A5082105361- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Planetary Science and Exploration
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Inertial Sensor and Navigation
- X-ray Spectroscopy and Fluorescence Analysis
- Space Satellite Systems and Control
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Nuclear Physics and Applications
- Cryospheric studies and observations
- Methane Hydrates and Related Phenomena
- Radio Astronomy Observations and Technology
- Statistical and numerical algorithms
- Atmospheric and Environmental Gas Dynamics
- Astrophysical Phenomena and Observations
- SAS software applications and methods
- Calibration and Measurement Techniques
- Scientific Research and Discoveries
- Superconducting and THz Device Technology
- Atmospheric aerosols and clouds
- Pulsars and Gravitational Waves Research
- Remote Sensing in Agriculture
- Geological and Geochemical Analysis
Finnish Geospatial Research Institute
2013-2024
Maanmittauslaitos
2018-2022
Geological Survey of Finland
2018-2022
Systèmes de Référence Temps-Espace
2012
Deleted Institution
2012
University of Helsinki
2004-2010
Nordic Optical Telescope
2005-2007
Helsinki Institute of Physics
2006
Aims.We present early optical spectroscopy of the afterglow gamma-ray burst GRB 060206 with aim determining metallicity absorber and physical conditions in circumburst medium. We also discuss how GRBs may be important complementary probes cosmic chemical evolution.
We have studied the afterglow of gamma-ray burst (GRB) February 18, 2006. This is a nearby long GRB, with very low peak energy, and therefore classified as an X-ray Flash (XRF). XRF 060218 clearly associated supernova -- dubbed SN 2006aj. present early spectra for 2006aj well optical lightcurves reaching out to 50 days past explosion. Our define rise times, lightcurve shapes absolute magnitudes in U, V R bands, we compare these data other relevant supernovae. evolved quite fast, somewhat...
The optical afterglow spectrum of GRB050401 (at z=2.8992+/-0.0004) shows the presence a DLA, with log(nHI)=22.6+/-0.3. This is highest column density ever observed in and about five times larger than strongest DLA detected so far any QSO spectrum. From spectrum, we also find very large Zn density, allowing us to infer an abundance [Zn/H]=-1.0+/-0.4. These columns are supported by X-ray from Swift-XRT which (in excess Galactic) log(nH)=22.21^{+0.06}_{-0.08} assuming solar abundances z=2.9)....
We present the results of third European Comparison Absolute Gravimeters held in Walferdange, Grand Duchy Luxembourg, November 2011. Twenty-two gravimeters from both metrological and non-metrological institutes are compared. For first time, corrections for laser beam diffraction self-attraction implemented. The gravity observations also corrected geophysical changes that occurred during comparison using a superconducting gravimeter. show these improve degree equivalence between gravimeters....
The bidirectional reflection distribution functions (BRDF) of snow have been measured at high spectral resolution various locations in Finland (Vuotso, Hyytia/spl uml/la/spl uml/, Sodankyla/spl Kilpisja/spl uml/rvi, Rovaniemi, uml/ again). types include fresh, new snow, both needle-like and hexagonal flakes, old, loose melting refrozen snow. All show strong forward scattering as previously reported, but there also appeared to be some enhancement the backward directions that has not reported...
In November 2013 an International Key Comparison, CCM.G-K2, was organized in the Underground Laboratory for Geodynamics Walferdange. The comparison has assembled 25 participants coming from 19 countries and four different continents. divided into two parts: key that included 10 NMIs or DIs, pilot study including all participants. global result given by confirms instruments are absolutely coherent to each other. results obtained confirm a good agreement between NMI instruments.
The validation of compatibility and long-term stability absolute gravimeters is a key component for the realization International Terrestrial Gravity Reference Frame (ITGRF) IAG relevant metrology, in particular kilogram. Because natural reference value gravity acceleration not accessible, international comparisons are well established. realized based on set accurate measurements functional model their processing. After CCM.G-K2.2023 comparison supplemented by additional ICAG-2023...
We have conducted absolute gravity (AG) measurements over several austral summer seasons at the Finnish Antarctic base Aboa, located in western Dronning Maud Land. The most recent were made January–February 2024. Aboa is situated on slope of Basen nunatak, approximately 470 m above sea level, 20 km from grounding line ice shelf, and 100 open sea. Individual AG measurement campaigns lasted 24 hours to two weeks, with optimal conditions for - stable, laboratory-level environment low...
We report on establishing the mobile Finnish Seismic Instrument Pool (FINNSIP) that is owned and operated by academic research institutions. The pool supports domestic international collaborative seismic research. At conclusion of 2020 to 2024 build-up stage, instrumentation includes 46 broadband seismometers digitizers, 5 accelerometers, 1216 71 Geospace SmartSolo autonomous geophone units, respectively, making FINNSIP one largest most coherent instrument pools in Europe public sector....
The CCM.G-K2.2017 comparison was organised for the purpose of determination degree equivalence national standards free-fall acceleration measurement. held in Changping Campus National Institute Metrology China (NIM), from October to November 2017. This is first time that such a organized outside Europe continent and establishes new global sites China. also largest ever with participation 13 instruments. We give list participants who actually performed measurements during comparison, data...
A novel shadowing and coherent-backscattering model is utilized in the analysis of single-scattering albedos phase functions, local surface roughness, regolith porosity specific lunar mare regions imaged by AMIE camera (Advanced Moon micro-Imager Experiment) onboard ESA SMART-1 mission. Shadowing due to particles accounted via ray-tracing computations for densely-packed particulate media with a fractional-Brownian-motion interface free space. The modeling allows us derive scattering function...
Aims: With this paper we want to investigate the highly variable afterglow light curve and environment of gamma-ray burst (GRB) 060526 at $z=3.221$. Methods: We present one largest photometric datasets ever obtained for a GRB afterglow, consisting multi-color data from ultraviolet near infrared. The set contains 412 points in total which add additional literature. Furthermore, low-resolution high signal-to-noise spectra afterglow. is modeled with both an analytical model using broken power...
Abstract We present an overview and the first systematic results on backscatter properties of snow samples with different grain properties. During a 2 year study we investigated effect apparent characteristics intensity enhancement in direction exact (retroreflection), using specific instrument designed for measurements. observed that sharp peak (the hot spot) occurs most types snow, which is not observable traditional goniometers. The key factors are temperature (related to changes...
Laboratory phase curves of planetary regolith analog materials are presented. A study is made the effect compaction material on its backscattering properties. Further also contribution surface roughness light scattering. First photometric measurements in a microgravity environment introduced as well some improvements laboratory experiment techniques. The show strong increase both reflectance and opposition amplitude under compaction. Also broadening width observed. These results contrast...
Abstract Gamma-ray burst afterglow observations in the Swift era have a perceived lack of achromatic jet breaks compared with BeppoSAX era. We present our multi-wavelength analysis GRB060206 as an illustrative example how inferences from optical and X-ray data might differ. The results temporal spectral analyses are compared, attempts made to fit within context standard blast wave model. find that while break appears more pronounced evidence for it alone is weak, actually consistent at about...
We present experiments on spectral bidirectional reflectance distribution function (BRDF) effects at backscatter and discuss the feasibility of new methods for laboratory field simulations remote sensing land surfaces. The extreme sharpness intensity peak allows both directional comparative experimental studies hot spots. demonstrate wavelength-dependent features in hot-spot signatures that facilitate extension BRDF measurements natural targets (such as forest understories ice surfaces) into...
In the framework of regional EURAMET.M.G-K2 comparison absolute gravimeters, 17 gravimeters were compared in November 2015. Four from different NMIs and DIs, they used to link CCM.G.K2 by means linking converter. Combined least-squares adjustments with weighted constraint was determine KCRV. Several pilot solutions are presented official solution demonstrate influences approaches (e.g. definition weights constraint) on results adjustment. case solution, all equivalence declared...
Since realising the idea that a man-made object can be intentionally placed into Earth's orbit, almost 10,000 satellites have been launched for multiple scientific, commercial and military purposes. These activities produce huge amount of junk comprised not only defunct artificial objects no longer serve useful purpose, but various collisions, explosions leaks produced millions pieces size varying from micrometers to meters. Space debris pose threat sustainable space near-earth environment...