HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT       #4789

PERIOD COVERED: 5am February 10 - 5am February 11, 2009 (DOY

                           041/1000z-042/1000z)

OBSERVATIONS SCHEDULED

WFPC2 11612

Eta Carinae's Continuing Instability and Recovery - the 2009 Event

Eta Carinae is the only really observable example of structural recovery

from a massive giant eruption, a "supernova imposter' event. Moreover it

is the only well-observed star above 100 Msun, and its

5.5-year-recurrent spectroscopic events provide extraordinary clues to

its surface instability. This truly unique combination of attributes

makes it valuable for understanding the most massive stars. A fresh

development arose a few years ago: The star has brightened much faster

than before, and appears to have entered a rapid stage in its

post-eruption recovery.

A spectroscopic event will occur at 2009.0, soon after the planned HST

servicing mission. Because of the recent secular trend, this event is

expected to differ from its well-observed 2003.5 predecessor. The

differences will be very important, because they offer clues to

very-massive-star structural instabilities that can't be observed in any

other known way.

Some of the needed observations require HST's high spatial resolution

and UV coverage. We propose an efficient, well-chosen set of STIS and

ACS observations around the critical time. If the servicing mission is

too late for the event, then a subset of the observations will still be

merited.

WFPC2 11966

The Recent Star Formation History of SINGS Galaxies

The Spitzer Legacy project SINGS provided a unique view of the current

state of star formation and dust in a sample of galaxies of all Hubble

types. This multi-wavelength view allowed the team to create current

star formation diagnostics that are independent of the dust content and

increased our understanding of the dust in galaxies. Even so, using the

SINGS data alone we can only make rough estimates of the recent star

formation history of these galaxies. The lack of high resolution

observations (especially U-band and H-alpha) means that it is impossible

to estimate the ages of young clusters. In addition, the low resolution

of the Spitzer and ground-based observations means that what appear to

be individual Spitzer sources can actually be composed of many

individual clusters with varying ages. We need to know the ages, star

formation histories, and extinction of these individual clusters to

understand how these clusters form and age and thus influence the

evolution of the galaxy. In this proposal we address this missing area

of SINGS by obtaining high-resolution WFPC2 UBVI & H-alpha observations

to not only accurately locate and determine the ages of the young

stellar clusters in the actively star forming SINGS galaxies but to also

address a variety of other scientific issues. Over 500 HST orbits and

500 hours of Spitzter observing time have been dedicated to observations

of the SINGS sample. But the HST observations have not been systematic.

By adding a relatively small fraction of this time for these requested

observations, we will greatly enhance the legacy value of the SINGS

observations by creating a uniform high resolution multi-wavelength HST

archive that matches the quality of the lower resolution SINGS archive.

WFPC2 11967

WFPC2 Imaging of the Lockman Hole

In order to understand galaxy evolution and constrain theoretical

models, we require both multiwavelength photometry (to robustly

determine physical parameters such as star formation rates and stellar

masses) and detailed morphological information. Galaxy morphology

encodes crucial information about galaxy formation history and the

physical processes that trigger star formation and AGN activity, and

high-resolution imaging for large samples of galaxies is currently only

obtainable with HST. The Lockman Hole has been the target of extensive

multi-wavelength observations from the X-ray to the radio, and will be

the target of the deepest wide-area blankfield thermal IR observations

with Herschel, but currently lacks comprehensive HST imaging. We propose

to obtain WFPC2 imaging of ~500 arcmin2 of the central region of the

Lockman Hole in F606W and F814W, to a depth of V606~26.8 and I814~26.

This imaging is crucial in order to characterize the sources detected at

other wavelengths.

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                 09                 09                   

OBAD with Maneuver  28                  28               

SIGNIFICANT EVENTS:  (None)