Status Report

NASA Hubble Space Telescope Daily Report #4021

By SpaceRef Editor
January 5, 2006
Filed under , ,
NASA Hubble Space Telescope Daily Report #4021

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT January 04, 2006 (DOY 004)



ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. Changes from cycle 13:- The default gain for WFC is 2 e-/DN. As before bias frames will be collected for both gain 1 and gain 2. Dark frames are acquired using the default gain {2}. This program cover the period Oct, 2 2005- May, 29-2006. The second half of the program has a different proposal number: 10758.

ACS/SBC 10554

Globular Cluster Systems of Elliptical Galaxies in Low Density Environments

We propose to use the ACS/WFC to determine colour {metallicity} distributions and luminosity functions for the globular cluster populations in a well-defined sample of elliptical galaxies in low- density environments, and to compare the results with similar samples taken from a rich cluster environment. Low-luminosity ellipticals are now recognized to play a pivotal role in testing hierarchical models of galaxy formation, and their globular cluster populations provide a unique probe of their star formation and metal enrichment history. The data will be used to {i} determine whether the bimodal colour distributions indicative of multiple formation epochs in luminous ellipticals are also prevalent in low-luminosity field ellipticals; {ii} place joint constraints on age and metallicity in systems with more than one population and determine the spread of ages in any one system; {iii} test whether cluster destruction processes {e.g. tidal shocking} are more effective in low-luminosity ellipticals, as predicted from their higher mass densities. ACS observations are essential to eliminate foreground/background contamination and to probe deep into the luminosity function to obtain a good statistical sample of clusters. The TAC has previously awarded HST time to two large surveys of globular cluster systems in rich cluster environments, but there is currently no comparable survey in low-density environments with which to compare these results.

ACS/WFC 10491

A Snapshot Survey of the most massive clusters of galaxies

We propose a snapshot survey of a sample of 124 high X-ray luminosity clusters in the redshift range 0.3-0.7. Similarly luminous clusters at these redshifts frequently exhibit strong gravitational lensing. The proposed observations will provide important constraints on the nature of the cluster mass distributions and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. We acknowledge the broad community interest in this sample and waive our data rights for these observations.


Life Before the Fall: Morphological Evolution of Galaxies in Groups Prior to Cluster Assembly at z=0.37

We propose to obtain a deep ACS/WFC mosaic of a protocluster comprised of 4 distinct galaxy groups that are gravitationally bound to each other at z=0.37. The galaxy groups have a total combined mass comparable to the Coma cluster and already have twice as many absorption line galaxies as the field. The SG1120 complex thus provides an unprecedented opportunity for determining whether “pre-processing” in the group environment is responsible for the bulk of observed diffences between galaxies in nearby clusters and those in the field. High resolution imaging with HST is needed to morphologically classify the group members and measure their structural parameters. By combining the early-type fraction and morphology-density relation in SG1120 with results from our wide-field spectroscopic survey, we will test whether spectral and morphological transformation timescales are decoupled on group scales and isolate the environmental mechanisms responsible for such evolution. We will also measure the Fundamental Plane and M/L ratios of the early-type members to constrain their formation epoch and how their stellar populations have evolved. Observations of the multiple galaxy groups in SG1120 provide a unique dataset to the community and will aid our understanding of how galaxies evolve in the still poorly studied group regime.


Environmental drivers of galaxy evolution: an HST survey of dwarf galaxy morphologies in the Abell

Galaxies in dense environments are subject to numerous physical processes that leave a lasting impact, yet studies of galaxy evolution to date have been limited to the most luminous galaxies — those least sensitive to environmental influence. We propose to explore the environmental drivers of DWARF galaxy evolution: with a mosaic of 9×9 ACS pointings in F606W we will determine morphologies for ~1200 galaxies down to M_V=-14 in the A901/902 supercluster, spanning 3×3 Mpc at z=0.16. The deep ACS data will allow us to probe their surface brightness profiles, shapes, sizes, asymmetry and fine structure such as tidal features. With the addition of extensive existing multi-wavelength data, we will probe the dependence of these important parameters on dark matter content {from weak lensing maps}, the hot intercluster medium {from deep XMM-Newton imaging}, and local galaxy density {from hyper-accurate COMBO-17 photometric redshifts with delta z=0.02 to m_R=24}, thus disentangling the various environmental processes shaping dwarf galaxy evolution. Furthermore, the 8000+ background galaxies at 0.2< z <1.0 will be of enormous scientific benefit for additional studies of weak lensing, AGN host galaxies, the morphology-density relation, and the merger rate as a function of redshift.

NIC1 10725

Photometric Stability

This NICMOS calibration proposal carries out photometric monitoring observations during Cycle 14. The format of the program is similar to that of the Cycle 12 program 9995 and Cycle 13 program 10381, but a few modifications were made. 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 is 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.

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

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 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 images. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors.

WFPC2 10751

WFPC2 CYCLE 14 Intflat Linearity Check and Filter Rotation Anomaly Monitor

Intflat observations will be taken to provide a linearity check: the linearity test consists of a series of intflats in F555W, in each gain and each shutter. A combination of intflats, visflats, and earthflats will be used to check the repeatability of filter wheel motions. {Intflat sequences tied to decons, visits 1-18 in prop 10363, have been moved to the cycle 14 decon proposal 10744 for easier scheduling.} Note: long-exposure WFPC2 intflats must be scheduled during ACS anneals to prevent stray light from the WFPC2 lamps from contaminating long ACS external exposures.


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

HSTARS: (None)



                         SCHEDULED      SUCCESSFUL
FGS GSacq                09                    09
FGS REacq                06                     06
OBAD with Maneuver   31                     31


SpaceRef staff editor.