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NASA Hubble Space Telescope Daily Report #4440

Status Report From: Space Telescope Science Institute
Posted: Wednesday, September 5, 2007


Notice: Due to the conversion of some ACS WFC or HRC observations into WFPC2, or NICMOS observations after the loss of ACS CCD science capability in January, there may be an occasional discrepancy between a proposal's listed (and correct) instrument usage and the abstract that follows it.


- Continuing to collect World Class Science

PERIOD COVERED: UT September 04, 2007 (DOY 247)


WFPC2 11036

Red Leaks Closeout

We observe the star 15Mon with 8 UV filters to check the impact of off-band flux {red-leak} in those filters. To derive the spectral shape of the red-leak, we cross each of the UV filters with F814W and F606W.

FGS 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is seriously incomplete for systems in the period range from years to millennia because the radial velocity variations are too small and the angular separations too close for easy detection. Here we propose to discover binaries in this observational gap through a Faint Guidance Sensor SNAP survey of relatively bright targets listed in the Galactic O Star Catalog. Our primary goal is to determine the binary frequency among those in the cluster/association, field, and runaway groups.  The results will help us assess the role of binaries in massive star formation and in the processes that lead to the ejection of massive stars from their natal clusters. The program will also lead to the identification of new, close binaries that will be targets of long term spectroscopic and high angular resolution observations to determine their masses and distances. The results will also be important for the interpretation of the spectra of suspected and newly identified binary and multiple systems.

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.

WFPC2 11022

WFPC2 Cycle 15 Decontaminations and Associated Observations

This proposal is for the WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check.

WFPC2 11038

Narrow Band and Ramp Filter Closeout

These observations are to improve calibration of narrow band and ramp filters. We also test for changes in the filter properties during WFPC2's 14 years on-board HST.

WFPC2 11201

Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images

In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in the Magellanic Clouds centered on background quasars. We used these data to determine the proper motions of the LMC and SMC to better than 5% and 15% respectively. These are by far the best determinations of the proper motions of these two galaxies. The results have a number of unexpected implications for the Milky Way-LMC-SMC system. The implied three-dimensional velocities are larger than previously believed, and are not much less than the escape velocity in a standard 10^12 solar mass Milky Way dark halo. Orbit calculations suggest the Clouds may not be bound to the Milky Way or may just be on their first passage, both of which would be unexpected in view of traditional interpretations of the Magellanic Stream. Alternatively, the Milky Way dark halo may be a factor of two more massive than previously believed, which would be surprising in view of other observational constraints. Also, the relative velocity between the LMC and SMC is larger than expected, leaving open the possibility that the Clouds may not be bound to each other. To further verify and refine our results we now request an epoch of WFPC2/PC data for the fields centered on 40 quasars that have at least one epoch of ACS imaging. We request execution in snapshot mode, as in our previous programs, to ensure the most efficient use of HST resources. A third epoch of data of these fields will provide crucial information to verify that there are no residual systematic effects in our previous measurements. More importantly, it will increase the time baseline from 2 to 5 yrs and will increase the number of fields with at least two epochs of data. This will reduce our uncertainties correspondingly, so that we can better address whether the Clouds are indeed bound to each other and to the Milky Way. It will also allow us to constrain the internal motions of various populations within the Clouds, and will allow us to determine a distance to the LMC using rotational parallax.

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 0.15< z <0.3. 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 {z>1} 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.


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


10983 Loss of Lock - Without Acquisition Failure @ 247/2041z GSAcq (1,2,1) at 247/19:45z was successful. At 247/20:13:57z began flagging in and out of Gyro Control (RGA Only / FGS/RGA). Additionally, Mnemonics FSUBLOL, FGSLOL, FGS_STAT began flagging in and out indicating a possible Loss of Lock. At 247/20:41:56z TERM EXP as scheduled. During this time FGS's maintained SCI INIT / LATCH on acquisition.


18142-0 Another LBBIAS after long M2G interval @ 247/1038z

18140-1 Recover NICMOS from Safe to SAA Oper @ 247/1704z

18143-0 Enable NICMOS Buffer Boxes 1 & 3 @ 247/1709Z


                             SCHEDULED      SUCCESSFUL    Failure 
FGS GSacq                     9                9 
FGS REacq                     5                5 
OBAD with Maneuver           28               28 
Loss of Lock (LOL)                                          1 


NICMOS Recovery to SAA Operate Flash Report

As of 247/17:04:35 UTC, NICMOS was brought up to its' SAA Operate state. As expected, the Buffer Box 2 temperature remained below -12 degC (at -12.12 degC), so the Buffer Box commanding was skipped in the SAA transition. At 247/17:09:22 UTC, Buffer Boxes 1 and 3 were powered on in an effort to warm Buffer Box 2. Once the temperature is above -12 degC, Buffer Box 2 will be powered on. As part of that effort, the instrument will be briefly transitioned from SAA Operate to Operate and back again to refresh the telemetry collection on all three Buffer Boxes.

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