Status Report

HST Daily Report # 3283 (Part 2)

By SpaceRef Editor
January 21, 2003
Filed under , ,

ACS 9438

The Origin of the Intergalactic Globular Cluster Population in Abell 1185

We request deep V and I observations with ACS to examine the properties of a newly discovered population of intergalactic globular clusters in the core of the rich galaxy cluster Abell 1185. Our previous WFPC2 observations of this field {GO-8164} revealed an excess of five times the number of objects at the expected magnitudes of globular clusters compared to the Hubble Deep Fields. The colors and luminosity function of these intergalactic globular clusters will place strong constraints on their origin, which in turn will yield new insights to the evolution of galaxy populations in dense environments

ACS/HRC 9473

Masses and IMF Variations in Super Star Clusters

We are proposing to obtain high spatial resolution images of a set of super star clusters for which we have been granted observing time to measure velocity dispersions via high- resolution ground-based optical echelle and K-band spectroscopy. The images will allow us to fit the light profiles and measure the radii of the clusters, and when combined with the velocity dispersions, will enable us to estimate the cluster masses. By comparing the mass-to-light ratios with those predicted from spectral synthesis models, we will investigate possible variations in the slope and lower mass cut-offs of the initial mass functions in these clusters. Correlations of the variations of these parameters with cluster environment may provide insight into the formation mechanisms for super star clusters. By comparing the light profiles obtained in a blue and red filter, we will also search for evidence of mass segregation in the clusters. Since these clusters are too young to have experienced dynamical mass segregation, differences in the light profiles of the clusters in the two filters could be due to processes that differentiate between high and low mass stars during the birth of the clusters and would provide further constraints on theoretical models of cluster formation. Since these clusters are far too compact to be resolved by any ground-based observations, the ACS/HRC on board HST is the only instrument capable of carrying out these observations.

ACS/WFC 9584

ACS Default {Archival} Pure Parallel Program II.

The Advanced Camera for Surveys (WFC) was used to test ACS pure parallels.

ACS/WFC 9492

Extragalactic Distances: the Need for Accurate Photometry of Blue Supergiants and Cepheids

The investigation of the Wind Momentum-Luminosity Relationship {WLR} of blue supergiant stars as an independent extragalactic distance indicator has reached a critical phase. Following our recent discovery and spectroscopic follow-up of several tens of stars outside of the Local Group in NGC 300 and NGC 3621, we can now calibrate the WLR in terms of spectral subtype and metallicity with a higher accuracy than hithertho possible with the statistically limited samples available in the nearby galaxies studied so far. This, however, requires high-resolution imaging to obtain accurate BVI photometry of a significant fraction of those stars for which we have spectroscopic information. This can be effectively accomplished with eight ACS/WFC fields in these two galaxies. As a further step, we can use the calibrated WLR to measure the first independent extragalactic distance. We then propose additional imaging of six ACS/WFC fields in M101 to select blue supergiant candidates for spectroscopic follow-up. Having recently discovered more than a hundred new Cepheids in NGC 300, the high-resolution imaging proposed for the photometry of blue supergiants can also be used, with no additional observing effort, to verify the effects of blending on the Cepheid distance to this galaxy, an important calibrator of secondary distance indicators.

FGS 9348

The Distances to AM CVn stars

We propose to determine the parallaxes and proper motions of the five brightest of the seven known AM CVn systems using the HST Fine Guidance Sensors. AM CVn systems are binaries where mass is transferred from a completely hydrogen-deficient, degenerate mass donor to a white dwarf primary through a helium accretion disk. A better understanding of these systems is crucial for a number of reasons:, to study the late stages of binary evolution, to study the effect of chemical composition on the physics of accretion discs; , o to estimate their contribution to the Supernovae Ia rate and , to estimate their contribution to the gravitational radiation background. All these studies rely critically on a determination of the distances to the currently known systems. With brightnesses in the range 13

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS QSO MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for low-z {z<1.65} metal absorption lines and found over 200 large rest equivalent width MgII-FeII systems. Previously, we empirically showed that such systems are good tracers of large neutral gas columns, with ~50% being classical damped Lyman alpha {DLA} systems {N_HI>=2*10^20 cm^-2}. Here we propose to follow up a well-defined subset of 79 of them to search for DLAs with 0.47


A NICMOS Study of Merging Nuclei in the Toomre Sequence: Finding Order Amid Chaos

The final death throes of merging spiral galaxy nuclei are hidden behind dusty maelstroms of colliding gas clouds and glaring star formation activity. The dynamically important centers of mass can only be uncovered by imaging at NIR wavelengths and with the high spatial resolution of HST. We propose a near-infrared imaging program to inspect the physical processes of merging at spatial scales of ~100 pc. The Toomre Sequence provides the best sample of merging galaxies for such a study, because it has been studied extensively from the ground, and the global properties are well understood. Our previous Cycle 9 WFPC2 images of the nuclei have revealed a wealth of information on star forming activity and dust, but based on those data alone it is impossible to determine the locations of the current centers

of mass. Determining the mass centers and stellar density profiles is important for understanding both the kinematics and the dynamical evolution of the nuclei, and the formation of nuclear density cusps in galaxies. We propose J, H and K band imaging of the nuclei in early and intermediate stage mergers in the Toomre Sequence. Because of the much reduced effect of dust extinction, the near-infrared images are also optimally suited to searches for nuclear rings and bars around the nuclei. Combined with our ongoing Cycle 9 program, these data will provide a detailed view of the structure and evolution of a sequence of merger nuclei.


Externally Illuminated Circumstellar Material in the Young Nebulous Cluster NGC 2024

HST imaging of the Orion M42 H II region has revealed circumstellar emission and absorption regions {“proplyds”} with sizes comparable to those expected for protoplanetary disks. Disk morphology is directly observed in a dozen cases; disk photoevaporation is now the working model to explain the ionized rims seen at more than 100 Trapezium cluster stars. Are the Trapezium circumstances unique? Different cluster ages, densities, and UV radiation fields may strongly affect proplyd characteristics. To address these questions, we have searched for proplyds in several other young nebulous clusters, and found that the embedded infrared cluster associated with the NGC 2024 H II region has a large group of strong proplyd candidates. Our WFPC2 images of the optically visible edge of the cluster have identified an HAlpha proplyd aligned toward a B0 star. Our VLA 3.6 cm maps show compact ionization regions coincident with 20 members of the infrared cluster – a result similar to the original VLA proplyd discovery in M42 by Churchwell {1987}. These results strongly indicate that infrared emission line imaging of selected cluster members should reveal many objects similar to the those in M42. We propose NIC2 Paschen Alpha and continuum imaging of fourteen of the NGC 2024 compact VLA sources. Our goal is to resolve and characterize their circumstellar structures, and compare them with those seen in M42.


NICMOS Post-SAA calibration – CR Persistence Part 1.

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 NICMOS Parallel Observing Program

We propose to manage the default set of pure parallels with NICMOS. Our experience with both our GO NICMOS parallel program and the public parallel NICMOS programs in cycle 7 prepared us to make optimal use of the parallel opportunities. The NICMOS G141 grism remains the most powerful survey tool for HAlpha emission-line galaxies at cosmologically interesting redshifts. It is particularly well suited to addressing two key uncertainties regarding the global history of star formation: the peak rate of star formation in the relatively unexplored but critical 1<= z <= 2 epoch, and the amount of star formation missing from UV continuum-based estimates due to high extinction. Our proposed deep G141 exposures will increase the sample of known HAlpha emission- line objects at z ~ 1.3 by roughly an order of magnitude. We will also obtain a mix of F110W and F160W images along random sight-lines to examine the space density and morphologies of the reddest galaxies. The nature of the extremely red galaxies remains unclear and our program of imaging and grism spectroscopy provides unique information

regarding both the incidence of obscured star bursts and the build up of stellar mass at intermediate redshifts. In addition to carrying out the parallel program we will populate a public database with calibrated spectra and images, and provide limited ground- based optical and near-IR data for the deepest parallel fields.

STIS 9607

CCD Bias Monitor – Part 1

Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and 1×1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns.

STIS 9605

CCD Dark Monitor-Part 1

Monitor the darks for the STIS CCD

STIS 9612

STIS CCD Hot Pixel Annealing Cycle 11

The effectiveness of the CCD hot pixel annealing process is assessed by measuring the dark current behavior before and after annealing and by searching for any window contamination effects. In addition CTE performance is examined by looking for traps in a low signal level flat. Follows on from proposal 8906.

STIS 9633

STIS parallel archive proposal – Nearby Galaxies – Imaging and Spectroscopy

Using parallel opportunities with STIS which were not allocated by the TAC, we propose to obtain deep STIS imagery with both the Clear {50CCD} and Long-Pass {F28X50LP} filters in order to make color-magnitude diagrams and luminosity functions for nearby galaxies. For local group galaxies, we also include G750L slitless spectroscopy to search for e.g., Carbon stars, late M giants and S-type stars. This survey will be useful to study the star formation histories, chemical evolution, and distances to these galaxies. These data will be placed immediately into the Hubble Data Archive.

STIS 9706

STIS Pure Parallel Imaging Program: Cycle 10

This is the default archival pure parallel program for STIS during cycle 10.

STIS 9487

UV Sounding of the M-Giant Atmosphere in the Symbiotic Binary EG-AND

EG-AND is an eclipsing system which provides us with the capability to study the structure of a fairly normal non- variable red giant point-by-point through its atmosphere. The white dwarf secondary provides a bright far-UV continuum source against which absorption from a broad range of ionization levels can be seen, ranging from molecular hydrogen close to the giant star to ionized material further away. The systemic velocity is such that these features are well resolved from the intervening ISM component. In addition, the system has low extinction {A_V = 0.15}, has never been observed to undergo an eruption, and has a circular orbit, so there is no periodic disturbance of the giant atmosphere. Both calculation and direct observation show that the effect of the dwarf star’s ionizing continuum on the red giant is minimal. We have an on-going FUSE program that has covered part of the orbital cycle. We have proposed for FUSE Cycle 3, and we request observing time with STIS to complete the picture. The resolution of the FUSE and STIS spectra are well-matched and suitable for detailed comparison of the intrinsic atmospheric features. Existing archival IUE data is insufficient for our purposes due to low resolution and/or low S/N. HRS data is of low S/N, partial wavelength coverage, and may suffer from instrumental scattered light. Even when both datasets are combined, some phases have never been observed in the UV.


Closing in on the Hydrogen Reionization Edge of the Universe.

The Space Telescope Imaging Spectrograph (CCD) was used in parallel constrain the Hydrogen reionization edge in emission that marks the transition from a neutral to a fully ionized IGM at a predicted redshifts.


D/H in Lyman Limit Absorbers with Simple Velocity Structure.

The Space Telescope Imaging Spectrograph (CCD) was used to observe the deuterium abundance in QSO absorbers that provides a direct measurement of the baryonic density of the Universe. This proposal will obtain new high resolution data of two carefully selected, intermediate redshift absorption systems.


Helical Flows and Rotation in Protostellar Jets.

The Space Telescope Imaging Spectrograph (CCD) was used to study the velocity structure of protostellar jets transverse to the jet flow axis. HST resolution would allow the search for rotation, e.g. a helical flow pattern, around the axis of an optical jet. Such a detection would provide strong evidence that jets act as outflowing channels for angular momentum, thus allowing infalling material to fully accrete onto the protostar.


The Origin and Physics of Gamma-Ray Bursts.

The Space Telescope Imaging Spectrograph (CCD) was used to make observations that will provide the most stringent tests yet performed of the hypothesis that GRBs are powered by the collapse of massive stars. STIS CCD spectroscopy will be used to detect broad atomic features of supernovae underlying GRB optical transients, at flux levels more than a factor of three fainter than SN 1998bw.

WFPC2 9598

Earth Flats

This proposal monitors flatfield stability. This proposal obtains sequences of Earth streak flats to construct high quality flat fields for the WFPC2 filter set. These flat fields will allow mapping of the OTA illumination pattern and will be used in conjunction with previous internal and external flats to generate new pipeline superflats. These Earth flats will complement the Earth flat data obtained during cycles 4-10.

WFPC2 9699

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans.

WFPC2 9676

POMS Test Proposal: WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure Parallel program. The program will be used to take parallel images of random areas of the sky, following the recommendations of the 2002 Parallels Working Group.

WFPC2 9634

POMS Test Proposal: WFII targeted parallel archive proposal

The parallel opportunities available with WFPC2 in the neighborhood of bright galaxies are treated in a slightly different way from the normal pure parallels. Local Group galaxies offer the opportunity for a closer look at young stellar populations. Narrow-band images in F656N can be used both to identify young stars via their emission lines, and to map the gas distribution in star-forming regions. Thus, the filter F656N is added to the four standard filters. Near more distant galaxies, up to about 10 Mpc, we can map the population of globular clusters; for this purpose, F300W is less useful, and only F450W, F606W, and F814W will be used.

WFPC2 9458

Probing the Formation & Evolution of M31’s Outer Disk and Halo

The fossil record of galaxy formation and evolution is imprinted on the spatial distribution, ages and metallicities of galactic stellar populations. The observations proposed here build significantly upon our extensive ground-based and archival WFPC2 programs and aim to constrain the formation and evolution of our nearest large neighbour, M31. We propose deep imaging of 8 fields in the outer disk and halo, several of which have been identified from our panoramic ground-based CCD survey {covering ~ 26 square degrees} to possess significant stellar density and/or potential metallicity variations. Deep colour-magnitude diagrams reaching ~2-3 magnitudes below the horizontal branch will be constructed, allowing detailed characterization of the luminous evolved stellar populations via the red giant metallicity distribution, the luminous asymptotic giant branch, the horizontal branch morphology and the red clump, as well as the detection of a main-sequence that may be present from any younger component. Our primary goals are to: {i} quantify the stellar population variations associated with M31 halo substructure, including the newly- discovered giant stellar stream, and {ii} derive stringent constraints on the age and metallicity of stars in the far outer disk. These observations will directly address two key predictions of cold dark matter hierarchical galaxy formation models.

WFPC2 9594


This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels

WFPC2 9599

WFPC2 Cycle 11 UV Earth Flats

Monitor flat field stability. This proposal obtains sequences of earth streak flats to improve the quality of pipeline flat fields for the WFPC2 UV filter set. These Earth flats will complement the UV earth flat data obtained during cycles 8-10.

WFPC2 9589

WFPC2 Decontaminations and Associated Observations Pt. 1/3

This proposal is for the monthly WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check.


Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) None



  • 1064-0  NICMOS RAD 2 Temperature Limit Change @ 017/1847z
  • 1064-2  NICMOS RAD 2 Temperature Limit Change @ 017/2112z
  • 0924-0  HSTAR Documentation for Guide Star Acq Failure/Loss of Lock @018/0844z
  • 0924-0  HSTAR Documentation for Guide Star Acq Failure/Loss of Lock @018/2003z
  • 0900-1  COMMAND PROBLEM @ 019/1700z
  • 0916-0 Tabulation of Slew Attitude Error (Miss-distance) @ 020/0136z
  • 1065-0  FGS 2 ME Temperature Limit @ 020/1615z
  • 0970-1  Equipment Shelf by FHST Temperature Limit Change @ 020/1914z
  • 0916-0  Tabulation of Slew Attitude Error (Miss-distance) @ 021/0855z

                          SCHEDULED     SUCCESSFUL    FAILURE TIMES FGS GSacq             29                       29 FGS REacq             26                       26 FHST Update           54                       54 LOSS of LOCK 


Unrecoverable 32K ENG data loss 020/21:27:11z to 020/21:35:34z, due to WSC equipment problems preventing GCMRs (Ref: CDS #32177).

SpaceRef staff editor.