Search Publications
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…
The Star Formation Reference Survey. I. Survey Description and Basic Data
Sturm, E.; Barmby, P.; Zezas, A. +17 more
Star formation is arguably the most important physical process in the cosmos. It is a fundamental driver of galaxy evolution and the ultimate source of most of the energy emitted by galaxies in the local universe. A correct interpretation of star formation rate (SFR) measures is therefore essential to our understanding of galaxy formation and evol…
Characterization and Improvement of the Image Quality of the Data Taken with the Infrared Camera (IRC) Mid-Infrared Channels on Board AKARI
Oyabu, Shinki; Onaka, Takashi; Tanabé, Toshihiko +7 more
Mid-infrared images frequently suffer artifacts and extended point-spread functions (PSFs). We investigate the characteristics of the artifacts and the PSFs in images obtained with the infrared camera (IRC) on board AKARI at four mid-infrared bands of the S7 (7 µm), S11 (11 µm), L15 (15 µm), and L24 (24 µm). Removal of the …
AKARI-CAS—Online Service for AKARI All-Sky Catalogues
Oyabu, S.; Yamamura, I.; Ishihara, D. +10 more
The AKARI All-Sky Catalogues are an important infrared astronomical database for next-generation astronomy that take over the IRAS catalog. We have developed an online service, AKARI Catalogue Archive Server (AKARI-CAS), for astronomers. The service includes useful and attractive search tools and visual tools. One of the new features of AKARI-CAS …
Effects of High-Energy Ionizing Particles on the Si:As Mid-Infrared Detector Array on Board the AKARI Satellite
Oyabu, S.; Wada, T.; Mori, T. +6 more
We evaluate the effects of high-energy ionizing particles on the Si:As impurity band conduction (IBC) mid-infrared detector on board AKARI, the Japanese infrared astronomical satellite. IBC-type detectors are known to be little influenced by ionizing radiation. However, we find that the detector is significantly affected by in-orbit ionizing radia…
NSV 11154 Is a New R Coronae Borealis Star
Welch, D. L.; Grindlay, J. E.; Clayton, Geoffrey C. +7 more
NSV 11154 has been confirmed as a new member of the rare hydrogen-deficient R Coronae Borealis (RCB) stars based on new photometric and spectroscopic data. Using new photometry, as well as archival plates from the Harvard archive, we have constructed the historical light curve of NSV 11154 from 1896 to the present. The light curve shows the sudden…
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…