The Faint Intergalactic Medium Redshifted Emission Balloon (FIREBall-2) is a UV multi-object spectrograph designed to detect emission from the circumgalactic and circumquasar medium at low redshifts (0.3 < z < 1.0). The FIREBall-2 spectrograph uses a suborbital balloon vehicle to access a stratospheric transmission window centered around 205 nm and is fed by a 1-m primary parabolic mirror and a 2-mirror field corrector that allows an ≈11’ x 35’ field of view. The slit-mask spectrograph can access dozens of galaxy targets per field, with each target spectrum read out on a UV electron-multiplying CCD detector. Following a flight in 2018, several refurbishments and modifications were made to the instrument and telescope to prepare for additional flight opportunities. Here we present an overview of upgrades and improvements made since the previous flight and discuss the 2023 field campaign, which culminated in a flight from Fort Sumner, New Mexico in September, 2023.
FIREBall-2 is a Balloon-Borne UV telescope designed to observe faint UV emission from the circumgalactic medium around low redshift galaxies (z 0.3 - 1.0). FIREBall-2 employs a 1m telescope with a multi-object spectrograph, custom-designed slit-masks and a delta-doped EMCCD detector. FIREBall-2 achieves steady 1-2” pointing with a CNES-provided coarse guidance system complemented by a fine guidance system which provides real time, on-sky feedback with an sCMOS camera embedded within the spectrograph enclosure. The guider system provides a live video stream, computes translational and rotational offsets and sends high rate (30 Hz) gondola pointing error corrections, while also handling slit mask selection and in-flight optimization of the image focus and PSF. We review the current state of the system after testing and use during FIREBall-2’s 2018 and 2023 campaigns and discuss its performance, challenges and development of its hardware and software functions ahead of its next flight campaign.
We present the integration of a new calibration system into the Faint Intergalactic-medium Redshifted Emission Balloon-2 (FIREBall-2), which added in-flight calibration capability for the recent September 2023 flight. This system is composed of a calibration source box containing zinc and deuterium lamp sources, focusing optics, electronics, sensors, and a fiber-fed calibration cap with an optical shutter mounted on the spectrograph tank. We discuss how the calibration cap is optimized to be evenly illuminated through non-sequential modeling for the near-UV (191 to 221 nm) for spectrograph slit mask position calibration, electron multiplying charged-coupled device (EMCCD) gain amplification verification, and wavelength calibration. Then, we present the pre-flight performance testing results of the calibration system and their implications for in-flight measurements. FIREBall-2 flew in 2023, but did not collect calibration data due to early termination of the flight.
The integration of a new calibration system into FIREBall-2 (Faint Intergalactic Redshifted Emission Balloon-2) allows in-flight calibration capability for the upcoming Fall 2023 flight. This system is made up of a calibration box that contains zinc and deuterium lamp sources, focusing optics, electronics, and sensors, and a fiber-fed calibration cap with an optical shutter mounted on the spectrograph tank. We discuss how the calibration cap is optimized to be evenly illuminated through nonsequential modeling for the near-UV (200-208nm). Then, we present the pre-flight performance testing results of the calibration system and their implications for in-flight measurements.
We present a comprehensive stray light analysis and mitigation strategy for the FIREBall-2 ultraviolet balloon telescope. Using nonsequential optical modeling, we identified the most problematic stray light paths, which impacted telescope performance during the 2018 flight campaign. After confirming the correspondence between the simulation results and postflight calibration measurements of stray light contributions, a system of baffles was designed to minimize stray light contamination. The baffles were fabricated and coated to maximize stray light collection ability. Once completed, the baffles will be integrated into FIREBall-2 and tested for performance preceding the upcoming flight campaign. Given our analysis results, we anticipate a substantial reduction in the effects of stray light.
This conference presentation was prepared for the Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray conference at SPIE Astronomical Telescopes and Instrumentation, 2022.
DICOS is a technological demonstrator under a stratospheric balloon for advanced pointing and wavefront stability technologies. The aim is to reach 10 mas fine pointing and 20 nm rms wavefront error (WFE), with 1 nm rms stability. The sizing case comes from the coronography technique for exoplanets direct detection. The instrument is based on a 40 cm telescope made in aluminum and mounted in a CARMEN gondola. The deformations and pointing errors are compensated by active loops driving a deformable mirror (DM) with 97 actuators. The current funded phase of the project will end in 2024 by a full-scale ground demonstration.
The payload of the Faint Intergalactic Redshifted Emission Balloon (FIREBall-2), the second generation of the FIREBall instrument (PI: C. Martin, Caltech), has been calibrated and launched from the NASA Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. FIREBall-2 was launched for the first time on the September 22, 2018, and the payload performed the very first multi-object acquisition from space using a multi-object spectrograph. Our performance-oriented paper presents the calibration and last ground adjustments of FIREBall-2, the in-flight performance assessed based on the flight data, and the predicted instrument’s ultimate sensitivity. This analysis predicts that future flights of FIREBall-2 should be able to detect the HI Lyα resonance line in galaxies at z ∼ 0.67, but will find it challenging to spatially resolve the circumgalactic medium.
PILOT (Polarized Instrument for Long wavelength Observations of the Tenuous interstellar medium) is a balloonborne astronomy experiment designed to study the polarization of dust emission in the diffuse interstellar medium in our Galaxy. The PILOT instrument allows observations at wavelengths 240 μm and 550 μm with an angular resolution of about two arcminutes. The observations performed during the two first flights performed from Timmins, Ontario Canada, and from Alice-springs, Australia, respectively in September 2015 and in April 2017 have demonstrated the good performances of the instrument. Pilot optics is composed of an off axis Gregorian type telescope combined with a refractive re-imager system. All optical elements, except the primary mirror, which is at ambient temperature, are inside a cryostat and cooled down to 3K. The whole optical system is aligned on ground at room temperature using dedicated means and procedures in order to keep the tight requirements on the focus position and ensure the instrument optical performances during the various phases of a flight. We’ll present the optical performances and the firsts results obtained during the two first flight campaigns. The talk describes the system analysis, the alignment methods, and finally the inflight performances.
Here we discuss advances in UV technology over the last decade, with an emphasis on photon counting, low noise, high efficiency detectors in sub-orbital programs. We focus on the use of innovative UV detectors in a NASA astrophysics balloon telescope, FIREBall-2, which successfully flew in the Fall of 2018. The FIREBall-2 telescope is designed to make observations of distant galaxies to understand more about how they evolve by looking for diffuse hydrogen in the galactic halo. The payload utilizes a 1.0-meter class telescope with an ultraviolet multi-object spectrograph and is a joint collaboration between Caltech, JPL, LAM, CNES, Columbia, the University of Arizona, and NASA. The improved detector technology that was tested on FIREBall-2 can be applied to any UV mission. We discuss the results of the flight and detector performance. We will also discuss the utility of sub-orbital platforms (both balloon payloads and rockets) for testing new technologies and proof-of-concept scientific ideas.
In the frame of the CNES Pleiades satellite, a reduction of the star tracker low frequency error, which is the most penalizing error for the satellite attitude control, was performed. For that purpose, the SED36 star tracker was developed, with a design based on the flight qualified SED16/26. In this paper, the SED36 main features will be first presented. Then, the reduction process of the low frequency error will be developed, particularly the optimization of the optical distortion calibration. The result is an attitude low frequency error of 1.1" at 3 sigma along transverse axes. The implementation of these improvements to HYDRA, the new multi-head APS star tracker developed by SODERN, will finally be presented.
PILOT (Polarized Instrument for Long wavelength Observations of the Tenuous interstellar medium) is a balloonborne astronomy experiment designed to study the polarization of dust emission in the diffuse interstellar medium in our Galaxy. The PILOT instrument allows observations at wavelengths 240 μm (1.2THz) with an angular resolution about two arc-minutes. The observations performed during the first flight in September 2015 at Timmins, Ontario Canada, have demonstrated the optical performances of the instrument.
PILOT is a balloon-borne astronomy experiment designed to study the polarization of dust emission in the diffuse
interstellar medium in our Galaxy at wavelengths 240 μm with an angular resolution about two arcminutes. Pilot optics
is composed an off-axis Gregorian type telescope and a refractive re-imager system. All optical elements, except the
primary mirror, are in a cryostat cooled to 3K. We combined the optical, 3D dimensional measurement methods and
thermo-elastic modeling to perform the optical alignment. The talk describes the system analysis, the alignment
procedure, and finally the performances obtained during the first flight in September 2015.
PILOT is a stratospheric experiment designed to measure the polarization of dust FIR emission, towards the diffuse interstellar medium. The first PILOT flight was carried out from Timmins in Ontario-Canada on September 20th 2015. The flight has been part of a launch campaign operated by the CNES, which has allowed to launch 4 experiments, including PILOT. The purpose of this paper is to describe the performance of the instrument in flight and to perform a first comparison with those achieved during ground tests. The analysis of the flight data is on-going, in particular the identification of instrumental systematic effects, the minimization of their impact and the quantification of their remaining effect on the polarization data. At the end of this paper, we shortly illustrate the quality of the scientific observations obtained during this first flight, at the current stage of systematic effect removal.
FIREBALL (the Faint Intergalactic Redshifted Emission Balloon, funded by CNES-NASA, PI C.Martin, Caltech) is a balloon-borne 1m telescope coupled to an ultraviolet Multi Object Spectrometer (MOS), designed to study the faint and diffuse emission of the circumgalactic medium. The third flight of the experiment is planned in summer 2017. The goal of this paper is to describe the accurate pointing system of the 5-metres high / 1500kg gondola - that has been designed to fulfill stringent pointing requirements: less than 1 arcsec in elevation and cross elevation, and about 1 arcmin in field rotation (around the line of sight axis), over long integration time (a few hours). The pointing system is based on a multi stage closed loop scheme (4 Degrees Of Freedom), relying on a 1DOF gondola azimuth controller, a 2DOF gimbal frame supporting a 1.2-meter plano siderostat, and a 1DOF field rotation control system. The attitude determination is based on the hybridization of two accurate sensors: a Fiber Optic Gyrometer measurement unit and a star sensor integrated inside the instrument. The manuscript presents the design of the ACS. We also focus on flight train stability issues - due to the pendulum and torsion modes -, on the geometric equations specific to a siderostat pointing system, and on the description of the tests facilities.
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