Daily Report #4549

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4549

PERIOD COVERED: UT April 21, 2008 (DOY 112)

OBSERVATIONS SCHEDULED

ACS/SBC 11151

Evaluating the Role of Photoevaporation of Protoplanetary Disk Dispersal

Emission produced by accretion onto the central star leads to
photoevaporation, which may play a fundamental role in disk dispersal.
Models of disk photoevaporation by the central star are challenged by two
potential problems: the emission produced by accretion will be substantially
weaker for low-mass stars, and photoevaporation must continue as accretion
slows. Existing FUV spectra of CTTSs are biased to solar-mass stars with
high accretion rates, and are therefore insufficient to address these
problems. We propose use HST/ACS SBC PR130L to obtain FUV spectra of WTTSs
and of CTTSs at low masses and mass accretion rates to provide crucial data
to evaluate photoevaporation models. We will estimate the FUV and EUV
luminosities of low-mass CTTSs with small mass accretion rates, CTTSs with
transition disks and slowed accretion, and of magnetically-active WTTSs.

WFPC2 11024

WFPC2 CYCLE 15 INTERNAL MONITOR

This calibration proposal is the Cycle 15 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A variety of
internal exposures are obtained in order to provide a monitor of the
integrity of the CCD camera electronics in both bays {both gain 7 and gain
15 -- to test stability of gains and bias levels}, a test for quantum
efficiency in the CCDs, and a monitor for possible buildup of contaminants
on the CCD windows. These also provide raw data for generating annual
super-bias reference files for the calibration pipeline.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

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.

NIC2 11148

High Contrast Imaging of Dusty White Dwarfs

For the past 18 years, only one white dwarf with a circumstellar dust disk
was known to exist. In the last two years, six new disks have been
discovered. Since all material inwards of a few AU should be scoured clean
during post main sequence evolution, the primary explanation is the presence
of a planetary system that is perturbing relic planetesimals into the tidal
disruption radius of the white dwarf. Dusty disks around white dwarfs should
be markers for planets and we propose to use high contrast imaging to search
for faint companions down to 6 M_$J$ that may be feeding the disks. White
dwarfs are uniquely suited for planet searches, where the planet/white dwarf
contrast is less than for main sequence stars.

NIC2/WFPC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3z2.7
Using HST and Spitzer

We aim to determine physical properties of IR luminous galaxies at
0.3z2.7 by requesting coordinated HST/NIC2 and MIPS 70um observations
of a unique, 24um flux-limited sample with complete Spitzer mid-IR
spectroscopy. The 150 sources investigated in this program have S{24um}
0.8mJy and their mid-IR spectra have already provided the majority
targets with spectroscopic redshifts {0.3z2.7}. The proposed 150~orbits of
NIC2 and 66~hours of MIPS 70um will provide the physical measurements of the
light distribution at the rest-frame ~8000A and better estimates of the
bolometric luminosity. Combining these parameters together with the rich
suite of spectral diagnostics from the mid-IR spectra, we will {1} measure
how common mergers are among LIRGs and ULIRGs at 0.3z2.7, and establish if
major mergers are the drivers of z1 ULIRGs, as in the local Universe. {2}
study the co-evolution of star formation and blackhole accretion by
investigating the relations between the fraction of starburst/AGN measured
from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the
current best estimates of the far-IR emission, thus L{bol} for this sample,
and establish if the relative contribution of mid-to-far IR dust emission is
correlated with morphology {resolved vs. unresolved}.

WFPC2 11070

WFPC2 CYCLE 15 Standard Darks - part II

This dark calibration program obtains dark frames every week in order to
provide data for the ongoing calibration of the CCD dark current rate, and
to monitor and characterize the evolution of hot pixels. Over an extended
period these data will also provide a monitor of radiation damage to the
CCDs.

WFPC2 11185

Search for H-poor/He-rich Inclusions and a Solution to the Abundance,
Temperature Problems

Our recent abundance survey of a large sample of Galactic planetary nebulae
(PNe) has led to the discovery of a group of super-metal-rich nebulae whose
spectra are characterized by prominent optical recombination lines (ORLs)
from C, N, O, & Ne ions and a large Balmer discontinuity jump. The heavy
element abundances derived from ORLs for several PNe are more than an order
of magnitude higher than those derived from the traditional method based on
collisionally excited lines (CELs), while the Balmer jump yields electron
temperatures (Te) significantly lower than values derived from the [O III]
5007/4363 CEL line ratio. A proposition that aspires to explain both the
nebular abundance and Te problems is one according to which these nebulae
contain (at least) two distinct emission regions - one of "normal" Te (~
10000 K) and chemical composition (~solar) and another of very low Te that
is H- deficient, thus having high helium and metal abundances relative to
hydrogen. The latter component emits strong He and heavy element ORLs but
essentially no CELs. The consistent picture that emerges from fitting a
2-component photoionization model to the spectroscopic data is that the
H-poor component is in high-density inclusions, which provide only a minor
fraction of the total nebular mass. We propose to directly detect these
inclusions in the planetary nebula M 1-42 using WFPC2 (PC) to make a high
spatial resolution image in the He I 5876 A ORL and ratio it to Halpha. With
NICMOS (NIC1), we plan to observe the He I 10830 A line, which is
substantially collisionally excited, along with Palpha 18760 A. The ratio
image of He I 10830 to Palpha is expected to be less likely to show the
inclusions, thus serving as an important control to the optical imaging. M
1-42 is one of the most extreme cases of the abundance and Te problem; it is
reasonably bright and compact. This program has the potential to resolve a
serious challenge to our current understanding of nebular astrophysics.

WFPC2 11222

Direct Detection and Mapping of Star Forming Regions in Nearby, Luminous
Quasars

We propose to carry out narrow-band emission line imaging observations of 8
quasars at z=0.05-0.15 with the WFPC2 ramp filters and with the NICMOS
narrow-band filters. We will obtain images in the [O II], [O III], H-beta,
and Pa-alpha emission line bands to carry out a series of diagnostic tests
aimed at detecting and mapping out star-forming regions in the quasar host
galaxies. This direct detection of star-forming regions will confirm
indirect indications for star formation in quasar host galaxies. It will
provide a crucial test for models of quasar and galaxy evolution, that
predict the co-existence of starbursts and "monsters" and will solve the
puzzle of why different indicators of star formation give contradictory
results. A secondary science goal is to assess suggested correlations
between quasar luminosity and the size of the narrow-line region.

WFPC2 11312

The Local Cluster Substructure Survey {LoCuSS}: Deep Strong Lensing
Observations with WFPC2

LoCuSS is a systematic and detailed investigation of the mass, substructure,
and thermodynamics of 100 X-ray luminous galaxy clusters at 0.15z0.3. The
primary goal is to test our recent suggestion that this population is
dominated by dynamically immature disturbed clusters, and that the observed
mass-temperature relation suffers strong structural segregation. If
confirmed, this would represent a paradigm shift in our observational
understanding of clusters, that were hitherto believed to be dominated by
mature, undisturbed systems. We propose to complete our successful Cycle 15
program {SNAP:10881} which prior to premature termination had delivered
robust weak-lensing detections in 17 clusters, and candidate strongly-lensed
arcs in 11 of these 17. These strong and weak lensing signals will give an
accurate measure of the total mass and structure of the dark matter
distribution that we will subsequently compare with X-ray and Sunyaev
Zeldovich Effect observables. The broader applications of our project
include 1} the calibration of mass-temperature and mass-SZE scaling
relations which will be critical for the calibration of proposed dark energy
experiments, and 2} the low redshift baseline study of the demographics of
massive clusters to aid interpretation of future high redshift {z1} cluster
samples. To complete the all-important high resolution imaging component of
our survey, we request deep WFPC2 observations of 20 clusters through the
F606W filter, for which wide-field weak-lensing data are already available
from our Subaru imaging program. The combination of deep WFPC2 and Subaru
data for these 20 clusters will enable us to achieve the science program
approved by the Cycle 15 TAC.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports of
potential non-nominal performance that will be investigated.)

HSTARS:

11262 - GSAcq (1,2,1) failed due to QSTOP flag on FGS 1

At 112/10:33:46 GSAcq (1,2,1) scheduled from 10:30:47-10:38:10 failed due to
QF1STOPF and QSTOP Flags on FGS 1. Fine lock was briefly achieved but, no
s-curves were observed. Pre-acquisition OBADs RSS values were 3437.94 and
6.55 arc-seconds respectively. Post acquisition OBAD Map RSS value was 3.71
arc-seconds.

Additionally, received 4 ACS 779 Status Buffer Messages ("Fold Mechanism
Move was Blocked") following the failure of the GSacq. This resulted in the
TDF to be down when the Fold mechanism move was commanded. Flight Software
Error Count (JERRCNT) incremented to 86. OPS Note 1645-15 was executed to
change JERRCNT limit to 86.

11264 - GSAcq (2,1,1) failed due to Scan Step Limit Exceeded on FGS 2

REacq (2,1,1) failed 3 times

At Acquisition of Signal (112/18:02:23) GSAcq (2,1,1) scheduled from
16:54:19-17:01:35 had failed due to Scan Step Limit Exceeded on FGS 2.
Received QSTEPEXC and QSTOP flags on FGS 2. Pre-acquisition OBADs RSS Error
value was 3828.70 and 12.54 arc-seconds respectively. Post acquisition OBAD
MAP RSS Error value was 10.15. Awaiting engineering data dump to complete
further analysis.

REACQ(2,1,1) at 20:04:12 was successful in obtaining fine lock.

REACQ(2,1,1) at 18:28:19 also failed with 486 ESB message "a0c" (FGS coarse
mode angle check failed).

REACQ(2,1,1) at 21:42:05 failed with 486 ESB message "a0c" (FGS coarse mode
angle check failed).

REACQ(2,1,1) at 23:28:15 appears to have succeeded, #44 commands did update
but entire event happened without telemetry

REACQ(2,1,1) at 01:10:00 failed with 486 ESB message "a0c" (FGS coarse mode
angle check failed).

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 08 06
FGS REacq 06 03
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)