HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science



DAILY REPORT #4914



PERIOD COVERED: 5am August 20 - 5am August 21, 2009 (DOY 232/09:00z-233/09:00z)



OBSERVATIONS SCHEDULED



ACS/WFC3 11465



ACS CCD Monitoring and Calibration for WFC3



This program is a smaller version of our routine CCD monitoring program,

designed to run throughout SMOV, after which our regular Cycle 17 CAL

proposal will begin. This program obtains the bias and dark frames

needed to generate reference files for calibrating science data, and

allows us to monitor detector noise and the growth of hot pixels.



ACS/WFC3 11695



Searching for the Bottom of the Initial Mass Function



The measurement of the minimum mass of the IMF would provide a

fundamental test of theories of star and planet formation. In a Cycle 13

program, we used ACS and ground- based near-IR imaging and spectroscopy

to measure the IMF down to a completeness limit of 10 M_Jup (i~24) in a

800"x1000" area in the southern subcluster of the Chamaeleon I

star-forming region (2 Myr, 160 pc). There is no sign of a low-mass

cutoff in this IMF measurement. To provide a better constraint on the

minimum mass of the IMF, we propose to obtain ACS images of this field

again and use the two ACS epochs to identify substellar cluster members

down to the detection limit of the data (i~27) via their proper motions.

In this way, we will improve the completeness limit of our IMF

measurement to 3 M_Jup. In addition, to improve the number statistics of

our measurement of the substellar IMF in Chamaeleon I, we propose to

double the number of objects in the IMF sample by performing ACS imaging

of a second field toward the northern subcluster.



ACS/WFC3 11887



CCD Stability Monitor



This program will verify that the low frequency flat fielding, the

photometry, and the geometric distortion are stable in time and across

the field of view of the CCD arrays. A moderately crowded stellar field

in the cluster 47 Tuc is observed with the ACS (at the cluster core) and

WFC3 (6 arcmin West of the cluster core) using the full suite of broad

and narrow band imaging filters. The positions and magnitudes of objects

will be used to monitor local and large scale variations in the plate

scale and the sensitivity of the detectors and to derive an independent

measure of the detector CTE. The UV sensitivity for the SBC and ACS will

be addressed in the UV contamination monitor program (11886, PI=Smith).



One additional orbit will be obtained at the beginning of the cycle will

allow a verification of the CCD gain ratios for WFC3 using gain 2.0,

1.4, 1.0, 0.5 and for ACS using gain 4.0 and 2.0. In addition, one

subarray exposure with the WFC3 will allow a verification that

photometry obtained in full-frame and in sub-array modes are repeatable

to better than 1%. This test is important for the ACS Photometric Cross-

Calibration program (11889, PI=Bohlin) which uses sub-array exposures.



FGS 11704



The Ages of Globular Clusters and the Population II Distance Scale



Globular clusters are the oldest objects in the universe whose age can

be accurately determined. The dominant error in globular cluster age

determinations is the uncertain Population II distance scale. We propose

to use FGS 1R to obtain parallaxes with an accuracy of 0.2

milliarcsecond for 9 main sequence stars with [Fe/H] < -1.5. This will

determine the absolute magnitude of these stars with accuracies of 0.04

to 0.06mag. This data will be used to determine the distance to 24

metal-poor globular clusters using main sequence fitting. These

distances (with errors of 0.05 mag) will be used to determine the ages

of globular clusters using the luminosity of the subgiant branch as an

age indicator. This will yield absolute ages with an accuracy 5%, about

a factor of two improvement over current estimates. Coupled with

existing parallaxes for more metal-rich stars, we will be able to

accurately determine the age for globular clusters over a wide range of

metallicities in order to study the early formation history of the Milky

Way and provide an independent estimate of the age of the universe.



The Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an

absolute magnitude error less than 0.18 mag which is suitable for use in

main sequence fitting. Previous attempts at main sequence fitting to

metal-poor globular clusters have had to rely on theoretical

calibrations of the color of the main sequence. Our HST parallax program

will remove this source of possible systematic error and yield distances

to metal- poor globular clusters which are significantly more accurate

than possible with the current parallax data. The HST parallax data will

have errors which are 10 times smaller than the current parallax data.

Using the HST parallaxes, we will obtain main sequence fitting distances

to 11 globular clusters which contain over 500 RR Lyrae stars. This will

allow us to calibrate the absolute magnitude of RR Lyrae stars, a

commonly used Population II distance indicator.



NIC2/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. {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}.



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



Monitor the darks for the STIS CCD.



STIS/CCD 11846



CCD Bias Monitor-Part 1



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 11852



STIS CCD Spectroscopic Flats C17



Obtain pixel-to-pixel lamp flat fields for the STIS CCD in spectroscopic

mode.



STIS/CCD 11858



CCD Spectroscopic Dispersion Solution



Constrain wavelength and spatial distortion maps using internal wavecals

obtained with all 6 gratings (G230LB, G230MB, G430L, G430M, G750L,

G750M) supported for use with the CCD. Data will be obtained for the

nearly identical set of 38 central wavelengths used in the 9617 and

10025 programs.



STIS/MA1/MA2 11859



MAMA Dispersion Solutions



Wavelength dispersion solutions will be determined on a yearly basis as

part of a long- term monitoring program. Deep engineering wavecals for

each MAMA grating will be obtained at common cenwaves. Intermediate

settings will also be taken to check the reliability of derived

dispersion solutions. Final selection was determined on basis of past

monitoring and C17 requirements. The internal wavelength calibrations

will be taken using the LINE line lamp. Extra-deep wavecals are included

for some echelle modes and first order modes to ensure detection of weak

lines.



STIS20 11402



STIS-20 NUV MAMA Dark Monitor



The STIS NUV-MAMA dark current is dominated by a phosphorescent glow

from the detector window. Meta-stable states in this window are

populated by cosmic ray impacts, which, days later, can be thermally

excited to an unstable state from which they decay, emitting a UV

photon. The equilibrium population of these meta-stable states is larger

at lower temperatures; so warming up the detector from its cold safing

will lead to a large, but temporary, increase in the dark current.



To monitor the decay of this glow, and to determine the equilibrium dark

current for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should be

taken each week during the SMOV period. Once the observed dark current

has reached an approximate equilibrium with the mean detector

temperature, the frequency of this monitor can be reduced to one pair of

darks per week.



WFC3/IR 11915



IR Internal Flat Fields



This program is the same as 11433 (SMOV) and depends on the completion

of the IR initial alignment (program 11425). This version contains three

instances of 37 internal orbits; to be scheduled early, middle, and near

the end of Cycle 17, in order to use the entire 110-orbit allocation.



In this test, we will study the stability and structure of the IR

channel flat field images through all filter elements in the WFC3-IR

channel. Flats will be monitored, i.e. to capture any temporal trends in

the flat fields, and delta flats produced. High signal observations will

provide a map of the pixel-to-pixel flat field structure, as well as

identify the positions of any dust particles.



WFC3/UVI 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 (11909), will be

used to generate the necessary superbias and superdark reference files

for the calibration pipeline (CDBS).



WFC3/UVI 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.



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:

18683-5 - Install WFC3 CS FSW 4.00 and NSSC-I BQ 9.0.6 @ 232/1830z



COMPLETED OPS NOTES: (None)



SCHEDULED SUCCESSFUL

FGS GSAcq 12 12

FGS REAcq 03 03

OBAD with Maneuver 06 06



SIGNIFICANT EVENTS:



Flash Report:

Wide Field Camera 3 CS Flight Software version 4.00 and NSSC-I Flight

Software version BQ 9.0.6 have been successfully loaded via Ops Request

18683-5