Notice: For the foreseeable future, the daily reports may contain

apparent discrepancies between some proposal descriptions and the listed

instrument usage. This is due to the conversion of previously approved

ACS WFC or HRC observations into WFPC2, or NICMOS observations

subsequent to the loss of ACS CCD science capability in late January.

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      # 4341

PERIOD COVERED: UT April 13,14,15, 2007 (DOY 103,104,105)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

A new proceedure proposed to alleviate the CR-persistence problem of

NICMOS. Dark frames will be obtained immediately upon exiting the SAA

contour 23, and everytime 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.

WFPC2 11085

Europa in Eclipse: Tenuous Atmosphere, Electromagnetic Activity and

Surface Luminescence HST Proposal 11085 We propose to image Europa

during its orbital eclipse by Jupiter. This will form the basis of an

investigation into the nature of the tenuous atmosphere, electromagnetic

environment and surface material of Europa. We will compare the FUV

oxygen line at 1356A to the optical line at 6300A and seek optical

auroral hydrogen emission in Halpha. With broad continuum filters, we

will search for optical emissions from other atmospheric constituents

and for fluorescence of the surface material, arising from the very high

level of incident energetic particle radiation. The high spatial

resolution of ACS will allow us to fully resolve scales of interest and

allow us to distinguish easily the different terrains on Europa's

surface. In particular we wish to compare luminesence in regions

dominated by ice to those of potentially organic red material.

WFPC2 11083

The Structure, Formation and Evolution of Galactic Cores and Nuclei

A surprising result has emerged from the ACS Virgo Cluster Survey

{ACSVCS}, a program to obtain ACS/WFC gz imaging for a large, unbiased

sample of 100 early-type galaxies in the Virgo Cluster. On subarcsecond

scales {i.e., <0.1"-1"}, the HST brightness profiles vary systematically

from the brightest giants {which have nearly constant surface brightness

cores} to the faintest dwarfs {which have compact stellar nuclei}.

Remarkably, the fraction of galaxy mass contributed by the nuclei in the

faint galaxies is identical to that contributed by supermassive black

holes in the bright galaxies {0.2%}. These findings strongly suggest

that a single mechanism is responsible for both types of Central Massive

Object: most likely internally or externally modulated gas inflows that

feed central black holes or lead to the formation of "nuclear star

clusters". Understanding the history of gas accretion, star formation

and chemical enrichment on subarcsecond scales has thus emerged as the

single most pressing question in the study of nearby galactic nuclei,

either active or quiescent. We propose an ambitious HST program {199

orbits} that constitutes the next, obvious step forward:

high-resolution, ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W}

imaging for the complete ACSVCS sample. By capitalizing on HST's unique

ability to provide high-resolution images with a sharp and stable PSF at

UV and IR wavelengths, we will leverage the existing optical HST data to

obtain the most complete picture currently possible for the history of

star formation and chemical enrichment on these small scales. Equally

important, this program will lead to a significant improvement in the

measured structural parameters and density distributions for the stellar

nuclei and the underlying galaxies, and provide a sensitive measure of

"frosting" by young stars in the galaxy cores. By virtue of its superb

image quality and stable PSF, NICMOS is the sole instrument capable of

the IR observations proposed here. In the case of the WFPC2

observations, high-resolution UV imaging {< 0.1"} is a capability unique

to HST, yet one that could be lost at any any time.

NIC3 11082

NICMOS Imaging of GOODS: Probing the Evolution of the Earliest Massive

Galaxies, Galaxies Beyond Reionization, and the High Redshift Obscured

Universe

Deep near-infrared imaging provides the only avenue towards

understanding a host of astrophysical problems, including: finding

galaxies and AGN at z > 7, the evolution of the most massive galaxies,

the triggering of star formation in dusty galaxies, and revealing

properties of obscured AGN. As such, we propose to observe 60 selected

areas of the GOODS North and South fields with NICMOS Camera 3 in the

F160W band pointed at known massive M > 10^11 M_0 galaxies at z > 2

discovered through deep Spitzer imaging. The depth we will reach {26.5

AB at 5 sigma} in H_160 allows us to study the internal properties of

these galaxies, including their sizes and morphologies, and to

understand how scaling relations such as the Kormendy relationship

evolved. Although NIC3 is out of focus and undersampled, it is currently

our best opportunity to study these galaxies, while also sampling enough

area to perform a general NIR survey 1/3 the size of an ACS GOODS field.

These data will be a significant resource, invaluable for many other

science goals, including discovering high redshift galaxies at z > 7,

the evolution of galaxies onto the Hubble sequence, as well as examining

obscured AGN and dusty star formation at z > 1.5. The GOODS fields are

the natural location for HST to perform a deep NICMOS imaging program,

as extensive data from space and ground based observatories such as

Chandra, GALEX, Spitzer, NOAO, Keck, Subaru, VLT, JCMT, and the VLA are

currently available for these regions. Deep high-resolution

near-infrared observations are the one missing ingredient to this

survey, filling in an important gap to create the deepest, largest, and

most uniform data set for studying the faint and distant universe. The

importance of these images will increase with time as new facilities

come on line, most notably WFC3 and ALMA, and for the planning of future

JWST observations.

ACS/SBC 11074

ACS/SBC Darks in Support of Specific SBC Science Observations

This program provides SBC DARK visits to be scheduled in conjuction with

certain specific science observations which require the SBC to be turned

on in the orbit preceeding the science observation.

NIC1/NIC2/NIC3 11060

NICMOS Photometric Stability Monitoring

This NICMOS calibration proposal carries out photometric monitoring

observations during Cycle 15. The format is the same as the Cycle 14

version of the program {10725}, but a few modifications were made with

respect to the Cycle 12 program 9995 and Cycle 13 program 10381.

Provisions had to be made to adopt to 2-gyro mode {G191B2B was added as

extra target to provide target visibility through most of the year}.

Where before 4 or 7 dithers were made in a filter before we moved to the

next filter, now we observe all filters at one position before moving to

the next dither position. While the previous method was chosen to

minimize the effect of persistence, we now realize that persistence may

be connected to charge trapping and by moving through the filter such

that the count rate increases, we reach equilibrium more quickly between

charge being trapped and released. We have also increased exposure times

where possible to reduce the charge trapping non- linearity effects.

WFPC2 11031

CTE Background Dependence Closeout

Measuring the charge transfer efficiency {CTE} of an astronomical CCD

camera is crucial to determining the CCD's photometric fidelity across

the field of view. WFPC2's CTE has degraded steadily over the last 13

years because of continuous exposure to trapped particles in HST's

radiation environment. The fraction of photometric signal lost from

WFPC2's CTI {charge transfer inefficiency} is a function of WFPC2's time

in orbit, the integrated signal in the image, the location of the image

on the CCD, and the background signal. Routine monitoring of WFPC2's CTE

over the last 13 years permits an assessment of all but the last

condition. The dependence of CTE on background signal must be

characterized, however, because a large fraction of WFPC2 images have

been obtained under conditions of significant sky background. This

program aims to assess the end-of-life CTE of WFPC2's CCDs separately as

a function of background signal. Traditional images of an off-center

field in NGC 5139 {Omega Cen} are recorded after preflashing {or before

postflashing} the CCDs with internal lamps to provide average background

signals of 0-160 e-, which span the range of sky backgrounds observed in

~99% of long-exposure narrow- and broad-band WFPC2 images.

ACS/SBC 10907

Testing the first direct measurement of cataclysmic variable evolution:

the search for a circumbinary disk or a low?mass companion around NN

Serpentis

We obtained high time-resolution photometry using the high speed CCD

camera ULTRACAM between 2002 and 2004, which revealed a gradual

reduction in the orbital period of the pre- cataclysmic variable NN

Serpentis. There are three possible explanations for this period change:

firstly, we may have been successful in obtaining the first and only

direct measurement of the braking rate of a close binary system, in

which case our measured values are approximately 2 orders of magnitude

greater than predicted, and pose serious problems for the theory of

close binary evolution. Secondly, the unusually high braking rate may be

caused by the presence of a circumbinary disk, which would help to

answer two of the outstanding problems with current CV theory - namely

the high mass- transfer rates seen in some CVs, and the fact that the

minimum observed value in the CV period distribution is approximately

15% longer than expected. Finally, our observations could be explained

by a light travel-time effect caused by a third body in orbit around the

binary, which would raise major questions about the evolutionary history

of the system, in particular how a third body has managed to remain in a

stable orbit throughout periods of intense mass-loss in the central

binary. We intend to use IRAC observations to search for a mid-infrared

excess in the spectral energy distribution of NN Ser, which would

confirm the presence of either a disk or a third body. We then propose

to use HST imaging to attempt to resolve a third body, allowing us to

discriminate between the two possibilities. If both methods fail to

reveal any extra system components, we will have ruled out our only

remaining alternatives to a genuinely high angular momentum loss rate in

this system, with profound implications for CV evolution.

WFPC2 10890

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

The formative phase 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,

restricting us to the study of 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 bright at mid-IR wavelengths

{F[24um]>0.8mJy}, but deep ground based imaging suggests extremely faint

{and in some cases extended} optical counterparts {R~24-27}. Deep K-band

images show barely resolved galaxies. Mid-infrared spectroscopy with

Spitzer/IRS reveals that they have redshifts z ~ 2-2.5, suggesting

bolometric luminosities ~10^{13-14}Lsun! We propose to obtain deep ACS

F814W and NIC2 F160W images of these sources and their environs in order

to determine kpc-scale morphologies and surface photometry for these

galaxies. The proposed observations will help us determine whether these

extreme objects are merging systems, massive obscured starbursts {with

obscuration on kpc scales!} or very reddened {locally obscured} AGN

hosted by intrinsically low-luminosity galaxies.

WFPC2 10880

The host galaxies of QSO2s: AGN feeding and evolution at high

luminosities

Now that the presence of supermassive black holes in the nuclei of

galaxies is a well established fact, other questions related to the AGN

phenomena still have to be answered. Problems of particular interest are

how the AGN gets fed, how the black hole evolves and how the evolution

of the black hole is related to the evolution of the galaxy bulge. Here

we propose to address some of these issues using ACS/WFC + F775W

snapshot images of 73 QSO2s with redshifts in the range 0.3<z<0.4. These

observations will be combined with similar archival data of QSO1s and

ground based data of Seyfert and normal galaxies. First, we will

intestigate whether interactions are the most important feeding

mechanism in high luminosity AGNs. This will be done in a quantitative

way, comparing the asymmetry indices of QSO2 hosts with those of lower

luminosity AGNs and normal galaxies. Second, we will do a detailed study

of the morphology of the host galaxies of both QSO types, to determine

if they are similar, or if there is an evolutionary trend from QSO2s to

QSO1s. The results from this project will represent an important step in

the understanding of AGN evolution, and may also introduce a substantial

modification to the Unified Model.

WFPC2 10877

A Snapshot Survey of the Sites of Recent, Nearby Supernovae

During the past few years, robotic {or nearly robotic} searches for

supernovae {SNe}, most notably our Lick Observatory Supernova Search

{LOSS}, have found hundreds of SNe, many of them in quite nearby

galaxies {cz < 4000 km/s}. Most of the objects were discovered before

maximum brightness, and have follow-up photometry and spectroscopy; they

include some of the best-studied SNe to date. We propose to conduct a

snapshot imaging survey of the sites of some of these nearby objects, to

obtain late-time photometry that {through the shape of the light and

color curves} will help reveal the origin of their lingering energy. The

images will also provide high-resolution information on the local

environments of SNe that are far superior to what we can procure from

the ground. For example, we will obtain color-color and color-magnitude

diagrams of stars in these SN sites, to determine the SN progenitor

masses and constraints on the reddening. Recovery of the SNe in the new

HST images will also allow us to actually pinpoint their progenitor

stars in cases where pre- explosion images exist in the HST archive.

This proposal is an extension of our successful Cycle 13 snapshot survey

with ACS. It is complementary to our Cycle 15 archival proposal, which

is a continuation of our long-standing program to use existing HST

images to glean information about SN environments.

WFPC2 10873

The Radio-quiet Jet Flow in Markarian 34

The properties of AGN jet flows are notoriously difficult to ascertain.

We are currently studying jets in Seyferts by combining emission-line

diagnostics with radio observations. We have devised a method of

analysis which -- with only modest and reasonable assumptions -- leads

to a physical description of the jet flow: its mass, momentum and energy

flux, along with its density, velocity and Mach number. We have applied

this method to a rich dataset on Markarian 78 and discovered that its

jet is very weak, slow, and dense relative to the kind of jets found in

radio loud AGN {Whittle \& Wilson 2004, Whittle et al 2005, 2006}. Such

a difference between radio quiet and radio loud jet flows would be a

major result -- if it were found to be generally true. We have more

modest observations of a further six Seyferts with jets, but only one of

these -- Mkn 34 -- approaches Mkn 78 as a clean enough case to allow our

full analysis. Our existing VLA and STIS data are excellent, but the HST

archive emission-line and continuum images are of poor quality and low

resolution. We are requesting just 3 orbits to obtain higher S/N images

at high resolution {ACS/HRC} in [OIII] 5007, [OII] 3727, green and red

continuum, bringing the total dataset up to a par with that of Mkn 78.

We will then be able to apply our full analysis to determine the nature

of the jet flow in this second radio quiet AGN.

ACS/SBC 10872

Lyman Continuum Emission in Galaxies at z=1.2

Lyman continuum photons produced in massive starbursts may have played a

dominant role in the reionization of the Universe. Starbursts are

important contributors to the ionizing metagalactic background at lower

redshifts as well. However, their contribution to the background depends

upon the fraction of ionizing radiation that escapes from the intrinsic

opacity of galaxies below the Lyman limit. Current surveys suggest

escape fractions of a few percent, up to 10%, with very few detections

{as opposed to upper limits} having been reported. No detections have

been reported in the epochs between z=0.1 and z=2. We propose to measure

the fraction of escaping Lyman continuum radiation from 15 luminous

z~1.2 galaxies in the GOODS fields. Using the tremendous sensitivity of

the ACS Solar- blind Channel, we will reach AB=30 mag., allowing us to

detect an escape fraction of 1%. We will correlate the amount of

escaping radiation with the photometric and morphological properties of

the galaxies. A non-detection in all sources would imply that QSOs

provide the overwhelming majority of ionizing radiation at z=1.3, and it

would strongly indicate that the properties of galaxies at higher

redshift have to be significantly different for galaxies to dominate

reionization. The deep FUV images will also be useful for extending the

FUV study of other galaxies in the GOODS fields.

ACS/SBC 10862

Comprehensive Auroral Imaging of Jupiter and Saturn during the

International Heliophysical Year

A comprehensive set of observations of the auroral emissions from

Jupiter and Saturn is proposed for the International Heliophysical Year

in 2007, a unique period of especially concentrated measurements of

space physics phenomena throughout the solar system. We propose to

determine the physical relationship of the various auroral processes at

Jupiter and Saturn with conditions in the solar wind at each planet.

This can be accomplished with campaigns of observations, with a sampling

interval not to exceed one day, covering at least one solar rotation.

The solar wind plasma density approaching Jupiter will be measured by

the New Horizons spacecraft, and a separate campaign near opposition in

May 2007 will determine the effect of large-scale variations in the

interplanetary magnetic field {IMF} on the Jovian aurora by

extrapolation from near-Earth solar wind measurements. A similar Saturn

campaign near opposition in Jan. 2007 will combine extrapolated solar

wind data with measurements from a wide range of locations within the

Saturn magnetosphere by Cassini. In the course of making these

observations, it will be possible to fully map the auroral footprints of

Io and the other satellites to determine both the local magnetic field

geometry and the controlling factors in the electromagnetic interaction

of each satellite with the corotating magnetic field and plasma density.

Also in the course of making these observations, the auroral emission

properties will be compared with the properties of the near-IR

ionospheric emissions {from ground-based observations} and non thermal

radio emissions, from ground-based observations for Jupiter?s decametric

radiation and Cassini plasma wave measurements of the Saturn Kilometric

Radiation {SKR}.

NIC3 10839

The NICMOS Polarimetric Calibration

Recently, it has been shown that NICMOS possesses an instrumental

polarization at a level of 1.2%. This completely inhibits the data

reduction in a number of previous GO programs, and hampers the ability

of the instrument to perform high accuracy polarimetry. In all, 90

orbits of HST data are affected, with potentially many more in Cycle 15.

We propose to obtain high signal to noise observations of three

polarimetric standards at the cardinal roll angles of the NICMOS

polarizers for both NIC1 and NIC2. These observations are designed to

fully characterize the instrumental polarization in order for NICMOS to

reach its full potential by enabling high accuracy polarimetry of

sources with polarizations around 1%. The residual polarization will

also be determined as a function of position and spectral energy

distribution. Our group will rapidly turn around the required data

products and produce reports and software for the accurate

representation of the instrumental polarization. These items will be

presented to STScI and for dissemination among the wider astronomical

community.

WFPC2 10829

Secular Evolution at the End of the Hubble Sequence

The bulgeless disk galaxies at the end of the Hubble Sequence evolve at

a glacial pace relative to their more violent, earlier-type cousins. The

causes of their internal, or secular evolution are important because

secular evolution represents the future fate of all galaxies in our

accelerating Universe and is a key ingredient to understanding galaxy

evolution in lower-density environments at present. The rate of secular

evolution is largely determined by the stability of the cold ISM against

collapse, star formation, and the buildup of a central bulge. Key

diagnostics of the ISM's stability are the presence of compact molecular

clouds and narrow dust lanes. Surprisingly, edge-on, pure disk galaxies

with circular velocities below 120 km/s do not appear to contain such

dust lanes. We propose to obtain ACS/WFC F606W images of a well-selected

sample of extremely late-type disk galaxies to measure the

characteristic scale size of the cold ISM and determine if they possess

the unstable, cold ISM necessary to drive secular evolution. Our sample

has been carefully constructed to include disk galaxies above and below

the critical circular velocity of 120 km/s where the dust properties of

edge-on disks change so remarkably. We will then use surface brightness

profiles to search for nuclear star clusters and pseudobulges, which are

early indicators that secular evolution is at work, as well as measure

the pitch angle of the dust lanes as a function of radius to estimate

the central mass concentrations.

ACS/SBC 10814

The Masses for ultraluminous X-ray sources

Ultraluminous X-ray sources are non-nuclear sources in normal disk

galaxies that are either stellar mass black holes that are

super-Eddington emitters, or 1E3-1E4 Msolar black holes emitting

normally. We can distinguish between these models by obtaining

constraints for the mass of the primary, which can be accomplished

through UV objective prism spectra. This strategy begins with the

optical identification of the secondary and identification of its

spectral type in order to determine its mass and the Roche Lobe radius.

Secondly, we need to determine whether an accretion disk is present and

if its high ionization UV line luminosities point to a stellar mass

black hole or a more massive object. Finally, if the black hole is

1E3-1E4 Msolar, the orbital velocity of the secondary is so large that a

Doppler shift will be detectable, even at the modest resolution of the

prism.

WFPC2 10809

The nature of "dry" mergers in the nearby Universe

Recent studies have shown that "dry" mergers of red, bulge-dominated

galaxies at low redshift play an important role in shaping today's most

massive ellipticals. These mergers have been identified in extremely

deep ground-based images of red sequence galaxies at z ~ 0.1. The

ground-based images reach surface brightness limits of AB ~ 29, but lack

the resolution to study the morphologies of the galaxies inside the

effective radius. Here we propose to obtain ACS images of a

representative sample of 40 of these red sequence galaxies: 15 ongoing

dry mergers, 15 remnants, and 10 undisturbed objects. We will measure

the isophote shapes and ellipticities of the galaxies, their dust

content, morphological fine structure {shells and ripples}, AGN content,

and their location on the Fundamental Plane. By comparing galaxies in

different stages of the merging process we can constrain the amount of

gas associated with these red mergers, the effect of active nuclei, and

track structural changes. As two galaxies can be observed in a single

orbit 20 orbits are requested to observe the 40 galaxies.

WFPC2 10798

Dark Halos and Substructure from Arcs & Einstein Rings

The surface brightness distribution of extended gravitationally lensed

arcs and Einstein rings contains super-resolved information about the

lensed object, and, more excitingly, about the smooth and clumpy mass

distribution of the lens galaxies. The source and lens information can

non-parametrically be separated, resulting in a direct "gravitational

image" of the inner mass-distribution of cosmologically-distant galaxies

{Koopmans 2005; Koopmans et al. 2006 [astro-ph/0601628]}. With this goal

in mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W WFC

imaging of 20 new gravitational-lens systems with spatially resolved

lensed sources, of the 35 new lens systems discovered by the Sloan Lens

ACS Survey {Bolton et al. 2005} so far, 15 of which are being imaged in

Cycle-14. Each system has been selected from the SDSS and confirmed in

two time- efficient HST-ACS snapshot programs {cycle 13&14}.

High-fidelity multi-color HST images are required {not delivered by the

420s snapshots} to isolate these lensed images {properly cleaned,

dithered and extinction-corrected} from the lens galaxy surface

brightness distribution, and apply our "gravitational maging" technique.

Our sample of 35 early-type lens galaxies to date is by far the largest,

still growing, and most uniformly selected. This minimizes selection

biases and small-number statistics, compared to smaller, often

serendipitously discovered, samples. Moreover, using the WFC provides

information on the field around the lens, higher S/N and a better

understood PSF, compared with the HRC, and one retains high spatial

resolution through drizzling. The sample of galaxy mass distributions -

determined through this method from the arcs and Einstein ring HST

images - will be studied to: {i} measure the smooth mass distribution of

the lens galaxies {dark and luminous mass are separated using the HST

images and the stellar M/L values derived from a joint stellar-dynamical

analysis of each system}; {ii} quantify statistically and individually

the incidence of mass-substructure {with or without obvious luminous

counter- parts such as dwarf galaxies}. Since dark-matter substructure

could be more prevalent at higher redshift, both results provide a

direct test of this prediction of the CDM hierarchical

structure-formation model.

WFPC2 10786

Rotational state and composition of Pluto's outer satellites

We propose an intricate set of observations aimed at discovering the

rotational state of the newly discovered satellites of Pluto, S/2005 P1

and S/2005 P2. These observations will indicate if the satellites are in

synchronous rotation or not. If they are not, then the observations will

determine the rotational period or provide tight constraints on the

amplitude. The other primary goal is to extend the wavelength coverage

of the colors of the surface and allow us to constrain the surface

compositions of both objects. From these data we will also be able to

significantly improve the orbits of P1 and P2, improve the measurement

of the bulk density of Charon, and search for albedo changes on the

surface of Pluto.

FGS 10612

Binary Stars in Cyg OB2: Relics of Massive Star Formation in a

Super-Star Cluster

We propose to make a high angular resolution SNAP survey of the massive

stars in the nearby, super-star cluster Cyg OB2. We will use FGS1r TRANS

mode observations to search for astrometric companions in the separation

range of 0.01 to 1.00 arcsec and in the magnitude difference range

smaller than 4 magnitudes. The observations will test the idea that the

formation of very massive stars involves mergers and the presence of

nearby companions. Discovery of companions to massive stars in this

relatively nearby complex will provide guidance in the interpretation of

apparently supermassive stars in distant locations. The search for

companions will also be important for verification of fundamental

parameters derived from spectroscopy, adjustments to main sequence

fitting and distance estimations, determining third light contributions

of eclipsing binaries, identifying wide colliding wind binaries,

studying the relationship between orbital and spin angular momentum, and

discovering binaries amenable to future mass determinations. The massive

star environment in Cyg OB2 may be similar to the kinds found in the

earliest epoch of star formation, so that a study of the role of

binaries in Cyg OB2 will help us understand the formation processes of

the first stars in the Universe.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS:

10778 - GSAcq (1,2,1) failed to RGA Hold (Gyro Control)

           At AOS (103/22:48:00) GSAcq (1,2,1) scheduled at 103/22:21:38-22:28:56

           had failed to RGA hold (Gyro Control) due to QSTOP flag on FGS2.

           OBAD MAP RSS: 5.31 a-s

COMPLETED OPS REQUEST:

18033-1 - LGA Support for TCS Engineering Data

COMPLETED OPS NOTES: (None)

                         SCHEDULED      SUCCESSFUL  

FGS GSacq                 23                  22         

FGS REacq                 17                  17                 

OBAD with Maneuver   80                  80                

SIGNIFICANT EVENTS: (None)