73 research outputs found
Alignment and preliminary outcomes of an ELT-size instrument to a very large telescope: LINC-NIRVANA at LBT
LINC-NIRVANA (LN) is a high resolution, near infrared imager that uses a
multiple field-of-view, layer-oriented, multi-conjugate AO system, consisting
of four multi-pyramid wavefront sensors (two for each arm of the Large
Binocular Telescope, each conjugated to a different altitude). The system
employs up to 40 star probes, looking at up to 20 natural guide stars
simultaneously. Its final goal is to perform Fizeau interferometric imaging,
thereby achieving ELT-like spatial resolution (22.8 m baseline resolution). For
this reason, LN is also equipped with a fringe tracker, a beam combiner and a
NIR science camera, for a total of more than 250 optical components and an
overall size of approximately 6x4x4.5 meters. This paper describes the
tradeoffs evaluated in order to achieve the alignment of the system to the
telescope. We note that LN is comparable in size to planned ELT
instrumentation. The impact of such alignment strategies will be compared and
the selected procedure, where the LBT telescope is, in fact, aligned to the
instrument, will be described. Furthermore, results coming from early
night-time commissioning of the system will be presented.Comment: 8 pages, 6 pages, AO4ELT5 Proceedings, 201
Unveiling the submerged part of the iceberg: radio-loud narrow-line Seyfert 1s with SKA
Narrow-line Seyfert 1 galaxies (NLS1) are active galactic nuclei (AGN) known to have small masses of the central black hole and high accretion rates. NLS1s are generally radio-quiet, but a small part of them (about 7\%) are radio-loud. The recent discovery of powerful relativistic jets in radio-loud NLS1s (RLNLS1s), emitting at high-energy -rays, opened intriguing questions. The observed luminosity of the jet is generally weak, smaller than blazars, although when rescaled for the mass of the central black hole, it becomes of the same order of magnitude of the latter. The weak luminosity, and hence observed flux, resulted in a small number of known RLNLS1. From a recent survey of RLNLS1s, it was found that only 8 out of 42 sources had radio flux density at 1.4 GHz greater than 100 mJy, while 21 out of 42 had flux density smaller than 10 mJy. In addition, given the strong variability at all wavelengths, with present-day facilities RLNLS1s can often only be detected during high activity periods. The Square Kilometer Array (SKA), with its superior sensitivity, will break this limit, allowing us to unveil a relatively unknown population of jetted AGN. We present the results of a study aimed at evaluating the scenario that could emerge after the advent of SKA
SOXS: a wide band spectrograph to follow up transients
SOXS (Son Of X-Shooter) will be a spectrograph for the ESO NTT telescope
capable to cover the optical and NIR bands, based on the heritage of the
X-Shooter at the ESO-VLT. SOXS will be built and run by an international
consortium, carrying out rapid and longer term Target of Opportunity requests
on a variety of astronomical objects. SOXS will observe all kind of transient
and variable sources from different surveys. These will be a mixture of fast
alerts (e.g. gamma-ray bursts, gravitational waves, neutrino events), mid-term
alerts (e.g. supernovae, X-ray transients), fixed time events (e.g. close-by
passage of minor bodies). While the focus is on transients and variables, still
there is a wide range of other astrophysical targets and science topics that
will benefit from SOXS. The design foresees a spectrograph with a
Resolution-Slit product ~ 4500, capable of simultaneously observing over the
entire band the complete spectral range from the U- to the H-band. The limiting
magnitude of R~20 (1 hr at S/N~10) is suited to study transients identified
from on-going imaging surveys. Light imaging capabilities in the optical band
(grizy) are also envisaged to allow for multi-band photometry of the faintest
transients. This paper outlines the status of the project, now in Final Design
Phase.Comment: 12 pages, 14 figures, to be published in SPIE Proceedings 1070
Data processing on simulated data for SHARK-NIR
A robust post processing technique is mandatory to analyse the coronagraphic
high contrast imaging data. Angular Differential Imaging (ADI) and Principal
Component Analysis (PCA) are the most used approaches to suppress the
quasi-static structure in the Point Spread Function (PSF) in order to revealing
planets at different separations from the host star. The focus of this work is
to apply these two data reduction techniques to obtain the best limit detection
for each coronagraphic setting that has been simulated for the SHARK-NIR, a
coronagraphic camera that will be implemented at the Large Binocular Telescope
(LBT). We investigated different seeing conditions () for stellar
magnitude ranging from R=6 to R=14, with particular care in finding the best
compromise between quasi-static speckle subtraction and planet detection.Comment: 9 pages, 8 figures, proceeding for the fifth Adaptive Optics for
Extremely Large Telescopes (AO4ELT5) meeting in 201
55 Cancri e's occultation captured with CHEOPS
Past occultation and phase-curve observations of the ultra-short period
super-Earth 55 Cnc e obtained at visible and infrared wavelengths have been
challenging to reconcile with a planetary reflection and emission model. In
this study, we analyse a set of 41 occultations obtained over a two-year
timespan with the CHEOPS satellite. We report the detection of 55 Cnc e's
occultation with an average depth of ppm. We derive a corresponding
2- upper limit on the geometric albedo of once
decontaminated from the thermal emission measured by Spitzer at 4.5m.
CHEOPS's photometric performance enables, for the first time, the detection of
individual occultations of this super-Earth in the visible and identifies
short-timescale photometric corrugations likely induced by stellar granulation.
We also find a clear 47.3-day sinusoidal pattern in the time-dependent
occultation depths that we are unable to relate to stellar noise, nor
instrumental systematics, but whose planetary origin could be tested with
upcoming JWST occultation observations of this iconic super-Earth.Comment: In press. Accepted for publication in Astronomy and Astrophysics on
13 October 2022. 10 pages, 7 figures and 3 table
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