HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      # 4629

PERIOD COVERED: 5am June 10 - 5am June 11, 2008 (DOY 162/0900z-163/0900z)

OBSERVATIONS SCHEDULED

NIC1/NIC2 11155

Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging

and Polarimetry

We propose to take advantage of the sensitive coronagraphic capabilities

of NICMOS to obtain multiwavelength coronagraphic imaging and

polarimetry of primordial dust disks around young intermediate-mass

stars {Herbig Ae stars}, in order to advance our understanding of how

dust grains are assembled into larger bodies. Because the polarization

of scattered light is strongly dependent on scattering particle size and

composition, coronagraphic imaging polarimetry with NICMOS provides a

uniquely powerful tool for measuring grain properties in spatially

resolved circumstellar disks. It is widely believed that planets form

via the gradual accretion of planetesimals in gas-rich, dusty

circumstellar disks, but the connection between this suspected process

and the circumstellar disks that we can now observe around other stars

remains very uncertain. Our proposed observations, together with

powerful 3-D radiative transfer codes, will enable us to quantitatively

determine dust grain properties as a function of location within disks,

and thus to test whether dust grains around young stars are in fact

growing in size during the putative planet-formation epoch. HST imaging

polarimetry of Herbig Ae stars will complement and extend existing

polarimetric studies of disks around lower-mass T Tauri stars and debris

disks around older main-sequence stars. When combined with these

previous studies, the proposed research will help us establish the

influence of stellar mass on the growth of dust grains into larger

planetesimals, and ultimately to planets. Our results will also let us

calibrate models of the thermal emission from these disks, a critical

need for validating the properties of more distant disks inferred on the

basis of spectral information alone.

NIC1/NIC2/NIC3 11318

NICMOS Cycle 16 Multiaccum Darks

The purpose of this proposal is to monitor the dark current, read noise,

and shading profile for all three NICMOS detectors throughout the

duration of Cycle 16. This proposal is a slightly modified version of

proposal 10380 of cycle 13 and 9993 of cycle12 and is the same as Cycle

15. Covers the period from April 08 to November 08 (inclusive)

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 i

mages. Each observation will need its own CRMAP, as different SAA

passages leave different imprints on the NICMOS detectors.

NIC2/WFPC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3<z<2.7

Using HST and Spitzer

We aim to determine physical properties of IR luminous galaxies at

0.3<z<2.7 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 {0.3<z<2.7}. 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 0.3<z<2.7, and establish if major mergers are the drivers

of z>1 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 11129

The Star Formation History of the Fornax Dwarf Spheroidal Galaxy

The Fornax dwarf spheroidal galaxy is one of the most luminous dwarf

satellites of the Milky Way. It is unusual in many ways: it hosts 5

globular clusters, shows some relatively young stars, and has faint

sub-structures which have been interpreted as signs of recent

interactions. It is thus of great interest to learn the complete star

formation history {SFH} of Fornax to establish a link between its

evolutionary path and the predictions from numerical simulations, as a

test of our understanding of dwarf galaxy evolution. Yet many questions

remain open. Is the old stellar population made up of stars formed in a

very early burst, perhaps before the epoch of re-ionization, or the

result of a more continuous star formation between 13 and 9 Gyr ago ?

How quickly did Fornax increase its metallicity during its initial

assembly and during subsequent episodes of star formation ? Are

accretion episodes required to explain the age-metallicity history of

Fornax ? However, there has never been a comprehensive study of the

global SFH of the Fornax field based on data of sufficient depth to

unambiguously measure the age mixture of the stellar populations and

their spatial variation. We propose to use the WFPC2 to obtain very deep

images in several fields across the central region of Fornax in order to

reach the oldest main-sequence turnoffs. The number of fields is

determined by the need to measure the SFH over different regions with

distinct kinematics and metallicity. The resolution achievable with HST

is crucial to answer these questions because, to derive the age

distribution of the oldest stars, we are interested in I magnitude

differences of the order 0.2 mag in crowded fields at V=24.5. We will

directly measure the time variation in star-formation rate over the

entire galaxy history, from first stars coeval with the Milky Way halo

to the youngest populations 200 Myr ago. The combination of detailed CMD

analysis with WFPC2 with our existing metallicity and kinematic

information will allow us to trace out the early phases of its

evolution.

WFPC2 11235

HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies

in the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared

selected galaxies exceeds that of optically selected galaxies. These

`luminous infrared galaxies' {LIRGs} are primarily interacting or

merging disk galaxies undergoing enhanced star formation and Active

Galactic Nuclei {AGN} activity, possibly triggered as the objects

transform into massive S0 and elliptical merger remnants. We propose

NICMOS NIC2 imaging of the nuclear regions of a complete sample of 88

L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised

Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}.

This sample is ideal not only in its completeness and sample size, but

also in the proximity and brightness of the galaxies. The superb

sensitivity and resolution of NICMOS NIC2 on HST enables a unique

opportunity to study the detailed structure of the nuclear regions,

where dust obscuration may mask star clusters, AGN and additional nuclei

from optical view, with a resolution significantly higher than possible

with Spitzer IRAC. This survey thus provides a crucial component to our

study of the dynamics and evolution of IR galaxies presently underway

with Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88

galaxies. Imaging will be done with the F160W filter {H-band} to examine

as a function of both luminosity and merger stage {i} the luminosity and

distribution of embedded star clusters, {ii} the presence of optically

obscured AGN and nuclei, {iii} the correlation between the distribution

of 1.6 micron emission and the mid- IR emission as detected by Spitzer

IRAC, {iv} the evidence of bars or bridges that may funnel fuel into the

nuclear region, and {v} the ages of star clusters for which photometry

is available via ACS/WFC observations. The NICMOS data, combined with

the HST ACS, Spitzer, and GALEX observations of this sample, will result

in the most comprehensive study of merging and interacting galaxies to

date.

WFPC2 11340

X-ray Observations of 11 Millisecond Pulsars in M28

We propose a deep X-ray survey of the globular cluster M28 which will

yield a wealth of important and unique science, ranging from the first

direct measurement of the magnetic field of a millisecond pulsar and

constraints on the neutron star equation of state to likely

X-ray/optical (HST) detection of a re-exchanged binary MSP. The proposed

joint HST WFPC2 observation will tie the X-ray, optical, and radio data

to a common astrometric frame allowing an unambiguous identification of

numerous cataclysmic variables and active binaries in M28 as well as

making possible the first direct optical detection of a millisecond

pulsar.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS:

11334 - REAcq(2,1,2) failed to RGA Hold (Gyro Control)

           Upon acquisition of signal at 162/12:34:30, REAcq(2,1,2) scheduled at

           162/12:30:52 - 12:38:57 was observed to have failed to RGA Hold due to

           stop flag (QF2STOPF) on FGS-2. Pre-acq OBAD1 attitude correction (RSS)

           value was not available due to LOS. OBAD2 had (RSS) value of 5.48

           arcseconds. Post-acq OBAD/MAP had (RSS) value of 13.10 arcseconds. Prior

           GSAcq(2,1,2) at 162/10:55:26 was successful.

           Possible Observations Affected: WFPCII 87 thru 91, Proposal # 11340.

           NICMOS 19, 20, Proposal # 11318

           At AOS 162/14:17:45, subsequent REAcq(2,1,2) at 162/14:06:46 also failed

           to RGA Hold due to stop flag on FGS-2.

           Observations Affected: WFPC 92 thru 96 Proposal # 11340. NICMOS 24, 25

           Proposal # 11318

11335 - NICMOS Status Buffer Message

           Parameter=1, Time= 4274; NIC in Operate mode; next obs at

           163/05:28:10z.#668 indicates MECH_UNSTABLE_INDUCTOSYN Description:

           "While verifying the mechanical position following a mechanism movement,

           consecutive position calculations give inconsistent values. This

           indicates the inductosyn coarse and fine positions are changing. "FSW

           Action: Status Buffer Message ERROR Parameter indicates: Mechanism no.

           (FW1=0, FW2=1, FW3=2, FOMX=3, FOMY=4). Ground Action: None.

           Obs might be affected: NIC #26-28 of Proposal #11155.

           Ops Request 18241-0, to reset the NICMOS error counter, was

           successfully executed at 162/19:35:45.

COMPLETED OPS REQUEST:

18241-0 - Execute ROP NS-11 Reset NICMOS Error Counter @ 162/1935z

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL 

FGS GSacq               06                 06                 

FGS REacq               08                 06     

OBAD with Maneuver 28                 27                 

SIGNIFICANT EVENTS: (None)