NASA Hubble Space Telescope Daily Report #5061
HUBBLE SPACE TELESCOPE DAILY REPORT #5061
Continuing to Collect World Class Science
PERIOD COVERED: 5am March 25 – 5am March 26, 2010 (DOY 084/09:00z-085/09:00z)
OBSERVATIONS SCHEDULED
ACS/WFC 11679
Probing The Globular Cluster / Low Mass X-ray Binary Connection in Early-type Galaxies At Low X-ray Luminosities
Combined high-resolution images from Hubble and Chandra (CXO) have revolutionized our understanding of extragalactic low-mass X-ray binaries (LMXBs) and globular clusters (GCs), yet their connection in early-type galaxies has remained unstudied at the luminosities of the Galactic LMXBs in GCs. NGC 3379 and NGC 4278 are be the first prototypical elliptical galaxies with complete, deep CXO observations enabling the study of LMXBs at lower luminosities. We propose completing mosaic ACS observations of both galaxies (5 fields per galaxy) that will provide the most comprehensive view into the connection between GCs and LMXBs in early-type galaxies. We will detect ~860 and ~270 GCs in all of NGC 4278 and NGC 3379, respectively. These two galaxies will have among the greatest number of detected GC-LMXBs to date (~130 & 50) and will include the faintest GC-LMXBs in a normal early-type galaxy. We will measure the fraction of GCs which contain LMXBs, as a function of X-ray luminosity, galactocentric distance, color, and GC half-light radius. Using the radial profiles of optical light, GCs, and LMXBs, we will determine the percentage of field LMXBs which may have originated in GCs. We will use the measured GC properties over the entire extent of both galaxies to constrain theories of GC formation and evolution. This is a resubmission of an approved Cycle 15 program (10835) which was only partially completed.
ACS/WFC 11715
The Luminous Galactic Cepheid RS Puppis: A Geometric Distance from its Nested Light Echoes
RS Puppis is one of the most luminous Cepheids in the Milky Way (P = 41.4 days) and an analog of the bright Cepheids used to measure extragalactic distances. An accurate distance would help anchor the zero-point of the bright end of the period-luminosity relation, but at a distance of about 2 kpc it is too far away for a trigonometric parallax with existing instrumentation.
RS Pup is unique in being surrounded by a reflection nebula, whose brightness varies as pulses of light from the Cepheid propagate outwards. Members of our team have used ground-based imaging of the nebula to derive phase lags in the light variations of individual features in the nebula, and have inferred a seemingly very precise geometric distance to the star. However, there is an unavoidable ambiguity involving the cycle counts, which was resolved by assuming that the features lie in the plane of the sky. If this assumption is incorrect, a large systematic error would be introduced into the distance measurement.
We show that polarimetric imaging using the high spatial resolution of ACS/WFC and its ability to image close to the star can resolve this ambiguity and yield a reliable geometric distance to RS Pup. We will also obtain a wide-field multicolor image of the nebula, in order to study its morphology and the mass-loss history of the Cepheid.
COS/FUV 12011
Magnetic Heating of the Outer Atmospheres of Very Low Mass Dwarfs
The detections of FUV and X-ray emissions from very low mass stars and brown dwarfs have confirmed that stellar magnetic activity can survive even at these low stellar masses. The emissions are qualitatively similar to those from active stars, despite the dramatic differences between the characteristics of an ultracool (>M7) stellar atmosphere and those of earlier type cool stars. It is currently an open question how the structures and magnetic heating which exists in these very low mass stars compare with those seen in higher mass active stars. We propose to take Chandra and HST/COS spectra of two nearby active very low mass stars in order to determine the effect that these large-scale fields have on transition region and coronal structures.
NIC2/WFC3/IR 11548
Infrared Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation
We propose NICMOS and WFC3/IR observations of a sample of 252 protostars identified in the Orion A cloud with the Spitzer Space Telescope. These observations will image the scattered light escaping the protostellar envelopes, providing information on the shapes of outflow cavities, the inclinations of the protostars, and the overall morphologies of the envelopes. In addition, we ask for Spitzer time to obtain 55-95 micron spectra of 75 of the protostars. Combining these new data with existing 3.6 to 70 micron photometry and forthcoming 5-40 micron spectra measured with the Spitzer Space Telescope, we will determine the physical properties of the protostars such as envelope density, luminosity, infall rate, and outflow cavity opening angle. By examining how these properties vary with stellar density (i.e. clusters vs. groups vs. isolation) and the properties of the surrounding molecular cloud; we can directly measure how the surrounding environment influences protostellar evolution, and consequently, the formation of stars and planetary systems. Ultimately, this data will guide the development of a theory of protostellar evolution.
S/C 11550
COS-GTO: X-Ray Binaries
This is a program to obtain UV spectra of soft X-ray transients (SXTs) in their quiescent states. The target, A0620-00, is an interacting binary system with a K7V donor star and a 9.7 M_solar black hole accretor. Our observations will use the COS G140L and STIS G230L modes to obtain low spectral resolution (R= 1000-2000), broadband (1230-3200 A) spectra of A0620-00. We will also obtain contemporaneous optical spectra of the system, which varies on time scales of days. The data will be used to establish the broadband SED of the system and to measure emission line strengths and widths in the UV. The dereddened SED will be modeled to determine the structure and temperature of the accretion disk. The FUV region of the spectrum, which has not been observed before, will be a key parameter in constraining the temperature and inner truncation radius of the disk, which is believed to transition to an advection-dominated accretion flow (ADAF) at large distances from the black hole in quiescent SXTs. The UV line spectrum, and in particular the NV 1240 and CIV 1550 transitions, will show whether C depletions, which have been seen in the NIR spectrum of the donor star, are present in the accretion disk and whether enhanced N abundances are also seen, indicative of CNO processing of material during the evolutionary history of the binary. Comparison of emission line velocities between the optical HI emission and the ionized UV metal transitions will also be used to constrain the relative extents of the photoionized disk chromosphere and the bulk of the disk in quiescent black hole binaries.
STIS/CC 11845
CCD Dark Monitor Part 2
Monitor the darks for the STIS CCD.
STIS/CC 11847
CCD Bias Monitor-Part 2
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/CCD 11849
STIS CCD Hot Pixel Annealing
This purpose of this activity is to repair radiation induced hot pixel damage to the STIS CCD by warming the CCD to the ambient instrument temperature and annealing radiation-damaged pixels.
Radiation damage creates hot pixels in the STIS CCD Detector. Many of these hot pixels can be repaired by warming the CCD from its normal operating temperature near -83 deg. C to the ambient instrument temperature (~ +5 deg. C) for several hours. The number of hot pixels repaired is a function of annealing temperature. 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.
WFC3/UV/IR 11709
Stretching the Diversity of Cosmic Explosions: The Supernovae of Gamma-ray Bursts
While the association between gamma-ray bursts (GRBs) and massive stars is robust, there is a large diversity of properties among supernovae (SNe) associated with GRBs. The converse is also true: Several recent events show that there is a large brightness range among high energy transients associated with SNe. As part of a comprehensive program, we propose to use HST in order to search for and characterize the SNe associated with GRB.
HST offers the means to cleanly separate the light curve of the GRB afterglow from the supernova, and to remove the contamination from the host galaxy, opening a clear path to the fundamental parameters of the SN, and thence to the progenitor. From these observations, we will determine the absolute magnitude at maximum, the shape of the spectral energy distribution, and any change over time of the energy distribution. We will also measure the rate of decay of the exponential tail.
Merged with the ground-based data that we will obtain for each event, we will be able to compare our data set to models and constrain the energy of the explosion, the mass of the ejecta and the mass of Nickel synthesized during the explosion. These results will shed light on the apparent variety of supernovae associated with gamma-ray bursts and X-ray flashes, and on the relation between these SNe and other, more common, types of core-collapse explosions.
WFC3/UVIS 11905
WFC3 UVIS CCD Daily Monitor
The behavior of the WFC3 UVIS CCD will be monitored daily with a set of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray biases are acquired at less frequent intervals throughout the cycle to support subarray science observations. The internals from this proposal, along with those from the anneal procedure (Proposal 11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).
WFC3/UVIS 11908
Cycle 17: UVIS Bowtie Monitor
Ground testing revealed an intermittent hysteresis type effect in the UVIS detector (both CCDs) at the level of ~1%, lasting hours to days. Initially found via an unexpected bowtie-shaped feature in flatfield ratios, subsequent lab tests on similar e2v devices have since shown that it is also present as simply an overall offset across the entire CCD, i.e., a QE offset without any discernable pattern. These lab tests have further revealed that overexposing the detector to count levels several times full well fills the traps and effectively neutralizes the bowtie. Each visit in this proposal acquires a set of three 3×3 binned internal flatfields: the first unsaturated image will be used to detect any bowtie, the second, highly exposed image will neutralize the bowtie if it is present, and the final image will allow for verification that the bowtie is gone.
WFC3/UVIS 11924
WFC3/UVIS External and Internal CTE Monitor
CCD detector Charge Transfer Inefficiency (CTI)-induced losses in photometry and astrometry will be measured using observations of the rich open cluster NGC6791 and with the EPER (Extended Pixel Edge Response) method using tungsten lamp flat field exposures. Although we do not expect to see CTE effects at the outset of Cycle 17, this CTE monitoring program is the first of a multi-cycle program to monitor and establish CTE-induced losses with time. We expect to measure CTE effects with a precision comparable to the ACS measurements.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 13 13
FGS REAcq 3 3
OBAD with Maneuver 9 9
SIGNIFICANT EVENTS: (None)
