Status Report

NASA Hubble Space Telescope Daily Report # 3622

By SpaceRef Editor
May 31, 2004
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




ACS 10058

Improved wavelength calibration for the WFC G800L grism

ACS G800L observations of an emission line star {the WC Wolf-Rayet
star WR96} and a compact planetary nebula {LMC-SMP81} will be obtained
to provide improved coverage of the field variation of the dispersion
solution for the WFC and G800L grism. A direct image and a
corresponding grism image will be taken at many different positions
across the WFC field. By fitting the emission lines, the field
dependence of the wavelength zero point and dispersion will be
measured. The WR star was already used in Cycle 11 calibrations and
these observations provide improved spatial coverage to map the
variation of the dispersion with position. The observations of the
fainter planetary nebula provide an independent wavelength calibration
for a few points over the field.

ACS/HRC 9851

Host Galaxies of Reverberation-Mapped AGNs

We propose to obtain unsaturated ACS high-resolution images of all
reverberation-mapped active galactic nuclei in order to remove the
point-like nuclear light from each image, thus yielding a
"nucleus-free" image of the host galaxy. This will allow investigation
of host-galaxy properties: our particular interest is determination of
the host-galaxy starlight contribution to the reverberation mapping
observations, which is necessary for accurate determination of the
relationship between the AGN continuum flux and the size of the broad
Balmer-line emitting region of AGNs. Because this relationship is used
to estimate black-hole masses of large samples of distant AGNs,
correct determination of the slope of this relationship is critically


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.


Galaxy Evolution in Action : The Detailed Morphology of Post-Starburst

If galaxies evolve morphologically, then some should be in transition
between late and early types. One proposed evolutionary mechanism is a
galaxy-galaxy merger, but evolved merger products are difficult to
find. Fortunately, spectroscopic surveys have now uncovered large
numbers of E+A galaxies, a class of objects whose post-starburst
spectra, current lack of HI gas, and pressure-supported kinematics
suggest that they are the missing panel that connects the "Toomre
sequence" of merging spirals with normal ellipticals and S0s. Our
first HST observations of five of these galaxies are intriguing. We
find a considerable range of tidally disturbed morphologies, an "E+A"
fundamental plane, significant differences among the color gradients
within 1 kpc {~0.8”}, and populations of bright, blue globular
clusters. These initial results are difficult to interpret, however,
because they are drawn from a small sample of galaxies whose very blue
overall colors may have selected a particular evolutionary path of
E+As. Here we propose for ACS imaging of the remaining 15 E+As from
the Las Campanas Redshift Survey to probe the full range of E+A
properties. The proposed observations will allow us to 1} determine
what fraction of the interactions that lead to E+As destroy all
disk-like structures {and therefore necessarily lead to elliptical
formation}, 2} measure the inner color gradients and constrain the
spatial distribution of stars produced as gas sinks to the center
during a merger, and 3} determine whether these interactions produce
globular clusters in the required numbers to account for the increased
specific frequency of clusters in early-type galaxies.

ACS/WFC 9788

A Narrow-band Snapshot Survey of Nearby Galaxies

We propose to use ACS/WFC to conduct the first comprehensive HST
narrow-band {H-alpha + [N II]} imaging survey of the central regions
of nearby bulge-dominated disk {S0 to Sbc} galaxies. This survey will
cover, at high angular resolution extending over a large field, an
unprecedented number of galaxies representing many different
environments. It will have important applications for many
astrophysical problems of current interest, and it will be an
invaluable addition to the HST legacy. The observations will be
conducted in snapshot mode, drawing targets from a complete sample of
145 galaxies selected from the Palomar spectroscopic survey of nearby
galaxies. Our group will use the data for two primary applications.
First, we will search for nuclear emission-line disks suitable for
future kinematic measurements with STIS, in order to better constrain
the recently discovered relations between black hole mass and bulge
properties. Preliminary imaging of the type proposed here must be
done, sooner or later, if we are to make progress in this exciting new
field. Second, we will investigate a number of issues related to
extragalactic star formation. Specifically, we will systematically
characterize the properties of H II regions and super star clusters on
all galactic scales, from circumnuclear regions to the large-scale

ACS/WFC 9892

H-alpha Snapshots of Nearby Galaxies observed in F300W: Quantifying
Star Formation in a Dusty Universe

Previous studies of nearby galaxies show large discrepancies between
different star formation {SF} indicators on large {>100 pc, or even
global} scales: the strikingly complex interplay of young stars, dust
and ionized gas are the primary cause of this variance. The few
galaxies in the HST Archive with both WFPC2 H-alpha and mid-UV {F255W
or F300W} imaging show this complex geometry extending down to <10 pc
scales. We propose a SNAPshot survey in the ACS/WFC H-alpha filter of
48 galaxies of all Hubble types, that are nearby but beyond the Local
Group, and that were previously imaged with WFPC2 in the mid-UV and in
F814W. We aim to provide a benchmark for understanding the SF
processes in both normal and star-bursting galaxies, at spatial
resolutions unattainable from the ground for a large and varied galaxy
sample. These data can be applied to a wide range of astrophysical
problems and will, therefore, be made public immediately. Our science
goals are to: {1} spatially resolve the dust clouds and filaments
which strongly affect mid-UV and H-alpha derived SF rates, {2} test
how the large-scale correlation between H-alpha and mid-UV flux breaks
down on pc scales, and {3} model the propagation of star formation by
comparing the SF over time scales of ~100 Myr {via mid-UV} and ~5 Myr
{via H-alpha}. This will {4} significantly improve our insight into,
and calibration of SF in UV-bright galaxies at high z, and into the
cosmic SF history.


Young Massive Clusters in Spiral Galaxies and the Connection with Open

We propose to carry out a census of star clusters in the disks of the
nearby spiral galaxies NGC 45, NGC 1313, NGC 4395, NGC 5236 and NGC
7793. Using ACS, we will identify much fainter and older star clusters
than possible in previous ground-based surveys, or even in HST imaging
of more distant galaxies. For the first time, we will directly
explore the connection between young "massive” {or "super”} star
clusters {YMCs} and lower-mass "open” clusters in different star
forming environments. We will test the universality of the luminosity-
and mass functions of stellar clusters and establish whether the
presence of YMCs is a result of a top-heavy cluster luminosity
function, or follows from generally richer cluster systems. Our target
galaxies span a range of morphological properties, surface brightness
and star formation rate. Some of them are known from ground-based
studies to host large numbers of YMCs while others have more modest
cluster populations. However, previous ground-based data were
restricted to luminous clusters younger than about 500 Myr. Here we
will extend the search to clusters formed throughout the entire
lifetime of each galaxy and reach clusters with properties typical of
the Milky Way open clusters. This will allow us to close the gap
between studies of extragalactic and Galactic disk clusters.

NIC/NIC3 9865

The NICMOS Parallel Observing Program

We propose to continue managing the NICMOS pure parallel program.
Based on our experience, we are well prepared to make optimal use of
the parallel opportunities. The improved sensitivity and efficiency of
our observations will substantially increase the number of
line-emitting galaxies detected. As our previous work has
demonstrated, the most frequently detected line is Halpha at
0.7<z<1.9, which provides an excellent measure of current star
formation rate. We will also detect star-forming and active galaxies
in other redshift ranges using other emission lines. The grism
observations will produce by far the best available Halpha luminosity
functions over the crucial–but poorly observed–redshift range where
galaxies appear to have assembled most of their stellar mass. This key
process of galaxy evolution needs to be studied with IR data; we found
that observations at shorter wavelengths appear to have missed a large
fraction of the star-formation in galaxies, due to dust reddening.
We will also obtain deep F110W and F160W images, to examine the space
densities and morphologies of faint red galaxies. In addition to
carrying out the public parallels, we will make the fully reduced and
calibrated images and spectra available on-line, with some
ground-based data for the deepest parallel fields included.

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

A new procedure proposed to alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained immediately upon exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled within 50
minutes of coming out of the SAA. The darks will be obtained in
parallel in all three NICMOS Cameras. The POST-SAA darks will be
non-standard reference files available to users with a USEAFTER
date/time mark. The keyword ‘USEAFTER=date/time’ will also be added to
the header of each POST-SAA DARK frame. The keyword must be populated
with the time, in addition to the date, because HST crosses the SAA ~8
times per day so each POST-SAA DARK will need to have the appropriate
time specified, for users to identify the ones they need. Both the raw
and processed images will be archived as POST-SAA DARKSs. Generally we
expect that all NICMOS science/calibration observations started within
50 minutes of leaving an SAA will need such maps to remove the CR
persistence from the science images. Each observation will need its
own CRMAP, as different SAA passages leave different imprints on the
NICMOS detectors.

STIS 9718

SMC Extinction Curve Towards a Quiescent Molecular Cloud

The lack of 2175 A bump in the SMC extinction curve is interpreted as
an absence of small carbon grains. ISO mid-IR observations support
this interpretation by showing that PAH features are absent in the
spectra of SMC and LMC massive star forming regions. However, the only
ISO observation of an SMC quiescent molecular cloud shows all PAH
features, indicating a PAH abundance relative to large dust grains
similar to that of Milky Way clouds. We identified a reddened B2III
star associated with this cloud. We propose to observe it with STIS to
derive the xetinction curve of SMC dust away from HII regions. This
observation will provide the first measure of the extinction
properties of SMC dust away from star forming regions. It will allow
us to disentangle the effects of metallicity and star formation on the
SMC extinction curve and dust composition and to assess the relevance
of the SMC bump-free extinction curve to low metallicity and/or
starburst galaxies in general.

STIS/CCD 10018

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 10020

CCD Bias Monitor – Part 2

Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1,
and 1×1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.


UV extinction by dust in unexplored LMC environments

The ensemble of results from studies of the UV extinction in the Milky
Way, Magellanic Clouds {MC}, M31 and M33, indicates a complex
dependence of the dust properties with environment, where starburst
activity and metallicity are relevant factors. Work in the LMC to
date, based on IUE data, has several drawbacks: a} only supergiants
could be used, b} they all have moderate extinction, c} the IUE S/N is
limited, d} the large IUE slit may include light from other sources,
such as scattered light from dust or faint companion stars, e} studies
are confined to few {extreme} environments. We propose to obtain UV
extinction curves more accurate than previous ones {from STIS spectra
of main sequence stars with higher reddening}, sampling four
environments in the LMC with different levels of star formation
activity, including the general field, hitherto unexplored. The
results will characterize the properties of dust in different
conditions, at the LMC metallicity, which is useful to intepret
integrated properties of distant galaxies, as well as GALEX upcoming
UV surveys. A complementary study is under way with FUSE in the far-UV
range. The combined results will provide insight on the properties of
small grains.

WFPC2 10070

WFPC2 CYCLE 12 Supplemental Darks Part 2/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot


Age-dating Star Clusters in M101

M101 represents perhaps our best chance to study the stellar
population of a luminous, late type spiral galaxy, due to both its
proximity and its face-on orientation. For these reasons, 13 orbits of
HST ACS observing time were allocated in Cycle 11 to obtain a 4×4
mosaic image of M101 in BVI . Unfortunately, a degeneracy between age
and reddening exists when only these three bands are available. Hence,
we propose to augment these observations by obtaining WFPC2 U band and
ACS H alpha images. This will enable the accurate determination of
ages for the young clusters, secure identifications of 75-100 old
globular clusters, and allow a quantitative study of the HII region
sizes and structures. Some of the specific questions we will address
are: How do the young clusters form and evolve? What fraction of the
clusters dissolve and on what timescales? Do clusters evolve with a
continuum of properties? Using WFPC2 and ACS in parallel, and making
use of the fact that M101 is in the CVZ, allows us to greatly enhance
the science return of previous HST observations for the cost of only 4


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.) None

                      SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq                09             09                            
FGS REacq                06             06                 
FHST Update              17             17


Successfully completed third and final round of OBAD Data Collections,
Sections N, O, P, I, and Q @ 148/03:15Z, adding four more scheduled
OBAD/Rate Control combinations to the eleven collected over the past
two days. (OR 17169 with attached script).

Successfully executed the 4th FGS-2R TRTTT with macro kicking off at
148/18:02Z and 19:42Z, for the 1st and 2nd runs, respectively (OR
17170-2). OTA SE remained on console to monitor the successful GS
Acquisition (1,3,1) @ 148/20:41Z. Due to TDRSS schedule, data were
not available until SSR engineering data playback @ 148/21:50Z.
Continuous MERGED data will be available 5/28/04 (am) for the analysis
to begin.

SpaceRef staff editor.