NASA Hubble Space Telescope Daily Report # 3403
HUBBLE SPACE TELESCOPE
DAILY REPORT # 3403
PERIOD COVERED: DOYs 192-194
OBSERVATIONS SCHEDULED
ACS 9661
ACS Polarization Calibration
This proposal aims to calibrate the polarization modes most heavily
used in Cycle 11. We need L-flat observations, observations of a
polarized star and an unpolarized star, and an observation of an
extended polarized source.
ACS 9482
ACS Pure Parallel Lyman-Alpha Emission Survey {APPLES}
Ly-alpha line emission is an efficient tool for identifying young
galaxies at high redshift, because it is strong in galaxies with young
stars and little or no dust — properties expected in galaxies
undergoing their first burst of star- formation. Slitless spectroscopy
with the ACS Wide-Field Camera and G800L grism allows an unmatched
search efficiency for such objects over the uninterrupted range 4 <~ z
<~ 7. We propose the ACS Pure Parallel Ly-alpha Emission Survey
{“APPLES”}, to exploit this unique HST capability and so obtain the
largest and most uniform sample of high redshift Ly-alpha emitters
yet. Parallel observations will allow this survey to be conducted with
minimal impact on HST resources, and we will place reduced images and
extracted spectra in the public domain within three months of
observation. We aim to find ~ 1000 Ly-alpha emitters, 5 times the
biggest current sample of Ly-alpha emitters. This unprecedented sample
will provide robust statistics on the populations and evolution of
Ly-alpha emitters between redshifts 4–7; a robust measurement of the
reionization redshift completely independent of the Gunn-Peterson
trough; spatial clustering information for Ly-alpha emitters which
would let us probe their bias function and hence halo mass as a
function of redshift; many galaxies at redshift exceeding 6; and lower
redshift serendipitous discoveries.
ACS 9674
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 9984
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 9401
The ACS Virgo Cluster Survey
We propose the most comprehensive imaging survey to date of
low-redshift, early-type galaxies. Our goal is to exploit the
exceptional imaging capabilities of the ACS by acquiring deep images
— in the SDSS g^ and z^ bandpasses — for 163 E, S0, dE, dE, N and
dS0 galaxies in Virgo, the nearest rich cluster. This extraordinary
dataset would likely constitute one of the principal legacies of HST,
and would have widespread applications for many diverse areas of
astrophysics. Our immediate scientific objectives are threefold: {1}
measure metallicities, ages and radii for the many thousands of
globular clusters {GCs} in these galaxies, and use this information to
derive the protogalactic mass spectrum of each galaxy; {2} measure the
central luminosity and color profile of each galaxy, and use this
information to carry out a completely independent test of the merging
hierarchy inferred from the GCs, with the aid of N-body codes that
simulate the merger of galaxies containing massive black holes; and
{3} calibrate the z^ -band SBF method, measure Virgo’s 3-D structure,
and carry out the definitive study of the GC luminosity function’s
precision as a standard candle. Our proposed Virgo Cluster Survey will
yield a database of unprecedented depth, precision and uniformity, and
will enable us to study the record of galaxy and cluster formation in
a level of detail which will never be possible with more distant
systems.
ACS 9352
The Deceleration Test from Treasury Type Ia Supernovae at Redshifts 1.2
to 1.6
Type Ia supernovae {SNe Ia} provide the only direct evidence for an
accelerating universe, an extraordinary result that needs a rigorous
test. The case for cosmic acceleration rests on the observation that
SNe Ia at z ~ 0.5 are ~ 0.25 mag fainter than they would be in a
universe without acceleration. A powerful and straightforward way to
assess the reliability of the SN Ia measurement and the conceptual
framework of its interpretation is to look for cosmic deceleration at
z >= 1. This would be a clear signature of a mixed dark-matter and
dark-energy universe. Systematic errors in the SN Ia result attributed
to grey dust or cosmic evolution of the SN Ia peak luminosity would
not show this change of sign. We have demonstrated proof of this
concept with a single SN Ia, SN 1997ff at z = 1.7, found and followed
by HST. The results suggest an early epoch of deceleration, but this
is too important a conclusion to rest on just one object. Here we
propose to use HST for observations of six SNe Ia in the range 1.2 <=
z <= 1.6, that will be discovered as a byproduct from proposed
Treasury programs for high-latitude ACS surveys. Six objects will
provide a much firmer foundation for a conclusion that touches on
important questions of fundamental physics.
ACS/HRC 9823
Rings of Uranus: Dynamics, Particle Properties and Shepherding Moons
We propose to image the rings and small inner satellites of Uranus
using the High Resolution Channel of the ACS. The revolutionary
capabilities of the ACS will allow us to address a variety of
important questions relating to ring properties and ring-moon
interactions. Observations at a range of wavelengths and phase angles
will reveal the opposition surges of these rings and moons, providing
information on color and surface structure. Measurements of the ring
in front of the planet will provide complementary information on
optical depth; any variations of optical depth with wavelength will
reveal the rings’ poorly-constrained population of embedded dust. The
rings of Uranus are closing rapidly as the planet approaches equinox
in 2007, an event that takes place only every 42 years. Using this
opportunity, our observations will be repeated at different solar and
terrestrial tilt angles; this sequence of images will be particularly
valuable for constraining the physical thickness and packing density
of the rings. We will place particular emphasis on the rotational
variations of the Epsilon Ring, whose radial width {and therefore its
packing density} varies by a factor of five. In addition, a set of
deep exposures targeted just off the planet will enable us to detect
any 4-5 km moons embedded within the ring system. Dynamicists invoke
numerous such moons to "shepherd" the many sharp ring boundaries, so
this will serve as a definitive test of the theory.
ACS/WFC 9891
A snapshot survey of rich stellar clusters in the Large and Small
Magellanic Clouds
Rich stellar clusters are vital to a wide variety of astrophysical
research, from stellar evolution studies to the formation and
evolution of galaxies. In this context, it is important to understand
how rich star clusters form and evolve. The cluster systems in the LMC
and SMC are particularly important in achieving this, because they are
the only systems which contain clusters at all stages of evolution
while being close enough to be studied as fully resolved stellar
populations – although in general this requires the capabilities of
HST. We have recently investigated the structural evolution of LMC and
SMC clusters using archival WFPC2 data, and demonstrated a dramatic
trend in the sizes of these clusters with age. We have shown that this
trend likely represents genuine structural evolution in these
clusters, although it is not clear whether we are observing a
dynamical process or the signature of changing formation conditions.
This result has implications for all astronomical research involving
massive stellar clusters. To develop this work further requires the
extension of our two samples, so that they are statistically
quantifiable. This will allow a number of key questions regarding the
structural evolution trend to be answered. We propose a two-colour
ACS/WFC SNAP survey of rich Magellanic Cloud clusters to achieve this
aim. The unique resolution and sensitivity of ACS/WFC is required for
success, because of the crowded nature of the targets. The SNAP data
will have a large number of additional applications, both to globular
cluster and Magellanic Cloud research.
ACS/WFC 9751
Accurate Mass Determination of the Ancient White Dwarf ER 8 Through
Astrometric Microlensing
We propose to determine the mass of the very cool white dwarf ER 8
through astrometric microlensing. We have predicted that ER 8 will
pass very close to a 15th-mag background star in January 2006, with an
impact parameter of less than 0.05 arcsec. As it passes in front, it
will cause a deflection of the background star’s image by >8
milliarcsec, an amount easily detectable with HST/FGS. The
gravitational deflection angle depends only on the distances and
relative positions of the stars, and on the mass of the white dwarf.
Since the distances and positions can be determined precisely before
the event, the astrometric measurement offers a unique and direct
method to measure the mass of the white dwarf to high accuracy {<5%}.
Unlike all other stellar mass determinations, this technique works for
single stars {but only if they are nearby and of sufficient mass}. The
mass of ER 8 is of special interest because it is a member of the
Galactic halo, and appears to be the oldest known field white dwarf.
This object can thus set a lower limit on the age of the Galactic
halo, but since white-dwarf cooling rates depend on their masses, the
mass is a necessary ingredient in the age determination. As a
byproduct, we will obtain an accurate parallax for ER 8, and thus its
luminosity and {from its effective temperature} its radius. Such
quantities are at present rather poorly known for the coolest white
dwarfs, and will provide strong constraints on white-dwarf physics.
ACS/WFC/HRC 9895
The Role of Groups in the Evolution of Galaxies at Intermediate Redshifts
Groups are the most common environment experienced by galaxies, yet
they remain the least studied. The tidal fields and dynamical friction
encountered by galaxies in groups probably holds the key to
understanding the role of environment in driving the evolution of
galaxies since z ~ 1. To study the evolution of galaxies in the group
environment, we propose the first unbiased HST study of groups at
moderate redshifts. Unlike previous HST group samples, that relied on
radio or X-ray properties, our kinematically selected sample is drawn
from a large redshift survey and is not biased towards unusually dense
groups. HST imaging is essential to determine the morphology of
galaxies in these systems and contrast this with the properties of
galaxies in denser and more evolved groups and rich clusters at these
epochs. HST data are also required to adequately compare the
properties of groups at intermediate redshifts with local group
samples derived from the 2df and Sloan surveys. We will combine the
HST images with deep ground-based observations to study how
morphologies and stellar populations of galaxies in groups have
evolved in time. These observations are key to understanding the
decline in the volume averaged star formation rate in the universe.
ACS/WFPC2 9481
Pure Parallel Near-UV Observations with WFPC2 within High-Latitude ACS
Survey Fields
In anticipation of the allocation of ACS high-latitude imaging
survey{s}, we request a modification of the default pure parallel
program for those WFPC2 parallels that fall within the ACS survey
field. Rather than duplicate the red bands which will be done much
better with ACS, we propose to observe in the near-ultraviolet F300W
filter. These data will enable study of the rest-frame ultraviolet
morphology of galaxies at 0<z<1. We will determine the morphological
k-correction, and the location of star formation within galaxies,
using a sample that is likely to be nearly complete with
multi-wavelength photometry and spectroscopic redshifts. The results
can be used to interpret observations of higher redshift galaxies by
ACS.
GTO/ACS 9291
Formation of High Redshift Radio Galaxies
This programme uses ACS observations of high redshift radio galaxies
{HzRGs} to investigate massive galaxy and cluster formation in the
early Universe. By carrying out deep observations of a few z > 3.8
targets the following four questions will be studied: {1} Are HzRGs
massive central-cluster galaxies formed through hierarchical assembly
of Lyman break galaxies? Detailed brightness distributions colors and
morphologies of HzRG clumps will be measured and compared with those
of Lyman break galaxies. {2} Are HzRGs located in dense {proto-}
clusters and if so what are the properties of the associated
large-scale structures? Lyman alpha excesses, colors and morphologies
of objects in field will be used to search for companion galaxies of
HzRGs. {3} What are the origin and fate of giant gas halos associated
with HzRGs and what role do they play in the formation of massive
galaxies? The morphologies and locations of Ly-alpha clumps will be
compared with those of continuum clumps. {4} Is nuclear activity a
source of star formation in the early Universe? The properties of
continuum and Ly-alpha clumps along will be compared in relation to
the radio jet.
NIC3 9824
NIC3 SNAPs of nearby galaxies imaged in the mid-UV: the remarkable
cool stellar population in late-type galaxies.
We propose a NIC3 H-band {F160W} SNAPshot survey of 48 nearby mid- to
late-type galaxies covering all inclinations. In Cycle 9 and 10, we
imaged ~100 galaxies in the mid-UV {F300W/F255W} and I-band {F814W}
with WFPC2, and obtained UBVR CCD surface photometry from the ground.
Early-mid-type galaxies show the usual small radial color-gradients,
where disks become somewhat bluer at larger radii. But, remarkably,
the majority of {lower luminosity, smaller and rounder} late-type
galaxies shows the opposite trend and becomes redder outwards in all
filters. While young UV/blue-bright stellar populations dominate their
inner morphology, most late-type galaxies must have a significant halo
or thick disk of older stars. Combining our proposed NIC3 H-band with
existing WFPC2 images will span the wavelength range 0.29-1.6 micron
at resolutions of 0.04-0.16" {FWHM}. This Panchromatic Nearby Galaxy
Atlas will be applicable to a wide range of problems, and will be made
public immediately. Our NIC3/F160W science goals are to: {1} Establish
the nature of the old outer stellar population. All target galaxies
have z<0.005, allowing us to resolve any luminous, cool supergiant
population. NIC3 is essential to make a pixel-to-pixel color-magnitude
study of the nature, distribution and uniformity of the outer stellar
populations, which will constrain dwarf galaxy formation theories. {2}
Determine galaxy structure at 5-20 pc resolution, tracing the old
stellar population and mass distribution compared to the star-forming
regions seen in the mid-UV. A range of inclinations is needed to
distinguish between old thick disks or halos in late-type galaxies.
{3} Make a multi-wavelength pixel-to-pixel decomposition to help
delineate the effects of dust, age, and metallicity. Since we must
cover a range of inclinations, NIC3 H-band is essential to map the
effects from dust, and see how these may affect the studies of {1} and
{2}.
NICMOS 8791
NICMOS Post-SAA calibration – CR Persistence Part 2
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 9608
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.
STIS 9606
CCD Dark Monitor-Part 2
Monitor the darks for the STIS CCD.
STIS 9615
Cycle 11 MAMA Dark Monitor
This test performs the routine monitoring of the MAMA detector dark
noise. This proposal will provide the primary means of checking on
health of the MAMA detectors systems through frequent monitoring of
the background count rate. The purpose is to look for evidence of
change in dark indicative of detector problem developing.
STIS 9613
STIS CCD Spectroscopic Flats C11
Obtain CCD flats on the STIS CCD in spectroscopic mode.
STIS 9708
STIS Pure Parallel Imaging Program: Cycle 11
This is the default archival pure parallel program for STIS during cycle
11.
STIS 9783
The Ages of Nuclear Star Clusters in Early-type Spiral Galaxies
We propose to obtain STIS G430L spectra of the previously identified
nuclear star cluster in a sample of 16 spiral galaxies of early to
intermediate Hubble type. HST’s spatial resolution is required to
separate the nuclear cluster from the underlying galaxy bulge.
Analysis of the spectra with population synthesis methods will reveal
the cluster ages. We will use the age distribution to constrain the
duty cycle of nuclear cluster formation. Comparison of the results to
those for a larger sample of nuclear clusters in late-type, bulgeless
galaxies will allow us to investigate possible differences between the
formation mechanisms of nuclear clusters in early and late Hubble
types. Such differences might be expected because galaxy bulges show a
dichotomy: in late Hubble types, the surface brightness profiles are
best described by an exponential, while they follow a de Vaucouleurs
law in earlier types. Although the reason for this dichotomy is still
unknown, it is plausible that galaxy bulges have different formation
mechanisms at the two ends of the Hubble sequence. We know that {1}
nuclear cluster formation is linked to the funneling of gas towards
the nucleus via gravitational torques from stellar bars, {2} a nuclear
mass concentration can make bars unstable, and {3} unstable bars can
form bulges. Therefore, the age distribution of nuclear star clusters
contains important clues to the evolution of galaxy centers and
promises new insight into the origin of the Hubble sequence.
STIS 9786
The Next Generation Spectral Library
We propose to continue the Cycle 10 snapshot program to produce a Next
Generation Spectral Library of 600 stars for use in modeling the
integrated light of galaxies and clusters. This program is using the
low dispersion UV and optical gratings of STIS. The library will be
roughly equally divided among four metallicities, very low {[Fe/H] lt
-1.5}, low {[Fe/H] -1.5 to -0.5}, near-solar {[Fe/H] -0.3 to 0.1}, and
super-solar {[Fe/H] gt 0.2}, well-sampling the entire HR-diagram in
each bin. Such a library will surpass all extant compilations and have
lasting archival value, well into the Next Generation Space Telescope
era. Because of the universal utility and community-broad nature of
this venture, we waive the entire proprietary period.
STIS/CCD/MA2 9491
The Oxygen Abundance in the Metal-Poor Halo Star HD 140283 from UV-OH
lines
Oxygen is critical in numerous astrophysical contexts, including the
derivation of globular cluster ages and the early history of the
Galaxy’s chemistry. However, its abundance, particularly in metal-poor
stars, remains controversial, with optical, IR and UV abundance
indicators in dwarfs and giants yielding different abundance patterns;
a flat O/Fe ratio with Fe/H is suggested by OI and IR-OH lines, while
a monotonically increasing O/Fe trend with decreasing Fe/H is measured
from OI and UV-OH lines with a factor of 10 difference at Fe/H=-3. We
propose an in-depth study of the UV- OH lines in the halo subgiant HD
140283 with R=110, 000 and S/N=200 spectra and state-of-the-art 3-D
model atmospheres. Understanding UV-OH lines is particularly important
because these provide the sole means of measuring the oxygen abundance
in the most metal-poor stars and therefore in the early Galaxy. STIS
will for the first time provide several dozen unblended UV-OH lines.
Predictions about the variation of line strength with excitation
potential and the asymmetries of the OH line profiles will be tested
and used to refine the cool outer layers of the 3-D models where the
OH lines are formed. The end result will be an accurate oxygen
abundance, a thorough understanding of OH line formation, and a good
characterization of the atmosphere of a metal-poor star.
STIS/MA1/CCD 9464
Exploring the Role of Acoustic Heating in Cool Dwarfs and Subgiants
Recent observations cast doubt on the importance of acoustic waves for
chromospheric heating in stars. These include low upper limits to
their contribution to upper layers of the solar chromosphere, and
evidence for significant magnetic heating contribution even in
“basal" activity stars. These findings contradict the widely accepted
picture that acoustic heating accounts for a significant fraction, the
“basal component”, of chromospheric heating in inactive stars. To
help resolve this issue, we propose to observe two very inactive stars
with significantly different properties to search for specific
signatures of upward propagating acoustic waves: blue-shifts and
enhanced blue wings in chromospheric lines. Solar data show that the
degree of blue-shift can be used to estimate the acoustic contribution
to chromospheric heating. We will compare the data to HST spectra of
similar stars, and solar spectra from the SUMER instrument on SOHO.
Lack of a significant acoustic signature in our targets would indicate
that magnetic heating generated by a local {turbulent, non-cycling}
dynamo is responsible for the basal component of chromospheric heating
in inactive stars. Our targets may be in a phase analogous to the
solar Maunder minimum, and the HST spectra might serve as a proxy for
the solar spectrum in this state. The spectra will also be used for
emission measure analysis differentially between the Sun and
solar-like stars.
STIS/MA2 9474
Intriguing Transient Sources in M87
We have found a remarkable number of transient point sources in M87.
Within the jet itself we have observed dramatic changes in less than a
year. The point sources are seen well in the bluest regions of the
spectrum, where we obtain high spatial resolution, are free from
cosmic ray artifacts and obtain excellent discrimination against the
underlying old, red galaxy. They display a variety of unusual
properties: one is brighter than any in the catalogue of novae in M31;
several are very close to the jet; another hints at rapid variability.
We propose to investigate the population of transient sources in M87
and to probe the intrinsic jet variability on short timescales by
taking images in the near UV. Do the sources show nova-type light
curves? Is there a decline-rate/luminosity relation? If yes, may we
use it for distance estimation, as in Galactic novae, and hence
constrain the still very important Virgo distance. Are there very
rapidly varying sources, flare stars or gravitational lenses? Is the
variable stellar population related to the excess globular cluster
frequency in M87? Is there a population of flickering objects in and
around the jet, which may be responsive emission arising from their
close proximity to a BL Lac nucleus {viewed down the jet axis}? Can we
find variability in the jet itself indicative of light week length
scales?
WFPC2 9740
CIII] Imagery of Planetary Nebulae and HII Regions — A Snap Program
We propose to undertake a SNAP program of WFPC2 imagery of several
planetary nebulae and extragalactic HII regions with the F185W filter
to study the spatial variation of the CIII] 1909 Angstrom emission
lines across the nebulae. Much of our current knowledge of carbon
abundances in planetary nebulae and HII regions are based on UV
spectroscopic observations of this line yet there have not been any
studies of its spatial variations in nebulae compared to several of
the prominent optical lines {e.g. [OIII] 5007 Angstroms}. Such
observations, coupled with photoionization modeling of the nebulae,
will enable us to assess the utility of using the CIII] line in
abundance calculations of C/O and C/H in nebulae and possibly permit
improved empirical emission-line diagnostic techniques for ionization
corrections to get the elemental carbon abundances from C++/O++
observations based on CIII]/[OIII] 1909/5007. We also plan to study
the spatial variation of the CIII] 1909 Angstrom collisionally excited
lines against the CII 4267 Angstrom permitted line in many of the
nebulae using previous and planned ground-based longslit echelle
spectroscopy coupled with the HST WFPC2 F185W imagery.
WFPC2 9710
POMS Test Proposal: WFII backup parallel archive proposal
This is a POMS test proposal designed to simulate scientific plans.
WFPC2 9709
POMS Test Proposal: WFII parallel archive proposal
This is the generic target version of the WFPC2 Archival Pure Parallel
program. The program will be used to take parallel images of random
areas of the sky, following the recommendations of the 2002 Parallels
Working Group.
WFPC2 9595
WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt3/3
This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot
pixels.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)
HSTAR 9082: GS Acquisition (3,2,3) @ 194/08:33:54Z resulted in FL
backup on FGS 2 (2,0,2) FHST U2,3FM update @ 194/08:19:19Z showed
attitude/vehicl-0.701, 10.856, and 3.061. FHST Map @ 194/15:39 showed
errors of 7.110, -1.080, and 1.718 arcsec. Under investigation.
HSTAR 9083: GS Acquisition (3,1,3) @ 194/16:52:27Z resulted in
FLbackup on FGS 1 due to 194/16:56:18Z, 16:58:02Z, and 17:00:34Z.
Under investigation.
COMPLETED OPS REQs: None
OPS NOTES EXECUTED: None
SCHEDULED SUCCESSFUL FAILURE TIMES FGS GSacq 34 34 FGS REacq 13 13 FHST Update 70 69 195/0329z LOSS of LOCK
SIGNIFICANT EVENTS: None