Daily Report #4523

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4523

PERIOD COVERED: UT January 009, 2008 (DOY 009)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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 DARKs. 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 11219

Active Galactic Nuclei in nearby galaxies: a new view of the origin of the
radio-loud radio-quiet dichotomy?

Using archival HST and Chandra observations of 34 nearby early-type galaxies
{drawn from a complete radio selected sample} we have found evidence that
the radio-loud/radio-quiet dichotomy is directly connected to the structure
of the inner regions of their host galaxies in the following sense: [1]
Radio-loud AGN are associated with galaxies with shallow cores in their
light profiles [2] Radio-quiet AGN are only hosted by galaxies with steep
cusps. Since the brightness profile is determined by the galaxy's evolution,
through its merger history, our results suggest that the same process sets
the AGN flavour. This provides us with a novel tool to explore the
co-evolution of galaxies and supermassive black holes, and it opens a new
path to understand the origin of the radio-loud/radio-quiet AGN dichotomy.
Currently our analysis is statistically incomplete as the brightness profile
is not available for 82 of the 116 targets. Most galaxies were not observed
with HST, while in some cases the study is obstructed by the presence of
dust features. We here propose to perform an infrared NICMOS snapshot survey
of these 82 galaxies. This will enable us to i} test the reality of the
dichotomic behaviour in a substantially larger sample; ii} extend the
comparison between radio-loud and radio-quiet AGN to a larger range of
luminosities.

NIC3 10874

Search for Extremely Faint z7 Galaxy Population with Cosmic Lenses

Deep UDF/NICMOS observations find a significant decrease in the number of
galaxy candidates between redshift z=6 and 7, but the sample at z7 is too
small to draw conclusions. From our observations of 15 clusters we have
found a number of bright z-dropouts, aided by the lensing amplification. We
propose deep NICMOS observations of the best cases of cluster centers where
a rare combination of a significant lensing effect and the richness in
z-band dropouts in background may dramatically increase the discovery rate.
The NICMOS images will reach an unprecedented depth of AB~27.8, or AB~30 in
nonlensed intrinsic magnitude, and may find many faint {~0.05L*} galaxies at
z=7-10, at a level that the UDF reaches for z~6 objects. We produce
precision mass distribution maps from weak-lensing models, which enable us
to derive the candidates' intrinsic magnitudes and their luminosity
function. The knowledge of such faint galaxy population at z7 will
facilitate the models of the IGM reionization and future JWST planning.

WFPC2 11104

The nature of radio transients

We have conducted the first ever blind, wide-field survey for radio
transients (Levinson et al. 2002; Gal-Yam et al. 2006). We have discovered
four radio transients and explored their nature using radio and optical
follow-up observations. One is a known pulsar, one is a z~0.1 AGN, and one
is most probably an optically obscured radio supernova (SN) in the nearby
galaxy NGC 4216 (the first such event to be discovered by a wide field radio
survey). The last source appears not to be associated with a bright host
galaxy (to a limit of R 24.5 mag). We request 4 orbits of WFPC2 F606W
imaging to check whether we can establish an association between this radio
transient and any of three nearby faint resolved galaxies we have detected
from the ground. If the source is associated with any of these galaxies it
would represent a new type of extra-galactic radio bursts, more luminous
than, e.g., radio afterglows of gamma-ray bursts. Alternatively, ruling out
an association with these galaxies would disfavor an extra-galactic nature
of this object, and suggest instead that this is a radio outburst of a faint
Galactic compact object, probably a new type of radio-flaring neutron star.
If this is the case, the high luminosity (9 mJy) and relatively high
galactic latitude (33 degrees) of this source may indicate it is relatively
nearby. This single source represents a large population (comparable in sky
density to AGN, pulsars, and radio SNe) and thus merits intensive study. A
modest investment of HST time, leveraged by massive ground-based radio and
optical efforts, will allow us to identify a new class of radio sources, and
complete a census of the variable radio sky down to ~6 mJy, leaving no
unidentified objects. This result can be directly scaled to predict the
number and type of transient sources expected to be detected by future
surveys with the next generation radio arrays, such as ATA and SKA. Since
our science critically requires HST's spatial resolution (rather than
sensitivity) it is perfectly suited to be carried out with WFPC2.

WFPC2 11217

The Light Echoes around V838 Monocerotis

V838 Monocerotis, which burst upon the astronomical scene in early 2002, is
a completely unanticipated new object. It underwent a large-amplitude and
very luminous outburst, during which its spectrum remained that of an
extremely cool supergiant. A rapidly evolving set of light echoes around
V838 Mon was discovered soon after the outburst, and quickly became the most
spectacular display of the phenomenon ever seen. These light echoes provide
the means to accomplish three unique types of measurements based on
continued HST imaging during the event: {1} Study effects of MHD turbulence
at high resolution and in 3 dimensions; {2} Construct the first unambiguous
and fully 3-D map of a circumstellar dust envelope in the Milky Way; {3}
Study dust physics in a unique setting where the spectrum and light curve of
the illumination, and the scattering angle, are unambiguously known. We have
also used our HST data to determine the distance to V838 Mon through direct
geometric techniques. Because of the extreme rarity of light echoes, this is
almost certainly the only opportunity to achieve such results during the
lifetime of HST. We propose two visits during Cycle 16, in order to continue
the mapping of the circumstellar dust and to accomplish the other goals
listed above.

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:

18169-0 Add G1 UKF Input Configuration

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 05 05
FGS REacq 08 08
OBAD with Maneuver 26 26

SIGNIFICANT EVENTS:

Ops Request 18169-0 execution succeeded at 2008/009 14:11:43. The Kalman
filter was disabled, gyro 1 input was enabled, and the UKF was
re-initialized. UKF performance was nominal following re-initialization;
peak attitude estimate errors of about 3 degrees RSS occurred after
initialization and steady-state performance exhibited less than 1 degree
error. This UKF re-configuration establishes the OGS OOT input configuration
for pre-test performance monitoring.