HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4526
PERIOD
COVERED: UT January 014, 2008 (DOY 014)
OBSERVATIONS
SCHEDULED
SIGNIFICANT
EVENTS: (None)
WFPC2
10829
Secular
Evolution at the End of the Hubble Sequence
The
bulgeless disk galaxies at the end of the Hubble Sequence evolve at
a
glacial pace relative to their more violent, earlier-type cousins. The
causes
of their internal, or secular evolution are important because
secular
evolution represents the future fate of all galaxies in our
accelerating
Universe and is a key ingredient to understanding galaxy
evolution
in lower-density environments at present. The rate of secular
evolution
is largely determined by the stability of the cold ISM against
collapse,
star formation, and the buildup of a central bulge. Key
diagnostics
of the ISM's stability are the presence of compact molecular
clouds
and narrow dust lanes. Surprisingly, edge-on, pure disk galaxies
with
circular velocities below 120 km/s do not appear to contain such
dust
lanes. We propose to obtain ACS/WFC F606W images of a well-selected
sample
of extremely late-type disk galaxies to measure the
characteristic
scale size of the cold ISM and determine if they possess
the
unstable, cold ISM necessary to drive secular evolution. Our sample
has
been carefully constructed to include disk galaxies above and below
the
critical circular velocity of 120 km/s where the dust properties of
edge-on
disks change so remarkably. We will then use surface brightness
profiles
to search for nuclear star clusters and pseudobulges, which are
early
indicators that secular evolution is at work, as well as measure
the
pitch angle of the dust lanes as a function of radius to estimate
the
central mass concentrations.
NIC1/NIC2/NIC3
8794
NICMOS Post-SAA calibration - CR Persistence Part 5
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 DARKs. 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.
NIC3
11195
Morphologies
of the Most Extreme High-Redshift Mid-IR-luminous Galaxies
II:
The `Bump' Sources
The
formative phase of some of the most massive galaxies may be
extremely
luminous, characterized by intense star- and AGN-formation.
Till
now, few such galaxies have been unambiguously identified at high
redshift,
and thus far we have been restricted to studying the
low-redshift
ultraluminous infrared galaxies as possible analogs. We
have
recently discovered a sample of objects which may indeed represent
this
early phase in galaxy formation, and are undertaking an extensive
multiwavelength
study of this population. These objects are optically
extremely
faint {R>26} but nevertheless bright at mid-infrared
wavelengths
{F[24um] > 0.5 mJy}. Mid-infrared spectroscopy with
Spitzer/IRS
reveals that they have redshifts z~2, implying luminosities
~1E13
Lsun. Their mid-IR SEDs fall into two broad, perhaps overlapping,
categories.
Sources with brighter F[24um] exhibit power-law SEDs and SiO
absorption
features in their mid-IR spectra characteristic of AGN,
whereas
those with fainter F[24um] show a "bump" characteristic of the
redshifted
1.6um peak from a stellar population, and PAH emission
characteristic
of starformation. We have begun obtaining HST images of
the
brighter sources in Cycle 15 to obtain identifications and determine
kpc-scale
morphologies for these galaxies. Here, we aim to target the
second
class {the "bump" sources} with the goal of determining if these
constitute
morphologically different objects, or simply a "low-AGN"
state
of the brighter class. The proposed observations will help us
determine
whether these objects are merging systems, massive obscured
starbursts
{with obscuration on kpc scales!} or very reddened {locally
obscured}
AGN hosted by intrinsically low-luminosity galaxies.
WFPC2
10890
Morphologies
of the Most Extreme High-Redshift Mid-IR-Luminous Galaxies
The
formative phase of the most massive galaxies may be extremely
luminous,
characterized by intense star- and AGN-formation. Till now,
few
such galaxies have been unambiguously identified at high redshift,
restricting
us to the study of low-redshift ultraluminous infrared
galaxies
as possible analogs. We have recently discovered a sample of
objects
which may indeed represent this early phase in galaxy formation,
and
are undertaking an extensive multiwavelength study of this
population.
These objects are bright at mid-IR wavelengths
{F[24um]>0.8mJy},
but deep ground based imaging suggests extremely faint
{and
in some cases extended} optical counterparts {R~24-27}. Deep K-band
images
show barely resolved galaxies. Mid-infrared spectroscopy with
Spitzer/IRS
reveals that they have redshifts z ~ 2-2.5, suggesting
bolometric
luminosities ~10^{13-14}Lsun! We propose to obtain deep ACS
F814W
and NIC2 F160W images of these sources and their environs in order
to
determine kpc-scale morphologies and surface photometry for these
galaxies.
The proposed observations will help us determine whether these
extreme
objects are merging systems, massive obscured starbursts {with
obscuration
on kpc scales!} or very reddened {locally obscured} AGN
hosted
by intrinsically low-luminosity galaxies.
WFPC2
11327
Red
leaks
The
aim of this program is to measure the red leaks in the 8 WFPC2 UV???
filters
(F122M, F300W, F255W, F218W, F185W, F170W, F160BW, F122M). We
will
use red crossing filters to isolate and directly measure the leaks.
No
observations of this kind have ever been performed with WFPC2 to
check
the red leaks in the UV filters, most of them being extensively
used
by GO/GTO programs. A previous calibration program has only imaged
spectrophotometric
standard stars with UV filters (no filter crossing)
thus
the red leak is hard to measure using this data. The throughput
curves
for some of the UV filters (F300W, F255W, F218W, F185W) in
synphot
have incomplete information, some of them have gaps in the
measurements
as wide as 3000A.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
(None)
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
09
09
FGS
REacq
05
05
OBAD
with Maneuver 28
28
SIGNIFICANT
EVENTS: (None)