LEMUR: Large European Module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission

Understanding the solar outer atmosphere requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1" and 0.3"), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 17 and 127 nm. The LEMUR slit covers 280" on the Sun with 0.14" per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km/s or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission.Comment: 35 pages, 14 figures. To appear on Experimental Astronom

LEMUR: Large European Module for Solar Ultraviolet Research

The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1 and 0.3), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Angstrom and 1270 Angstrom. The LEMUR slit covers 280 on the Sun with 0.14 per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s 1 or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission

In-orbit performances of the EIT instrument on board SOHO and intercalibration with the EIT Calroc Sounding Rocket program

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Stray light testing of WISPR baffle development model

Solar Probe Plus (SPP) is a NASA mission developed to visit and study the sun closer than ever before. SPP is designed to orbit as close as 7 million km (9.86 solar radii) from Sun center. One of its instruments: WISPR (Wide-Field Imager for Solar Probe Plus) will be the first ‘local’ imager to provide the relation between the large-scale corona and the in-situ measurements.The Centre Spatial de Liège in Belgium (CSL) owns a stray light test facility for In Field and Out of Field of View stray light measurements. This facility is updated to realize a stray light test on the WISPR Development Model (DM).WISP

STEREO: Heliospheric Imager design, pre-flight, and in-flight response comparison

The Heliospheric Imager (HI) is part of the SECCHI suite of instruments on-board the two STEREO observatories launched in October 2006. The two HI instruments provide stereographic image pairs of solar coronal plasma and coronal mass ejections (CME) over a field of view ranging from 13 to 330 R[SUB]0[/SUB]. The HI instrument is a combination of two refractive optical systems with a two stage multi-vane baffle system. The key challenge of the instrument design is the rejection of the solar disk light by the front baffle, with total straylight attenuation at the detector level of the order of 10[SUP]-13[/SUP] to 10[SUP]-15[/SUP]. Optical systems and baffles were designed and tested to reach the required rejection. This paper presents the pre-flight optical tests performed under vacuum on the two HI flight models in flight temperature conditions. These tests included an end-to-end straylight verification of the front baffle efficiency, a co-alignment and an optical calibration of the optical systems. A comparison of the theoretical predictions of the instrument response and performance with the calibration results is presented. The instrument in-flight photometric and stray light performance are also presented and compared with the expected results

MiniCOR: A Miniature Coronagraph for Interplanetary CubeSat

Coronagraphs occupy a unique place in Heliophysics, critical to both NASA and NOAA programs. They are the primary means for the study of the extended solar corona and its short and long term activity. In addition, coronagraphs are the only instrument that can image coronal mass ejections (CMEs) leaving the Sun and provide critical information for space weather forecasting. We describe a low cost miniaturized CubeSat coronagraph, MiniCOR, designed to operate in deep space, which will return data with higher cadence and sensitivity than that from the SOHO/LASCO coronagraphs. MiniCOR is a six unit (6U) sciencecraft with a tightly integrated, single instrument interplanetary flight system optimized for science. MiniCOR fully exploits recent technology advances in CubeSat technology and active pixel sensors. With a factor of 2.9 improvement in light gathering power over SOHO and quasi-continuous data collection, MiniCOR can observe the slow solar wind, CMEs and shocks with sufficient signal-to-noise ratio (SNR) to open new windows on our understanding of the inner heliosphere. An operating MiniCOR would provide coronagraphic observations in support of the upcoming Solar Probe Plus (SPP) and Solar Orbiter (SO) missions

Concept Study Report: Extreme-Ultraviolet Imaging Spectrometer Solar-B

We propose a next generation Extreme-ultraviolet Imaging Spectrometer (EIS) that for the first time combines high spectral, spatial, and temporal resolution in a single solar spectroscopic instrument. The instrument consists of a multilayer-coated off-axis telescope mirror and a multilayer-coated grating spectrometer. The telescope mirror forms solar images on the spectrometer entrance slit assembly. The spectrometer forms stigmatic spectra of the solar region located at the slit. This region is selected by the articulated telescope mirror. Monochromatic images are obtained either by rastering the solar region across a narrow entrance slit, or by using a very wide slit (called a slot) in place of the slit. Monochromatic images of the region centered on the slot are obtained in a single exposure. Half of each optic is coated to maximize reflectance at 195 Angstroms; the other half to maximize reflectance at 270 Angstroms. The two Extreme Ultraviolet (EUV) wavelength bands have been selected to maximize spectral and dynamical and plasma diagnostic capabilities. Spectral lines are observed that are formed over a temperature range from about 0.1 MK to about 20 MK. The main EIS instrument characteristics are: wavelength bands - 180 to 204 Angstroms; 250 to 290 Angstroms; spectral resolution - 0.0223 Angstroms/pixel (34.3km/s at 195 Angstroms and 23.6 km/s at 284 Angstroms); slit dimensions - 4 slits, two currently specified dimensions are 1" x 1024" and 50" x 1024" (the slot); largest spatial field of view in a single exposure - 50" x 1024"; highest time resolution for active region velocity studies - 4.4 s