Daily # 4240

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4240

PERIOD COVERED: UT November 14, 2006 (DOY 318)

OBSERVATIONS SCHEDULED

ACS/WFC 10885

Deep Photometry of NGC 1569: Understanding the Closest and Strongest
Starburst of the Nearby Universe

Massive starbursts drive the evolution of galaxies at high redshift,
but they can only be studied in detail in the nearby Universe where
they are much rarer. The dwarf irregular galaxy NGC 1569 at 2.2 Mpc is
the closest example of a true starburst. It has sustained
exceptionally high star formation {SF} activity over the last Gyr, 2-3
orders of magnitude higher than in normal dwarf irregulars and
spirals. This SF has been probed extensively by previous HST
observations that have reached just below the tip of the red giant
branch {RGB}. But the data have not been able to constrain the more
ancient SF history {SFH}, so that our understanding remains very
incomplete. It is an open question whether NGC 1569 just started to
form stars around 1 Gyr ago, or whether significant SF was already
active before that. We do not know what triggered the recent SF, how
long the current intense SF activity has been going on, and whether
such SF activity has been a more common occurrence in the past history
of this galaxy. More importantly, most of these questions remain
unanswered for other starburst galaxies in the nearby and distant
universe as well. HST is the only telescope that can do the necessary
crowded-field photometry to resolve these issues. We propose to use
ACS/WFC to build a deep I vs. V-I color-magnitude diagram {CMD} that
goes some 4 magnitudes deeper than the RGB tip. This will detect and
characterize the red clump {RC} and horizontal branch {HB} features.
The CMD will be interpreted by fitting synthetic CMDs constructed from
evolutionary tracks to infer the SFH. The joint constraints from the
presence, apparent magnitude, and width of the RC, HB and RGB features
will independently constrain both the age and metallicity of the old
and evolved stellar population of NGC 1569, the presence of multiple
bursts if any, and their duration and metallicity spread. This will
reveal the evolutionary status over cosmic time, and more generally
will constrain the processes at play in the origin and evolution of
galaxies. This project is only possible because of the high
sensitivity of ACS, and it can be done very efficiently because of the
location of NGC 1569 in the CVZ. Since NGC 1569 is so close, it may be
the only nearby starburst for which these issues can be addressed in
the foreseeable future.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

A new procedure proposed to alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained immediately upon exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled within 50
minutes of coming out of the SAA. The darks will be obtained in
parallel in all three NICMOS Cameras. The POST-SAA darks will be
non-standard reference files available to users with a USEAFTER
date/time mark. The keyword 'USEAFTER=date/time' will also be added to
the header of each POST-SAA DARK frame. The keyword must be populated
with the time, in addition to the date, because HST crosses the SAA ~8
times per day so each POST-SAA DARK will need to have the appropriate
time specified, for users to identify the ones they need. Both the raw
and processed images will be archived as POST-SAA DARKSs. Generally we
expect that all NICMOS science/calibration observations started within
50 minutes of leaving an SAA will need such maps to remove the CR
persistence from the science images. Each observation will need its
own CRMAP, as different SAA passages leave different imprints on the
NICMOS detectors.

NIC2 10893

Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble
Diagram

We propose building a high-z Hubble Diagram using type Ia supernovae
observed in the infrared rest-frame J-band. The infrared has a number
of exceptional properties. The effect of dust extinction is minimal,
reducing a major systematic tha may be biasing dark energy
measurements. Also, recent work indicates that type Ia supernovae are
true standard candles in the infrared meaning that our Hubble diagram
will be resistant to possible evolution in the Phillips relation over
cosmic time. High signal-to-noise measurements of 9 type Ia events at
z~0.4 will be compared with an independent optical Hubble diagram from
the ESSENCE project to test for a shift in the derived dark energy
equation of state due to a systematic bias. Because of the bright sky
background, H-band photometry of z~0.4 supernovae is not feasible from
the ground. Only the superb image quality and dark infrared sky seen
by HST makes this test possible. This experiment may also lead to a
better, more reliable way of mapping the expansion history of the
universe with the Joint Dark Energy Mission.

NIC2, ACS/WFC 10802

SHOES-Supernovae, HO, for the Equation of State of Dark energy

The present uncertainty in the value of the Hubble constant {resulting
in an uncertainty in Omega_M} and the paucity of Type Ia supernovae at
redshifts exceeding 1 are now the leading obstacles to determining the
nature of dark energy. We propose a single, integrated set of
observations for Cycle 15 that will provide a 40% improvement in
constraints on dark energy. This program will observe known Cepheids
in six reliable hosts of Type Ia supernovae with NICMOS, reducing the
uncertainty in H_0 by a factor of two because of the smaller
dispersion along the instability strip, the diminished extinction, and
the weaker metallicity dependence in the infrared. In parallel with
ACS, at the same time the NICMOS observations are underway, we will
discover and follow a sample of Type Ia supernovae at z 1. Together,
these measurements, along with prior constraints from WMAP, will
provide a great improvement in HST's ability to distinguish between a
static, cosmological constant and dynamical dark energy. The Hubble
Space Telescope is the only instrument in the world that can make
these IR measurements of Cepheids beyond the Local Group, and it is
the only telescope in the world that can be used to find and follow
supernovae at z 1. Our program exploits both of these unique
capabilities of HST to learn more about one of the greatest mysteries
in science.

WFPC2 10745

WFPC2 CYCLE 14 INTERNAL MONITOR

This calibration proposal is the Cycle 14 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{both gain 7 and gain 15 -- to test stability of gains and bias
levels}, a test for quantum efficiency in the CCDs, and a monitor for
possible buildup of contaminants on the CCD windows. These also
provide raw data for generating annual super-bias reference files for
the calibration pipeline.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

10511 - GSAcq(2,3,2) required multiple attempts to achieve CT-DV

GSAcq(2,3,2) scheduled for 314:04:28:37 required two attempts to
achieve CT-DV on FGS2. The acquisition was successful.

10512 - GSAcq (2,1,2) failed due to Scan Step Limit Exceeded on FGS 2

Immediately after AOS(318/18:37:00) @ 318/18:37:28 GSAcq (2,1,2)
scheduled from 318/18:34:04-18:41:24 failed due to scan step limit
exceeded on FGS 2. OBAD #2 RSS value = 7.36 a-s. OBAD MAP RSS value =
3.38 a-s.

10513 - GSacq(2,1,2) failed due to search radius limit exceeded.

GSacq(2,1,2) scheduled at 319/02:54:24 failed at 02:59:28 due to
search radius limit exceeded on FGS 2. 486 STB message "a05" FGS
coarse track failed-search limit exceeded was received. OBAD1 showed
errors of V1=-6754.80, V2=301.24, V3=250.42, and RSS=6766.15. OBAD2
showed errors of V1=-6.08, V2=-5.13, V3=-2.55, and RSS=8.35.

Subsequent REacqs(2,1,2) at 319/04:21:12, 319/06:00:51, 319/07:37:10
and 319/08:48:43 all failed to RGA Hold due to search radius limit
exceeded on FGS-2. Additional 486 ESB message "a05" associated with
each REacq was received.

COMPLETED OPS REQUEST:
17949-1 - Uplink Atmospheric Density Parameter
17950-1 - Enable Dynamic Inertia
17953-2 - FSW 3.0B EEPROM Installation

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 04 02
FGS REacq 07 03
OBAD with Maneuver 22 22

SIGNIFICANT EVENTS:

Flash Report: FSW 3.0B EEPROM Installation & Atmospheric Density
Update FSW 3.0B was successfully installed in HST486 EEPROM via OR
17953.