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 z>7 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 z>7

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 z>7 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.