A prototype for the real-time analysis of the Cherenkov Telescope Array

Abstract

The Cherenkov Telescope Array (CTA) observatory will be one of the biggest ground-based very-high-energy (VHE) γ-ray observatory. CTA will achieve a factor of 10 improvement in sensitivity from some tens of GeV to beyond 100 TeV with respect to existing telescopes.The CTA observatory will be capable of issuing alerts on variable and transient sources to maximize the scientific return. To capture these phenomena during their evolution and for effective communication to the astrophysical community, speed is crucial. This requires a system with a reliable automated trigger that can issue alerts immediately upon detection of γ-ray flares. This will be accomplished by means of a Real-Time Analysis (RTA) pipeline, a key system of the CTA observatory. The latency and sensitivity requirements of the alarm system impose a challenge because of the anticipated large data rate, between 0.5 and 8 GB/s. As a consequence, substantial efforts toward the optimization of highthroughput computing service are envisioned.For these reasons our working group has started the development of a prototype of the Real-Time Analysis pipeline. The main goals of this prototype are to test: (i) a set of frameworks and design patterns useful for the inter-process communication between software processes running on memory; (ii) the sustainability of the foreseen CTA data rate in terms of data throughput with different hardware (e.g. accelerators) and software configurations, (iii) the reuse of nonreal-time algorithms or how much we need to simplify algorithms to be compliant with CTA requirements, (iv) interface issues between the different CTA systems. In this work we focus on goals (i) and (ii).

FLaapLUC : A pipeline for the generation of prompt alerts on transient Fermi -LATγ-ray sources

“…For instance, it is conceivable to adapt such a system for online triggering alerts for the future CTA observatory (CTA Consortium et al, 2013), if events could be reconstructed fast enough (see e.g. Bulgarelli et al, 2014).…”

Parallel waveform extraction algorithms for the Cherenkov Telescope Array Real-Time Analysis

“…The algorithm input is the camera data generated from the CTA PROD2 simulations [8] and saved using the Streaming Data Format (SDF) [9]. In order to simulate correctly an RTA pipeline and access the camera raw data we used the PacketLib C++ library, preloading the raw camera packets into a circular buffer.…”

Performance study of a signal‐extraction algorithm using different parallelisation strategies for the Cherenkov Telescope Array's real‐time‐analysis software

“…is detected. Such a science alert system—the real‐time‐analysis (RTA) pipeline—is being implemented as a set of serially linked processes with the following requirements: Latency of alerts must be within 30 seconds since the triggering event came about. The RTA must be available during more than 98 percent of the observation time. The final analysis can not surpass the sensitivity of the RTA by a three‐fold factor. The search for transient occurrences must be conducted on different spatio‐temporal scales. Each sub‐array will have its own RTA pipeline running in parallel alongside others. …”

“…The fact that the CTA on‐site analysis (OSA) is conducted on hardware located at the telescopes, as a consequence of constraints imposed by the observatory's features, obliges a search for efficient computing solutions that maximise the FLOPS/W ratio (ie, the most performance with the least energy consumption) and can deal with the huge amount of measured data; the estimated rate oscillates between 0.5 and 8 GiB/s since it will be determined by certain parameters: array layout, data‐reduction schema, trigger criteria, etc.…”