GAMMA RAY BURST FOLLOW UP USING GROUND BASED METHODS: INSTRUMENTATION, OBSERVATION AND ANALYSIS

Abstract

Since the 1973 announcement of the initial Vela detection of Gamma-Ray Bursts (GRBs) in 1967, these powerful events have been of significant interest. The study of GRBs has advanced our knowledge of plasma physics, particle physics, cosmology, among many other fields. However, even with the advancement in understanding gained through various detections, both multi-wavelength and multi-messenger, there is still much to be learned by observing these transients in as many different ways as possible. This dissertation will explore the development of instrumentation (RIMAS and PRIME), operational software, data reduction software, and observations aimed at furthering the study of GRBs. Rapid infrared IMAger Spectrometer (RIMAS) is a near-infrared (NIR) imager spectrometer operating in wavelengths from 0.97 to 2.37 microns, and will be installed on the 4.3 m Lowell Discovery Telescope (LDT) in Happy Jack, Arizona. Among other features, RIMAS has four broad band filters (Y, J, H, K), and three spectral modes (spectral resolving powers, R~30, 300 and 5000). Completing this instrument required the development, integration and testing of multiple detector readout systems, cryogenic systems, spectral and imaging modes, communication systems, and cooling systems. Furthermore, software needed to be developed to reduce RIMAS data so that it will be ready to contribute to scientific discoveries shortly after commissioning. Due to the development of this software, observers will quickly obtain high signal-to-noise exposures, astronomically and photometrically calibrated stacked images, and one-dimensional spectra that are flux and wavelength calibrated. PRime-focus Infrared Microlensing Experiments (PRIME) is a 1.8 m telescope with 1.56 square degree field of view (FOV) (0.5”/pixel) operating in the NIR (0.82-1.78 microns) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO). The primary science objective for PRIME is to perform a time-domain survey of the Galactic Bulge for the purpose of observing microlensing events caused by transiting exoplanets. In doing so, it will support the Nancy Grace Roman Space Telescope (RST) mission by taking baseline measurements of this field before RST launch, while testing the performance of RST package H4RG-10 detectors. After RST launch, PRIME will perform simultaneous observation with RST of the Galactic Bulge to perform parallax measurements. PRIME is also continuously available for Target of Opportunity (ToO) observations, making it a powerful tool for observing GRB and gravitational wave (GW) counterparts. Since commissioning in October 2022, PRIME has been observing a time domain survey of the Galactic Bulge searching for microlensing events, observing high-energy transients (GRBs, X-ray bursts, GWs, and supernovae), and performing an all-sky survey in J-band. During the course of this thesis work, the development of PRIME's camera greatly mirrors that of RIMAS, with lessons learned shared between them. Most notable in this development is the integration and testing of PRIME's detectors and detector readout system. This is the first instance of these detectors and electronics being used on-sky, and as such required the development of custom software and thorough testing. Beyond these instrumentation efforts, photometric and spectroscopic observations were performed in the optical for various GRB afterglows, GRB host galaxies, and GW counterpart candidates using LDT's optical imager, Large Monolithic Imager (LMI), and optical spectrograph, DeVeny. After the commissioning of PRIME, over 40 high-energy transients (GRBs, X-ray Bursts, LIGO/Virgo/KAGRA (LVK) probability fields) were observed with the new telescope. These events were observed as soon as possible after initial detection, and observed over multiple epochs when assessing the evolution of detected counterparts. Further observations were also obtained when sources were not well localized, and further observations could lead to the detection of variable sources. These have resulted in the PRIME detection of the brightest GRB of all time, GRB 221009A, the night after PRIME's first light, and helped determine that this extreme GRB was powered by a structured jet. PRIME observations of GRB 230307A helped determine that the progenitor system was a lanthanide rich kilonova despite its long duration. Observations and software developed for LDT during this thesis work searched for and categorized potential optical GW counterparts, analyzed the environments surrounding GRBs, and searched for a supernova associated with GRB 221009A.