HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT      #5021

PERIOD COVERED: 5am January 27 - 5am January 28, 2010 (DOY 027/10:00z-028/10:00z)

OBSERVATIONS SCHEDULED

ACS/WFC3 11879

CCD Daily Monitor (Part 1)

This program comprises basic tests for measuring the read noise and dark

current of the ACS WFC and for tracking the growth of hot pixels. The

recorded frames are used to create bias and dark reference images for

science data reduction and calibration. This program will be executed

four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To

facilitate scheduling, this program is split into three proposals. This

proposal covers 352 orbits (22 weeks) from 31 August 2009 to 31 January

2010.

STIS/CCD 11634

Probing the Collimation of Pristine Post-AGB Jets with STIS

The shaping of planetary and protoplanetary nebulae (PNe and PPNe) is

probably the most exciting yet least understood problem in the late

evolution of ~1-8 solar mass stars. An increasing number of astronomers

believe that fast jet-like winds ejected in the PPN phase are

responsible for carving out the diverse shapes in the dense envelopes of

the Asymptotic Giant Branch (AGB) stars. To date, the properties of

these post-AGB jets have not been characterized and, indeed, their

launching/collimation mechanism is still subject to controversial

debate. This is due to the lack of the direct observations probing the

spatio-kinematic structure of post-AGB winds in the stellar vicinity

(~10e16cm), which is only possible with HST+STIS.

Recently, STIS observations have allowed us for the first time the

DIRECT study of the structure and kinematics of the elusive post-AGB

winds in one PPN, He3-1475 (Sanchez Contreras & Sahai 2001). Those winds

have been discovered through H-alpha blue-shifted absorption features in

the inner 0.3"-0.7" of the nebula. These STIS observations have revealed

an ultra-fast collimated outflow relatively unaffected by the

interaction with the AGB wind that is totally hidden in ground-based

spectroscopic observations and HST images. The discovery of the pristine

ultra-fast (~2300km/s) jet in He3-1475 is the first observational

confirmation of the presence of collimated outflows as close as ~10e16cm

from the central star. Most importantly, the spatio-kinematic structure

of the ultra-fast jet clearly rules out hydrodynamical collimation alone

and favors magnetic wind collimation. Therefore, STIS observations

provide a unique method of probing the structure, kinematics, and

collimation mechanism of the elusive post-AGB winds. We now propose

similar observations for a sample of bipolar PPNe with ongoing post-AGB

ejections in order to investigate the frequency of jets like those in

He3-1475 in other PPNe and elucidate their nature and collimation

mechanism. The observational characterization of these winds is

indispensable for understanding this violent and important phase of

post-AGB 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.

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the

MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each

detector. However, starting Oct 5, pairs are only included for weeks

that the LRP has external MAMA observations planned. The weekly pairs of

exposures for each detector are linked so that they are taken at

opposite ends of the same SAA free interval. This pairing of exposures

will make it easier to separate long and short term temporal variability

from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once every

six months. These are groups of five 1314s FUV-MAMA Time-Tag darks or

five 3x315s NUV ACCUM darks distributed over a single SAA-free interval.

This will give more information on the brightness of the FUV MAMA dark

current as a function of the amount of time that the HV has been on, and

for the NUV MAMA will give a better measure of the short term

temperature dependence.

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 11577

Opening New Windows on the Antennae with WFC3

We propose to use WFC3 to provide key observations of young star

clusters in "The Antennae" (NGC4038/39). Of prime importance is the

WFC3's ability to push the limiting UV magnitude FIVE mag deeper than

our previous WFPC2 observations. This corresponds to pushing the

limiting cluster mass from ~10**5 to ~10**3 solar masses for cluster

ages ~10**8 yrs. In addition, the much wider field of view of the WFC3

IR channel will allow us to map out both colliding disks rather than

just the Overlap Region between them. This will be especially important

for finding the youngest clusters that are still embedded in their

placental cocoons. The extensive set of narrow-band filters will provide

an effective means for determining the properties of shocks, which are

believed to be a primary triggering mechanism for star formation. We

will also use ACS in parallel with WFC3 to observe portions of both the

northern and southern tails at no additional orbital cost. Finally, one

additional primary WFC3 orbit will be used to supplement existing HST

observations of the star-forming "dwarf" galaxy at the end of the

southern tail. Hence, when completed we will have full UBVI + H_alpha

coverage (or more for the main galaxy) of four different environments in

the Antennae. In conjunction with the extensive multi- wavelength

database we have collected (both HST and ground based) these

observations will provide answers to fundamental questions such as: How

do these clusters form and evolve? How is star formation triggered? How

do star clusters affect the local and global ISM, and the evolution of

the galaxy as a whole? The Antennae galaxies are the nearest example of

a major disk--disk merger, and hence may represent our best chance for

understanding how mergers form tremendous numbers of clusters and stars,

both in the local universe and during galaxy assembly at high redshift.

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/IR 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into

the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass, but

their small numbers, coupled with their stochastic pasts, make it

impossible to construct a unique formation history from the dynamical or

compositional characteristics of them alone. In contrast, the huge

numbers of small bodies scattered throughout and even beyond the

planets, while insignificant by mass, provide an almost unlimited number

of probes of the statistical conditions, history, and interactions in

the solar system. To date, attempts to understand the formation and

evolution of the Kuiper Belt have largely been dynamical simulations

where a hypothesized starting condition is evolved under the

gravitational influence of the early giant planets and an attempt is

made to reproduce the current observed populations. With little

compositional information known for the real Kuiper Belt, the test

particles in the simulation are free to have any formation location and

history as long as they end at the correct point. Allowing compositional

information to guide and constrain the formation, thermal, and

collisional histories of these objects would add an entire new dimension

to our understanding of the evolution of the outer solar system. While

ground based compositional studies have hit their flux limits already

with only a few objects sampled, we propose to exploit the new

capabilities of WFC3 to perform the first ever large-scale

dynamical-compositional study of Kuiper Belt Objects (KBOs) and their

progeny to study the chemical, dynamical, and collisional history of the

region of the giant planets. The sensitivity of the WFC3 observations

will allow us to go up to two magnitudes deeper than our ground based

studies, allowing us the capability of optimally selecting a target list

for a large survey rather than simply taking the few objects that can be

measured, as we have had to do to date. We have carefully constructed a

sample of 120 objects which provides both overall breadth, for a general

understanding of these objects, plus a large enough number of objects in

the individual dynamical subclass to allow detailed comparison between

and within these groups. These objects will likely define the core

Kuiper Belt compositional sample for years to come. While we have many

specific results anticipated to come from this survey, as with any

project where the field is rich, our current knowledge level is low, and

a new instrument suddenly appears which can exploit vastly larger

segments of the population, the potential for discovery -- both

anticipated and not -- is extraordinary.

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                9                  9          

OBAD with Maneuver  6                   6

SIGNIFICANT EVENTS: (None)