In-flight measurement of the absolute energy scale of the Fermi Large Area Telescope

The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron-plus-positron (CRE) spectrum in low earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between ~6 and ~13 GeV with an estimated uncertainty of ~2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.Comment: 11 pages, 7 figures, submitted to Astroparticle Physic

The Second Fermi Large Area Telescope Catalog of Gamma-Ray Pulsars

This catalog summarizes 117 high-confidence 0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars.We compare the gammaray properties with those in the radio, optical, and X-ray bands.We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermiﾒs selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions

The need for GNSS position integrity and authentication in ITS: Conceptual and practical limitations in urban contexts

This tutorial paper highlights possible issues related to the integrity and authentication of the GNSS position in road applications. In fact, the Global Navigation Satellite System (GNSS) community is already aware of the conceptual and practical problems related to the availability of the position integrity (i.e. position confidence, protection level) and authentication in urban scenarios. However, these issues seem not to be widely known in the Intelligent Transportation Systems (ITS) domain. These limitations need to be carefully considered and addressed in the perspective of deploying reliable and robust systems based on positioning informatio

The need for GNSS position integrity and authentication in ITS: Conceptual and practical limitations in urban contexts

This tutorial paper highlights possible issues related to the integrity and authentication of the GNSS position in road applications. In fact, the Global Navigation Satellite System (GNSS) community is already aware of the conceptual and practical problems related to the availability of the position integrity (i.e. position confidence, protection level) and authentication in urban scenarios. However, these issues seem not to be widely known in the Intelligent Transportation Systems (ITS) domain. These limitations need to be carefully considered and addressed in the perspective of deploying reliable and robust systems based on positioning information

High accurate positioning for autonomous vehicles enabled by connectivity

International audienc