332 research outputs found
Design and construction of the IMACS-IFU, a 2000-element integral field unit
The IMACS-IFU is an Integral Field Unit built for the IMACS spectrograph at
the Magellan-I-Telescope at Las Campanas Observatory. It consists of two
rectangular fields of 5 by 7 arcseconds, separated by roughly one arcminute.
With a total number of 2000 spatial elements it is the second largest
fiber-lenslet based IFU worldwide, working in a wavelength range between 400
and 900 nm. Due to the equally sized fields classical background subtraction,
beam switching and shuffling are possible observation techniques. One
particular design challenge was the single, half a metre long curved slit in
combination with a non telecentric output. Besides the construction some
preliminary results are described.Comment: 10 pages, 7 figures, 1 table. Proceedings for SPIE poster 5492-175 of
SPIE Symposium "Astronomical Telescopes and Instrumentation", June 2004,
Glasgo
Optical Design Trade Study for the Wide Field Infrared Survey Telescope [WFIRST]
The Wide Field Infrared Survey Telescope (WFIRST) mission concept was ranked first in new space astrophysics mission by the Astro2010 Decadal Survey incorporating the Joint Dark Energy Mission (JDEM)-Omega payload concept and multiple science white papers. This mission is based on a space telescope at L2 studying exoplanets [via gravitational microlensing], probing dark energy, and surveying the near infrared sky. Since the release of NWNH, the WFIRST project has been working with the WFIRST science definition team (SDT) to refine mission and payload concepts. We present the driving requirements. The current interim reference mission point design, based on the use of a 1.3m unobscured aperture three mirror anastigmat form, with focal imaging and slitless spectroscopy science channels, is consistent with the requirements, requires no technology development, and out performs the JDEM-Omega design
Systems and methods for mirror mounting with minimized distortion
A method for mounting a mirror for use in a telescope includes attaching the mirror to a plurality of adjustable mounts; determining a distortion in the mirror caused by the plurality adjustable mounts, and, if the distortion is determined to be above a predetermined level: adjusting one or more of the adjustable mounts; and determining the distortion in the mirror caused by the adjustable mounts; and in the event the determined distortion is determined to be at or below the predetermined level, rigidizing the adjustable mounts
The night-sky at the Calar Alto Observatory II: The sky at the near infrared
We present here the characterization of the night sky-brightness at the
near-infrared, the telescope seeing, and the fraction of useful time at the
Calar Alto observatory. For this study we have collected a large dataset
comprising 7311 near-infrared images taken regularly along the last four years
for the ALHAMBRA survey (J, H and Ks-bands), together with a more reduced
dataset of additional near-infrared images taken for the current study. In
addition we collected the information derived by the meteorological station at
the observatory during the last 10 years, together with the results from the
cloud sensor for the last ~2 years. We analyze the dependency of the
near-infrared night sky-brightness with the airmass and the seasons, studying
its origins and proposing a zenithal correction. A strong correlation is found
between the night sky-brightness in the Ks-band and the air temperature, with a
gradient of ~ -0.08 mag per 1 C degree. The typical (darkest) night
sky-brightness in the J, H and Ks-band are 15.95 mag (16.95 mag), 13.99 mag
(14.98 mag) and 12.39 mag (13.55 mag), respectively. These values show that
Calar Alto is as dark in the near-infrared as most of the other astronomical
astronomical sites in the world that we could compare with. Only Mauna Kea is
clearly darker in the Ks-band. The typical telescope seeing at the 3.5m is
~1.0" when converted to the V-band, being only slightly larger than the
atmospheric seeing measured at the same time by the seeing monitor, ~0.9".
Finally we estimate the fraction of useful time based on the relative humidity,
gust wind speed and presence of clouds. This fraction, ~72%, is very similar to
the one derived in Paper I, based on the fraction of time when the extinction
monitor is working.Comment: 15 pages, 6 figures, accepted to be published in PAS
A Search for Peculiar Objects with the NASA Orbital Debris Observatory 3-m Liquid Mirror Telescope
The NASA Orbital Debris Observatory (NODO) astronomical survey uses a transit
3-m liquid mirror telescope to observe a strip of sky in 20 narrow-band
filters. In this article, we analyze a subset of data from the 1996 observing
season. The catalog consists of 18,000 objects with 10<V<19 observed in 10
narrow-band filters ranging from 500 nm to 950 nm. We first demonstrate the
reliability of the data by fitting the Bahcall-Soneira model of the Galaxy to
the NODO magnitude counts and color counts at various galactic latitudes. We
then perform a hierarchical clustering analysis on the sample to extract 206
objects, out of a total of 18,000, showing peculiar spectral energy
distributions. It is a measure of the reliability of the instrument that we
extract so few peculiar objects.
Although the data and results, per se, may not seem otherwise particularly
remarkable, this work constitutes a milestone in optical astronomy since this
is the first article that demonstrates astromomical research with a radically
new type of mirror.Comment: 24 pages, 15 figures, 3 tables, gzipped-Postscript Revised version
27/04, added references and changed conten
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