HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT      #4960

PERIOD COVERED: 5am October 27 - 5am October 28, 2009 (DOY 300/09:00z-301/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC 11689

Direct Observations of Dark Matter from a Second Bullet: The Spectacular

Abell 2744

Vigorous cluster mergers provide a unique opportunity to directly "see"

dark matter and to probe its properties through the analysis of the

segregation of the baryonic and non-baryonic components. This is

accomplished through detailed comparison of the mass distributions as

traced by X-ray emitting gas and by gravitational lensing. This

condition is rare and so far only one cluster has met these

requirements, the so-called "bullet" cluster, producing exciting results

and placing constraints to the properties of dark matter. These

constraints have a broad impact on models for formation of structure and

on galaxy evolution. This multi-wavelength analysis has the potential

confront alternative gravity models such as MOND. Therefore, it is

crucial to find new ?bullet clusters? to corroborate and improve

previous measurements. This is the most direct way to constrain dark

matter properties and A2744 is ideal for corroborating this study since

it maximizes all the requirements for this analysis. Here, we propose to

carry out such analysis through combined ACS and Chandra observations of

the cluster merger Abell 2744.

ACS/WFC3 11882

CCD Hot Pixel Annealing

All the data for this program is acquired using internal targets (lamps)

only, so all of the exposures should be taken during Earth occultation

time (but not during SAA passages). This program emulates the ACS

pre-flight ground calibration and post launch SMOV testing (program

8948), so that results from each epoch can be directly compared.

Extended Pixel Edge Response (EPER) and First Pixel Response (FPR) data

will be obtained over a range of signal levels for the Wide Field

Channel (WFC). The High Resolution Channel (HRC) visits have been

removed since it could not be repaired during SM4.

COS/FUV 11541

COS-GTO: COOL, WARM AND HOT GAS IN THE COSMIC WEB AND IN GALAXY HALOS

COS G130M and G160M 20, 000 resolution observations will be obtained for

17 QSOs to study cool, warm and hot gas in the cosmic web and in galaxy

halos. 5 QSOs with z from 0.177 to 0.574 and sum z = 1.68 will be

observed with S/N = 40-50 per resolution element. 12 QSOs with z = 0.286

to 0.669 and sum z = 5.57 will be observed with S/N = 30-40. The

observations will allow a wide range of IGM studies including

determining the frequency of occurrence of the different types of

absorption systems detected, along with studies of the physical

conditions and elemental abundances in the different systems. Special

emphasis will be given to a study of the properties of highly ionized

IGM as traced by O VI, O V, O IV, N V, and C IV. The high S/N of the

observations will allow a search for broad Lyman alpha absorption and

weak metal line absorption that can be crucial for the evaluation of

physical conditions and elemental abundances. Supporting ground based

observations will allow studies of the association of the absorbers with

galaxy structures along the 17 lines of sight. The overall goal of the

program will be to obtain the information that will allow an assessment

of the baryonic content of the IGM as revealed by UV and EUV absorption

lines seen in the spectra of QSOs.

COS/FUV 11997

FUV Internal/External Wavelength Scale Monitor

This program monitors the offsets between the wavelength scale set by

the internal wavecal versus that defined by absorption lines in external

targets. This is accomplished by observing two external targets in the

SMC: SK191 with G130M and G160M and Cl* NGC 330 ROB B37 with G140L

(SK191 is too bright to be observed with G140L). The cenwaves observed

in this program are a subset of the ones used during Cycle 17. Observing

all cenwaves would require a considerably larger number of orbits.

Constraints on scheduling of each target are placed so that each target

is observed once every ~2-3 months. Observing the two targets every

month would also require a considerably larger number of orbits.

FGS 11790

HST/FGS Astrometric Search for Young Planets Around Beta Pic and AU Mic

AU Mic is a nearby Vega-type debris disk star. Its disk system has been

spatially resolved in exquisite detail, predominantly via the ACS

coronagraph and WFPC2 cameras onboard HST. These images exhibit a wealth

of morphological features which provide compelling indirect evidence

that AU Mic likely harbors short-period planetary body/bodies. We

propose to use the superlative astrometric capabilities of HST/FGS to

directly detect these planets, hence provide the first direct planet

detection in a Vega-type system whose disk has been imaged at high

spatial resolution.

NIC2/WFC3/IR 11548

Infrared Imaging of Protostars in the Orion A Cloud: The Role of

Environment in Star Formation

We propose NICMOS and WFC3/IR observations of a sample of 252 protostars

identified in the Orion A cloud with the Spitzer Space Telescope. These

observations will image the scattered light escaping the protostellar

envelopes, providing information on the shapes of outflow cavities, the

inclinations of the protostars, and the overall morphologies of the

envelopes. In addition, we ask for Spitzer time to obtain 55-95 micron

spectra of 75 of the protostars. Combining these new data with existing

3.6 to 70 micron photometry and forthcoming 5-40 micron spectra measured

with the Spitzer Space Telescope, we will determine the physical

properties of the protostars such as envelope density, luminosity,

infall rate, and outflow cavity opening angle. By examining how these

properties vary with stellar density (i.e. clusters vs. groups vs.

isolation) and the properties of the surrounding molecular cloud; we can

directly measure how the surrounding environment influences protostellar

evolution, and consequently, the formation of stars and planetary

systems. Ultimately, this data will guide the development of a theory of

protostellar evolution.

STIS/CCD 11844

CCD Dark Monitor Part 1

The purpose of this proposal is to monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

The purpose of this proposal is to monitor the bias in the 1x1, 1x2,

2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up

high-S/N superbiases and track the evolution of hot columns.

WFC3/ACS/UVIS 11360

Star Formation in Nearby Galaxies

Star formation is a fundamental astrophysical process; it controls

phenomena ranging from the evolution of galaxies and nucleosynthesis to

the origins of planetary systems and abodes for life. The WFC3,

optimized at both UV and IR wavelengths and equipped with an extensive

array of narrow-band filters, brings unique capabilities to this area of

study. The WFC3 Scientific Oversight Committee (SOC) proposes an

integrated program on star formation in the nearby universe which will

fully exploit these new abilities. Our targets range from the

well-resolved R136 in 30 Dor in the LMC (the nearest super star cluster)

and M82 (the nearest starbursting galaxy) to about half a dozen other

nearby galaxies that sample a wide range of star-formation rates and

environments. Our program consists of broad band multiwavelength imaging

over the entire range from the UV to the near-IR, aimed at studying the

ages and metallicities of stellar populations, revealing young stars

that are still hidden by dust at optical wavelengths, and showing the

integrated properties of star clusters. Narrow-band imaging of the same

environments will allow us to measure star-formation rates, gas

pressure, chemical abundances, extinction, and shock morphologies. The

primary scientific issues to be addressed are: (1) What triggers star

formation? (2) How do the properties of star-forming regions vary among

different types of galaxies and environments of different gas densities

and compositions? (3) How do these different environments affect the

history of star formation? (4) Is the stellar initial mass function

universal or determined by local conditions?

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more

reliably removed from science data using darks taken with the same

exposure sequences as the science data, than with a single dark current

image scaled by desired exposure time. Therefore, dark current images

must be collected using all sample sequences that will be used in

science observations. These observations will be used to monitor changes

in the dark current of the WFC3-IR channel on a day-to-day basis, and to

build calibration dark current ramps for each of the sample sequences to

be used by GOs in Cycle 17. For each sample sequence/array size

combination, a median ramp will be created and delivered to the

calibration database system (CDBS).

WFC3/UV 11730

Continued Proper Motions of the Magellanic Clouds: Orbits, Internal

Kinematics, and Distance

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. The results had a number of unexpected implications

for the Milky Way-LMC-SMC system and received considerable attention in

the literature and in the press. The implied three-dimensional

velocities are larger than previously believed and close to the escape

velocity in a standard 10^12 solar mass Milky Way dark halo. Our orbit

calculations suggest the Clouds may not be bound to the Milky Way or may

just be on their first passage, both of which are unexpected in view of

traditional interpretations of the Magellanic Stream. Alternatively, the

Milky Way dark halo may be a factor 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 was

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

requested an additional epoch data in Cycle 16 which is being executed

with WFPC2/PC due to the failure of ACS. A detailed analysis of one LMC

field shows that the field proper motion using all three epochs of data

is consistent within 1-sigma with the two-epoch data, thus verifying

that there are no major systematic effects in our previous measurements.

The random errors, however, are only smaller by a factor of 1.4 because

of the relatively large errors in the WFPC2 data. A prediction for a

fourth epoch with measurement errors similar to epochs 1 and 2 shows

that the uncertainties will improve by a factor of 3. This will allow us

to 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 to determine a

distance to the LMC using rotational parallax. Continuation of this

highly successful program is therefore likely to provide important

additional insights. Execution in SNAPshot mode guarantees maximally

efficient use of HST resources.

WFC3/UVIS 11594

A WFC3 Grism Survey for Lyman Limit Absorption at z=2

We propose to conduct a spectroscopic survey of Lyman limit absorbers at

redshifts 1.8 < z < 2.5, using WFC3 and the G280 grism. This proposal

intends to complete an approved Cycle 15 SNAP program (10878), which was

cut short due to the ACS failure. We have selected 64 quasars at 2.3 < z

< 2.6 from the Sloan Digital Sky Survey Spectroscopic Quasar Sample, for

which no BAL signature is found at the QSO redshift and no strong metal

absorption lines are present at z > 2.3 along the lines of sight. The

survey has three main observational goals. First, we will determine the

redshift frequency dn/dz of the LLS over the column density range 16.0 <

log(NHI) < 20.3 cm^-2. Second, we will measure the column density

frequency distribution f(N) for the partial Lyman limit systems (PLLS)

over the column density range 16.0 < log(NHI) < 17.5 cm^-2. Third, we

will identify those sightlines which could provide a measurement of the

primordial D/H ratio. By carrying out this survey, we can also help

place meaningful constraints on two key quantities of cosmological

relevance. First, we will estimate the amount of metals in the LLS using

the f(N), and ground based observations of metal line transitions.

Second, by determining f(N) of the PLLS, we can constrain the amplitude

of the ionizing UV background at z~2 to a greater precision. This survey

is ideal for a snapshot observing program, because the on-object

integration times are all well below 30 minutes, and follow-up

observations from the ground require minimal telescope time due to the

QSO sample being bright.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of

full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K

subarray biases are acquired at less frequent intervals throughout the

cycle to support subarray science observations. The internals from this

proposal, along with those from the anneal procedure (Proposal 11909),

will be used to generate the necessary superbias and superdark reference

files for the calibration pipeline (CDBS).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the

UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.

Initially found via an unexpected bowtie-shaped feature in flatfield

ratios, subsequent lab tests on similar e2v devices have since shown

that it is also present as simply an overall offset across the entire

CCD, i.e., a QE offset without any discernable pattern. These lab tests

have further revealed that overexposing the detector to count levels

several times full well fills the traps and effectively neutralizes the

bowtie. Each visit in this proposal acquires a set of three 3x3 binned

internal flatfields: the first unsaturated image will be used to detect

any bowtie, the second, highly exposed image will neutralize the bowtie

if it is present, and the final image will allow for verification that

the bowtie is gone.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

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

HSTARS:

12056 - GSAcq (2,1,1) at 300/23:34z and REAcq at 301/01:10:08z, 301/02:39:47z

           and 301/04:15:42z all failed to RGA Hold due to Scan Step Limit

           Exceeded on FGS-1.

           Observations affected: COS 15-30 Proposal ID#11541, ACS 61-62 Proposal ID#11882,

           STIS 12-16 Proposal ID#11846, WFC3 60-62 Proposal ID#11905.

12057 - GSAcq(2,1,1) at 301/05:51:38z and REAcq(2,1,1) at 301/07:27:30z  both failed

           with Search Radius Limit exceeded on both FGS 1 and FGS 2.

           Observations affected: COS 31-45, proposal ID#11541.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                      SCHEDULED      SUCCESSFUL 

FGS GSAcq               7                   5  

FGS REAcq               9                   5    

OBAD with Maneuver 5                   5                

SIGNIFICANT EVENTS: (None)