HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      # 4570

PERIOD COVERED: UT March 18, 2008 (DOY 078)

OBSERVATIONS SCHEDULED

FGS 11295

Trigonometric Calibration of the Distance Scale for Classical Novae

The distance scale for classical novae is important for understanding

the stellar physics of their thermonuclear runaways, their contribution

to Galactic nucleosynthesis, and their use as extragalactic standard

candles. Although it is known that there is a relationship between their

absolute magnitudes at maximum light and their subsequent rates of

decline--the well-known maximum-magnitude rate-of-decline {MMRD}

relation--it is difficult to set the zero-point for the MMRD because of

the very uncertain distances of Galactic novae. We propose to measure

precise trigonometric parallaxes for the quiescent remnants of the four

nearest classical novae. We will use the Fine Guidance Sensors, which

are proven to be capable of measuring parallaxes with errors of ~0.2

mas, well below what is possible from the ground.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

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 i

mages. Each observation will need its own CRMAP, as different SAA

passages leave different imprints on the NICMOS detectors.

NIC3 11195

Morphologies of the Most Extreme High-Redshift Mid-IR-luminous Galaxies

II: The `Bump' Sources

The formative phase of some of the most massive galaxies may be

extremely luminous, characterized by intense star- and AGN-formation.

Till now, few such galaxies have been unambiguously identified at high

redshift, and thus far we have been restricted to studying the

low-redshift ultraluminous infrared galaxies as possible analogs. We

have recently discovered a sample of objects which may indeed represent

this early phase in galaxy formation, and are undertaking an extensive

multiwavelength study of this population. These objects are optically

extremely faint {R>26} but nevertheless bright at mid-infrared

wavelengths {F[24um] > 0.5 mJy}. Mid-infrared spectroscopy with

Spitzer/IRS reveals that they have redshifts z~2, implying luminosities

~1E13 Lsun. Their mid-IR SEDs fall into two broad, perhaps overlapping,

categories. Sources with brighter F[24um] exhibit power-law SEDs and SiO

absorption features in their mid-IR spectra characteristic of AGN,

whereas those with fainter F[24um] show a "bump" characteristic of the

redshifted 1.6um peak from a stellar population, and PAH emission

characteristic of starformation. We have begun obtaining HST images of

the brighter sources in Cycle 15 to obtain identifications and determine

kpc-scale morphologies for these galaxies. Here, we aim to target the

second class {the "bump" sources} with the goal of determining if these

constitute morphologically different objects, or simply a "low-AGN"

state of the brighter class. The proposed observations will help us

determine whether these objects are merging systems, massive obscured

starbursts {with obscuration on kpc scales!} or very reddened {locally

obscured} AGN hosted by intrinsically low-luminosity galaxies.

NIC3 11333

NICMOS non-linearity tests

This program incorporates a number of tests to analyze the count rate

dependent non-linearity seen in NICMOS spectro-photometric observations.

We will observe a field with stars of a range in luminosity in NGC3603

with NICMOS in NIC1: F090M, F110W, F140W, F160W NIC2: F110W, F160W,

F187W, F205W, and F222M NIC3: F110W, F150W, F160W, F175W, and F222M. We

will repeat the observations with flatfield lamp on, creating

artificially high count-rates, allowing tests of NICMOS linearity as

function of count rate. We first take exposures with the lamp off, then

exposures with the lamp on, and repeat at the end with lamp off.

Finally, we continue with taking darks during occultation.

We will furthermore observe spectro-photometric standard P041C using the

G096, G141, and G206 grisms in NIC3, and repeat the lamp off/on/off test

to artificially create a high background.

WFPC2 11207

Star Formation in the Perseus Cluster Cooling Flow

We propose to obtain high resolution, UV/optical imaging of the

"accretion populations" in the massive cooling flow of the Perseus

cluster of galaxies. New GALEX observations show that the dominant

galaxy in this nearby cluster, NGC 1275, has an extended network of

UV-bright populations apparently formed recently from the intracluster

gas. Cluster cooling flows are the most prominent of the environments

where we can readily observe the cycle of gas accretion, star formation,

and feedback from active nuclei that is thought to play a central role

in the formation and evolution of galaxies. Because they can be readily

age-dated, the accretion populations help to trace the sequence of

exchange of material between galaxies and the intracluster medium. The

ACS/SBC and WFPC2/PC cameras offer the highest spatial resolution and

best panchromatic performance available to map the spatial and age

distribution of the accretion populations and their relationship to

radio-emitting plasma and the hot intracluster gas.

WFPC2 11235

HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies

in the Local Universe At luminosities above 10^11.4 L_sun, the space

density of far-infrared selected galaxies exceeds that of optically

selected galaxies. These `luminous infrared galaxies' {LIRGs} are

primarily interacting or merging disk galaxies undergoing enhanced star

formation and Active Galactic Nuclei {AGN} activity, possibly triggered

as the objects transform into massive S0 and elliptical merger remnants.

We propose NICMOS NIC2 imaging of the nuclear regions of a complete

sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS

Revised Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24

Jy}. This sample is ideal not only in its completeness and sample size,

but also in the proximity and brightness of the galaxies. The superb

sensitivity and resolution of NICMOS NIC2 on HST enables a unique

opportunity to study the detailed structure of the nuclear regions,

where dust obscuration may mask star clusters, AGN and additional nuclei

from optical view, with a resolution significantly higher than possible

with Spitzer IRAC. This survey thus provides a crucial component to our

study of the dynamics and evolution of IR galaxies presently underway

with Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88

galaxies. Imaging will be done with the F160W filter {H-band} to examine

as a function of both luminosity and merger stage {i} the luminosity and

distribution of embedded star clusters, {ii} the presence of optically

obscured AGN and nuclei, {iii} the correlation between the distribution

of 1.6 micron emission and the mid- IR emission as detected by Spitzer

IRAC, {iv} the evidence of bars or bridges that may funnel fuel into the

nuclear region, and {v} the ages of star clusters for which photometry

is available via ACS/WFC observations. The NICMOS data, combined with

the HST ACS, Spitzer, and GALEX observations of this sample, will result

in the most comprehensive study of merging and interacting galaxies to

date.

WFPC2 11343

Identifying the host galaxies for optically dark gamma-ray bursts

We propose to use the high spatial resolution capabilities of Chandra to

obtain precise positions for a sample of Gamma-ray bursts (GRBs) with no

optical afterglows, where the optical light is supresssed relative to

the X-ray flux. These bursts are likely to be highly obscured and may

have different environments from the optically bright GRBs. Our Chandra

observations will (unlike Swift-XRT positions) allow for the unique

identification of a host galaxy. To locate these host galaxies we will

follow up our Chandra positions with deep optical and IR observations

with HST. The ultimate aim is to understand any differences between the

host galaxies of optically dark and bright GRBs, and how these affect

the use of GRBs as tracers of starformation and galaxy evolution at high

redshift.

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               10                   10               

FGS REacq               04                   04                 

OBAD with Maneuver 28                   28                 

SIGNIFICANT EVENTS: (None)