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Daily Report #4492



 
 
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Old November 20th 07, 04:27 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #4492

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science
capability in January, there may be an occasional discrepancy between
a proposal's listed (and correct) instrument usage and the abstract
that follows it.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** # 4492

PERIOD COVERED: UT November 19, 2007 (DOY 323)

OBSERVATIONS SCHEDULED

WFPC2 10583

Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects ?

We are requesting 32 HST orbits to help ascertain the nature of the
population that gives rise to the observed set of microlensing events
towards the LMC. The SuperMACHO project is an ongoing ground-based
survey on the CTIO 4m that has demonstrated the ability to detect LMC
microlensing events in real-time via frame subtraction. The
improvement in angular resolution and photometric accuracy available
from HST will allow us to 1} confirm that the detected flux excursions
arise from LMC source stars rather than extended objects {such as for
background supernovae or AGN}, and 2} obtain reliable baseline flux
measurements for the objects in their unlensed state. The latter
measurement is important to resolve degeneracies between the event
timescale and baseline flux, which will yield a tighter constraint on
the microlensing optical depth.

WFPC2 11024

WFPC2 CYCLE 15 INTERNAL MONITOR

This calibration proposal is the Cycle 15 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.

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 11197

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 that 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 Phillip's relation over
cosmic time. High signal-to-noise measurements of 16 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. In Cycle 15 we obtained
NICMOS photometry of 8 ESSENCE supernovae and are awaiting template
observations to place them on the IR Hubble diagram. Here we request
another 8 supernovae be studied in the final season of the ESSENCE
search. 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.

S/C 4974

TRTTEST

The Transient Response Test is for the periodic performance monitoring
of the FGS 2R servo A mechanism.

WFPC2 11035

Photometric Zero Points Closeout

Updated zero points will be obtained by observing NGC 2419 for which
extensive BVRI ground based observations exist, and the field in 47
Tuc used for frequent monitoring of ACS. For NGC 2419 emphasis is
given to repeating observations obtained in earlier epochs, and to
covering filters near standard BVRI. For 47 Tuc emphasis is given to
covering a large set of broadband filters from F300W through F850LP to
maximize transformation capabilities between filters of WFPC2 and
ACS.

WFPC2 11070

WFPC2 CYCLE 15 Standard Darks - part II

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing calibration of the CCD dark current
rate, and to monitor and characterize the evolution of hot pixels.
Over an extended period these data will also provide a monitor of
radiation damage to the CCDs.

WFPC2 11126

Resolving the Smallest Galaxies

An order of magnitude more dwarf galaxies are expected to inhabit the
Local Group, based on currently accepted galaxy formation models, than
have been observed. This discrepancy has been noted in environments
ranging from the field to rich clusters, with evidence emerging that
lower density regions contain fewer dwarfs per giant than higher
density regions, in further contrast to model predictions. One
possible explanation for this involves the effects of reionization on
the forming galaxies and naturally explains both the dearth of dwarf
galaxies and the apparent environmental dependence. However, before
such theories can be fully tested, we require a better understanding
of the distribution of dwarf galaxies. Currently, there is no complete
census of the faintest dwarf galaxies in any environment. The
discovery of the smallest and faintest dwarfs is hampered by the
limitations in detecting such faint and low surface brightness
galaxies, and this is compounded by the great difficulty in
determining accurate distances to, or ascertaining group membership
for, such faint objects. The M81 group provides a unique means for
establishing membership for galaxies in a low density region complete
to magnitudes as faint as M_R ~ -7. With a distance modulus of 27.8,
the tip of the red giant branch {TRGB} appears at I ~ 24, just within
the reach of ground based surveys. We currently have surveyed a 30
square degree region around M81 with the CFHT/Megacam. From these
images we have detected 15 new candidate dwarf galaxies. We propose to
use the HST with WFPC2 to image these 15 galaxies in F606W and F814W
bands in order to construct a color-magnitude diagram down to I = 25.5
from which to measure accurate TRGB distances to these candidate
galaxies and determine star formation and metallicity histories. The
overall project will provide a survey of the dwarf galaxies in the M81
group environment with unprecedented completeness to a limit of M_R
-7.

WFPC2 11130

AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge
Paradigm, Part II

The recent progress in the study of central black holes in galactic
nuclei has led to a general consensus that supermassive {10^6-10^9
solar mass} black holes are closely connected with the formation and
evolutionary history of large galaxies, especially their bulge
component. Two outstanding issues, however, remain unresolved. Can
central black holes form in the absence of a bulge? And does the mass
function of central black holes extend below 10^6 solar masses?
Intermediate-mass black holes {10^6 solar masses}, if they exist, may
offer important clues to the nature of the seeds of supermassive black
holes. Using the SDSS, our group has successfully uncovered a new
population of AGNs with intermediate-mass black holes that reside in
low-luminosity galaxies. However, very little is known about the
detailed morphologies or structural parameters of the host galaxies
themselves, including the crucial question of whether they have bulges
or not. Surprisingly, the majority of the targets of our Cycle 14
pilot program have structural properties similar to dwarf elliptical
galaxies. The statistics from this initial study, however, are really
too sparse to reach definitive conclusions on this important new class
of black holes. We wish to extend this study to a larger sample, by
using the Snapshot mode to obtain WFPC2 F814W images from a parent
sample of 175 AGNs with intermediate-mass black holes selected from
our final SDSS search. We are particularly keen to determine whether
the hosts contain bulges, and if so, how the fundamental plane
properties of the host depend on the mass of their central black
holes. We will also investigate the environment of this unique class
of AGNs.

WFPC2 11218

Snapshot Survey for Planetary Nebulae in Globular Clusters of the
Local Group

Planetary nebulae {PNe} in globular clusters {GCs} raise a number of
interesting issues related to stellar and galactic evolution. The
number of PNe known in Milky Way GCs, 4, is surprisingly low if one
assumes that all stars pass through a PN stage. However, it is likely
that the remnants of stars now evolving in Galactic GCs leave the AGB
so slowly that any ejected nebula dissipates long before the star
becomes hot enough to ionize it. Thus there should not be ANY PNe in
Milky Way GCs--but there are four! It has been suggested that these
PNe are the result of mergers of binary stars within GCs, i.e., that
they are descendants of blue stragglers. The frequency of occurrence
of PNe in external galaxies poses more questions, because it shows a
range of almost an order of magnitude. I propose a Snapshot survey
aimed at discovering PNe in the GC systems of Local Group galaxies
more distant than the Magellanic Clouds. These clusters, some of which
may be much younger than their counterparts in the Milky Way, might
contain many more PNe than those of our own galaxy. I will use the
standard technique of emission-line and continuum imaging, which
easily discloses PNe.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11072 - GSAcq(1,2,2) failed to RGA Hold (Gyro Control)

Upon acquisition of signal (AOS) at 324/02:23:17, the
GSAcq(1,2,2)scheduled at 324/02:17:29 - 02:25:34 had failed to RGA
Hold due to (QF2STOPF) stop flag indication on FGS-2. Pre-acquisition
OBAD1 attitude correction value not available due to LOS. Pre-acq
OBAD2 had (RSS) value of 12.62 arcseconds. Post-acq OBAD/MAP not
scheduled.

11073 - REAcq (1,2,2) results in FLBU (1,0,1)

REAcq (1,2,2) scheduled from 324/06:48:11 - 06:55:43 failed to fine
lock back up (FLBU 1,0,1) due to QSTOP flag on FGS2. Pre-acquisition
OBAD #1 had an RSS value of 2618.65 arc-seconds and OBAD #2 had an RSS
value of 9.11 arc-seconds. An OBAD MAP was not scheduled. No 486 STB
messages were noted. This reacquisition is using the same guide stars
as were used in HSTAR 11072.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSacq************** 05***************** 04
FGS REacq************** 07***************** 07
OBAD with Maneuver **** 28***************** 28

SIGNIFICANT EVENTS:

Flash Report: TRTT Successful

The sixteenth run of the Transient Response Trending Test (TRTT) was
successfully completed via Ops Request 18156 at 323/15:57z this
morning. Analysis will be presented at the next GSAWG meeting.


 




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