Spacetime is foamy due to quantum fluctuations. Various gedanken experiments show that distances fluctuate by amounts consistent with the holographic principle, hence the name "holographic quantum foam" (HQF). One important prediction of HQF is that necessarily there exists a dark sector in the universe. The resulting cosmology is found (at least qualitatively) to be consistent with observations. Interestingly the quanta of the dark sector are found not to obey the familiar (fermionic or bosonic) statistics, but the exotic statistics known as infinite statistics (or quantum Boltzmann statistics). The most important challenge now is to check if HQF is consistent with experiments/observations. One way is to look for observational evidence of blurred distant point-sources due to physics at the Planck scale. For over two decades it has been debated whether those tiny inherent uncertainties in time and path-length can accumulate in transiting electromagnetic wavefronts from quasars and Gamma-Ray Bursts (GRBs). But a recent event is special: GRB221009A was extremely bright and energetic. That allowed follow-up across the whole spectrum from the optical/near-infrared through to X-rays, and including the highest-ever-recorded energy gamma-rays; all consistent with blurring by HQF. Those data, and a calculation of the HQF-widened point-spread function (PSF) for real telescopes viewing a GRB are presented.

Spacetime is foamy: it undergoes quantum fluctuations, with distance uncertainty scaling as the cube root of distances, consistent with the holographic principle - hence the name "Holographic Quantum Foam" (HQF). HQF, in conjunction with thermodynamics, naturally demands the existence of a dark sector, the quanta of which obey infinite statistics. Applied to the cosmos, HQF yields a cosmology with critical energy density and a dynamical cosmological constant, as well as a phenomenologically viable dark matter sector. An early cosmic acceleration can also be traced to HQF. Most importantly, it is verified by observations of gamma-ray burst GRB 221009A: the brightest ever seen in the optical/near-infrared through to X-rays; even at 251TeV. That is possible only for HQF if accounting for how real telescopes see foam.

The "foamy" nature of spacetime at the Planck scale was an idea first introduced by John Wheeler in the 1950s. And for the last twenty years or so it has been debated whether those inherent uncertainties in time and path-length might also accumulate in transiting electromagnetic wavefronts, resulting in measurable blurring for images of distant galaxies and quasars. A confusing aspect is that "pointlike" objects will always be blurred out somewhat by the optics of a telescope, especially in the optical. But it turns out that Gamma-Ray Bursts (GRBs) are more useful to test this, and have been observed by a host of ground-based and space-based telescopes, including by the Fermi observatory for well over a decade. And a recent one was unprecedented: GRB221009A was extremely bright, allowing follow-up from the infrared through the ultraviolet to X-rays and gamma-rays, including a first association with photons at high TeV energies. I will discuss how that observation is in direct tension with the calculus of how spacetime "foaminess" can add up in an image of a pointsource at cosmological distances, which at high-enough energy could spread these out over the whole sky without resulting in photon loss. A simple multiwavelength average of foam-induced blurring consistent with holographic quantum gravity is described, analogous to atmospheric seeing from the ground. This fits with measured instrumental point-spread functions and with the highest-energy localization of GRB221009A, resolving the observational issues and pointing to a key physical implication: spacetime does not look smooth.

Viewing high-redshift sources at near-opposite directions on the sky can ensure, using light-travel-time arguments, acausality between their emitted photons. One utility would be true random-number generation through sensing these via two independent telescopes that each flip a switch based on the latest-arrived colours; for example, to autonomously control a quantum-mechanical (QM) experiment. Although demonstrated with distant quasars, those were not fully acausal pairs, which are restricted when simultaneously viewed from the ground at any single observatory. In optical light, such faint sources also require a large telescope aperture to avoid sampling assumptions when imaged at fast camera framerates: unsensed intrinsic correlations between them or equivalently correlated noise may ruin the expectation of pure randomness. One such case that could spoil a QM test is considered. Based on that, the allowed geometries and instrumental limits are modelled for any two ground-based sites, and their data are simulated. For comparison, an analysis of photometry from the Gemini twin 8 m telescopes is presented using the archival data of well-separated bright stars obtained with the instruments ‘Alopeke (on Gemini North in Hawai’i) and Zorro (on Gemini-South in Chile) simultaneously in two bands (centred at 562nm and 832nm) with 17 Hz framerate. No flux correlation is found; these results were used to calibrate an analytic model predicting where a search with a signal-to-noise over 50 at 50 Hz can be made using the same instrumentation. Finally, the software PDQ (Predict Different Quasars) is presented, which searches a large catalogue of known quasars, reporting those with a brightness and visibility suitable to verify acausal, uncorrelated photons at these limits.

REVOLT (Research, Experiment and Validation of Adaptive Optics with a Legacy Telescope) is an adaptive optics (AO) system on the 1.2-m telescope at the Herzberg Astronomy and Astrophysics Research Centre which is intended to demonstrate various AO developments, technologies, and algorithms. This AO system is a platform to test the Herzberg Extensible Adaptive optics Real-time Toolkit (HEART) where new AO control features can be exercised on-sky ahead of deployment on a facility class instrument. In this paper, we present various analysis of the telemetry produced by HEART and its various wavefront-sensing arms that enable both open- and closed-loop operation including a closed-loop Shack-Hartmann wavefront sensor, a closed-loop pyramid wavefront sensor, and an open-loop Shack-Hartmann. Employing REVOLT's single-conjugate AO configuration, we look at extracting the Fried parameter and other atmospheric parameters from the telemetry and compare the results to an in-situ Ring Image Next Generation Scintillation Sensor (RINGSS) atmospheric seeing monitor and optical turbulence profiler. Finally, we discuss the AO s ystem's r ejection-transfer f unction and overall system's performance.

Gamma-ray burst GRB221009A was of unprecedented brightness in gamma-rays and X-rays, and through to the far ultraviolet, allowing for identification within a host galaxy at redshift z=0.151 by multiple space and ground-based optical/near-infrared telescopes and enabling a first association - via cosmic-ray air-shower events - with a photon of 251 TeV. That is in direct tension with a potentially observable phenomenon of quantum gravity (QG), where spacetime "foaminess" accumulates in wavefronts propagating cosmological distances, and at high-enough energy could render distant yet bright pointlike objects invisible, by effectively spreading their photons out over the whole sky. But this effect would not result in photon loss, so it remains distinct from any absorption by extragalactic background light. A simple multiwavelength average of foam-induced blurring is described, analogous to atmospheric seeing from the ground. When scaled within the fields of view for the Fermi and Swift instruments, it fits all z<5 GRB angular-resolution data of 10 MeV or any lesser peak energy and can still be consistent with the highest-energy localization of GRB221009A: a limiting bound of about 1 degree is in agreement with a holographic QG-favored formulation.

Gamma-ray burst GRB221009A was of unprecedented brightness in the γ-rays and X-rays through to the far ultraviolet, allowing for identification within a host galaxy at redshift z=0.151 by multiple space and ground-based optical/near-infrared telescopes and enabling a first association—via cosmic-ray air-shower events—with a photon of 251 TeV. That is in direct tension with a potentially observable phenomenon of quantum gravity (QG), where spacetime “foaminess” accumulates in wavefronts propagating cosmological distances, and at high-enough energy could render distant yet bright pointlike objects invisible, by effectively spreading their photons out over the whole sky. But this effect would not result in photon loss, so it remains distinct from any absorption by extragalactic background light. A simple multiwavelength average of foam-induced blurring is described, analogous to atmospheric seeing from the ground. When scaled within the fields of view for the Fermi and Swift instruments, it fits all z≤5 GRB angular-resolution data of 10 MeV or any lesser peak energy and can still be consistent with the highest-energy localization of GRB221009A: a limiting bound of about 1 degree is in agreement with a holographic QG-favored formulation.

Effects of long-term atmospheric change were looked for in photometry employing Gemini North and South twin Multi-Object Spectrograph (GMOS-N and GMOS-S) archival data. The whole GMOS imaging database, beginning from 2003, was compared against the all-sky Gaia object catalog, yielding ∼10 6 Sloan r ′ -filter samples, ending in 2021. These were combined with reported sky and meteorological conditions, and versus a simple model of the atmosphere plus cloud together with simulated throughputs. One exceptionally extincted episode in 2009 is seen, as is a trend (similar at both sites) of about 2 mmag worsening attenuation per decade. This is consistent with solar-radiance transmissivity records going back over six decades, aerosol density measurements, and more than 0.2°C/decade rise in air temperature, which has implications for the calibration of historic data sets or future surveys.

Gemini Observatory has been awarded a major funding from the National Science Foundation to build a complete new state of the art multi-conjugate adaptive optics system for Gemini North. The system will be designed to provide an MCAO facility delivering close to diffraction limit correction in the near-infrared over a 2 arcminutes field of view and feed imaging and spectroscopic instruments. We present in this paper the results of the conceptual design phase with details on the new proposed laser guide star facilities and adaptive optics bench. We will present results on the performance simulation assessments as well as the developed selected science

Gemini Observatory has been awarded from the National Science Foundation a major fund to build a new state-of-the-art Multi Conjugate Adaptive Optics facility for Gemini North on Maunakea called GNAO. The current Telephone: 1+56 51 2205 642 baseline system will use two lasers each split in two to create an artificial constellation of four laser guide star to measure the distortions caused by the atmosphere. At least two deformable mirror conjugated to 0km and the main altitude layer above Maunakea will be used to correct these distortions. The facility will be designed to feed future instrumentation, initially a near infrared imager and potentially a visiting 4-arm multi object adaptive optics IFU spectrograph. 1 In this paper I will present the main characteristics of this exciting facility, its promises and its challenges. I will also present its conceptual design and results of trade studies conducted within the team and the Gemini Adaptive Optics Working Group. The expected first light is for October 2024.

As part of the National Science Foundation funded in the Era of MultiMessenger Astronomy (GEMMA) program, Gemini Observatory is developing GNAO, a widefield adaptive optics (AO) facility for Gemini-North on Maunakea, the only 8m-class open-access telescope available to the US astronomers in the northern hemisphere. GNAO will provide the user community with a queue-operated Multi-Conjugate AO (MCAO) system, enabling a wide range of innovative solar system, Galactic, and extragalactic science with a particular focus on synergies with JWST in the area of time-domain astronomy. The GNAO effort builds on institutional investment and experience with the more limited block-scheduled Gemini Multi-Conjugate System (GeMS), commissioned at Gemini South in 2013. The project involves close partnerships with the community through the recently established Gemini AO Working Group and the GNAO Science Team, as well as external instrument teams. The modular design of GNAO will enable a planned upgrade to a Ground Layer AO (GLAO) mode when combined with an Adaptive Secondary Mirror (ASM). By enhancing the natural seeing by an expected factor of two, GLAO will vastly improve Gemini North's observing efficiency for seeing-limited instruments and strengthen its survey capabilities for multi-messenger astronomy.

As part of the National Science Foundation funded "Gemini in the Era of MultiMessenger Astronomy" (GEMMA) program, Gemini Observatory is developing GNAO, a widefield adaptive optics (AO) facility for Gemini-North on Maunakea, the only 8m-class open-access telescope available to the US astronomers in the northern hemisphere. GNAO will provide the user community with a queue-operated Multi-Conjugate AO (MCAO) system, enabling a wide range of innovative solar system, Galactic, and extragalactic science with a particular focus on synergies with JWST in the area of time-domain astronomy. The GNAO effort builds on institutional investment and experience with the more limited block-scheduled Gemini Multi-Conjugate System (GeMS), commissioned at Gemini South in 2013. The project involves close partnerships with the community through the recently established Gemini AO Working Group and the GNAO Science Team, as well as external instrument teams. The modular design of GNAO will enable a planned upgrade to a Ground Layer AO (GLAO) mode when combined with an Adaptive Secondary Mirror (ASM). By enhancing the natural seeing by an expected factor of two, GLAO will vastly improve Gemini North's observing efficiency for seeing-limited instruments and strengthen its survey capabilities for multi-messenger astronomy.

There has been recent interest in quantum-mechanical tests aided by distant quasars. For two quasars of sufficient redshift at opposite directions on the sky, light-travel-time arguments can assure the acausality of their photons. And if those photons are used to set parameters in an Earth-based apparatus, coincidence cannot be due to their communication, closing the so-called "freedom of choice" loophole in the experiment. But this assumes no other interference right up to detection, including correlated instrumental errors, which must be carefully constrained. The Gemini North and South Multi-Object Spectrograph (GMOS) twins can simultaneously view pairs of quasars up to 180 degrees apart on the sky, and already provide a significant baseline record to investigate this. All GMOS broadband imaging frames were searched to find those that happen to contain a known quasar together with a suitable comparison star. Although individual photometry can be noisy among these 0.1 < z < 6 sources, in the aggregate, average site conditions and their relative photometric zeropoints are well characterized. The resulting dataset constitutes about 2 million correlated quasar-observation pairs over 14 years. A preliminary analysis of that is presented, with the intriguing result that paired-flux differences across the whole sky weakly deviate from flatness, to the limit consistent with Bell's Theorem. Can Gemini be used to prove the "spooky action at a distance" expected of quantum mechanics? Some prospects for future work and a more definitive test are considered.

Viewing two astronomical sources at large enough distance and angular separation can assure, by light-travel-time arguments, the acausality of their emitted photons. Using such photons to set apparatus parameters in a laboratory-based quantum-mechanical experiment could ensure those switch settings are independent and fair, allowing a loophole-free test of Bell's inequality. Quasars are a natural choice for this task, yet at ultimate extent it involves their simultaneous photometry towards opposite directions on the sky, which is untried. Cosmic isotropy can be invoked to set limits there, leaving fairness intact for causal pairs, but with a testable consequence of asymmetric bias: mean brightness correlations found less flat in sky angle than random, more acutely so inside a horizon of 90 degrees. Analysis of one dataset from the Gemini twin telescopes is presented, using over 14 years of archival broadband-optical images, serendipitously sampling thousands of quasars up to 180 degrees apart. These data reject a null result of no correlation with 97.7% confidence, instead consistent with a 3-sigma residual signal of 0.21 mag peaked at 65+/-3 degrees separation. Possible confirmatory observations are pointed to along with the improved experimental protocol of an Earth-wide test.

Viewing two sources at sufficient distance and angular separation can assure, by light-travel-time arguments, the acausality of their emitted photons. Using these photons to set different apparatus parameters in a laboratory-based quantum-mechanical experiment could ensure those settings are independent too, allowing a decisive, loophole-free test of Bellu0027s inequality. Quasars are a natural choice for such objects, as they are visible up to high redshift and pointlike. Yet applying them at the ultimate limit of the technique involves flux measurements in opposite directions on the sky. This presents a challenge to proving randomness against either noise or an underlying signal. By means of a virtual experiment and simple signal-to-noise calculations, bias in ground-based optical photometry while performing an Earth-wide test is explored, imposed by fluctuating sky conditions and instrumental errors including photometric zeropoints. Analysis for one useful dataset from the Gemini 8-meter telescopes is presented, using over 14 years of archival images obtained with their Multi-Object Spectrograph (GMOS) instrument pair, serendipitously sampling thousands of quasars up to 180 degrees apart. These do show correlation: an average pairwise broadband optical flux difference intriguingly consistent with the form of Bellu0027s inequality. That is interesting in itself, if not also a harm to experimental setting independence; some considerations for future observations are discussed.

Canada is a triangle-shaped country, roughly speaking. We all know that the Atlantic Ocean is at its eastern corner in the Maritimes, and off the west coast of British Columbia is the Pacific Ocean. The Arctic Ocean, however, makes up the bulk of Canada's coastline, along its pointy "top." That peaks closest to the North Pole in Nunavut, on the shores of Ellesmere Island. Running down this island, as on our western flank in the Rockies, is a range of permanently snowcapped mountains, with one topping 2600 m. It is a propitious geography, which along with that of northern Greenland, provides plenty of ice-locked, and windward, elevated coastal terrain; potentially perfect for astronomy. Actually, these mountains are about the same distance from either Halifax or Victoria (or Halifax to Victoria) as Victoria is from the amazing 4200-m summit of Maunakea, on the Big Island of Hawai'i - although they are not as easily reached.

Nighttime zenith sky spectral brightness in the 3.3-20 mu m wavelength region is reported for an observatory site nearby Eureka on Ellesmere Island in the Canadian High Arctic. Measurements are derived from an automated Fourier-transform spectrograph that operated there continuously over three consecutive winters. During that time, the median through the most transparent portion of the Q window was 460 Jy arcsec(-2), falling below 32 Jy arcsec(-2) in the N band, and to sub-Jansky levels by M and shortward, reaching only 36 mJy arcsec(-2) within L. Nearly six decades of twice-daily balloonsonde launches from Eureka, together with contemporaneous meteorological data plus a simple model, allows characterization of background stability and extrapolation into K band. This suggests that the study location has dark skies across the whole thermal infrared spectrum, typically sub-200 mu Jy arcsec(-2) at 2.4 mu m. That background is comparable to South Pole and more than an order of magnitude less than estimates for the best temperate astronomical sites, all at much higher elevation. Considerations relevant to future facilities, including for polar transient surveys, are discussed.

If spacetime is “foamy” travel along a lightpath must be subject to continual, random distance fluctuations ± δ l proportional to Planck length lP ~ 10−35 m (Lieu & Hillman 2003). Although each “kick” by itself is tiny, these may accumulate. Accounting for redshifted (bluer) emitted photons, over a cosmological distance L = (1+z)LC for co-moving distance LC, the resultant phase perturbations Δ φ = 2π δ l/λ at observed wavelength λ could grow independently of telescope diameter D to a maximum of Δφmax=(1+z)Δφ0 (Steinbring 2007) where Δφ0=2π a0 (lPα/λ)L1 - α follows Ng et al. (2003). Here a0 ~ 1 and α specifies the quantum-gravity model: 1/2 implies a random walk and 2/3 is consistent with the holographic principle; a vanishingly small ΔφP=Δφmax/[(1 + z) a0 (L/lP)1 - α]=2π lP/λ is approached when α=1.

Microscopic fluctuations inherent to the fuzziness of spacetime at the Planck scale might accumulate in wavefronts propagating a cosmological distance and lead to noticeable blurring in an image of a pointlike source. Distant quasars viewed in the optical and ultraviolet with Hubble Space Telescope (HST} may show this weakly, and if real suggests a stronger effect should be seen for Gamma-Ray Bursts (GRBs) in X-rays and gamma-rays. Those telescopes, however, operate far from their diffraction limits. A description of how Planck-scale-induced blurring could be sensed at high energy, even with cosmic rays, while still agreeing with the HST results is discussed. It predicts dilated apparent source size and inflated uncertainties in positional centroids, effectively a threshold angular accuracy restricting knowledge of source location on the sky. These outcomes are found to be consistent with an analysis of the 10 highest-redshift GRB detections reported for the Fermi satellite. Confusion with photon cascade and scattering phenomena is also possible; prospects for a definitive multiwavelength measurement are considered.