FIREBall-2 is a stratospheric balloon-borne 1-m telescope coupled to a UV multi-object slit spectrograph designed to map the faint UV emission surrounding z~0.7 galaxies and quasars through their Lyman-alpha line emission. This spectro-imager had its first launch on September 22nd 2018 out of Ft. Sumner, NM, USA. Because the balloon was punctured, the flight was abruptly interrupted. Instead of the nominal 8 hours above 32 km altitude, the instrument could only perform science acquisition for 45 minutes at this altitude. In addition, the shape of the deflated balloon, combined with a full Moon, revealed a severe off-axis scattered light path, directly into the UV science detector and about 100 times larger than expected. In preparation for the next flight, and in addition to describing FIREBall-2's upgrade, this paper discusses the exposure time calculator (ETC) that has been designed to analyze the instrument's optimal performance (explore the instrument's limitations and subtle trade-offs).
@article{arxiv.2211.15491,
title = {FIREBall-2: flight preparation of a proven balloon payload to image the intermediate redshift circumgalactic medium},
author = {Vincent Picouet and David Valls-Gabaud and Bruno Milliard and David Schiminovich and Drew M. Miles and Keri Hoadley and Erika Hamden and D. Christopher Martin and Gillian Kyne and Trent Brendel and Aafaque Raza Khan and Jean Evrard and Zeren Lin and Haeun Chung and Simran Agarwal and Ignacio Cevallos Aleman and Charles-Antoine Chevrier and Jess Li and Nicole Melso and Shouleh Nikzad and Didier Vibert and Nicolas Bray},
journal= {arXiv preprint arXiv:2211.15491},
year = {2022}
}