Search Publications
An Empirical Pixel-Based Correction for Imperfect CTE. I. HST’s Advanced Camera for Surveys
Anderson, Jay; Bedin, Luigi R.
We use an empirical approach to characterize the effect of charge-transfer efficiency (CTE) losses in images taken with the Wide-Field Channel of the Advanced Camera for Surveys (ACS). The study is based on profiles of warm pixels in 168 dark exposures taken between 2009 September and October. The dark exposures allow us to explore charge traps th…
On the Stellar Content of the Carina Dwarf Spheroidal Galaxy
Walker, A. R.; Prada Moroni, P. G.; Degl'Innocenti, S. +20 more
We present deep, accurate, and homogeneous multiband optical (U, B, V, I) photometry of the Carina dwarf spheroidal galaxy, based on more than 4000 individual CCD images from three different ground-based telescopes. Special attention was given to the photometric calibration, and the precision for the B, V, and I bands is generally better than 0.01…
Optical Observations of the Rapidly Expanding Type Ia Supernova 2007gi
Wang, L.; Filippenko, A. V.; Brown, P. J. +13 more
We present optical photometry and spectra for the Type Ia supernova (SN Ia) 2007gi in the nearby galaxy NGC 4036. SN 2007gi is characterized by extremely high-velocity (HV) features of the intermediate-mass elements (Si, Ca, and S), with expansion velocities (vexp) approaching ∼15,500 km s-1 near-maximum brightness (compared …
On the Absolute Age of the Globular Cluster M92
Walker, A. R.; Weiss, A.; Prada Moroni, P. G. +15 more
We present precise and deep optical photometry of the globular M92. Data were collected in three different photometric systems: Sloan Digital Sky Survey (g‧, r‧, i‧, and z‧ MegaCam at CFHT), Johnson-Kron-Cousins (B, V, and I; various ground-based telescopes), and Advanced Camera for Surveys (ACS) Vegamag…
A Photometric Catalog of 77 Newly Recognized Star Clusters in M31
Massey, Philip; Olsen, Knut; Bianchi, Luciana +2 more
This paper describes the results of a Hubble Space Telescope (HST) WFPC2 search for star clusters in active star-formation regions of M31. Nine of the clusters were previously cataloged and 77 are new. Our 23 fields cover key areas of the galaxy’s recent star-formation activity. We provide a catalog of positions and integrated magnitudes in four c…
The Kyoto Tridimensional Spectrograph II on Subaru and the University of Hawaii 88 in Telescopes
Ishii, M.; Sugai, H.; Ishigaki, T. +11 more
In order to investigate physical conditions of ionized gas in galaxies, as well as its kinematics, we have developed the Kyoto tridimensional spectrograph II. It is a multimode optical instrument, including integral field spectrograph (IFS) and Fabry-Perot imager modes. We have designed it compact so that we can mount it on 2 m class telescopes as…
High-Resolution UV Absorption Observations of the Local Interstellar Cavity
Welsh, Barry Y.; Lallement, Rosine
We present far-ultraviolet (1245-1680 Å), high-resolution (R ∼ 3 km s-1) spectroscopic observations of three early-type stars (HD 32630, HD 158427, and HD 175191) located within 75 pc of the Sun recorded with the recently refurbished HST-STIS instrument. These data have allowed an absorption study of the local interstellar gas to invest…
Determination of Fundamental Properties of an M31 Globular Cluster from Main-Sequence Photometry
Fan, Zhou; Zhou, Xu; Ma, Jun +5 more
M31 globular cluster B379 is the first extragalactic cluster whose age was determined by main-sequence photometry. In the main-sequence photometric method, the age of a cluster is obtained by fitting its color-magnitude diagram (CMD) with stellar evolutionary models. However, different stellar evolutionary models use different parameters of stella…
Observing Exoplanets with SOFIA
Krabbe, A.; Angerhausen, D.; Iserlohe, C.
In this article we present an analysis of possible science cases for NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) in the field of extrasolar planet detection and characterization. Advantages of SOFIA and its instruments for exoplanet observations are illustrated and possible targets are introduced. Possible future instrumentatio…
Noise and Bias In Square-Root Compression Schemes
Rhodes, Jason; Bernstein, Gary M.; Bebek, Chris +3 more
We investigate data compression schemes for proposed all-sky diffraction-limited visible/NIR sky surveys aimed at the dark-energy problem. We show that lossy square-root compression to 1 bit pixel-1 of noise, followed by standard lossless compression algorithms, reduces the images to 2.5-4 bits pixel-1, depending primarily up…