Note, the next Daily Report won’t appear until 12/26

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      # 4512

PERIOD COVERED: UT December 20, 2007 (DOY 354)

OBSERVATIONS SCHEDULED

ACS/SBC 11145

Probing the Planet Forming Region of T Tauri Stars in Chamaeleon

By studying the inner, planet-forming regions of circumstellar disks

around low-mass pre- main sequence stars we can refine theories of giant

planet formation and develop timescales for the evolution of disks and

their planets. Spitzer infrared observations of T Tauri stars in the

Chamaeleon star-forming region have given us an unprecedented look at

dust evolution in young objects. However, despite this ground breaking

progress in studying the dust in young disks, the gas properties of the

inner disk remain essentially unknown. Using ACS on HST, we propose to

measure the H_2 emission originating in the innermost disk regions of

classical T Tauri stars in different stages of evolution with the

objective of revealing the timescales of gas dissipation and its

relationship to dust evolution. This proposal is part of a comprehensive

effort with approved programs on Spitzer, Gemini, and Magellan that aim

to characterize the state of gas and dust in disks where planets may

already have formed.

ACS/SBC 11199

A Hard Look at Stellar Disks at the Epoch of Planet Formation

We propose to use HST/ACS/SBC and Chandra/ACIS-S3 to observe the high

energy fluxes of 4 stars surrounded by disks in the newly discovered

aggregate 25 Ori, the most populous 10 Myr group known within 500 pc.

Our observations will cover the 1-25A and 1250-2000A bandpasses, and

will complement our optical and Spitzer data for these objects, to

provide essential input to physically-consistent models of disk

structure and chemistry in the age range around 10 Myr, thought to be a

critical period in the planet- forming process. We will be able to

determine the Ne/O ratio and determine if the anomalous metal abundances

observed in X-ray spectra of young stars are an evolutionary or an

environmental effect. Our proposed observations will double the number

of 10 Myr old accreting stars with known high energy radiation fields,

and will be the first FUV observations of low mass accreting stars in an

OB association.

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 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3

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}.

NIC3 11107

Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy

Formation in the Early Universe

We have used the ultraviolet all-sky imaging survey currently being

conducted by the Galaxy Evolution Explorer {GALEX} to identify for the

first time a rare population of low- redshift starbursts with properties

remarkably similar to high-redshift Lyman Break Galaxies {LBGs}. These

"compact UV luminous galaxies" {UVLGs} resemble LBGs in terms of size,

SFR, surface brightness, mass, metallicity, kinematics, dust, and color.

The UVLG sample offers the unique opportunity of investigating some very

important properties of LBGs that have remained virtually inaccessible

at high redshift: their morphology and the mechanism that drives their

star formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS

in order to 1} characterize their morphology and look for signs of

interactions and mergers, and 2} probe their star formation histories

over a variety of timescales. The images show a striking trend of

small-scale mergers turning large amounts of gas into vigorous

starbursts {a process referred to as dissipational or "wet" merging}.

Here, we propose to complete our sample of 31 LBG analogs using the

ACS/SBC F150LP {FUV} and WFPC2 F606W {R} filters in order to create a

statistical sample to study the mechanism that triggers star formation

in UVLGs and its implications for the nature of LBGs. Specifically, we

will 1} study the trend between galaxy merging and SFR in UVLGs, 2}

artificially redshift the FUV images to z=1-4 and compare morphologies

with those in similarly sized samples of LBGs at the same rest-frame

wavelengths in e.g. GOODS, UDF, and COSMOS, 3} determine the presence

and morphology of significant stellar mass in "pre-burst" stars, and 4}

study their immediate environment. Together with our Spitzer

{IRAC+MIPS}, GALEX, SDSS and radio data, the HST observations will form

a unique union of data that may for the first time shed light on how the

earliest major episodes of star formation in high redshift galaxies came

about. This proposal was adapted from an ACS HRC+WFC proposal to meet

the new Cycle 16 observing constraints, and can be carried out using the

ACS/SBC and WFPC2 without compromising our original science goals.

WFPC2 10915

ACS Nearby Galaxy Survey

Existing HST observations of nearby galaxies comprise a sparse and

highly non-uniform archive, making comprehensive comparative studies

among galaxies essentially impossible. We propose to secure HST's

lasting impact on the study of nearby galaxies by undertaking a

systematic, complete, and carefully crafted imaging survey of ALL

galaxies in the Local Universe outside the Local Group. The resulting

images will allow unprecedented measurements of: {1} the star formation

history {SFH} of a >100 Mpc^3 volume of the Universe with a time

resolution of Delta[log{t}]=0.25; {2} correlations between spatially

resolved SFHs and environment; {3} the structure and properties of thick

disks and stellar halos; and {4} the color distributions, sizes, and

specific frequencies of globular and disk clusters as a function of

galaxy mass and environment. To reach these goals, we will use a

combination of wide-field tiling and pointed deep imaging to obtain

uniform data on all 72 galaxies within a volume-limited sample extending

to ~3.5 Mpc, with an extension to the M81 group. For each galaxy, the

wide-field imaging will cover out to ~1.5 times the optical radius and

will reach photometric depths of at least 2 magnitudes below the tip of

the red giant branch throughout the limits of the survey volume. One

additional deep pointing per galaxy will reach SNR~10 for red clump

stars, sufficient to recover the ancient SFH from the color-magnitude

diagram. This proposal will produce photometric information for ~100

million stars {comparable to the number in the SDSS survey} and uniform

multi- color images of half a square degree of sky. The resulting

archive will establish the fundamental optical database for nearby

galaxies, in preparation for the shift of high- resolution imaging to

the near-infrared.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

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

HSTARS:

11110 - REacq(2,1,1) results in fine lock backup

           During LOS REacq(2,1,1) scheduled at 354/16:11:17 resulted in fine lock

           backup using FGS 2, with QF1STOPF and QSTOP flags set on FGS 1. OBAD 2

           showed errors of V1= -8.21, V2= -5.72, V3= -10.63, RSS = 14.60.

11111 - REAcq(2,1,1) results in fine lock backup (2,0,2) using FGS-2

           Upon acquisition of signal at 354/21:19:15, the REAcq(2,1,1) scheduled

           at 354/20:58:10 - 21:06:15 had resulted to fine lock backup (2,0,2)

           using FGS-2, due to stop flag (QF1STOPF) indication on the primary

           FGS-1. Pre-acquisition OBAD1 attitude error correction (RSS) not

           available pending future ETR Dump. OBAD2 had (RSS) value of 10.05

           arcseconds. Post-acq OBAD/MAP not scheduled.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL  

FGS GSacq               07                  07                

FGS REacq               08                  08                

OBAD with Maneuver 30                  30               

SIGNIFICANT EVENTS:

Ops Request 18165 was successfully executed at 17:09:26 on day 354 (December 20) to uplink the

 new value for the Universal Kalman Filter (UKF) bias states process noise (Qab).  

In M2G intervals after the UKF re-start, the UKF attitude estimate remained within approximately 3 degrees

of the commanded vehicle pointing, despite some adverse magnetic field conditions (e.g. SAA passages).  

During telemetry-available F2G and T2G post-OBAD intervals, the UKF attitude estimate remained within

approximately 2 degrees of the known vehicle pointing.  No innovations or residuals failures or other anomalous

signatures occurred.  Real-time monitoring ended at 354/20:15.  

PCS will continue to trend UKF performance and assess the effects of this change.