scholarly journals Results from Verification of Reference Irradiance and Radiance Sources Laboratory Calibration Experiment Campaign

2020 ◽  
Vol 12 (14) ◽  
pp. 2220
Author(s):  
Agnieszka Białek ◽  
Teresa Goodman ◽  
Emma Woolliams ◽  
Johannes F. S. Brachmann ◽  
Thomas Schwarzmaier ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Spectral Range ◽  
Effective Field ◽  
Field Of View ◽  
Spectral Irradiance ◽  
Spectral Bands ◽  
Calibration Experiment ◽  
Comparison Results ◽  
Laboratory Calibration ◽  
Filament Lamps

We present the results from Verification of Reference Irradiance and Radiance Sources Laboratory Calibration Experiment Campaign. Ten international laboratories took part in the measurements. The spectral irradiance comparison included the measurements of the 1000 W tungsten halogen filament lamps in the spectral range of 350 nm–900 nm in the pilot laboratory. The radiance comparison took a form of round robin where each participant in turn received two transfer radiometers and did the radiance calibration in their own laboratory. The transfer radiometers have seven spectral bands covering the wavelength range from 400 nm–700 nm. The irradiance comparison results showed an agreement between all lamps within ±1.5%. The radiance comparison results presented higher than expected discrepancies at the level of ±4%. Additional investigation to determine the causes for these discrepancies identified them as a combination of the size-of-source effect and instrument effective field of view that affected some of the results.

Results of Spatial Structure of Atmosphere Radiation in a Spectral Range (1.5–2) µm Research

2018 ◽  
pp. 7-13
Author(s):  
Anton M. Mishchenko ◽  
Sergei S. Rachkovsky ◽  
Vladimir A. Smolin ◽  
Igor V . Yakimenko
Keyword(s):  
Spatial Structure ◽  
Unmanned Aerial Vehicle ◽  
Wavelength Range ◽  
Spectral Range ◽  
Near Ir ◽  
Optoelectronic Systems ◽  
Aerial Vehicle

Results of experimental studying radiation spatial structure of atmosphere background nonuniformities and of an unmanned aerial vehicle being the detection object are presented. The question on a possibility of its detection using optoelectronic systems against the background of a cloudy field in the near IR wavelength range is also considered.

scholarly journals A Set of Grisms for FORS

1995 ◽  
Vol 149 ◽  
pp. 27-28 ◽  
Author(s):  
W. Fürtig ◽  
W. Seifert
Keyword(s):  
Wavelength Range ◽  
Field Of View ◽  
Parallel Beam ◽  
First Order ◽  
Large Telescopes ◽  
The University ◽  
Low Dispersion

The University Observatories of München and Göttingen and the Landessternwarte Heidelberg are building in cooperation with ESO two almost identical FOcal Reducer /low-dispersion Spectrographs (FORS) for the ESO Very Large Telescopes. FORS allows low-dispersion multiobject spectroscopy (19 slits) and longslit spectroscopy in the wavelength range of 330 to 1100 nm. A set of standard grisms with reciprocal dispersions of 45 ...230 Å/mm working in the first order are foreseen. With a slitwidth of 1 arcsec the resulting spectral resolutions range from 180 to 1800.For further FORS details see Appenzeller and Rupprecht (1992) and Seifert et al. (1994).The standard grisms are located in a grism wheel in the parallel beam between the collimator and the camera. Seven of eight positions are available for grisms. The free diameter of the grisms is 135 mm to cover the whole field of view of FORS. To avoid reflection ghosts the entrance surfaces are all tilted by .

scholarly journals Design of a hybrid refractive-diffractive telescope for observations in UV

2020 ◽  
Vol 50 (2-3) ◽  
pp. 159-168
Author(s):  
Grzegorz Fluder
Keyword(s):  
Spectral Range ◽  
Field Of View ◽  
Space Telescopes ◽  
Diffractive Element ◽  
Negative Effect ◽  
Element Type ◽  
Spectral Ranges ◽  
Reflective Systems

Abstract Telescopes are one of the common types of satellite payloads. They are used both for Earth and astronomical observations. By using space telescopes it is possible to eliminate the negative effect of the atmosphere on image quality. Additionally, observations in some spectral ranges can be performed only from space due to absorption of certain wavelengths in the atmosphere. One such range is UV below 300 nm, which is of particular interest when it comes to the investigation of hot objects. Reflective telescopes are commonly used in this spectral range, although many classical designs are limited in their useful field of view to values below 1°. In this paper a hybrid refractive-diffractive telescope design working in a 200 nm – 300 nm spectral range with a field of view 10°×10° is proposed. Its performance is compared to purely refractive and reflective systems and significant improvement in the imaging quality of the system and decrease of its size is shown. The choice of the diffractive element type is explained. Parameters of the systems are based on the requirements for a proposed Polish mission UVSat which aims to enable long-term observations of a large number of stars exhibiting UV variance.

scholarly journals ESO Spectroscopic Facility

2017 ◽  
Vol 13 (S334) ◽  
pp. 242-247
Author(s):  
Luca Pasquini ◽  
B. Delabre ◽  
R. S. Ellis ◽  
J. Marrero ◽  
L. Cavaller ◽  
...  
Keyword(s):  
High Resolution ◽  
Wavelength Range ◽  
Focal Plane ◽  
Working Group ◽  
Field Of View ◽  
High Resolution Spectroscopy ◽  
Wide Field ◽  
Low Resolution ◽  
Field Unit ◽  
Integral Field

AbstractWe present the concept of a novel facility dedicated to massively-multiplexed spectroscopy. The telescope has a very wide field Cassegrain focus optimised for fibre feeding. With a Field of View (FoV) of 2.5 degrees diameter and a 11.4m pupil, it will be the largest etendue telescope. The large focal plane can easily host up to 16.000 fibres. In addition, a gravity invariant focus for the central 10 arc-minutes is available to host a giant integral field unit (IFU). The 3 lenses corrector includes an ADC, and has good performance in the 360-1300 nm wavelength range. The top level science requirements were developed by a dedicated ESO working group, and one of the primary cases is high resolution spectroscopy of GAIA stars and, in general, how our Galaxy formed and evolves. The facility will therefore be equipped with both, high and low resolution spectrographs. We stress the importance of developing the telescope and instrument designs simultaneously. The most relevant R&D aspect is also briefly discussed.

Thermophysical model of the Moon from 3.7 to 15 μm

2020 ◽  
Author(s):  
Thomas G. Müller ◽  
Martin J. Burgdorf ◽  
Stefan A. Buehler ◽  
Marc Prange
Keyword(s):  
Surface Roughness ◽  
Wavelength Range ◽  
Thermal Flux ◽  
Field Of View ◽  
Spectral Energy ◽  
The Moon ◽  
Mid Infrared ◽  
Thermophysical Model ◽  
Wide Range ◽  
Model Fits

<p>We present a thermophysical model (TPM) of the Moon which matches the observed, global, disk-integrated thermal flux densities of the Moon in the mid-infrared wavelength range for a phase angle range from -90° to +90°.<br />The model was tested and verified against serendipitous multi-channel HIRS measurements of the Moon obtained by different meteorological satellites (NOAA-11, NOAA-14, NOAA-15, NOAA-17, NOAA-18, NOAA-19, MetOp-A, MetOp-B). The sporadic intrusions of the Moon in the deep space view of these instruments have been extracted in cases where the entire Moon was within the instruments' field of view. The HIRS long-wavelengths channels 1-12 cover the range from 6.5 to 15 μm, the short-wavelengths channels 13-19 are in the 3.7 to 4.6 μm range.</p> <p>The model is based on an asteroid TPM concept (Lagerros 1996, 1997, 1998; Müller & Lagerros 1998, 2002), using the known global properties of the Moon (like size, shape, spin properties, geometric albedo, thermal inertia, surface roughness, see Keihm 1984; Racca 1995; Rozitis & Green 2011; Hayne et al. 2017), combined with a model for the spectral hemispherical emissivity which varies between 0.6 and 1.0 in the HIRS wavelength range (Shaw 1998; ECOSTRESS data base: https://ecostress.jpl.nasa.gov/). The spectral emissivity as well as characteristics of the surface roughness are crucial to explain the well-calibrated measurements.</p> <p>Our Moon model fits the flux densities for the currently available 22 epochs (each time up to 19 channels) with an absolute accuracy of 5-10%. The phase curves at the different wavelengths are well explained. The spectral energy distributions are very sensitive to emissivity and roughness properties. Here, we see minor variations in the model fits, depending on the origin (phase and aspect angle related) of the thermal emission. We also investigated the influence of reflected sunlight at short wavelengths.</p> <p>Our TPM of the Moon has a wide range of applications: (i) for Earth-observing weather satellites in the context of field of view and photometric calibration (e.g., Burgdorf et al. 2020); (ii) for interplanetary space missions (e.g., Hayabusa2, OSIRIS-REx or BepiColombo) with infrared instruments on board for an in-space characterization of instrument properites (e.g., Okada et al. 2018); (iii) to shed light on the thermal mid-infrared properties of the lunar surface on a global scale; and, (iv) to benchmark thermophysical model techniques for asteroids in the regime below 10 μm (e.g., observed by WISE in the W1 and W2 bands at 3.4 and 4.6 μm, by Spitzer-IRAC at 3.55 and 4.49 μm or from ground in M band at around 5 μm).</p> <p><br />References:<br />Burgdorf M., et al. 2020, Remote Sens. 12, 1488; Hayne, P. et al. 2017, JGRE 122, 237; Keihm, S.J. 1984, Icarus 60, 568; Lagerros 1996,  A&A 310, 1011; Lagerros 1997, A&A 325, 1226; Lagerros 1998, A&A 332, 1123; Müller & Lagerros 1998, A&A 338, 340; Müller & Lagerros 2002, A&A 381, 324; Okada T. et al. 2018, P&SS 158, 46; Racca G. 1995, P&SS 43, 835; Rozitis & Green 2011, MNRAS 415, 2042.</p> <p> </p>

Calibration of the Spectral Radiance of a Low Current Carbon Arc between 185 nm and 340 nm

1978 ◽  
Vol 33 (4) ◽  
pp. 502-504 ◽  
Author(s):  
D. Einfeld ◽  
D. Stuck
Keyword(s):  
Synchrotron Radiation ◽  
Wavelength Range ◽  
Spectral Range ◽  
Spectral Radiance ◽  
Electron Synchrotron ◽  
Carbon Arc ◽  
Arc Current

The spectral radiance Lλ of a low current carbon arc (current 7.3 amps, voltage 65 V) has been calibrated in the spectral range from the air cut-off (λ ≈ 185 nm) to 340 nm with an uncertainty of ± 3% utilizing the electron synchrotron radiation of DESY, Hamburg. In the wavelength range above 260 nm these values differ by less than ± 6% from the measurements of Magdeburg and Schurer.

scholarly journals GMOS IFU Observations of the Gas Kinematics in the Radio Galaxy Arp 102B

2009 ◽  
Vol 5 (S267) ◽  
pp. 395-395
Author(s):  
Guilherme d. S. Couto ◽  
Thaisa Storchi-Bergmann ◽  
Rogemar A. Riffel ◽  
D. J. Axon ◽  
A. Robinson
Keyword(s):  
Wavelength Range ◽  
Radio Galaxy ◽  
Field Of View ◽  
Trace Gas ◽  
Spiral Arms ◽  
Gas Kinematics ◽  
Integral Field Spectroscopy ◽  
Field Spectroscopy ◽  
Integral Field

The goal of this work is to map the gas excitation and kinematics in the inner ~ 2 kiloparsecs of the radio-galaxy Arp 102B. Though being classified as an E0 galaxy, Arp 102B shows a nuclear gas spiral (Fathi et al., in preparation). Previous studies of the gas kinematics in nuclear spirals have led to the conclusion that these structures usually trace gas inflows (Fathi et al. 2006; [Storchi-Bergmann et al. 2007; [Riffel et al. 2008). We have used integral field spectroscopy obtained with GMOS instrument of the Gemini North telescope to investigate the nature of the nuclear spiral arms. The spectra cover the wavelength range 4400–7300 Å over a field of view of 5.″5 × 3.″9 (2.7 kpc × 1.9 kpc).

scholarly journals Enhancement of the Transparency and Flatness of Engraved Facets in a Broadband Range by Optimizing Its Engraved Structure

2020 ◽  
Author(s):  
Ioseph Gurwich ◽  
Yakov Greenberg ◽  
Kobi Harush ◽  
Yarden Tzabari Tzabari
Keyword(s):  
Standard Deviation ◽  
Wavelength Range ◽  
Spectral Range ◽  
Transmission Efficiency ◽  
Size And Shape ◽  
Input And Output ◽  
Wide Wavelength Range ◽  
Theoretical Results ◽  
Reflective Surfaces

Achieving devices to be transparent is the task considered in the last time in many aspects and for different purposes. One issue of these problems is making anti-reflective surfaces in a wide wavelength range and keeping it flat enough. The authors of the previous publication showed that one could enhance a flat facet's transmission efficiency by suitable engraving. They used smoothed conical fingers and holes. Here, we widen the class of anti-reflective metasurfaces under consideration, following the requirements of the model developed in the previous paper. We involve also smoothed pyramidal fingers. The obtained results provide the improved engraved structure, with parameters dependent on the required spectral range, and the facet format. The predicted level of transmittance is close to 99\%, and the flatness(estimated by the standard deviation) as 0.2\%. This improvement is significant enough for high and broadband transmittance. In this work, we show that the randomization of the engraving parameters does not provide any significant effect for small facets. We also discuss a simple way of comparing experimental and theoretical results for a waveguide with the considered input and output features. In this study, as well as in our previous work, we restrict ourselves by rectangular facets. We also discuss the limitations that originated from the size and shape of the waveguide facets.

Sign in / Sign up

Export Citation Format

Share Document