HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      #4916

PERIOD COVERED: 5am August 24 - 5am August 25, 2009 (DOY 236/09:00z-237/09:00z)

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.

COS 11484

COS FUV Optics Alignment and Focus

After FUV detector functionality has been confirmed in COS25 (program

11483) and the initial focus updates determined in COS08 and COS 09

(programs 11468 and 11469), a sequence of 13 FUV focus-sweep exposures

of a sharp-lined external target will be made with each grating (4

orbits per grating) to perform a fine-focus sweep. After the data are

analyzed, a patchable constant SMS update of OSM1 focus for each grating

will be uplinked. A verification visit will be executed after the

uplink. Observations require high S/N and should be taken in TIME-TAG

(FLASH=YES) mode.

COS23 11356

COS FUV Initial On-Orbit Turn-On

This proposal specifies the procedure for SMOV initial HV turn-on and

ramp-up of the COS FUV detector. (The FUV will have been commanded to

its Operate state to support execution of proposal 11353.) The procedure

is detailed in the Observing Description, but in summary, the following

is done: The initial transition from FUV Operate to HVLow is broken into

two parts, with a gap of 4 hours between turning on the HV and ramping

to the HVLow (SAA) voltage. This will be followed by 5 cycles of HV

ramp-up and return to HVLow. Cycles will ramp up to successively higher

(magnitude) voltage, with the fifth cycle going to the nominal operating

values. There will be a gap of at least 4 hours between cycles. All HV

ramp-up will be done at 10 sec per HV "step". The step rate and cycle

voltage values (for Segments A and B) must be patched in FSW in each

cycle prior to the HV ramp commanding. Memory monitors will be set on

the patched memory locations. Immediately after any HV commanding, and 4

hours after ramp-up commanding, the DCE memory will be dumped.

Immediately after HV ramp-up commanding higher than HVLow, short DARK &

WAVE exposures will be obtained. Visits 01 and 02, and all the

subsequent even numbered visits (the ones 4 hours after HV ramp-ups),

end with NSSC-1 COS event flag 3 being set. If the flag remains set,

subsequent FUV commanding will be skipped. Thus, Operations Requests

must be in place to clear the flag prior to those subsequent visits.

Real-time monitoring of the telemetry will be used to guide the

decisions whether or not to clear the flag. The final visit (13)

provides a scheduled final opportunity to clear flag 3, and if the flag

is cleared, initiates nominal FUV HV commanding and requests a DARK

exposure.

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.

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.

STIS26 11395

STIS-26 MAMA Image Stability

The maximum thermal motion of the MAMA detectors occurs in the first

portion of the orbit immediately following a large angle maneuver

leading to maximum external changes on the portion of axial bay closest

to the STIS instrument. By the second orbit on the same target, the

thermal motions settle down to a significant displacement right after

target rise, a possible change later in the orbit due to sun/bright

earth/dark earth/ deep space. We will follow these changes for two

orbits with each MAMA with internal lamp and the medium dispersion

echelle formats in order to obtain a two-dimension series of reference

points on the 2-dimensional detector format. Exposures will be done

using the 0.1X0.03 aperture and medium resolution echelle gratings, and

will have exposure times of 120 seconds for deep, sharp spectral line

images.

For each orbit, six spectral line images will follow each other, then

dark frames are interposed with exposure times extending from 300

seconds to 600 seconds. This provides frequent sampling in the portion

of the orbit where thermal flexure is largest, while avoiding excessive

lamp use when shifts are expected to be slower. The dark frames will

also provide a useful addition to the calibration of the MAMA detector

dark current.

Note that E140M test is from hot to cold and the E230M test is from cold

to hot. If noticeable changes are measured, the complimentary test pair

should be considered at a later date.

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 (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 11549

UVIS and IR Pointing Stability

This calibration proposal measures the pointing stability of the WFC3

UVIS and IR channels.

Three conditions will be tested: 1) 2-orbit stability after sitting at a

constant thermal attitude for 10 orbits 2) 2-orbit stability after

sitting at a hot thermal attitude for 10 orbits and then slewing to a

cold attitude 3) 2-orbit stability after sitting at a cold thermal

attitude for 10 orbits and then slewing to a hot attitude

Stability measurements will be made by a series of short observations of

a globular cluster.

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               05                 05                

FGS REAcq               12                 12               

OBAD with Maneuver 02                 02               

SIGNIFICANT EVENTS: (None)