Timing techniques applied to distributed modular high-energy astronomy: the H.E.R.M.E.S. project (original) (raw)
Related papers
Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation
arXiv (Cornell University), 2023
Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorption and emission limit the use of ground facilities. Thanks to continuing technological improvements, miniaturised space instruments operating as distributed-aperture constellations are offering new capabilities for the study of high energy transients to complement ageing existing satellites. In this paper we characterise the performance of the upcoming joint SpIRIT and HERMES-TP/SP constellation for the localisation of high-energy transients through triangulation of signal arrival times. SpIRIT is an Australian technology and science demonstrator satellite designed to operate in a low-Earth Sun-synchronous Polar orbit that will augment the science operations for the equatorial HERMES-TP/SP constellation. In this work we simulate the improvement to the localisation capabilities of the HERMES-TP/SP constellation when SpIRIT is included in an orbital plane nearly perpendicular (inclination = 97.6°) to the HERMES-TP/SP orbits. For the fraction of GRBs detected by three of the HERMES satellites plus SpIRIT, we find that the combined constellation is capable of localising 60% of long GRBs to within ∼ 30 deg 2 on the sky, and 60% of short GRBs within ∼ 1850 deg 2 (1σ confidence regions), though it is beyond the scope of this work to characterise or rule out systematic uncertainty of the same order of magnitude. Based purely on statistical GRB localisation capabilities (i.e., excluding systematic uncertainties and sky coverage), these figures for long GRBs are comparable to those reported by the Fermi Gamma Burst Monitor instrument. These localisation statistics represents a reduction of the uncertainty for the burst localisation region for both long and short GRBs by a factor of ∼ 5 compared to the HERMES-TP/SP alone. Further improvements by an additional factor of 2 (or 4) can be achieved by launching an additional 4 (or 6) SpIRIT-like satellites into a Polar orbit respectively, which would both increase the fraction of sky covered by multiple satellite elements, and also enable localisation of ≥ 60% of long GRBs to within a radius of ∼ 1.5°(statistical uncertainty) on the sky, clearly demonstrating the value of a distributed all-sky high energy transient monitor composed of nano-satellites.
HERMES: An ultra-wide band X and gamma-ray transient monitor on board a nano-satellite constellation
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
The High Energy Modular Ensemble of Satellites (HERMES) project is aimed to realize a modular X/gamma-ray monitor for transient events, to be placed on-board of a nano-satellite bus (e.g. CubeSat). This expandable platform will achieve a significant impact on Gamma Ray Burst (GRB) science and on
CAMELOT: Cubesats Applied for MEasuring and LOcalising Transients mission overview
Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray, 2018
We propose a fleet of nanosatellites to perform an all-sky monitoring and timing based localisation of gamma-ray transients. The fleet of at least nine 3U cubesats shall be equipped with large and thin CsI(Tl) scintillator based soft gamma-ray detectors read out by multi-pixel photon counters. For bright short gamma-ray bursts (GRBs), by cross-correlating their light curves, the fleet shall be able to determine the time difference of the arriving GRB signal between the satellites and thus determine the source position with an accuracy of ∼ 10. This requirement demands precise time synchronization and accurate time stamping of the detected gamma-ray photons, which will be achieved by using on-board GPS receivers. Rapid follow up observations at other wavelengths require the capability for fast, nearly simultaneous downlink of data using a global inter-satellite communication network. In terms of all-sky coverage, the proposed fleet will outperform all GRB monitoring missions.
GRID: a student project to monitor the transient gamma-ray sky in the multi-messenger astronomy era
Experimental Astronomy
The Gamma-Ray Integrated Detectors (GRID) is a space mission concept dedicated to monitoring the transient gamma-ray sky in the energy range from 10 keV to 2 MeV using scintillation detectors onboard CubeSats in low Earth orbits. The primary targets of GRID are the gamma-ray bursts (GRBs) in the local universe. The scientific goal of GRID is, in synergy with ground-based gravitational wave (GW) detectors such as LIGO and VIRGO, to accumulate a sample of GRBs associated with the merger of two compact stars and study jets and related physics of those objects. It also involves observing and studying other gamma-ray transients such as long GRBs, soft gamma-ray repeaters, terrestrial gamma-ray flashes, and solar flares. With multiple CubeSats in various orbits, GRID is unaffected by the Earth occultation and serves as a full-time and all-sky monitor. Assuming a horizon of 200 Mpc for ground-based GW detectors, we expect to see a few associated GW-GRB events per year. With about 10 CubeSats in operation, GRID is capable of localizing a faint GRB like 170817A with a 90% error radius of about 10 degrees, through triangulation and flux modulation. GRID is proposed and developed by students, with considerable contribution from undergraduate students, and will remain operated as a student project in the future. The current GRID collaboration involves more than 20 institutes and keeps growing. On August 29th, the first GRID detector onboard a CubeSat was launched into a Sun-synchronous orbit and is currently under test.
GRBAlpha: a 1U CubeSat mission for validating timing-based gamma-ray burst localization
Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray
GRBAlpha is a 1U CubeSat mission with an expected launch date in the first half of 2021. It carries a 75 × 75 × 5 mm CsI(Tl) scintillator, read out by a dual-channel multi-pixel photon counter (MPPC) setup, to detect gamma-ray bursts (GRBs). The GRB detector is an in-orbit demonstration for the detector system on the Cubesats Applied for MEasuring and LOcalising Transients (CAMELOT) mission. While GRBAlpha provides 1/8th of the expected effective area of CAMELOT, the comparison of the observed light curves with other existing GRB monitoring satellites will allow us to validate the core idea of CAMELOT, i.e. the feasibility of timing-based localization.
The scientific payload on-board the HERMES-TP and HERMES-SP CubeSat missions
Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray, 2020
HERMES (High Energy Rapid Modular Ensemble of Satellites) Technological and Scientific pathfinder is a space borne mission based on a LEO constellation of nano-satellites. The 3U CubeSat buses host new miniaturized detectors to probe the temporal emission of bright high-energy transients such as Gamma-Ray Bursts (GRBs). Fast transient localization, in * yuri.evangelista@inaf.it; hermes-sp.eu a field of view of several steradians and with arcmin-level accuracy, is gained by comparing time delays among the same event detection epochs occurred on at least 3 nano-satellites. With a launch date in 2022, HERMES transient monitoring represents a keystone capability to complement the next generation of gravitational wave experiments. In this paper we will illustrate the HERMES payload design, highlighting the technical solutions adopted to allow a wide-energy-band and sensitive X-ray and gamma-ray detector to be accommodated in a CubeSat 1U volume together with its complete control electronics and data handling system.
2020
The timing-based localization, which utilize the triangulation principle with the different arrival time of gammaray photons, with a fleet of Cubesats is a unique and powerful solution for the future all-sky gamma-ray observation, which is a key for identification of the electromagnetic counterpart of the gravitational wave sources. The Cubesats Applied for MEasuring and Localising Transients (CAMELOT) mission is now being promoted by the Hungarian and Japanese collaboration with a basic concept of the nine Cubesats constellations in low earth orbit. The simulation framework for estimation of the localization capability has been developed including orbital parameters, an algorithm to estimate the expected observed profile of gamma-ray photons, finding the peak of the cross-correlation function, and a statistical method to find a best-fit position and its uncertainty. It is revealed that a degree-scale localization uncertainty can be achieved by the CAMELOT mission concept for bright...
Scanning Telescope for Optical Transient Detection Simultaneously With the Gamma-ray Bursts
1998
We discuss the project of wide field optical telescope with panoramic photometrical detector for optical transients (OTs) detection simultaneously with gamma-ray bursters registration. The telescope with the size of focal field of 2circ-3circ scans gamma-ray telescope field of view. The focal picture is transmitted by fiber set onto a matrix of 10000 avalanche photodiods (APDs) with quantum efficiency about 80% and dead time of 10^{-6} s. Using APD as a detector allows investigating fine time structure of OT (flashes of about 10^{-4} s have been detected in the light curves of GRBs). It is possible to detect OTs of 17m at duration of 1 s and 13m at duration 1 ms by 1m telescope (1:1). The positional accuracy is better than 2^{''} and the probability of OT detection in the field of 30circ-40circ (the same as the BeppoSAX one) is about 1%.
A proposed network of gamma-ray burst detectors on the global navigation satellite system Galileo G2
Astronomy & Astrophysics
The accurate localization of gamma-ray bursts (GRBs) remains a crucial task. Historically, improved localizations have led to the discovery of afterglow emission and the realization of their cosmological distribution via redshift measurements; however, a more recent requirement comes with the potential of studying the kilonovae of neutron star mergers. Gravitational wave detectors are expected to provide locations to not better than 10 square degrees over the next decade. With their increasing horizon for merger detections the intensity of the gamma-ray and kilonova emission also drops, making their identification in large error boxes a challenge. Thus, a localization via the gamma-ray emission seems to be the best chance to mitigate this problem. Here we propose to equip some of the second-generation Galileo satellites with dedicated GRB detectors. This saves costs for launches and satellites for a dedicated GRB network, the large orbital radius is beneficial for triangulation, and...
The High Energy Telescope on EXIST: Hunting High Redshift GRBs and other Exotic Transients
Proceedings of The Extreme sky: Sampling the Universe above 10 keV — PoS(extremesky2009)
The High Energy Telescope (HET) on EXIST is designed to locate high redshift Gamma-Ray Bursts (GRBs) and other rare transients fast (<10 sec) and accurately (< 20″) in order to allow rapid (<1-2 min) follow-up observations with onboard X-ray/optical/IR imaging and spectroscopy. The HET employs coded-aperture imaging with a 4.5 m 2 imaging CZT detector array and hybrid tungsten mask. The wide energy band coverage (5-600 keV) is optimal for capturing these transients and highly obscured AGN. The continuous scan with the wide field of view (90º × 70º at 10% coding fraction) increases the chance of capturing rare elusive events such as soft Gamma-ray repeaters and tidal disruption events of stars by dormant supermassive black holes. Sweeping nearly the entire sky every two orbits (3 hour), EXIST will also establish a finely-sampled long-term history of the X-ray variability of many X-ray sources, opening up a new time domain for variability studies. In light of the new EXIST design concept, we review the observing strategy to maximize the science return and report on our recent balloon flight test of a prototype for the CZT detectors needed for HET.