NASA Hubble Space Telescope Daily Report # 4466
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 DAILY REPORT # 4466
– Continuing to collect World Class Science
PERIOD COVERED: UT October 11, 2007 (DOY 284)
OBSERVATIONS SCHEDULED
FGS 11211
An Astrometric Calibration of Population II Distance Indicators
In 2002 HST produced a highly precise parallax for RR Lyrae. That measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a useful result, judged by the over ten refereed citations each year since. It is, however, unsatisfactory to have the direct, parallax-based, distance scale of Population II variables based on a single star. We propose, therefore, to obtain the parallaxes of four additional RR Lyrae stars and two Population II Cepheids, or W Vir stars. The Population II Cepheids lie with the RR Lyrae stars on a common K-band Period-Luminosity relation. Using these parallaxes to inform that relationship, we anticipate a zero-point error of 0.04 magnitude. This result should greatly strengthen confidence in the Population II distance scale and increase our understanding of RR Lyrae star and Pop II Cepheid astrophysics.
FGS 11295
Trigonometric Calibration of the Distance Scale for Classical Novae
The distance scale for classical novae is important for understanding the stellar physics of their thermonuclear runaways, their contribution to Galactic nucleosynthesis, and their use as extragalactic standard candles. Although it is known that there is a relationship between their absolute magnitudes at maximum light and their subsequent rates of decline–the well-known maximum-magnitude rate-of-decline {MMRD} relation–it is difficult to set the zero-point for the MMRD because of the very uncertain distances of Galactic novae. We propose to measure precise trigonometric parallaxes for the quiescent remnants of the four nearest classical novae. We will use the Fine Guidance Sensors, which are proven to be capable of measuring parallaxes with errors of ~0.2 mas, well below what is possible from the ground.
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 11219
Active Galactic Nuclei in nearby galaxies: a new view of the origin of the radio-loud radio- quiet dichotomy?
Using archival HST and Chandra observations of 34 nearby early-type galaxies {drawn from a complete radio selected sample} we have found evidence that the radio-loud/radio-quiet dichotomy is directly connected to the structure of the inner regions of their host galaxies in the following sense: [1] Radio-loud AGN are associated with galaxies with shallow cores in their light profiles [2] Radio-quiet AGN are only hosted by galaxies with steep cusps. Since the brightness profile is determined by the galaxy’s evolution, through its merger history, our results suggest that the same process sets the AGN flavour. This provides us with a novel tool to explore the co-evolution of galaxies and supermassive black holes, and it opens a new path to understand the origin of the radio-loud/radio-quiet AGN dichotomy. Currently our analysis is statistically incomplete as the brightness profile is not available for 82 of the 116 targets. Most galaxies were not observed with HST, while in some cases the study is obstructed by the presence of dust features. We here propose to perform an infrared NICMOS snapshot survey of these 82 galaxies. This will enable us to i} test the reality of the dichotomic behaviour in a substantially larger sample; ii} extend the comparison between radio-loud and radio-quiet AGN to a larger range of luminosities. WFPC2 11039
Polarizers Closeout
Observations of standard stars and a highly polarized reflection nebula are made as a final calibration for the WFPC2 polarizers. VISFLATS are also obtained.
WFPC2 11103
A Snapshot Survey of The Most Massive Clusters of Galaxies
We propose the continuation of our highly successful SNAPshot survey of a sample of 125 very X-ray luminous clusters in the redshift range 0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14 and Cycle15 these systems frequently exhibit strong gravitational lensing as well as spectacular examples of violent galaxy interactions. The proposed observations will provide important constraints on the cluster mass distributions, the physical nature of galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. All of our primary science goals require only the detection and characterization of high-surface-brightness features and are thus achievable even at the reduced sensitivity of WFPC2. Because of their high redshift and thus compact angular scale our target clusters are less adversely affected by the smaller field of view of WFPC2 than more nearby systems. Acknowledging the broad community interest in this sample we waive our data rights for these observations. Due to a clerical error at STScI our approved Cycle15 SNAP program was barred from execution for 3 months and only 6 observations have been performed to date – reinstating this SNAP at Cycle16 priority is of paramount importance to reach meaningful statistics.
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 11178
Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries
The recent discovery of numerous transneptunian binaries {TNBs} opens a window into dynamical conditions in the protoplanetary disk where they formed as well as the history of subsequent events which sculpted the outer Solar System and emplaced them onto their present day heliocentric orbits. To date, at least 47 TNBs have been discovered, but only about a dozen have had their mutual orbits and separate colors determined, frustrating their use to investigate numerous important scientific questions. The current shortage of data especially cripples scientific investigations requiring statistical comparisons among the ensemble characteristics. We propose to obtain sufficient astrometry and photometry of 23 TNBs to compute their mutual orbits and system masses and to determine separate primary and secondary colors, roughly tripling the sample for which this information is known, as well as extending it to include systems of two near-equal size bodies. To make the most efficient possible use of HST, we will use a Monte Carlo technique to optimally schedule our observations.
WFPC2 11202
The Structure of Early-type Galaxies: 0.1-100 Effective Radii
The structure, formation and evolution of early-type galaxies is still largely an open problem in cosmology: how does the Universe evolve from large linear scales dominated by dark matter to the highly non-linear scales of galaxies, where baryons and dark matter both play important, interacting, roles? To understand the complex physical processes involved in their formation scenario, and why they have the tight scaling relations that we observe today {e.g. the Fundamental Plane}, it is critically important not only to understand their stellar structure, but also their dark-matter distribution from the smallest to the largest scales. Over the last three years the SLACS collaboration has developed a toolbox to tackle these issues in a unique and encompassing way by combining new non-parametric strong lensing techniques, stellar dynamics, and most recently weak gravitational lensing, with high-quality Hubble Space Telescope imaging and VLT/Keck spectroscopic data of early-type lens systems. This allows us to break degeneracies that are inherent to each of these techniques separately and probe the mass structure of early-type galaxies from 0.1 to 100 effective radii. The large dynamic range to which lensing is sensitive allows us both to probe the clumpy substructure of these galaxies, as well as their low-density outer haloes. These methods have convincingly been demonstrated, by our team, using smaller pilot-samples of SLACS lens systems with HST data. In this proposal, we request observing time with WFPC2 and NICMOS to observe 53 strong lens systems from SLACS, to obtain complete multi-color imaging for each system. This would bring the total number of SLACS lens systems to 87 with completed HST imaging and effectively doubles the known number of galaxy-scale strong lenses. The deep HST images enable us to fully exploit our new techniques, beat down low-number statistics, and probe the structure and evolution of early-type galaxies, not only with a uniform data-set an order of magnitude larger than what is available now, but also with a fully coherent and self-consistent methodological approach!
WFPC2 11312
The Local Cluster Substructure Survey {LoCuSS}: Deep Strong Lensing Observations with WFPC2
LoCuSS is a systematic and detailed investigation of the mass, substructure, and thermodynamics of 100 X-ray luminous galaxy clusters at 0.15
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
11020 – REacq(1,2,1) failed to RGA Hold (Gyro Control) The REacq(1,2,1) scheduled at 285/01:40:50 – 01:48:54 failed to RGA Hold due to Search Radius Limit Exceeded Error on FGS-1. One 486 ESB “a05” (FGS Coarse Track failed-Search Radius Limit Exceeded was received at 285/01:46:16. Additional ESB
1805(x2)(T2G_MOVING_TARGET_DETECTED) were received. Pre-acquisition OBADs had (RSS) attitude correction values of 29.38 and 14.40 arcseconds. OBAD/MAP had 3-axis (RSS) error value of 171.29 arcseconds. Prior guide star acquisition was successful. COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FGS GSacq 11 11 FGS REacq 03 02 OBAD with Maneuver 27 27
SIGNIFICANT EVENTS: (None)
