Search Publications
Spectrophotometric Libraries, Revised Photonic Passbands, and Zero Points for UBVRI, Hipparcos, and Tycho Photometry
Murphy, Simon; Bessell, Michael
We have calculated improved photonic passbands for the UBVRI, Hipparcos Hp, and Tycho BT and VT standard systems using the extensive spectrophotometric libraries of NGSL and MILES. Using the Hp passband, we adjusted the absolute flux levels of stars in the spectrophotometric libraries so that their synth…
SEDfit: Software for Spectral Energy Distribution Fitting of Photometric Data
Sawicki, Marcin
This article describes SEDfit, the earliest—but continually upgraded—software package for spectral energy distribution fitting (SED fitting) of high-redshift photometric data, and the only one to properly treat nondetections. The principles of maximum-likelihood SED fitting are described, including formulae used for fitting both detected and undet…
On the Significance of Absorption Features in HST/COS Data
Danforth, Charles W.; France, Kevin; Stocke, John T. +2 more
We present empirical scaling relations for the significance of absorption features detected in medium-resolution, far-UV spectra obtained with the Cosmic Origins Spectrograph (COS). These relations properly account for both the extended wings of the COS line-spread function and the non-Poissonian noise properties of the data, which we characterize…
A Calibrated Measurement of the Near-IR Continuum Sky Brightness Using Magellan/FIRE
Simcoe, Robert A.; Sullivan, Peter W.
We characterize the near-IR sky background from 308 observations with the Folded-port InfraRed Echellette (FIRE) spectrograph at Magellan. A subset of 105 observations selected to minimize lunar and thermal effects gives a continuous, median spectrum from 0.83 to 2.5 µm, which we present in Table 2. The data are used to characterize the broa…
Optimizing Automated Classification of Variable Stars in New Synoptic Surveys
Bloom, Joshua S.; Richards, Joseph W.; Long, James P. +2 more
Efficient and automated classification of periodic variable stars is becoming increasingly important as the scale of astronomical surveys grows. Several recent articles have used methods from machine learning and statistics to construct classifiers on databases of labeled, multi-epoch sources with the intention of using these classifiers to automa…
A Search for Pulsations in Helium White Dwarfs
Howell, Steve B.; Fulton, Benjamin J.; Marsh, T. R. +5 more
The recent plethora of sky surveys, especially the Sloan Digital Sky Survey, have discovered many low-mass (M < 0.45 M⊙) white dwarfs that should have cores made of nearly pure helium. These WDs come in two varieties: those with masses 0.2 < M < 0.45 M⊙ and H envelopes so thin that they rapidly cool and those with M …
Aperture Photometry Tool Versus SExtractor for Noncrowded Fields
Gorjian, Varoujan; Law, Nicholas M.; Grillmair, Carl +28 more
Outputs from new software program Aperture Photometry Tool (APT) are compared with similar outputs from SExtractor for sources extracted from R-band optical images acquired by the Palomar Transient Factory (PTF), infrared mosaics constructed from Spitzer Space Telescope images, and a processed visible/near-infrared image from the Hubble Legacy Arc…
Identifying Contaminated K-Band Globular Cluster RR Lyrae Photometry
Gieren, W.; Turner, D.; Majaess, D.
Acquiring near-infrared K-band (2.2 µm) photometry for RR Lyrae variables in globular clusters and nearby galaxies is advantageous, since the resulting distances are less impacted by reddening and metallicity. However, K-band photometry for RR Lyrae variables in M5, Reticulum, M92, ω Cen, and M15 display clustercentric trends. The Hubble Spa…
Interstellar Gas in the Local Chimneys
Welsh, Barry Y.; Lallement, Rosine
We present ultraviolet absorption observations of four nearby (d < 250 pc) DA white dwarfs using spectral data (R ∼ 15 km s-1) obtained with the NASA HST Cosmic Origins Spectrograph (1150-1700 Å) and the Far Ultraviolet Spectroscopic Explorer (912-1170 Å). Two of these targets (WD2321 - 549 and WD2124 - 224) sample gas along the Sout…
Far-Ultraviolet Spectroscopy of Three Long-Period Novalike Variables
Sion, Edward M.; Godon, Patrick; Bisol, Alexandra C.
We have selected three novalike variables at the long-period extreme of novalike orbital periods: V363 Aur, RZ Gru, and AC Cnc, all with IUE archival far-ultraviolet spectra. All are UX UMa-type novalike variables and all have Porb > 7 hr. V363 Aur is a bona fide SW Sex star, and AC Cnc is a probable one, while RZ Gru has not proven …