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Authors:
Elizabeth J. Iles, Joss Bland-Hawthorn, Courtney Crawford, Scott Croom, Hillary Davis, May Gade Pedersen, Anne Green, Madusha Gunawardhana, Miguel Icaza-Lizaola, Helen Johnston, Emily F. Kerrison, Yifan Mai, Benjamin T. Montet, Kovi Rose, Tomas Rutherford, Manasvee Saraf, Ellen L. Sirks, Eckhart Spalding, Sujeeporn Tuntipong, Jesse van de Sande, Pavadol Yamsiri
PASA, 24, e166
Abstract:
Bars are ubiquitous morphological features in the observed distribution of galaxies. There are similarly many methods for classifying these features and, without a strict theoretical definition or common standard practice, this is often left to circumstance. So, we were concerned whether astronomers even agree on the bar which they perceive in a given galaxy and whether this could impact perceived scientific results. As an elementary test, we twenty-one astronomers with varied experience in studying resolved galaxies and circumstances, have each assessed 200 galaxy images, spanning the early phase of bar evolution in two different barred galaxy simulations. We find variations exist within the classification of all the standard bar parameters assessed: bar length, axis-ratio, pitch-angle and even whether a bar is present at all. If this is indicative of the wider community, it has implications for interpreting morphological trends, such as bar-end effects. Furthermore, we find that it is surprisingly not expertise but gender, followed by career stage, which gives rise to the largest discrepancies in the reported bar parameters. Currently, automation does not seem to be a viable solution, with bar classifications from two automated bar-finding algorithms tested and failing to find bars in snapshots where most astronomers agree a bar must exist. Increasing dependence on machine learning or crowdsourcing with a training dataset can only serve to obfuscate any existing biases if these originate from the specific astronomer producing the training material. On the strength of this small sample, we encourage an interim best practice to reduce the impact of any possible classification bias and set goals for the community to resolve the issue in the future.
Refereed papers
2025
2024
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Authors:
Philippe Voyer, Steven J. Benton, Christopher J. Damarena, Spencer W. Everett, Aurelien A. Fraisse, Ajay S. Gill, John W. Hartley, David Harvey, Michael Henderson, Bradley Holder, Eric M. Huff, Mathilde Jauzac, William C. Jones, David Lagattuta, Jason S.-Y. Leung, Lun Li, Thuy Vy T. Luu, Richard Massey, Jacqueline E. McCleary, Johanna M. Nagy, C. Barth Netterfieldi, Emaad Paracha, Susan F. Redmond, Jason D. Rhodes, Andrew Robertson, L. Javier Romualdez, Jürgen Schmoll, Mohamed M. Shaaban, Ellen L. Sirks, Georgios N. Vassilakis, & André Z. Vitorelli
SPIE Astronomical Telescopes + Instrumentation 2024
Abstract:
The Super-pressure Balloon-borne Imaging Telescope (SuperBIT) is a near-diffraction-limited 0.5m telescope that launched via NASA's super-pressure balloon technology on April 16, 2023. SuperBIT achieved precise pointing control through the use of three nested frames in conjunction with an optical Fine Guidance System (FGS), resulting in an average image stability of 0.055" over 300-second exposures. The SuperBIT FGS includes a tip-tilt fast-steering mirror that corrects for jitter on a pair of focal plane star cameras. In this paper, we leverage the empirical data from SuperBIT's successful 45-night stratospheric mission to inform the FGS design for the next-generation balloon-borne telescope. The Gigapixel Balloon-borne Imaging Telescope (GigaBIT) is designed to be a 1.35m wide-field, high resolution imaging telescope, with specifications to extend the scale and capabilities beyond those of its predecessor SuperBIT. A description and analysis of the SuperBIT FGS will be presented along with methodologies for extrapolating this data to enhance GigaBIT's FGS design and fine pointing control algorithm. We employ a systems engineering approach to outline and formalize the design constraints and specifications for GigaBIT's FGS. GigaBIT, building on the SuperBIT legacy, is set to enhance high-resolution astronomical imaging, marking a significant advancement in the field of balloon-borne telescopes.
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Authors:
Ajay S. Gill, Steven J. Benton, Christopher J. Damaren, Aurelien A. Fraisse, John W. Hartley, David Harvey, Bradley Holder, Eric M. Huff, Mathilde Jauzac, William C. Jones, David Lagattuta, Jason S.-Y. Leung, Lun Li, Thuy Vy T. Luu, Richard Massey, Jacqueline E. McCleary, Johanna M. Nagy, C. Barth Netterfield, Emaad Paracha, Susan F. Redmond, Jason D. Rhodes, Andrew Robertson, L. Javier Romualdez, Jürgen Schmoll, Mohamed M. Shaaban, Ellen L. Sirks, Georgios N. Vassilakis, & André Z. Vitorelli
AJ, 168, 2
Abstract:
SuperBIT was a 0.5 m near-UV to near-infrared wide-field telescope that launched on a NASA superpressure balloon into the stratosphere from New Zealand for a 45-night flight. SuperBIT acquired multiband images of galaxy clusters to study the properties of dark matter using weak gravitational lensing. We provide an overview of the instrument and its various subsystems. We then present the instrument performance from the flight, including the telescope and image stabilization system, the optical system, the power system, and the thermal system. SuperBIT successfully met the instrument's technical requirements, achieving a telescope pointing stability of 0\(.\!\!^{\prime\prime}\)34 ± 0\(.\!\!^{\prime\prime}\)10, a focal plane image stability of 0\(.\!\!^{\prime\prime}\)055 ± 0\(.\!\!^{\prime\prime}\)027, and a point-spread function FWHM of ∼0\(.\!\!^{\prime\prime}\)35 over 5-minute exposures throughout the 45-night flight. The telescope achieved a near-diffraction-limited point-spread function in all three science bands (\(u\), \(b\), and \(g\)). SuperBIT served as a pathfinder to the GigaBIT observatory, which will be a 1.34 m near-UV to near-infrared balloon-borne telescope.
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Authors:
Amy Etherington, James Nightingale, Richard Massey, Sut-Ieng Tam, XiaoYue Cao, Anna Niemiec, Qiuhan He, Andrew Robertson, Ran Li, Aristeidis Amvrosiadis, Shaun Cole, Jose Diego, Carlos Frenk, Brenda Frye, David Harvey, Mathilde Jauzac, Anton Koekemoer, David Lagattuta, Marceau Limousin, Guillaume Mahler, Ellen Sirks & Charles Steinhardt
MNRAS, 531, 3
Abstract:
The distribution of mass in galaxy-scale strong gravitational lenses is often modelled as an elliptical power-law plus ‘external shear’, which notionally accounts for neighbouring galaxies and cosmic shear along our line of sight. A small amount of external shear \(could\) come from these sources, but we show that the vast majority does not. Except in a handful of rare systems, the best-fitting values do not correlate with independent measurements of line-of-sight shear: from weak lensing in 45 \(\textit{Hubble Space Telescope}\) images, or in 50 mock images of lenses with complex distributions of mass. Instead, the best-fit external shear is aligned with the major or minor axis of 88 per cent of lens galaxies; and the amplitude of the external shear increases if that galaxy is discy. We conclude that ‘external shear’ attached to a power-law model is not physically meaningful, but a fudge to compensate for lack of model complexity. Since it biases other model parameters that \(are\) interpreted as physically meaningful in several science analyses (e.g. measuring galaxy evolution, dark matter physics or cosmological parameters), we recommend that future studies of galaxy-scale strong lensing should employ more flexible mass models.
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Authors:
Ellen L. Sirks, David Harvey, Richard Massey, Kyle A. Oman, Andrew Robertson, Carlos Frenk, Spencer Everett, Ajay S. Gill, David Lagattuta & Jacqueline McCleary
MNRAS, 530, 3
Abstract:
Terrestrial particle accelerators collide charged particles, then watch the trajectory of outgoing debris – but they cannot manipulate dark matter. Fortunately, dark matter is the main component of galaxy clusters, which are continuously pulled together by gravity. We show that galaxy cluster mergers can be exploited as enormous, natural dark matter colliders. We analyse hydrodynamical simulations of a universe containing self-interacting dark matter (SIDM) in which all particles interact via gravity, and dark matter particles can also scatter off each other via a massive mediator. During cluster collisions, SIDM spreads out and lags behind cluster member galaxies. Individual systems can have quirky dynamics that makes them difficult to interpret. Statistically, however, we find that the mean or median of dark matter’s spatial offset in many collisions can be robustly modelled, and is independent of our viewing angle and halo mass even in collisions between unequal-mass systems. If the SIDM cross-section were \(\sigma/m\) = 0.1 cm\(^{2}\) g\(^{−1}\) = 0.18 barn GeV\(^{−1}\), the ‘bulleticity’ lag would be ∼5 per cent that of gas due to ram pressure, and could be detected at 95 per cent confidence in weak lensing observations of ∼100 well-chosen clusters.
2023
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Authors:
Ellen Sirks, Richard Massey, Ajay Gill, Jason Anderson, Steven Benton, Anthony Brown, Paul Clark, Joshua English, Spencer Everett, Aurelien Fraisse, Hugo Franco, John Hartley, David Harvey, Bradley Holder, Andrew Hunter, Eric Huff, Andrew Hynous, Mathilde Jauzac, William Jones, Nikky Joyce, Duncan Kennedy, David Lagattuta, Jason Leung, Lun Li, Stephen Lishman, Thuy Vy Luu, Jacqueline McCleary, Johanna Nagy, Barth Netterfield, Emaad Paracha, Robert Purcaru, Susan Redmond, Jason Rhodes, Andrew Robertson, Javier Romualdez, Sarah Roth, Robert Salter, Jürgen Schmoll, Mohamed Shaaban, Roger Smith, Russell Smith, Sut Ieng Tam & Georgios Vassilakis
Aerospace 10, 960
See also this press release by the University of Sydney, and coverage at The Sydney Morning Herald, Cosmos Magazine, ScienceNews, IEEE Spectrum, Space.Com, Interesting Engineering, Newsweek etc.
For more information on the SuperBIT mission, see NASA's blog, SuperBIT's Instagram, SuperBIT's APOD, and its launch press release.
Abstract:
In April 2023, the SuperBIT telescope was lifted to the Earth’s stratosphere by a helium-filled super-pressure balloon to acquire astronomical imaging from above (99.5% of) the Earth’s atmosphere. It was launched from New Zealand and then, for 40 days, circumnavigated the globe five times at a latitude 40 to 50 degrees south. Attached to the telescope were four “DRS” (Data Recovery System) capsules containing 5 TB solid state data storage, plus a gnss receiver, Iridium transmitter, and parachute. Data from the telescope were copied to these, and two were dropped over Argentina. They drifted 61 km horizontally while they descended 32 km, but we predicted their descent vectors within 2.4 km: in this location, the discrepancy appears irreducible below ~2 km because of high speed, gusty winds and local topography. The capsules then reported their own locations within a few metres. We recovered the capsules and successfully retrieved all of SuperBIT’s data despite the telescope itself being later destroyed on landing.
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Authors:
Jacqueline McCleary, Spencer Everett, Mohamed Shaaban, Ajay Gill, Georgios Vassilakis, Eric Huff, Richard Massey, Steven J. Benton, Anthony Brown, Paul Clark, Bradley Holder, Aurelien Fraisse, Mathilde Jauzac, William C. Jones, David Lagattuta, Jason Leung, Lun Li, Thuy Vy Luu, Johanna M. Nagy, Barth Netterfield, Emaad Paracha, Susan Redmond, Jason Rhodes, Jürgen Schmoll, Ellen Sirks & Sut Ieng Tam
AJ, 166, 134
Abstract:
The Superpressure Balloon-borne Imaging Telescope (SuperBIT) is a diffraction-limited, wide-field, 0.5 m, near-infrared to near-ultraviolet observatory designed to exploit the stratosphere's space-like conditions. SuperBIT's 2023 science flight will deliver deep, blue imaging of galaxy clusters for gravitational lensing analysis. In preparation, we have developed a weak lensing measurement pipeline with modern algorithms for PSF characterization, shape measurement, and shear calibration. We validate our pipeline and forecast SuperBIT survey properties with simulated galaxy cluster observations in SuperBIT's near-UV and blue bandpasses. We predict imaging depth, galaxy number (source) density, and redshift distribution for observations in SuperBIT's three bluest filters; the effect of lensing sample selections is also considered. We find that in three hours of on-sky integration, SuperBIT can attain a depth of b = 26 mag and a total source density exceeding 40 galaxies per square arcminute. Even with the application of lensing-analysis catalog selections, we find b-band source densities between 25 and 30 galaxies per square arcminute with a median redshift of z = 1.1. Our analysis confirms SuperBIT's capability for weak gravitational lensing measurements in the blue.
2022
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Authors:
Mohamed Shaaban, Ajay Gill, Jacqueline McCleary, Richard Massey, Steven Benton, Anthony Brown, Christopher Damaren, Tim Eifler, Aurelien Fraisse, Spencer Everett, Mathew Galloway, Michael Henderson, Bradley Holder, Eric Huff, Mathilde Jauzac, William Jones, David Lagattuta, Jason Leung, Lun Li, Thuy Vy Luu Johanna Nagy, C. Barth Netterfield, Susan Redmond, Jason Rhodes, Andrew Robertson, Jurgen Schmoll, Ellen Sirks & Suresh Sivanandam
AJ, 164, 245
Abstract:
The statistical power of weak lensing measurements is principally driven by the number of high redshift galaxies whose shapes are resolved. Conventional wisdom and physical intuition suggest this is optimised by deep imaging at long (red or near IR) wavelengths, to avoid losing redshifted Balmer break and Lyman break galaxies. We use the synthetic Emission Line EL-COSMOS catalogue to simulate lensing observations using different filters, from various altitudes. Here were predict the number of exposures to achieve a target z > 0.3 source density, using off-the-shelf and custom filters. Ground-based observations are easily better at red wavelengths, as (more narrowly) are space-based observations. However, we find that SuperBIT, a diffraction-limited observatory operating in the stratosphere, should instead perform its lensing-quality observations at blue wavelengths.
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Authors:
Ellen Sirks, Kyle Oman, Andrew Robertson, Richard Massey & Carlos Frenk
MNRAS 511, 5927
Abstract:
We use the Cluster-EAGLE (C-EAGLE) hydrodynamical simulations to investigate the effects of self-interacting dark matter (SIDM) on galaxies as they fall into clusters. We find that SIDM galaxies follow similar orbits to their Cold Dark Matter (CDM) counterparts, but end up with ∼25 per cent less mass by the present day. One in three SIDM galaxies are entirely disrupted, compared to one in five CDM galaxies. However, the excess stripping will be harder to observe than suggested by previous DM-only simulations because the most stripped galaxies form cores and also lose stars: the most discriminating objects become unobservable. The best test will be to measure the stellar-to-halo mass relation (SHMR) for galaxies with stellar mass \(10^{10-11}\mathrm{M}_{\odot}\). This is 8 times higher in a cluster than in the field for a CDM universe, but 13 times higher for an SIDM universe. Given intrinsic scatter in the SHMR, these models could be distinguished with noise-free galaxy-galaxy strong lensing of ∼32 cluster galaxies.
2020
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Authors:
Ajay Gill, Steven J. Benton, Anthony M. Brown, Paul Clark, Christopher J. Damaren, Tim Eifler, Aurelien A. Fraisse, Mathew N. Galloway, John W. Hartley, Bradley Holder, Eric M. Huff, Mathilde Jauzac, William C. Jones, David Lagattuta, Jason S.-Y Leung, Lun Li, Thuy Vy T. Luu, Richard Massey, Jacqueline McCleary, James Mullaney, Johanna M. Nagy, C. Barth Netterfield, Susan Redmond, Jason D. Rhodes, L. Javier Romualdez, Jurgen Schmoll, Mohamed M. Shaaban, Ellen Sirks, Suresh Sivanandam & Sut-Ieng Tam
AJ 160, 266
Abstract:
This paper presents optical night sky brightness measurements from the stratosphere using CCD images taken with the Super-pressure Balloon-borne Imaging Telescope (SuperBIT). The data used for estimating the backgrounds were obtained during three commissioning flights in 2016, 2018, and 2019 at altitudes ranging from 28 km to 34 km above sea level. For a valid comparison of the brightness measurements from the stratosphere with measurements from mountain-top ground-based observatories (taken at zenith on the darkest moonless night at high Galactic and high ecliptic latitudes), the stratospheric brightness levels were zodiacal light and diffuse Galactic light subtracted, and the airglow brightness was projected to zenith. The stratospheric brightness was measured around 5.5 hours, 3 hours, and 2 hours before the local sunrise time in 2016, 2018, and 2019 respectively. The B, V, R, and I brightness levels in 2016 were 2.7, 1.0, 1.1, and 0.6 mag arcsec\(^{−2}\) darker than the darkest ground-based measurements. The B, V, and R brightness levels in 2018 were 1.3, 1.0, and 1.3 mag arcsec\(^{−2}\) darker than the darkest ground-based measurements. The U and I brightness levels in 2019 were 0.1 mag arcsec\(^{−2}\) brighter than the darkest ground-based measurements, whereas the B and V brightness levels were 0.8 and 0.6 mag arcsec\(^{−2}\) darker than the darkest ground-based measurements. The lower sky brightness levels, stable photometry, and lower atmospheric absorption make stratospheric observations from a balloon-borne platform a unique tool for astronomy. We plan to continue this work in a future mid-latitude long duration balloon flight with SuperBIT.
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Authors:
Ellen Sirks, Paul Clark, Richard Massey, S. Benton, A. Brown, C. J. Damaren, T. Eifler, A. Fraisse, C. Frenk, M. Funk, M. Galloway, A. Gill, J. Hartley, B. Holder, E. M. Huff, M. Jauzac, W. Jones, D. Lagattuta, J. Leung, L. Li, T. Luu, J. McCleary, J. Nagy, C. Netterfield, S. Redmond, J. Rhodes, L. Romualdez, J. Schmoll, M. Shaaban & S.-I. Tam
JInst 15, 5014
Abstract:
We present a publicly-available toolkit of flight-proven hardware and software to retrieve 5 TB of data or small physical samples from a stratospheric balloon platform. Before launch, a capsule is attached to the balloon, and rises with it. Upon remote command, the capsule is released and descends via parachute, continuously transmitting its location. Software to predict the trajectory can be used to select a safe but accessible landing site. We dropped two such capsules from the SuperBIT telescope, in September 2019. The capsules took ~37 minutes to descend from ~30 km altitude. They drifted 32 km and 19 km horizontally, but landed within 300 m and 600 m of their predicted landing sites. We found them easily, and successfully recovered the data. We welcome interest from other balloon teams for whom the technology would be useful.
2019
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Authors:
Javier Romualdez, Steven Benton, Anthony Brown, Paul Clark, Christopher Damaren, Tim Eifler, Aurelien Fraisse, Mathew Galloway, Ajay Gill, John Hartley, Bradley Holder, Eric Huff, Mathilde Jauzac, William Jones, David Lagattuta, Jason Leung, Lun Li, Thuy Vy Luu, Richard Massey, Jacqueline McCleary, James Mullaney, Johanna Nagy, C. Barth Netterfield, Susan Redmond, Jason D. Rhodes, Jürgen Schmoll, Mohamed Shaaban, Ellen Sirks & Sut-Ieng Tam
Review of Scientific Instruments 91, 4501
Abstract:
At a fraction the total cost of an equivalent orbital mission, scientific balloon-borne platforms, operating above 99.7% of the Earth's atmosphere, offer attractive, competitive, and effective observational capabilities -- namely space-like resolution, transmission, and backgrounds -- that are well suited for modern astronomy and cosmology. SuperBIT is a diffraction-limited, wide-field, 0.5 m telescope capable of exploiting these observing conditions in order to provide exquisite imaging throughout the near-IR to near-UV. It utilizes a robust active stabilization system that has consistently demonstrated a 1 sigma sky-fixed pointing stability at 48 milliarcseconds over multiple 1 hour observations at float. This is achieved by actively tracking compound pendulations via a three-axis gimballed platform, which provides sky-fixed telescope stability at < 500 milliarcseconds and corrects for field rotation, while employing high-bandwidth tip/tilt optics to remove residual disturbances across the science imaging focal plane. SuperBIT's performance during the 2019 commissioning flight benefited from a customized high-fidelity science-capable telescope designed with exceptional thermo- and opto-mechanical stability as well as tightly constrained static and dynamic coupling between high-rate sensors and telescope optics. At the currently demonstrated level of flight performance, SuperBIT capabilities now surpass the science requirements for a wide variety of experiments in cosmology, astrophysics and stellar dynamics.
2018
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Authors:
J Harnois-Déraps, A Amon, A Choi, V Demchenko, C Heymans, A Kannawadi, R Nakajima, E Sirks, L van Waerbeke, Yan-Chuan Cai, B Giblin, H Hildebrandt, H Hoekstra, L Miller, T Tröster
MNRAS 481, 1
Abstract:
We present a public suite of weak-lensing mock data, extending the Scinet Light Cone Simulations (SLICS) to simulate cross-correlation analyses with different cosmological probes. These mocks include Kilo Degree Survey (KiDS)-450- and LSST-like lensing data, cosmic microwave background lensing maps and simulated spectroscopic surveys that emulate the Galaxy And Mass Assembly, BOSS, and 2-degree Field Lensing galaxy surveys. With 844 independent realizations, our mocks are optimized for combined-probe covariance estimation, which we illustrate for the case of a joint measurement involving cosmic shear, galaxy–galaxy lensing, and galaxy clustering from KiDS-450 and BOSS data. With their high spatial resolution, the SLICS are also optimal for predicting the signal for novel lensing estimators, for the validation of analysis pipelines, and for testing a range of systematic effects such as the impact of neighbour-exclusion bias on the measured tomographic cosmic shear signal. For surveys like KiDS and Dark Energy Survey, where the rejection of neighbouring galaxies occurs within ∼2 arcsec, we show that the measured cosmic shear signal will be biased low, but by less than a per cent on the angular scales that are typically used in cosmic shear analyses. The amplitude of the neighbour-exclusion bias doubles in deeper, LSST-like data. The simulation products described in this paper are made available at http://slics.roe.ac.uk/.
2015
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Authors:
Charles Cockell, Toby Samuels, Ellen Sirks, Marisa Mayer, Indiarose Friswell, Natasha Nicholson, Ralf Moeller, Katja Nagler, Marina Raguse, Andrea Schröder, Thomas Berger, Petra Rettberg
Astronomy & Geophysics, 56, 1
Abstract:
Charles Cockell and colleagues describe an experiment that started in 2014 and will finish in 2514. It will document how long desiccated microbes can survive, with implications for life in the planetary crust and in space.
Non-refereed material
2019
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Authors:
Bill Jones, Barth Netterfield, Richard Massey, Jason Rhodes, Steven Benton, Anthony Brown, Paul Clark, Christopher Damaren, Tim Eifler, Aurelien Fraisse, Mathew Galloway, John Hartley, Brad Holder, Eric Huff, Mathilde Jauzac, David Lagattuta, Jason Leung, Lun Li, Vy Luu, Jacqueline McCleary, Johanna Nagy, Susan Redmond, Javier Romualdez, Jurgen Schmoll, Mohamaed Shaaban, & Ellen Sirks
BAAS 51, 171 and White paper #171 to the Astro2020 decadal survey on astronomy and astrophysics
Abstract:
We propose the development of a stratospheric balloon-borne observatory whose diffraction-limited, wide-field imaging capability far exceeds that of HST. The demand for sub arc-second resolution imaging to complement the new large terrestrial programs, such as LSST, will grow exponentially in the next decade. The proposed project will provide it.
Erdős number: 5 (P. Erdős → H. S. Shapiro → M. Tegmark → B. Jain → R. J. Massey → E. L. Sirks)
Image credit: SuperBIT, NASA