HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5123

PERIOD COVERED: 5am June 22 - 5am June 23, 2010 (DOY 173/09:00z-174/09:00z)

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

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

HSTARS:

12310 - GSAcq(2,1,1) scheduled at 173/21:05:45z and REAcq scheduled at

           173/22:00:26z both resulted in fine lock backup (2,0,2).

           Observations possibly affected: STIS 23 - 27 Proposal ID#11693;

           STIS 28 &29 Proposal ID#11857

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                      SCHEDULED SUCCESSFUL

FGS GSAcq               5              5

FGS REAcq               4              4

OBAD with Maneuver 4              4

SIGNIFICANT EVENTS: (None)

OBSERVATIONS SCHEDULED:

COS/FUV 11619

Definitive ISM Abundances through Low-mass X-ray Binaries as Lighthouses

We propose observations of the UV spectra of two low-mass X-ray binaries

(Sco X-1 and Cyg X-2) with existing Chandra X-Ray Observatory (CXO)

data. From the X-ray data we will measure total (phase-independent)

column densities of O, Ne, and Fe. From the UV data we will determine

gas-phase column densities of H and O. The data in conjunction will

allow us to make unique measurements of the total interstellar

abundances of oxygen, neon, and iron, and direct measurements of the

dust-phase abundances of O and Fe.

COS/FUV 11625

Beyond the Classical Paradigm of Stellar Winds: Investigating Clumping,

Rotation and the Weak Wind Problem in SMC O Stars

SMC O stars provide an unrivaled opportunity to probe star formation,

evolution, and the feedback of massive stars in an environment similar

to the epoch of the peak in star formation history. Two recent

breakthroughs in the study of hot, massive stars have important

consequences for understanding the chemical enrichment and buildup of

stellar mass in the Universe. The first is the realization that rotation

plays a major role in influencing the evolution of massive stars and

their feedback on the surrounding environment. The second is a drastic

downward revision of the mass loss rates of massive stars coming from an

improved description of their winds. STIS spectroscopy of SMC O stars

combined with state-of-the-art NLTE analyses has shed new light on these

two topics. A majority of SMC O stars reveal CNO- cycle processed

material brought at their surface by rotational mixing. Secondly, the

FUV wind lines of early O stars provide strong indications of the

clumped nature of their wind. Moreover, we first drew attention to some

late-O dwarfs showing extremely weak wind signatures. Consequently, we

have derived mass loss rates from STIS spectroscopy that are

significantly lower than the current theoretical predictions used in

evolutionary models. Because of the limited size of the current sample

(and some clear bias toward stars with sharp-lined spectra), these

results must however be viewed as tentative. Thanks to the high

efficiency of COS in the FUV range, we propose now to obtain

high-resolution FUV spectra with COS of a larger sample of SMC O stars

to study systematically rotation and wind properties of massive stars at

low metallicity. The analysis of the FUV wind lines will be based on our

2D extension of CMFGEN to model axi-symmetric rotating winds.

FGS 11789

An Astrometric Calibration of Population II Distance Indicators

In 2002, HST produced a highly precise parallax for RR Lyrae. That

measurement resulted in an absolute magnitude, M(V)= 0.61+/-0.11, a

useful result, judged by the over ten refereed citations each year

since. It is, however, unsatisfactory to have the direct,

parallax-based, distance scale of Population II variables based on a

single star. We propose, therefore, to obtain the parallaxes of four

additional RR Lyrae stars and two Population II Cepheids, or W Vir

stars. The Population II Cepheids lie with the RR Lyrae stars on a

common K-band Period-Luminosity relation. Using these parallaxes to

inform that relationship, we anticipate a zero point error of 0.04

magnitude. This result should greatly strengthen confidence in the

Population II distance scale and increase our understanding of RR Lyrae

star and Pop. II Cepheid astrophysics.

STIS/CC 11693

Follow-up Observations of Debris Disks around Two Solar-Type Stars

Circumstellar debris disks offer direct views into the structure of

extrasolar planetary systems. Their constituent dust, seen in scattered

light and thermal emission, is created by the collisions of asteroidal

and cometary parent bodies. The distribution of this dust provides

information on the location of the parent bodies, and can be strongly

affected by planetary perturbations. Dynamical signatures of planets can

include asymmetries, warps, central clearings, and radial gaps in a

disk, and thus are key features to search for in resolved images.

Following up recent Spitzer measurements, we have now detected two new,

nearby debris disks in scattered light. Our initial ACS F606W

coronagraphic images show faint ringlike structures around the

solar-type stars HD 10647 (F9V) and HD 207129 (G0V); both are also

spatially resolved in Spitzer/MIPS 70 micron images. The HD 10647 disk,

seen close to edge-on, represents the first disk ever imaged in

scattered light around a star known to have a radial velocity planet.

The inclined ring around HD 207129 is the faintest disk ever imaged in

scattered light, and seems in the MIPS image to be asymmetric like the

eccentric ring around Fomalhaut. We propose to obtain deep ACS

coronagraphic images of these two disks. Our goals are to get definitive

measurements of the dust spatial distributions (including disk

asymmetries and sharpness of the ring edges), and measure the overall

F606W-F814W color of each disk in order to constrain the dust

properties. The results will be a definitive exploration of the Kuiper

belts of two nearby, Sun-like stars. NOTE: HD 207129 was deleted from

this program.

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CC 11847

CCD Bias Monitor-Part 2

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 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/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/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.

WFC3/UVIS/IR 11909

UVIS Hot Pixel Anneal

The on-orbit radiation environment of WFC3 will continually generate new

hot pixels. This proposal performs the procedure required for repairing

those hot pixels in the UVIS CCDs. During an anneal, the two-stage

thermo-electric cooler (TEC) is turned off and the four-stage TEC is

used as a heater to bring the UVIS CCDs up to ~20 deg. C. As a result of

the CCD warmup, a majority of the hot pixels will be fixed; previous

instruments such as WFPC2 and ACS have seen repair rates of about 80%.

Internal UVIS exposures are taken before and after each anneal, to allow

an assessment of the procedure's effectiveness in WFC3, provide a check

of bias, global dark current, and hot pixel levels, as well as support

hysteresis (bowtie) monitoring and CDBS reference file generation. One

IR dark is taken after each anneal, to provide a check of the IR

detector.