HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      #4884

PERIOD COVERED: 5am July 9 - 5am July 10, 2009 (DOY 190/0900z-191/0900z)

OBSERVATIONS SCHEDULED

ACS 11374

CCD Flat Field Stability (Internal Tungsten Lamps)

The stability of the CCD flat fields will be investigated using the

internal tungsten calibration lamps and the standard filter subset

(F435W, F625W, F814W, and F850LP). High signal observations will be used

to assess the stability of the pixel-to-pixel flat field structure

(P-flat) and to verify the position of the dust motes. The stability of

the low-frequency flat fields (L-flats) will be assessed by comparing

internal exposures obtained just prior to the ACS failure in January

2007 and immediately following the ACS repair in August 2008. This is

activity number ACS-11.

ACS 11379

ACS CCD Image Quality Verification

This program will obtain a series of images to evaluate the point source

image quality over the field of view of the ACS WFC channel in normal

imaging (non-coronagraphic) mode, after the corrector mechanisms have

been used to optimize the image focus and symmetry. A moderate density

open cluster, NGC-188, will be the target, since it is available

year-round and has suitable density and magnitude distribution. Images

will be obtained in the F502N and F625W filters, with 0.5 px dithers in

each axis of the WFC to improve PSF sampling.

ACS 11397

CCD Sensitivity, Geometric Distortion and FF Stability

The stability and uniformity of the low-frequency flat fields (L-flats)

will be studied in detail for one filter in the WFC

(F606W) using multiple dithered pointings of 47 Tucanae. By moving the

same star over different portions of the detector and measuring relative

changes in brightness, any spatial variations in the detector response

can be measured. These star field observations will be used to verify

the L-flats derived from exposures using the internal lamps (program

11374).

High quality baseline measurements of the cluster provide a catalog

which is both astrometrically and photometrically well calibrated, so a

full-scale geometric distortion calibration of the CCDs is not

necessary. Instead, the stability of the distortion solution will be

verified to about 0.2 pixels using the centroid position of stars,

corrected for CTE and proper motions. These observations will also be

used to verify the recently computed time-dependent skew correction.

To supplement to the usual diagonal dither pattern, steps along the x

and y axes will allow a simultaneous evaluation of the detector CTE. Two

short exposures (WFC) will give an estimate of the CTE for different sky

backgrounds.

ACS 11510

External CTE Monitor

Observations of 47 Tuc with half-FOV sized dithers to check the impact

of CTE on photometry after SM4.

FGS 11788

The Architecture of Exoplanetary Systems

Are all planetary systems coplanar? Concordance cosmogony makes that

prediction. It is, however, a prediction of extrasolar planetary system

architecture as yet untested by direct observation for main sequence

stars other than the Sun. To provide such a test, we propose to carry

out FGS astrometric studies on four stars hosting seven companions. Our

understanding of the planet formation process will grow as we match not

only system architecture, but formed planet mass and true distance from

the primary with host star characteristics for a wide variety of host

stars and exoplanet masses.

We propose that a series of FGS astrometric observations with

demonstrated 1 millisecond of arc per-observation precision can

establish the degree of coplanarity and component true masses for four

extrasolar systems: HD 202206 (brown dwarf+planet); HD 128311

(planet+planet), HD 160691 = mu Arae (planet+planet), and HD 222404AB =

gamma Cephei (planet+star). In each case the companion is identified as

such by assuming that the minimum mass is the actual mass. For the last

target, a known stellar binary system, the companion orbit is stable

only if coplanar with the AB binary orbit.

WFC3 11432

UVIS Internal Flats

This proposal will be used to assess the stability of the flat field

structure for the UVIS detector. Flat fields will be obtained for all

filters using the internal D2 and Tungsten lamps.

This proposal corresponds to Activity Description ID WF19. It should

execute only after the following proposals have executed: WF08 - 11421

WF09 - 11422 WF11 - 11424 WF15 - 11428

WFC3 11435

WFC3 IR Fine Alignment

The corrector mechanism will be used to bring the IR channel of WFC3

into optimal alignment with the OTA using analysis of star images over

the field. Two visits are required; corrector offsets will be uplinked

after each visit via realtime command.

This proposal is activity ID WFC3-22

WFC3 11446

WFC3 UVIS Dark Current, Readnoise, and CTE

This proposal obtains full-frame, four-amp readout bias and dark frames

at regularly-spaced intervals throughout SMOV in order to assess and

monitor dark current, bad (warm, hot, dead) pixels, and readnoise. . In

addition, a set of internals using the WFC3 calsystem are taken to

provide a baseline CTE measurement.

WFC3-33

WFC3 11447

WFC3 IR Dark Current, Readnoise, and Background

This proposal obtains full-frame, four-amp readout images.

Un-illuminated internals are taken at regularly spaced intervals

throughout SMOV in order to assess and monitor readnoise and dark

current (of both light-sensitive pixels and reference pixels), and bad

(warm, hot, dead, variable) pixels. In addition, externals aimed at

fields with sparse stellar density are taken to measure diffuse

background light.

This program corresponds to WFC3-34.

WFC3 11808

WFC3 UVIS Bowtie Monitor

The UVIS detector was observed during ground testing to occasionally

exhibit flat field and dark variations with a bowtie pattern. These

variations are most significant as ~1% flat field (gain) variations

across the field of view. It is believed that this represents a state or

condition into which the detector can transition for reasons and under

circumstances which are not currently understood. It is also very

unlikely that most science observations will determine the state (bowtie

or no-bowtie) of the detector. Ground test data indicates that this

state is long lived (many hours to ~one day). Hysteresis or memory of

past light exposure is also associated with this state.

Recent evidence suggests that exposing the detector to ~200k to 500k

electrons may quench this state. This proposal obtains an internal flat

field sequence of three exposures: one at 10x full well with two at 0.5x

full well immediately before and after. Each exposure is 3x3 binned to

reduce the data volume required.

These visits should be scheduled 2x per day until further direction is

provided.

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:

18601-0 - NCS CPL Restart @ 190/2238z

18602-0 - Adjust NCS CPL Setpoint @ 191/0018z, 191/0123z

COMPLETED OPS NOTES: (None)

                      SCHEDULED      SUCCESSFUL

FGS GSAcq               7                    7                

FGS REAcq               8                    8           

OBAD with Maneuver 6                    6           

SIGNIFICANT EVENTS:

Flash Report:

The NCS CPL was successfully restarted with Ops Request 18601-0 @

190/22:38:50z. The +7 degC setpoint was maintained until stable

operation at that temperature was confirmed and then OR #18602-0 was

executed to warm the CPL in preparation for the NCC restart.