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Proposal Number: 10500002

Title: Measuring the Magnetic Fields of Central Compact Objects in Supernova Remnants

PI Name: Jules Halpern

X-ray timing studies of two X-ray pulsars in SNRs have detected no braking of their rotation, implying upper limits of 3E11 G on their surface dipole fields, well below those of ordinary young pulsars. We proposed that weak B-fields related to slow natal spin may be the physical basis of the class of Central Compact Objects (CCOs), including the unseen pulsar in SN 1987A. This proposal leverages existing timing data on CCO pulsars to determine if they are spinning down and, if so, to measure their magnetic fields by obtaining coherent timing solutions linking all previous data. Fields as small as 1E10 G can be measured in this way. Alternatively, accretion of supernova debris through a fallback disk may be occurring, which would be detectable as torque noise.

Proposal Number: 10500017

Title: Chandra Observation of the Southeast Rim of G347.3-0.5

PI Name: Stephen Murray

We propose an ACIS-I observation of the southeast shell of G347.3-0.5 in order to search for sharp nonthermal filaments and to establish a baseline for future expansion measurements.

Proposal Number: 10500031

Title: Search for a Period in the Cas-A CCO

PI Name: Stephen Murray

Looking for pulsation's from the Cas-A CCO

Proposal Number: 10500032

Title: Obtaining spatial and spectral information of a point source in RCW 86

PI Name: Jelle Kaastra

ROSAT found an unresolved source in the supernova remnant RCW 86, which may be the putative neutron star. However, the positional accuracy obtained with ROSAT and XMM-Newton are insufficient to see whether this source has an optical counter part (in which case it is likely to be a star or background source, rather than a neutron star). The source is located off center toward the SW of the remnant. The remnant is bright in the SW, so the source may be closer to the explosion center than expected based on the geometrical center. Chandra observed RCW 86 several times, but the point source was always outside the field of view. In one pointing on the SW, the source fell just in between the ACIS-I ACIS-S chip gaps. Here we propose to observe for a 2000 s in order to obtain an accurate position.

Proposal Number: 10500047

Title: Monitoring the spectral evolution of RXJ0720-3125 and determining its nature

PI Name: Jelle Kaastra

RX J0720.4-3125 belongs to a group of radio-quiet isolated neutron stars, whose spectra are characterized by a blackbody spectrum plus one or more broad absorption features. It is unique in that its blackbody temperature, and the depth of the absorption feature is variable. The cause for this spectral evolution is unclear, but one proposed model is free precession of a neutron star with two hot spots. Observing in this Chandra cycle will complete the coverage of a putative precession cycle with a period of~7-8 yr. This puts the precession hypothesis to the ultimate test.

Proposal Number: 10500050

Title: Observation of the central compact Object in RX J0852.0-4622

PI Name: Peter Predehl

We propose Chandra observations of the central compact object in RX J0852.0-4622.

Proposal Number: 10500065

Title: 2nd Epoch High Resolution Spectra of Cassiopeia A: Plasma Evolution and Doppler Mapping

PI Name: Claude Canizares

We propose to study the evolution of physical conditions in the bright X-ray ejecta of Cassiopeia A using a 2nd HETGS observation. Based on ACIS observations and plasma evolution models we expect to observe variations in the H- and He-like emission lines of Si and S. This will form an 8-year baseline to the 1st HETGS observation in 2001. We will also use these new data in conjunction with the 1st data set to map the 3-dimensional structure of the dynamically important X-ray ejecta.

Proposal Number: 10500072

Title: Galactic Supernova Remnant G340.6+0.3

PI Name: Gordon Garmire

We propose a 70 ks Chandra observation of SNR G340.6+0.3. This SNR shows distinctive X-ray line structures between N and S shells. Particularly, in the N region, strongly enhanced X-ray lines from highly ionized S, Ar, and Ca suggest ejecta-dominated emission, reminiscent of Cas A. The proposed Chandra observation is essential to reveal the nature of X-ray emission and the origin of this SNR.

Proposal Number: 10500078

Title: Long GRB Jet Breaks

PI Name: Gordon Garmire

In the standard fireball model for GRB afterglows, the jet opening angle can be determined from the achromatic jet break time by measuring the light curve until this break occurs. Swift XRT observations have shown that jet breaks are not observed in the first several days or weeks of a typical X-ray afterglow. This has important implications for the derived energetics of the GRB itself that cannot be resolved without a more complete sample of observed jet breaks. We propose to follow 4 carefully chosen long GRB afterglows with late-time Chandra observations in order to search for jet breaks occurring after the Swift observations end.

Proposal Number: 10500093

Title: Snap-shot survey of compact, radio-bright SNRs

PI Name: Gordon Garmire

We propose to observe a set of radio-bright remnants (SNRs) previously unobserved in X-rays. The SNRs have flat, non-thermal spectra suggesting efficient particle acceleration at the shock front. We also expect to find new pulsars or neutron stars within these remnants. These makes the selected SNRs good candidates for future TeV and GeV detections. The selected SNRs are also compact enough to be imaged within the ACIS-I field of view.

Proposal Number: 10500237

Title: Rediscovering the Young Ejecta-Dominated Supernova Remnant G350.1-0.3

PI Name: Patrick Slane

G350.1-0.3 is a small-diameter radio source whose complex morphology left it unclassified for years. Recent XMM observations make it clear that this is a young, bright ejecta-dominated SNR with an associated compact object. X-ray spectra reveal spatial variations in the ejecta abundances and ionization states, but the XMM resolution is insufficient to probe the emission on scales that are most relevant for investigating the ejecta structure. The poorly-measured position of the compact object also results in multiple candidate IR counterparts. We propose a Chandra observation of G350.1-0.3 to provide spectra of the ejecta on small spatial scales, to search for nonthermal filaments that are generally produced in young SNRs, and to obtain a high-precision position for the compact object.

Proposal Number: 10500274

Title: Chandra/Spitzer ToO Observations of a short-duration gamma-ray burst

PI Name: Kevin Hurley

We propose to observe a short GRB afterglow for 60 ks with Chandra, in conjunction with Spitzer observations. This is a continuation of a Spitzer/Chandra proposal which was accepted for Spitzer cycles AO-3 and AO-4, but never activated due to lack of a suitable burst. We have been granted Spitzer AO-5 ToO time until the cryogen runs out (2009 April 22), and are requesting Chandra time to support these observations. This is a multi-wavelength approach to the problem of understanding the short GRBs, involving two great observatories, as well as numerous ground-based facilities. By measuring the broad-band spectrum of the afterglow at several epochs, we can distinguish between the models proposed for the short bursts.

Proposal Number: 10500295

Title: Are all black widows alike?

PI Name: Vyacheslav Zavlin

We propose a Chandra observation of the eclipsing millisecond pulsar J2051-0827 in a 8.6 ks orbital period binary system with a low-mass companion. Optical observations have shown that this system is another example, in addition to PSR B1957+20, of a ``black widow pulsar'', whose relativistic pulsar wind ablates the stellar companion and creates an intrabinary shock. Studying the spectrum and light curve of the X-ray emission from the shocked relativistic wind provides an opportunity to elucidate the properties of the wind and understand the nature of this important class of millisecond pulsars.

Proposal Number: 10500298

Title: ToO Observations of Soft Gamma Repeaters

PI Name: Chryssa Kouveliotou

Soft Gamma Repeaters are rare sources of transient burst emission, probably magnetars (i.e. strongly magnetized neutron stars). Each of the SGRs has a persistent X-ray counterpart and some show coherent pulsations. During burst active phases, these counterparts undergo changes in their energy spectrum and pulse properties. Measuring the effects of burst activity are diagnostic of the burst mechanism and SGRs in general. In the event of detection of substantial burst activity from an SGR, we propose to make Chandra ToO observations of any of the four known sources, SGR 1900+14, SGR 1806-20, SGR 1627-41, SGR 0526-66, the two SGR candidates SGR 1801-23 and SGR 2013+34, as well as any newly discovered SGR source.

Proposal Number: 10500327

Title: An Extensive Study of the Youngest Galactic Supernova Remnant G1.9+0.3

PI Name: Stephen Reynolds

We have recently discovered that the smallest Galactic supernova remnant (SNR) in angular size, G1.9+0.3, is the youngest (known) Galactic SNR, with an age of about 100 years. The X-ray spectrum is lineless, well described by synchrotron emission with the highest rolloff frequency ever reported for a SNR. We propose a 500 ks Large Project observation of this unique object, which fills in a gap between SN 1987A (21 yr old) and Cas A (about 330). We wish to study detailed morphology, to compare with the 3 other Galactic synchrotron- dominated SNRs; spectra, to search for spatial variations and thermal emission; and variability, using this study for the first epoch. This object has enormous potential for the study of SNR hydrodynamics and strong-shock physics.

Proposal Number: 10500344

Title: New Pulsar Identifications of TeV Gamma-ray Sources

PI Name: Jules Halpern

Pulsar wind nebulae are the fastest growing class of Galactic TeV gamma-ray source as many unidentified HESS sources come to be identified with X-ray faint or "offset" PWNe. We propose to search for pulsations from new "TeV selected" pulsars seen in Chandra and XMM images of HESS sources. Determining pulsar ages and spin-down luminosities is important for testing models in which the TeV source is powered not by the supernova shell, but by inverse Compton scattering from high-energy PWNe electrons. Both the luminosity and the spatial extent of the TeV emission should depend on these basic pulsar spin parameters, as would the possible offset of the TeV nebula from the pulsar. These trends can be established by extending the observed sample.

Proposal Number: 10500347

Title: Searching for extragalactic soft gamma-ray repeaters

PI Name: Eran Ofek

The available observational evidence suggests that SGRs are highly magnetized (~10^14 G), young neutron stars. The best path to revealing the origin, evolution and formation channels of SGRs, is a detailed environmental study of a large sample of such objects. Unfortunately, current research of these objects is limited by the small number of known SGRs. We are planing to use GLAST/GBM in concert with Swift/XRT to identify SGR giant flares in nearby galaxies. However, in order to get arcsecond-accuracy locations of these events, which are needed for an environmental study, we ask for Chandra ToO of up to 2 events for which we will detect X-ray afterglows using Swift/XRT.

Proposal Number: 10500400

Title: Rapid Observations of Short Gamma-Ray Bursts: Accurate Positions Hold the Key to the Progenitor Population

PI Name: Edo Berger

Only 1/4 of all short GRBs are localized to sub-arcsecond accuracy, required for unambiguous host and redshift identifications, determination of the burst environment (disk, bulge, halo, IGM), and assessment of natal kicks. These properties determine the identity and ages of the progenitors, and the GRB explosion properties. Thus, much of our knowledge depends on a handful of events, which are moreover biased to high density environments by virtue of optical/UV/radio detections. Here we propose to double the fraction of events with sub-arcsecond positions, and overcome the density bias, using rapid Chandra observations of bursts with only Swift/XRT positions (3-6"). Swift data will guarantee Chandra detections at <4 days, and follow-up work will delineate the burst/host properties.

Proposal Number: 10500426

Title: PSRJ1832+0029: a unique target for pulsar emission physics

PI Name: Duncan Lorimer

We have discovered very unusual behavior in PSR J1832+0029, a 533-ms radio pulsar which switches between on and off states on timescales of several hundred days. Remarkably, the pulsar's spin-down rate almost doubles when the radio emission is on. This is even more dramatic than observed for PSR B1931+24 for which no satisfactory theory presently exists. Unlike PSR B1931+24, J1832+0029 is nearby (1.3 kpc) and an excellent target for X-ray detection. Here we request a 20 ks ACIS TOO to study the X-ray emission of PSR J1832+0029 in its off state, triggered by radio monitoring. Together with our recent GO observation, this TOO will help distinguish between radio emission quenching mechanisms that are either intrinsic to the pulsar or caused by accretion from an orbiting companion.

Proposal Number: 10500434

Title: Chandra Observations of New X-ray Supernovae

PI Name: David Pooley

We propose to continue our X-ray studies of Type II and Type Ib/c supernovae (SNe). The Swift satellite has ushered in a new era of studying SNe in the X-rays, obtaining densely sampled X-ray lightcurves for the first time. However, its spatial resolution is often not good enough to separate a SN from nearby sources. We propose short Chandra observations to alleviate this. These observations will assess the X-ray environment of newly discovered Swift SNe to determine any possible source confusion or contamination of the SN flux. Our strategy makes the best use of the capabilities of each observatory.

Proposal Number: 10500437

Title: The Spin and Magnetic Moment of the Neutron Star in Cassiopeia A

PI Name: Deepto Chakrabarty

How do the spin and magnetic moment of a neutron star relate to the properties of its massive progenitor and the supernova explosion? The best opportunity to study this question is the Cas A point source, the youngest known (300 yr) Galactic compact object. Its spectrum is unlike the classical Crab pulsar's, but is instead similar to both the more strongly magnetic "magnetars" and more weakly magnetic young pulsars. Much has been inferred about its progenitor and the supernova explosion from detailed studies of the supernova remnant. We propose to obtain a 500 ks HRC-S observation of the Cas A central point source, combining 350 ks of GO time and 150 ks of GTO time, in order to search for coherent pulsations down to the practical sensitivity limit of any current X-ray mission.

Proposal Number: 10500440

Title: Imaging the binary plerion

PI Name: George Pavlov

The radio pulsar B1259-63 is in an eccentric binary (e=0.87, P=3.4 yr) with a high-mass Be companion. Being dependent on binary orbital phase, the X-ray emission of this system is believed to be generated in a bow-shock pulsar wind nebula (PWN) formed by colliding winds from the pulsar and the companion. However, this very compact PWN has never been resolved in previous low-resolution observations. Imaging the B1259-63 PWN with the ACIS detector, we expect to detect a PWN tail, similar to those commonly observed behind solitary pulsars moving in the ISM with supersonic speeds, and a pulsar jet. Studying the properties of this unusual PWN will help to understand the nature of stellar and pulsar winds and their interaction.

Proposal Number: 10500481

Title: Prompt Study of Burst-Selected Outbursts from AXPs

PI Name: Gian Luca Israel

The discovery of transient AXPs has opened a new perspective in the field confirming that a relatively large number of members of this class has not been discovered yet, and suggesting that others would manifest themself in the future through outbursts. This proposal is aimed at gathering new insights on the physics of AXPs through the study of the very initial phases (within 10days) of their outbursts. In particular, we are proposing to select outbursts from known or still unknown magnetar candidates, to study them through fast-response (within hours) pointed observations and, therefore, to sample the still poorly explored phases of rapid timing/spectral variability just after the onset.

Proposal Number: 10500491

Title: An In-Depth Study of the Nearest Gamma-Ray Bursts

PI Name: Alicia Soderberg

Just a decade ago, astronomers thought stellar core-collapse was primarily a spherical process. Gamma-ray bursts, with collimated jets (powered by a central engine) and at the same time a spherical explosion (supernova) have upset this paradigm. Empirically there appears to be a wide range in the energy of the explosion. This opens up the possibility that "jet-driven" explosions are common in for all supernovae. Here we propose an in-depth study of the nearest gamma-ray bursts. Our synergistic multi-wavelength effort (radio, optical, Swift/XRT and proposed CXO) are designed to extract the true energy of these explosions.

Proposal Number: 10500533

Title: A Deep Chandra Observation of Supernova Remnant N49 in the LMC

PI Name: SANGWOOK PARK

N49 is a bright supernova remnant (SNR) in the Large Magellanic Cloud (LMC) showing complex substructures in X-rays, and thus is an excellent laboratory for the detailed study of the shock evolution in a clumpy environment. On the other hand, the origin (core-collapse vs thermonuclear explosion) of this SNR is unknown. Chandra ACIS observations provide a unique opportunity to study the metal-rich ejecta and shocked ISM, which will be useful to reveal the SNR origin and to study the detailed shock evolution process over a wide range of thermal states. Thus, we propose a 120 ks ACIS observation of SNR N49.

Proposal Number: 10500606

Title: X-ray emission from the double neutron star binary J1537+1155: Powered by the pulsar wind?

PI Name: Oleg Kargaltsev

We have discovered X-ray emission from the double neutron binary (DNSB) J1537+1155 in a 37 ks observation with Chandra. We found that the spectrum and the luminosity of J1537 are very similar to those of the famous double pulsar binary J0737-3039 (the only other DNSB detected in X-rays). However, unlike J0737, in J1537, whose orbit is more eccentric, we found evidence for variability with orbital phase, at a 3 sigma level. If confirmed, such variability proves that a substantial fraction of X-ray emission in DNSB can be produced via the interaction between the pulsar wind and the companion NS. We propose a follow-up 38 ks (one binary orbit) observation to verify the putative variability and test various models for X-ray emission of DNSBs.

Proposal Number: 10500627

Title: Time Variability of Synchrotron X-ray Emission in SNR RX J1713.7-3946

PI Name: Yasunobu Uchiyama

A recent detection of synchrotron X-ray variability in SNR RX J1713.7-3946 indicates that the interstellar magnetic field can be largely amplified at the expanding shock of a young SNR through magnetohydrodynamic waves generated by cosmic-rays themselves. Here we propose the follow-up Chandra ACIS-I observations of the northwestern shell of RX J1713.7-3946, with 3 x 30 ks monitoring observations, each spaced by 3-4 months. By tracking intra-year variability, we will infer the time history of electron acceleration and cooling. Also, by comparing with the previous observations, we will measure flux changes in lower brightness filaments as well as an expansion angular velocity, thereby testing the origin of TeV gamma-rays and predictions from a shock-acceleration theory.

Proposal Number: 10500639

Title: The Luminous Supernova Remnant in NGC4449: Charting the Future for SN 1987A

PI Name: Knox Long

The X-ray luminosity and the optical spectrum of the extraordinary young SNR in NGC4449 have changed since it was discovered in 1978. Here we propose to obtain a second-epoch Chandra ACIS S spectrum and contemporaneous optical (3300-7600 Ang) spectra of the SNR. We will compare the X-ray and optical spectra from different epochs and then model them to develop a more complete understanding of how the shock from this 50-100 year old SN is overrunning the circumstellar medium of the progenitor. We will use this to predict its future evolution and to compare this to the expected future of SN 1987A.

Proposal Number: 10500651

Title: X-ray observations of a TeV-emitting pulsar tail

PI Name: Zdenka Misanovic

A large number of recently detected TeV sources are still unidentified, although the attempts have been made recently to find their X-ray counterparts. For several of these extended TeV sources, young pulsars have been proposed as counterparts, although the pulsars are offset by 10-15 arcmin from the center of the TeV emission. The HESS source J1834-087 coincides with the shell SNR G23.3-0.3, which was proposed as its X-ray counterpart. However, we have recently detected a pulsar candidate and an elongated tail-like structure, possibly a PWN, at the SNR center. We argue that this PWN is a more likely HESS counterpart than the SNR shell. We propose a follow-up observation to confirm this identification.

Proposal Number: 10500659

Title: TINY HICCUPS TO TITANIC EXPLOSIONS: Tackling Transients in Anomalous X-ray Pulsars

PI Name: Victoria Kaspi

The past decade has seen major progress in neutron star astrophysics, with the discovery of magnetars in general, and the recognition that the Anomalous X-ray Pulsars (AXPs) fall in this class. AXPs have recently revealed surprising and dramatic variability behavior, which theorists have begun to show are highly constraining of physical models of magnetars, including their crusts, atmospheres, coronae and magnetospheres. In this proposal, we request Chandra/ACIS-S Target-of-Opportunity observations of one major Anomalous X-ray Pulsar (AXP) outburst in A10, in order to study in detail the evolution of the spectrum, pulsed fraction and pulse profile, for quantitative confrontation with recently developed models for the structure and electrodynamics of magnetars.

Proposal Number: 10500687

Title: A Deep Cycle 10 Chandra Observation of the Tycho Supernova Remnant

PI Name: John Hughes

We propose to obtain a very deep observation of the Tycho supernova remnant. Our observational goals include investigating the nature and origin of Fe-rich ejecta knots, and studying the spatial, spectral and temporal evolution of the nonthermal emission from the forward shock. Tycho is the ideal remnant for studies of cosmic-ray modified dynamics and for investigating key features of Type Ia supernova physics.

Proposal Number: 10500688

Title: Solving the Mystery of Type IIn Supernovae

PI Name: Poonam Chandra

X-ray observations of young supernovae provide unique constraints on the circumstellar density, profile, and elemental composition of the ejecta. Fingerprinting the exploded ejecta composition through X-ray spectroscopy can give clues to the mass and progenitor mass loss history of the exploding star. Both of these will help in understanding the relation of Type IIn progenitors to those of other classes of supernovae.

Proposal Number: 10500693

Title: The Weakly Magnetized Pulsar in Kes 79

PI Name: Jules Halpern

Our X-ray timing studies of two X-ray pulsars in SNRs detected no braking of their rotation, implying upper limits on their surface dipole fields well below those of ordinary young pulsars. We proposed that weak B-fields related to slow natal spin may be the physical basis of the class of Central Compact Objects (CCOs) including Cas A, and the unseen pulsar in SN 1987A. We propose to continue our timing program on the CCO pulsar PSR J1852+0040 in Kes 79 to determine if it is spinning down at all and, if so, to measure its magnetic field by obtaining a coherent timing solution linking all previous data. B-fields as small as 1e10 G can be measured in this way. Alternatively, accretion of supernova debris through a fallback disk may be occurring, which would be detectable as torque noise.

Proposal Number: 10500739

Title: A pulsar wind nebula in G18.95-1.1?

PI Name: Ralph Tuellmann

We propose to observe the central region of the composite SNR G18.95-1.1. Although this object has been extensively observed in the radio regime and to a minor extent in X-rays with ASCA and ROSAT, all searches for a point source have been unsuccessful. Our motivation to observe the G18.95-1.1 with Chandra is to detect an X-ray point source and perhaps non-thermal diffuse emission which could be the putative pulsar and its wind nebula. For this objective, high resolution observations are necessary to pinpoint the location of the source, making Chandra the only X-ray mission which with this study can be carried out.

Proposal Number: 10500753

Title: Chandra Cycle 10 Spatial and Spectral Monitoring of SNR 1987A

PI Name: David Burrows

Regular monitoring of SNR 1987A, the only supernova remnant in which we can study the early developmental stages in detail, is critical to testing models of remnant evolution, nonequilibrium ionization processes, and thin plasma spectra. SNR 1987A presents a unique opportunity to observe the birth and early evolution of a supernova remnant at high spatial and spectral resolution for the first time. We propose to continue our program of monitoring SNR 1987A in Cycle 10 at a roughly six month period.

Proposal Number: 10500758

Title: The High-B Radio Pulsar PSR J1718-3718: A Quiescent Magnetar?

PI Name: Maura McLaughlin

PSR J1718-3718 is a young radio pulsar with a magnetar-strength field. Its likely X-ray counterpart, which we serendipitously detected with Chandra, has a thermal spectrum resembling that of the transient AXP XTE J1810-197 in quiescence. Recently, a magnetar-like outburst was detected from rotation-powered PSR J1846-0248, showing that rotation-powered pulsars can exhibit magnetar behavior and suggesting that such activity may be correlated with magnetic field. With a magnetic field 50% higher than J1846-0258's, J1718-3718 may be a quiescent magnetar. We request ACIS-S observations to search for magnetar-like outbursts, detect X-ray pulsations, measure the pulsed fraction, improve the spectral parameters, and obtain a precise position in order to establish the nature of this source.

Proposal Number: 10500817

Title: The Unique Dynamical Vela Pulsar Wind Nebula

PI Name: George Pavlov

Chandra observations of the Vela pulsar-wind nebula (PWN) have revealed intriguing features in its structure and shown that the PWN brightness, shape, and spectrum change on a timescale as short as one week. Taking advantage of the known variability timescale, we propose a series of optimally sequenced observations to understand the PWN topology, dynamics, spectral structure, and interaction with the ambient matter.

Proposal Number: 10500822

Title: The Energetics and Environments of 'Naked' Supernovae

PI Name: Alicia Soderberg

Twenty years have passed since the peculiar class of SNe Ibc were recognized as core-collapse explosions. However, it is only recently that SNe Ibc have enjoyed a surge of interest thanks to their association with GRBs. Today, the most crucial question is whether SNe Ibc and GRBs arise from similar or distinct progenitor systems. Progress requires a detailed study of ordinary SNe Ibc, which out-number GRB-SNe by a factor of 100. Here we propose a focused program that leverages CXO data with those of Swift/XRT and VLA.

Proposal Number: 10500824

Title: A Deep HETG Probe of the CSM Interaction in SN1996cr

PI Name: Franz Bauer

SN1996cr is one of the closest and X-ray brightest SNe detected on the sky. Like SN1987A, it appears to have exploded into a wind-blown bubble, sparking a unique temporal evolution wherein its X-ray flux has increased for >8 years now. Serendipitous HETG data allow us to identify several strong, broad, asymmetric emission-line complexes in SN1996cr, although their low-signal leaves much to interpretation. We propose a deep HETG observation of SN1996cr to resolve these emission lines and elucidate their nature (velocity structure, line diagnostics, abundances). It is imperative to observe SN1996cr while it remains bright, as it is the only SN beside SN1987A where such an observation is practical and in many ways is more representative of CSM-interacting core-collapse SNe.

Proposal Number: 10500874

Title: Identifying the Nearest and Brightest Neutron Stars

PI Name: Derek Fox

Using catalog cross-correlation and over 400 ksec of Swift X-ray and UV observations, we have identified 19 candidate neutron stars from among the 18,811 sources of the ROSAT Bright Source Catalog. With one of these now confirmed as the eighth isolated neutron star, `Calvera,' we request Chandra observations of 16 remaining candidates to collect sub-arcsec positions and modest-quality X-ray spectra. Sub-arcsec X-ray positions are vital to confirm these objects as neutron stars by demonstrating the absence of optical counterparts to faint magnitudes (V > 25 mag). Chandra X-ray spectra will simultaneously yield blackbody temperatures and radii. This single program has the potential to dramatically increase the number of bright, nearby neutron stars that are known.

Proposal Number: 10500924

Title: AO-10 Observations of the Standard Candles Cas A and G21.5-09.

PI Name: CXC Calibration

We continue our annual observations of Cas A and G21.5-09 to monitor the HRC and ACIS.

Proposal Number: 10500927

Title: AO-10 Calibration Observations of E0102-72

PI Name: CXC Calibration

We have observed the oxygen rich supernova remnant E0102-72 every year since launch to monitor the low energy response of ACIS.

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