HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT      #5020

PERIOD COVERED: 5am January 26 - 5am January 27, 2010 (DOY 026/10:00z-027/10:00z)

OBSERVATIONS SCHEDULED

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.

S/C 12046

COS FUV DCE Memory Dump

Whenever the FUV detector high voltage is on, count rate and current

draw information is collected, monitored, and saved to DCE memory. Every

10 msec the detector samples the currents from the HV power supplies

(HVIA, HVIB) and the AUX power supply (AUXI). The last 1000 samples are

saved in memory, along with a histogram of the number of occurrences of

each current value.

In the case of a HV transient (known as a "crackle" on FUSE), where one

of these currents exceeds a preset threshold for a persistence time, the

HV will shut down, and the DCE memory will be dumped and examined as

part of the recovery procedure. However, if the current exceeds the

threshold for less than the persistence time (a "mini-crackle" in FUSE

parlance), there is no way to know without dumping DCE memory. By

dumping and examining the histograms regularly, we will be able to

monitor any changes in the rate of "mini-crackles" and thus learn

something about the state of the detector.

STIS/CC/MA 11516

COS-GTO: Cold ISM

With the COS, we will be able to observe interstellar spectra in a new

regime, translucent clouds, for atomic, ionic, and molecular lines and

bands, and extinction curves. The COS will allow us to observe stars

with total visual extinctions up to 10 magnitudes, and the grain size

indicator Rv up to 4.5. In translucent clouds we expect to see the

transition from neutral and ionized carbon to mostly C I, and then from

there, we should expect to see carbon increasingly locked up in

molecular form, as CO. Other species are expected to make similar

transitions, so we should find detectable abundances of molecules such

as H2O, OH, CS, CH2, SiO, and others; also, lower ionization fractions

of the metallic elements - and higher depletions of those elements as

well. Given that we expect to find higher depletions, we should see an

altered grain size distribution, which may show up in the extinction

curves, probably as lower far-UV extinction than in diffuse clouds.

Finally, we will search for neutral PAHs in absorption, as diffuse bands

in the UV, paralleling the optical DIBs (which are thought by some

scientists to be formed by singly-ionized PAHs). In translucent clouds,

models show that the PAHs will be neutral, not in cationic form.

STIS/CCD 11567

Boron Abundances in Rapidly Rotating Early-B Stars

Models of rotation in early-B stars predict that rotationally driven

mixing should deplete surface boron abundances during the main-sequence

lifetime of many stars. However, recent work has shown that many boron

depleted stars are intrinsically slow rotators for which models predict

no depletion should have occurred, while observations of nitrogen in

some more rapidly rotating stars show less mixing than the models

predict. Boron can provide unique information on the earliest stages of

mixing in B stars, but previous surveys have been biased towards narrow-

lined stars because of the difficulty in measuring boron abundances in

rapidly rotating stars. The two targets observed as part of our Cycle 13

SNAP program 10175, just before STIS failed, demonstrate that it is

possible to make useful boron abundance measurements for early-B stars

with Vsin(i) above 100 km/s. We propose to extend that survey to a large

enough sample of stars to allow statistically significant tests of

models of rotational mixing in early-B stars.

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.

STIS/CCD 11849

STIS CCD Hot Pixel Annealing

This purpose of this activity is to repair radiation induced hot pixel

damage to the STIS CCD by warming the CCD to the ambient instrument

temperature and annealing radiation-damaged pixels.

Radiation damage creates hot pixels in the STIS CCD Detector. Many of

these hot pixels can be repaired by warming the CCD from its normal

operating temperature near -83 deg. C to the ambient instrument

temperature (~ +5 deg. C) for several hours. The number of hot pixels

repaired is a function of annealing temperature. The effectiveness of

the CCD hot pixel annealing process is assessed by measuring the dark

current behavior before and after annealing and by searching for any

window contamination effects.

STIS/CCD/MA1 11737

The Distance Dependence of the Interstellar N/O Abundance Ratio: A Gould

Belt Influence?

The degree of elemental abundance homogeneity in the interstellar medium

is a function of the enrichment and mixing processes that govern

galactic chemical evolution. Observations of young stars and the

interstellar gas within ~500 pc of the Sun have revealed a local ISM

that is so well-mixed it is having an impact on ideas regarding the

formation of extrasolar planets. However, the situation just beyond the

local ISM is not so clear. Sensitive UV absorption line measurements

have recently revealed a pattern of inhomogeneities in the interstellar

O, N, and Kr gas-phase abundances at distances of ~500 pc and beyond

that appear nucleosynthetic in origin rather than due to dust depletion.

In particular, based on a sample of 13 sightlines, Knauth et al. (2006)

have found that the nearby stars (d < 500 pc) exhibit a mean

interstellar N/O abundance ratio that is significantly higher (0.18 dex)

than that toward the more distant stars. Interestingly, all of their

sightlines lie in the sky vicinity of the Gould Belt of OB associations,

molecular clouds, and diffuse gas encircling the Sun at a distance of

~400 pc. Is it possible that mixing processes have not yet smoothed out

the recent ISM enrichment by massive stars in the young Belt region? By

measuring the interstellar N/O ratios in a strategic new sample of

sightlines with STIS, we propose to test the apparent N/O homogeneity

inside the Gould Belt and determine if the apparent decline in the N/O

ratio with distance is robust and associated with the Belt region.

WFC3/ACS/IR 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, and (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).

WFC3/ACS/IR 11677

Is 47 Tuc Young? Measuring its White Dwarf Cooling Age and Completing a

Hubble Legacy

With this proposal we will firmly establish the age of 47 Tuc from its

cooling white dwarfs. 47 Tuc is the nearest and least reddened of the

metal-rich disk globular clusters. It is also the template used for

studying the giant branches of nearby resolved galaxies. In addition,

the age sensitive magnitude spread between the main sequence turnoff and

horizontal branch is identical for 47 Tuc, two bulge globular clusters

and the bulge field population. A precise relative age constraint for 47

Tuc, compared to the halo clusters M4 and NGC 6397, both of which we

recently dated via white dwarf cooling, would therefore constrain when

the bulge formed relative to the old halo globular clusters. Of

particular interest is that with the higher quality ACS data on NGC

6397, we are now capable with the technique of white dwarf cooling of

determining ages to an accuracy of +/-0.4 Gyrs at the 95% confidence

level. Ages derived from the cluster turnoff are not currently capable

of reaching this precision. The important role that 47 Tuc plays in

galaxy formation studies, and as the metal-rich template for the

globular clusters, makes the case for a white dwarf cooling age for this

metal-rich cluster compelling.

Several recent analyses have suggested that 47 Tuc is more than 2 Gyrs

younger than the Galactic halo. Others have suggested an age similar to

that of the most metal poor globular clusters. The current situation is

clearly uncertain and obviously a new approach to age dating this

important cluster is required.

With the observations of 47 Tuc, this project will complete a legacy for

HST. It will be the third globular cluster observed for white dwarf

cooling; the three covering almost the full metallicity range of the

cluster system. Unless JWST has its proposed bluer filters (700 and 900

nm) this science will not be possible perhaps for decades until a large

optical telescope is again in space. Ages for globular clusters from the

main sequence turnoff are less precise than those from white dwarf

cooling making the science with the current proposal truly urgent.

WFC3/IR 11189

Probing the Early Universe with GRBs

Cosmology is beginning to constrain the nature of the earliest stars and

galaxies to form in the Universe, but direct observation of galaxies at

z>6 remains highly challenging due to their scarcity, intrinsically

small size, and high luminosity distance. GRB afterglows, thanks to

their extreme luminosities, offer the possibility of circumventing these

normal constraints by providing redshifts and spectral information which

couldn't be obtained through direct observation of the host galaxies

themselves. In addition, the association of GRBs with massive stars

means that they are an indicator of star formation, and that their hosts

are likely responsible for a large proportion of the ionizing radiation

during that era. Our collaboration is conducting a campaign to rapidly

identify and study candidate very high redshift bursts, bringing to bear

a network of 2, 4 and 8m telescopes with near-IR instrumentation. Swift

has proven capable of detecting faint, distant GRBs, and reporting

accurate positions for many bursts in near real-time. Here we propose to

continue our HST program of targeting GRBs at z~6 and above. HST is

crucial to this endeavor, allowing us (a) to characterize the basic

properties, such as luminosity and color, and in some cases

morphologies, of the hosts, which is essential to understanding these

primordial galaxies and their relationship to other galaxy populations;

and (b) to monitor the late time afterglows and hence compare them to

lower-z bursts and test the use of GRBs as standard candles.

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/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: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                      SCHEDULED  SUCCESSFUL             

FGS GSAcq               6               6       

FGS REAcq               8               8       

OBAD with Maneuver 6               6       

SIGNIFICANT EVENTS: (None)