Status Report

NASA Hubble Space Telescope Daily Report # 4629

By SpaceRef Editor
June 13, 2008
Filed under , ,
NASA Hubble Space Telescope Daily Report # 4629


Continuing to collect World Class Science

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


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 images. 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

We aim to determine physical properties of IR luminous galaxies at 0.3 0.8mJy and their mid-IR spectra have already provided the majority

targets with spectroscopic redshifts {0.31 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.


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


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.


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


                       SCHEDULED      SUCCESSFUL

FGS GSacq               06                 06
FGS REacq               08                 06
OBAD with Maneuver      28                 27


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