108 research outputs found
Accurate Telescope Mount Positioning with MEMS Accelerometers
This paper describes the advantages and challenges of applying
microelectromechanical accelerometer systems (MEMS accelerometers) in order to
attain precise, accurate and stateless positioning of telescope mounts. This
provides a completely independent method from other forms of electronic,
optical, mechanical or magnetic feedback or real-time astrometry. Our goal is
to reach the sub-arcminute range which is well smaller than the field-of-view
of conventional imaging telescope systems. Here we present how this
sub-arcminute accuracy can be achieved with very cheap MEMS sensors and we also
detail how our procedures can be extended in order to attain even finer
measurements. In addition, our paper discusses how can a complete system design
be implemented in order to be a part of a telescope control system.Comment: Accepted for publication in PASP, 12 page
Examining the T Tauri system with SPHERE
Context. The prototypical low-mass young stellar object, T Tauri, is a
well-studied multiple system with at least three components. Aims. We aim to
explore the T Tau system with the highest spatial resolution, study the time
evolution of the known components, and re-determine the orbital parameters of
the stars. Methods. Near-infrared classical imaging and integral field
spectrograph observations were obtained during the Science Verification of
SPHERE, the new high-contrast imaging facility at the VLT. The obtained FWHM of
the primary star varies between 0.050" and 0.059", making these the highest
spatial resolution near-infrared images of the T Tauri system obtained to date.
Results. Our near-infrared images confirm the presence of extended emission
south of T Tau Sa, reported in the literature. New narrow-band images show, for
the first time, that this feature shows strong emission in both the Br-{\gamma}
and H2 1-0 S(1) lines. Broadband imaging at 2.27 {\mu}m shows that T Tau Sa is
0.92 mag brighter than T Tau Sb, which is in contrast to observations from Jan.
2014 (when T Tau Sa was fainter than Sb), and demonstrates that T Tau Sa has
entered a new period of high variability. The newly obtained astrometric
positions of T Tau Sa and Sb agree with orbital fits from previous works. The
orbit of T Tau S (the center of gravity of Sa and Sb) around T Tau N is poorly
constrained by the available observations and can be fit with a range of orbits
ranging from a nearly circular orbit with a period of 475 years to highly
eccentric orbits with periods up to 2.7*10^4 years. We also detected a feature
south of T Tau N, at a distance of mas, which shows the properties
of a new companion.Comment: Accepted by A&A Letter
Hexapod Design For All-Sky Sidereal Tracking
In this paper we describe a hexapod-based telescope mount system intended to
provide sidereal tracking for the Fly's Eye Camera project -- an upcoming
moderate, 21"/pixel resolution all-sky survey. By exploiting such a kind of
meter-sized telescope mount, we get a device which is both capable of
compensating for the apparent rotation of the celestial sphere and the same
design can be used independently from the actual geographical location. Our
construction is the sole currently operating hexapod telescope mount performing
dedicated optical imaging survey with a sub-arcsecond tracking precision.Comment: Accepted for publication in PASP, 10 page
Multi-epoch, high spatial resolution observations of multiple T Tauri systems
Context. In multiple pre-main-sequence systems the lifetime of circumstellar
disks appears to be shorter than around single stars, and the actual
dissipation process may depend on the binary parameters of the systems. Aims.
We report high spatial resolution observations of multiple T Tauri systems at
optical and infrared wavelengths. We determine if the components are
gravitationally bound and orbital motion is visible, derive orbital parameters
and investigate possible correlations between the binary parameters and disk
states. Methods. We selected 18 T Tau multiple systems (16 binary and two
triple systems, yielding binary pairs) in the Taurus-Auriga
star forming region from the survey by Leinert et al. (1993), with spectral
types from K1 to M5 and separations from 0.22" (31 AU) to 5.8" (814 AU). We
analysed data acquired in 2006-07 at Calar Alto using the AstraLux lucky
imaging system, along with data from SPHERE and NACO at the VLT, and from the
literature. Results. We found ten pairs to orbit each other, five pairs that
may show orbital motion and five likely common proper motion pairs. We found no
obvious correlation between the stellar parameters and binary configuration.
The 10 m infra-red excess varies between 0.1 and 7.2 magnitudes (similar
to the distribution in single stars, where it is between 1.7 and 9.1), implying
that the presence of the binary star does not greatly influence the emission
from the inner disk. Conclusions. We have detected orbital motion in young T
Tauri systems over a timescale of years. Further observations with
even longer temporal baseline will provide crucial information on the dynamics
of these young stellar systems.Comment: Accepted by A&
The Fly's Eye Camera System -- an instrument design for large \'etendue time-domain survey
In this paper we briefly summarize the design concepts of the Fly's Eye
Camera System, a proposed high resolution all-sky monitoring device which
intends to perform high cadence time domain astronomy in multiple optical
passbands while still accomplish a high \'etendue. Fundings have already been
accepted by the Hungarian Academy of Sciences in order to design and build a
Fly's Eye device unit. Beyond the technical details and the actual scientific
goals, this paper also discusses the possibilities and yields of a network
operation involving ~10 sites distributed geographically in a nearly
homogeneous manner. Currently, we expect to finalize the mount assembly -- that
performs the sidereal tracking during the exposures -- until the end of 2012
and to have a working prototype with a reduced number of individual cameras
sometimes in the spring or summer of 2013.Comment: Accepted for publication in AN, 4.05 pages. Website of the project:
http://flyseye.net
A triciklusos antidepresszĂvumok helye a fejfĂĄjĂĄsok kezelĂ©sĂ©ben
The two most important representatives of the primary headaches are migraine and tension-type headache. More than 10% of the population suffer from migraine and even a greater part, approximately 30-40% from tension-type headache. These two headache types have a great effect both on the individual and on the society. There are two types of therapeutic approaches to headaches: the abortive and the prophylactic therapy. Prophylactic treatment is used for frequent and/or difficult-to-treat headache attacks. Although both migraine and tension-type headache are often associated with depression, for their treatment - in contrast to the widespread medical opinion - not all antidepressants were found to be effective. Amitriptyline, which is a tricyclic antidepressant, is used as a prophylactic therapy for headache since 1968. Its efficacy has been demonstrated in several double-blind, placebo-controlled studies. Although the newer types of antidepressant, such as selective serotonin reuptake inhibitors and selective serotonin-norepinephrine reuptake inhibitor, have a more favorable side-effect profile than tricyclic antidepressants, their headache prophylactic effect has not been proven yet
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