273
The highly luminous flat-spectrum QSO 3C 273 {z=0.158, V=12.8,
M_V~-26.4} will be imaged with the WFC in the [O III]5007 and H-alpha
emission lines with the narrow-band filters FR601N and FR782N,
respectively. Off-band images in F475W and F850LP will also be acquired
to accurately subtract the underlying galaxy continuum. Combined with
the broad-band HRC coronagraphic images from the ERO program 8992, these
new images will offer the most complete and detailed view yet of the
host galaxy and environment of this QSO.
ACS 9656
Stability of the ACS CCD: geometry, flat fielding, photometry
A moderately crowded stellar field, located ~6′ West of the centre of
the cluster 47 Tuc, is observed repeatedly {every three weeks with the
WFC, every other month with the HRC} in various filters, spending 1
orbit per epoch. Different filters will be used every time, so that over
the course of the year all filters will have been employed at least
twice. The most common filters will be checked more frequently. The same
field has been observed in the course of the SMOV phase and the
positions and magnitudes of the most prominent stars have been
accurately measured. Although the field is neither a proper astrometric
nor a proper photometric standard one, the positions and magnitudes of
the objects in it can be used to monitor any local and large scale
variations in the platescale and sensitivity of the detectors. It should
be noted that for the filters which have already been used during the
SMOV phase it will be sufficient to take one single image, without
CR-SPLIT, since the exposure time is always short {20-30 sec} and there
will be so many stars that the few of them which are affected by cosmic
rays can be discarded as outliers in the photometry. For narrow and
medium band filters not exercised on this target in the SMOV phase,
however, a baseline will have to be set. This expenditure of time will
apply to the current cycle only. At variance with the approach used in
SMOV, there is no need for large telescope slews to place the same
objects on opposite sides of the detectors, thence allowing the
programme to remain compact and efficient. All exposure level parameters
are set to their default values, except for the amplifier gain of the
WFC exposures in the F606W band, which will be collected with the gain
value of 2 for the WFC for compatibility with the SMOV observations. The
exposure time is typically 30 seconds for the WFC, 60 sec for the HRC.
No attempt will be made to attain a predefined or the same orientation
on the sky amongst different epochs. Typically, for the WFC, five
exposures will be accommodated in one orbit. For the HRC, about 10
exposures can be fitted within one orbit
