NASA Hubble Space Telescope Daily Report #3980
HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science
DAILY REPORT # 3980
PERIOD COVERED: UT November 02, 2005 (DOY 306)
OBSERVATIONS SCHEDULED
ACS/HRC 10116
Towards an Accurate Calibration of the Galactic Cepheid P-L Zero Point
The young open cluster NGC 7790 is unique and astrophysically important because it contains three classical Cepheid variables {CF Cas, CE Cas A, and CE Cas B}. If the distance of NGC 7790 were known with certainty, these Cepheids would define the zero point for the galactic Cepheid Period-Luminosity {P-L} relationship. By a stroke of good luck, NGC 7790 also contains a 10th-mag eclipsing binary located near the turnoff of the main-sequence of the color-magnitude diagram of the cluster. This important eclipsing binary has been little studied until now and contains two B1IV-V+B3V stars with an orbital period of P=6.005 days. With HST we propose to secure the accurate distance and reddening of QX Cas {and thus of the Cepheids} by using eclipsing binaries as precise standard candles, as we have demonstrated in our work on the Large Magellanic Cloud. With absolute radii, temperatures, and luminosities of the stars known from ground-based and HST observations, the method is essentially geometric and free from many of the uncertainties that plague other less direct methods. Light and radial velocity curve data will be combined to determine the physical properties of the eclipsing binary and thus to secure an accurate distance and reddening for NGC 7790. The determination of the stars’ temperatures, reddenings and chemical abundances, and therefore the cluster’s distance, with the necessary accuracy can only be accomplished with HST. According to our previous experience, we expect a resulting distance determination with an accuracy of about 2-3%. Thus, the proposed HST observations could help eliminate the current nagging uncertainty of the galactic Cepheid zero point and provide the key for a firm calibration of the P-L relationship.
ACS/HRC 10525
Characterizing the Near-UV Environment of M Dwarfs: Implications for Extrasolar Planetary Searches and Astrobiology
We propose SNAP observations with the ACS HRC PR200L prism, designed to measure the near ultraviolet emission in a sample of 107 nearby M dwarfs. The sample spans the mass range from 0.1 – 0.6 solar masses {temperature range 2200K – 4000K} where the UV energy distributions vary widely between active and inactive stars. The strength and distribution of this UV emission can have critical consequences for the atmospheres of attendant planets. Our proposed observations will provide desperately needed constraints on models of the habitability zone and the atmospheres of possible terrestrial planets orbiting M dwarf hosts, and will be used to sharpen TPF target selection. In addition, the NUV data will be used in conjunction with existing optical, FUV and X-ray data to constrain a new generation of M dwarf atmospheric models, and to explore unanswered questions regarding the dynamo generation and magnetic heating in these low-mass stars.
ACS/HRC 10564
Resolving Ultracool White Dwarf Binaries
We propose an ACS/HRC imaging survey of the coolest white dwarfs known in order to search for binarity. Current models fail to match observed spectral energy distributions of these sub- 4000K stellar remnants, consistently predicting much lower luminosities than observed. A possible explanation is that they are binary in nature. Because these cool degenerates have no spectral features, the only way to investigate their apparent overluminosity is with very high resolution imaging, which can only be done with HST {these stars are far too faint to be observed with adaptive optics on the ground}. Optical wavelengths are ideal because the spectral energy distributions of these old degenerates peak near 600 nm. With the F435W filter we will be able to partially resolve equally luminous binaries as close as 0.02″, which corresponds to within 0.6 AU for over half of the 12 proposed target stars. The collected data will be critical in determining whether these stars represent the oldest white dwarfs in the solar neighborhood.
ACS/HRC/WFC 10729
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/HRC/WFC 10733
CCD Hot Pixel Annealing
Hot pixel annealing will continue to be performed once every 4 weeks. The CCD TECs will be turned off and heaters will be activated to bring the detector temperatures to about +20C. This state will be held for approximately 6 hours, after which the heaters are turned off, the TECs turned on, and the CCDs returned to normal operating condition. To assess the effectiveness of the annealing, a bias and four dark images will be taken before and after the annealing procedure for both WFC and HRC. The HRC darks are taken in parallel with the WFC darks. The charge transfer efficiency {CTE} of the ACS CCD detectors declines as damage due to on-orbit radiation exposure accumulates. This degradation has been closely monitored at regular intervals, because it is likely to determine the useful lifetime of the CCDs. We combine the annealling activity with the charge transfer efficiency monitoring and also merge into the routine dark image collection. To this end, the CTE monitoring exposures have been moved into this proposal . All the data for this program is acquired using internal targets {lamps} only, so all of the exposures should be taken during Earth occultation time {but not during SAA passages}. This program emulates the ACS pre-flight ground calibration and post-launch SMOV testing {program 8948}, so that results from each epoch can be directly compared. Extended Pixel Edge Response {EPER} and First Pixel Response {FPR} data will be obtained over a range of signal levels for both the Wide Field Channel {WFC}, and the High Resolution Channel {HRC}.
ACS/SBC 10506
Coordinated observations of Saturn’s auroral dynamic morphology and Cassini plasma measurements
Planetary FUV aurora is the most spectacular signature of the electrodynamical coupling between the solar wind, the planet’s magnetic field, and its atmosphere. Saturn’s magnetosphere has similarities both with the Earth’s magnetosphere, which is ‘open’ to solar wind interaction and Jupiter’s relatively ‘closed’ case with its large internal sources of plasma. HST observations of Saturn’s aurora have shown a much more complex and dynamic morphology than anticipated: a frequent ‘spiral’ structure, a changing size of the oval in response to variations of the solar wind dynamics pressure, and large brightness changes in a few ten of minutes following compression of the magnetosphere by the solar wind. In addition, the global morphology and some spots move at 70% of the planetary co-rotation, while some other features appear nearly fixed in local time. Recently, ideas have emerged to account for Saturn’s aurora specificities, although many aspects are still not understood due to the paucity of observational data. Electric current models suggest that the main oval is located at the limit between closed and open magnetic field lines, near the magnetopause. The availability of Cassini in Saturn’s magnetic environment now offers a unique opportunity for collaborative science. We thus propose to test the relationship between the aurora and conditions at Saturn’s magnetopause {MP} boundary. We plan to image the FUV aurora with ACS at times of inbound Cassini crossing of the MP from the upstream solar wind/magnetosheath region into the middle magnetosphere during an inbound segment of a Cassini’s orbit. FUV images will also reveal whether the main oval changes its size over the interval, possibly indicating evidence for changes in the amount of open flux in the system. These HST images of the aurora simultaneous with in situ measurements of the plasma characteristics and electrodynamics inside the magnetosphere are critical to obtain key observational tests and constraints to future ideas and models of Saturn’s auroral precipitation and magnetospheric processes involved.
ACS/SBC 10739
Internal Flat Field Stability
The stability of the CCD flat fields will be monitored using the calibration lamps and a sub-sample of the filter set. For the SBC imaging filters, differences in the low-frequency flat field structure with wavelength will be assessed. New high signal P-flats will be obtained for the SBC prisms.
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.
ACS/WFC 10592
An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in the Local Universe
At luminosities above 10^11.4 L_sun, the space density of far-infrared selected galaxies exceeds that of optically selected galaxies. These `luminous infrared galaxies’ {LIRGs} are primarily interacting or merging disk galaxies undergoing enhanced star formation and Active Galactic Nuclei {AGN} activity, possibly triggered as the objects transform into massive S0 and elliptical merger remnants. We propose ACS/WFC imaging of a complete sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}. This sample is ideal not only in its completeness and sample size, but also in the proximity and brightness of the galaxies. The superb sensitivity, resolution, and field of view of ACS/WFC on HST enables a unique opportunity to study the detailed structure of galaxies that sample all stages of the merger process. Imaging will be done with the F439W and F814W filters {B and I-band} to examine as a function of both luminosity and merger state {i} the evidence at optical wavelengths of star formation and AGN activity and the manner in which instabilities {bars and bridges} in the galaxies may funnel material to these active regions, {ii} the relationship between star formation and AGN activity, and {iii} the structural properties {AGN, bulge, and disk components} and fundamental parameters {effective radius and surface brightness} of LIRGs and their similarity with putative evolutionary byproducts {elliptical, S0 and classical AGN host galaxies}. This HST survey will also bridge the wavelength gap between a Spitzer imaging survey {covering seven bands in the 3.6-160 micron range} and a GALEX UV imaging survey of these galaxies, but will resolve complexes of star clusters and multiple nuclei at resolutions well beyond the capabilities of either Spitzer or GALEX. The combined datasets will result in the most comprehensive multiwavelength study of interacting and merging galaxies to date.
ACS/WFC 10635
Galaxy Transformation as probed by Morphology and Velocity Fields of Distant Cluster Galaxies
We seek to obtain ACS imaging of four distant {0.3 < z < 0.6} clusters of galaxies within a 6'x6' field covered by a 2x2 mosaic to determine morphological and structural parameters of late-type galaxies. We specifically concentrate on peculiarities indicative of past or ongoing interaction processes. The ~90 target galaxies have been {Period74} or will be {P75} observed with 3D- spectroscopy at ESO-VLT yielding 2D-velocity fields with unprecedented spatial coverage and sampling. The good spatial resolution of the ground-based data will be further enhanced by a deconvolution method based on the proposed ACS images. The velocity field and the morphology in restframe-UV light will reveal possible transformation mechanisms affecting not only the stellar populations but also the mass distribution of the galaxies. Additionally, it will be possible to pin down the nature of the interaction {e.g. tidally or ram-pressure induced}. This assessment gets supported by our N-body/SPH simulations {including star formation} of different interaction processes that allow the direct comparison of structural and kinematical characteristics at each time step with the observations on an individual basis taking into account all observational constraints for a given galaxy. All together, we will be able to explore the relative efficiency of the various proposed transformation phenomena. In the case of non-disturbed spirals, a rotation curve can be extracted from the full 2D velocity field with unprecedented quality, from which the maximum rotation speed can be derived with high confidence. In combination with accurate size and luminosity determinations from the ACS images, we will be able to establish the Tully-Fisher and Fundamental Plane relations of cluster spiral members at cosmological epochs. At these distances cluster assembly is predicted to peak and we can probe the galaxies' luminosity, size and mass evolution with robust methods. Together with our already existing sample of ~200 distant {z<=1} spiral galaxies in the field, we will put strong constraints on current theories of galaxy formation and evolution in different environments.
NIC1/NIC2/NIC3 8793
NICMOS Post-SAA calibration – CR Persistence Part 4
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.
NIC2 10177
Solar Systems In Formation: A NICMOS Coronagraphic Survey of Protoplanetary and Debris Disks
Until recently, despite decades of concerted effort applied to understanding the formation processes that gave birth to our solar system, the detailed morphology of circumstellar material that must eventually form planets has been virtually impossible to discern. The advent of high contrast, coronagraphic imaging as implemented with the instruments aboard HST has dramatically enhanced our understanding of natal planetary system formation. Even so, only a handful of evolved disks {~ 1 Myr and older} have been imaged and spatially resolved in light scattered from their constituent grains. To elucidate the physical processes and properties in potentially planet-forming circumstellar disks, and to understand the nature and evolution of their grains, a larger spatially resolved and photometrically reliable sample of such systems must be observed. Thus, we propose a highly sensitive circumstellar disk imaging survey of a well- defined and carefully selected sample of YSOs {1-10 Myr T Tau and HAeBe stars} and {> app 10 Myr} main sequence stars, to probe the posited epoch of planetary system formation, and to provide this critically needed imagery. Our resolved images will shed light on the spatial distributions of the dust in these thermally emissive disks. In combination with their long wavelength SEDs the physical properties of the grains will be discerned, or constrained by our photometrically accurate surface brightness sensitivity limits for faint disks which elude detection. Our sample builds on the success of the exploratory GTO 7233 program, using two- roll per orbit PSF-subtracted NICMOS coronagraphy to provide the highest detection sensitivity to the smallest disks around bright stars which can be imaged with HST. Our sample will discriminate between proposed evolutionary scenarios while providing a legacy of cataloged morphologies for interpreting mid- and far-IR SEDs that the recently launched Spitzer Space Telescope will deliver.
NIC2 10519
Testing the Stellar Coalescence and Accretion Disk Theories of Massive Star Formation with NICMOS
The importance of massive stars cannot be underestimated – they produce most of the heavy elements in the universe and dominate the evolution of the interstellar medium in their vicinity. In spite of their significance, our understanding of their formation is meager. Both accretion through disks, analogous to the process of low-mass star formation, and coalescence of low-mass stars through collisions in the dense cores of stellar clusters have been suggested. Possibly both mechanisms occur. High spatial resolution polarization measurements of the closest massive young stellar objects {YSOs} will enable us to search for evidence of disk accretion or coalescence in the form of patterns indicative of light scattered off a coherent disk or off a disk disrupted by an infalling star, respectively. Here we propose to use 2 micron polarimetry with NICMOS to identify the presence of accretion disks around massive YSOs or to characterize their environments as possibly disrupted from a close stellar encounter. There are only a few sources that meet the stringent selection criteria for this investigation {even with HST}, which we will examine here. High spatial resolution is required, but even more important, the point spread function {PSF} must be stable with time. Furthermore, the PSF must put minimal flux into large spatial scales, something that cannot be achieved with adaptive optics. This combination of high Strehl ratio and stable PSF can only be achieved from space.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS: 9999 – GSAcq (1,3,1) failed to T2G due to Search Radius Limit Exceeded on FGS3 @306/1223z
GSAcq(1,3,1) scheduled at 306/12:23:09 – 123:31:13 failed to T2G due to Search Radius Limit Exceeded on FGS3.
Prior OBAD1 at 306/12:09:24 showed vehicle axis errors: V1=-918.64, V2=-2238.30, V3=-544.28. 3-axis (RSS) value=2479.95 arcsec.
Prior OBAD2 at 306/12:18:39 showed V1=11.45, V2=46.75, V3=8.25, RSS value=48.83 arcsec.
Subsequent OPBAD (but no maneuver) at 306/12:31:13 showed V1=0.36, V2=-23.75, V3=-0.29, RSS=23.75 arcsec.
10001 – GSAcq(1,2,2) required three attempts to achieve CT-DV @301/0810z GSAcq(1,2,2) required three attempts to achieve CT-DV on FGS1. FGS1 entered Coarse Track for the first time at 08:13:41.135 . It successfully entered Fine Lock at 08:14:55.985 .
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS
GSacq 13 12 306/1223z
(HSTAR 9999)
FGS REacq 1 1
OBAD with Maneuver 25 25
SIGNIFICANT EVENTS: (None)
