Search Publications
IMACS: The Inamori-Magellan Areal Camera and Spectrograph on Magellan-Baade
Dressler, Alan; Kelson, Daniel; Shectman, Stephen +12 more
The Inamori-Magellan Areal Camera and Spectrograph (IMACS) is a wide-field, multipurpose imaging spectrograph on the Magellan-Baade telescope at Las Campanas Observatory. IMACS has two channels—f/2 and f/4, each with an 8K × 8K pixel mosaic of CCD detectors, that service the widest range of capabilities of any major spectrograph. These include wid…
Astrometry and Photometry with HST WFC3. II. Improved Geometric-Distortion Corrections for 10 Filters of the UVIS Channel
Anderson, J.; Bedin, L. R.; Bellini, A.
We present an improved geometric-distortion solution for the Hubble Space Telescope UVIS channel of Wide Field Camera 3 for 10 broadband filters. The solution is made up of three parts: (1) a third-order polynomial to deal with the general optical distortion, (2) a table of residuals that accounts for both chip-related anomalies and fine-structure…
Toward Precision LSST Weak-Lensing Measurement. I. Impacts of Atmospheric Turbulence and Optical Aberration
Tyson, J. Anthony; Jee, M. James
The weak-lensing science of the Large Synoptic Survey Telescope (LSST) project drives the need to carefully model and separate the instrumental artifacts from the intrinsic shear signal caused by gravitational lensing. The dominant source of the systematics for all ground-based telescopes is the spatial correlation of the point-spread function (PS…
Calibration of BVRI Photometry for the Wide Field Channel of the HST Advanced Camera for Surveys
Dolphin, Andrew E.; Shaw, Richard A.; Saha, Abhijit +1 more
We present new observations of two Galactic globular clusters, PAL4 and PAL14, using the Wide Field Channel of the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST) and reanalyze archival data from a third, NGC2419. We matched our photometry of hundreds of stars in these fields from the ACS images to existing ground-based…
The Efficacy of Galaxy Shape Parameters in Photometric Redshift Estimation: A Neural Network Approach
Lotz, J.; Griffith, R. L.; Singal, J. +2 more
We present a determination of the effects of including galaxy morphological parameters in photometric redshift estimation with an artificial neural network method. Neural networks, which recognize patterns in the information content of data in an unbiased way, can be a useful estimator of the additional information contained in extra parameters, s…
Data Characterization Using Artificial-Star Tests: Performance Evaluation
Deng, Licai; de Grijs, Richard; Liu, Qiang +1 more
Traditional artificial-star tests are widely applied to photometry in crowded stellar fields. However, to obtain reliable binary fractions (and their uncertainties) of remote, dense, and rich star clusters, one needs to recover huge numbers of artificial stars. Hence, this will consume much computation time for data reduction of the images to whic…
Multiphase High-Velocity Gas Detected within 7 kpc Toward the M13 Globular Cluster
Welsh, Barry Y.; Lallement, Rosine; Wheatley, Jonathan
We present medium-resolution ultraviolet interstellar absorption measurements recorded with the HST-COS and FUSE spectrographs toward the post-AGB star Barnard 29 in the M13 globular cluster. Inspection of the UV spectra has revealed absorption at in the absorption profiles of the C I, C II, , C IV, N I, N II, N V, O I, ALII, Si II, Si IV, S II an…
A Morphological Study of UV-Bright Stars and Emission Nebulae in a Selection of Star Formation Regions in M31
Krienke, O. Karl; Hodge, Paul W.; Luciana, Bianchi
Using the data from the NOAO Local Group Survey, we have measured the Hα fluxes of 291 nebulae associated with 21 of the van den Bergh OB associations. We have combined these data together with six-color HST WFPC2 photometry, in order to identify the most UV-bright stars in the region. The simple purpose of this article is to explore the spatial r…
A Far-Ultraviolet Spectroscopic Analysis of BZ Ursae Majoris
Sion, Edward M.; Godon, Patrick; Gänsicke, Boris T. +1 more
We present an analysis of the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) far-ultraviolet snapshot spectrum of the dwarf nova BZ UMa taken during quiescence. We find that the flux continuum is consistent with that of a white dwarf atmosphere with a temperature of 15,000 K, a projected rotational velocity of 200 km/s, non…
Modern Observations of Hubble’s First-discovered Cepheid in M31
Sabo, R.; Harris, B.; Henden, A. +9 more
We present a modern ephemeris and modern light curve of the first-discovered Cepheid variable in M31, Edwin Hubble’s M31-V1. Observers of the American Association of Variable Star Observers (AAVSO) undertook these observations during the latter half of 2010. The observations were in support of an outreach program by the Space Telescope Science Ins…