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In the framework of the Visible NEAs Observations Survey (ViNOS) that uses several telescopes at the Canary Islands observatories since 2018, we observed two super fast rotator NEAs, 2021 NY$_1$ and 2022 AB. We obtained photometry and spectrophotometry of both targets and visible spectroscopy of 2022 AB. Light curves of 2021 NY$_1$ obtained in 4 different nights between Sept. 30 and Oct. 16, 2021 return a rotation period $P=13.3449\pm0.0013$ minutes and a light curve amplitude $A = 1.00$ mag. We found that 2021 NY$_1$ is a very elongated super fast rotator with an axis ratio $a/b \ge 3.6$. We also report colours $(g-r) = 0.664 \pm 0.013$, $(r-i) = 0.186 \pm 0.013$, and $(i-z_s) = -0.117 \pm 0.012$ mag. These are compatible with an S-type asteroid. The light curves of 2022 AB obtained on Jan. 5 and Jan. 8, 2021 show a rotation period $P=3.0304\pm0.0008$ minutes, with amplitudes $A = 0.52$ and $A =0.54$ mag. 2022 AB is also an elongated object with axis ratio $a/b \ge 1.6$. The obtained colours are $(g-r) = 0.400 \pm 0.017$, $(r-i) = 0.133 \pm 0.017$, and $(i-z_s) = 0.093 \pm 0.016$. These colours are similar to those of the X-types, but with an unusually high $(g-r)$ value. Spectra obtained on Jan. 12 and Jan. 14, 2022, are consistent with the reported colours. The spectral upturn over the 0.4 - 0.6 $\mu m $ region of 2022 AB does not fit with any known asteroid taxonomical class or meteorite spectrum, confirming its unusual surface properties., Comment: 9 pages, 7 figures

Scientific complementary metal-oxide-semiconductor (CMOS) detectors have developed quickly in recent years thanks to their low cost and high availability. They also have some advantages over charge-coupled devices (CCDs), such as high frame rate or typically lower readout noise. These sensors started to be used in astronomy following the development of the first back-illuminated models. Therefore, it is worth studying their characteristics, advantages, and weaknesses. One of the most widespread CMOS sensors are those from the Sony IMX series, which are included in large astronomical survey projects based on small and fast telescopes because of their low cost, and capability for wide-field and high-cadence surveys. In this paper, we aim to characterize the IMX455M and IMX411M sensors, which are integrated into the QHY600 and QHY411 cameras, respectively, for use in astronomical observations. These are large (36 $\times$ 24 and 54 $\times$ 40 mm) native 16 bit sensors with 3.76 $μ$m pixels and are sensitive in the optical range. We present the results of the laboratory characterization of both cameras. They showed a very low dark current of 0.011 and 0.007 e$^{-}$ px$^{-1}$ s$^{-1}$ @$-$10 C for the QHY600 and QHY411 cameras, respectively. They also show the presence of warm pixels, $\sim$0.024% in the QHY600 and 0.005% in the QHY411. Warm pixels proved to be stable and linear with exposure time, and are therefore easily corrected using dark frames. Pixels affected by the Salt \& Pepper noise are $\sim$2% of the total and a method to correct for this effect is presented. Both cameras were attached to night telescopes and several on-sky tests were performed to prove their capabilities. On-sky tests demonstrate that these CMOS behave as well as CCDs of similar characteristics and (for example) they can attain photometric accuracies of a few milli-magnitudes., 17 pages, 15 figures. Accepted for publication in PASP

Summary In this work we present the design of the ATLAS (Asteroid Terrestrial-impact Last Alert System) unit that will be installed at Teide Observatory in Tenerife island (Spain). ATLAS-Teide will be built by the IAC and will operated as part of the ATLAS network in the framework of an operation and science exploitation agreement between the IAC and the ATLAS team at University of Hawaii. ATLAS-Teide will be the first ATLAS unit based on COTS. Its design is modular, each module (“building block”) consist of four Celestron RASA 11 telescopes that point to the same sky field, equipped with QHY600 CMOS cameras on a equatorial Direct Drive mount. Each module is equivalent to a 56cm effective diameter telescope and provides a 7.3 deg2 field of view and a 1.25 “/pix plate scale. ATLAS-Teide will consist of four ATLAS modules in a roll-off roof building. This configuration allows to cover the same sky area of the actual ATLAS telescopes. This design is cheaper to build and maintain, and more flexible than the actual one. The first ATLAS “building block” will be operational before the end of 2022 and we aim to complete the four modules of ATLAS-Teide by the end of 2023. The ATLAS survey. ATLAS is an asteroid impact early warning system developed by the University of Hawaii and funded by NASA (see http://atlas.fallingstar.com). It consists of four 50cm telescopes (Hawaii ×2, Chile, South Africa). Each ATLAS unit maps 1/4 of the night sky, making 4 observations of each field at intervals of one hour, detecting objects of V=19.5-20 in 30s exposures. The software automatically detects moving targets, discovering hundreds of new objects every night. It also allows thousands of these bodies to be observed, taking very precise astronomical and photometric measurements, making ATLAS one of the most prolific asteroid database. ATLAS also processes the survey data to find stationary transient events, which are immediately reported to the IAU. These include supernovae, starbursts, and fast transients like GRB afterglows, etc. It also has an agreement with LIGO to search for electromagnetic counterparts of gravitational wave sources. ATLAS is among the 3 main projects of the world in reporting this type of event, with more than 300 supernova candidates found per year. ATLAS-Teide, the next generation of ATLAS units. Late 2021, the IAC obtained funding from the Spanish “Subprograma Estatal de Infraestructuras de Investigación y Equipamiento Científico Técnico (Ref. EQC2021-007122-P)” to install an ATLAS unit at Teide Observatory. ATLAS-Teide will be the 5th ATLAS unit and will be operated together with the other four thanks to an agreement between the IAC and the Institute for Astronomy of the University of Hawaii (IfA-UH).The design of the existing ATLAS is based on a telescope that is a variant of the Wright-Schmidt cameras that use a 50cm Schmidt correcting foil, a 65cm spherical primary mirror and a 3-element field correcting lens and a f/D=2.0. Each telescope is equipped with ACAM, a back-illuminated 110Mpix CCD camera providing a field of view of 5.4 x 5.4 deg and a plate scale of 1.88 “/pix. The design and construction of the telescope is of the company DFM Engineering Inc. After several interactions with DFM we have concluded that doing it with them is actually impossible and that it is necessary to opt for another design. After studying different options, we concluded that the best solution is to design a new ATLAS unit using a modular structure based on existing “commercial off-the-shelf” (COTS) equipment. It should have capabilities similar to the telescopes that ATLAS currently has in terms of detection limit and sky area covered per night. The solution we found is cheaper to build and maintain, very efficient and more flexible than the current ATLAS. The new ATLAS design is based on optic telescope assemblies (OTAs) Celestron model RASA11, QHY600 CMOS cameras that use back-illuminated IMX-455 chip from SONY, with 9576*6388 pixels of 3.76 microns, and mounts of the L-series of the PlaneWave company. An ATLAS module or “building block” consists of four RASA 11 telescopes mounted together on a L-series PlaneWave equatorial mount (see Fig. 1), each one equipped with a QHY600 camera. All 4 telescopes point to the same field, so, combining the 4 images obtained simultaneously we have a system with an equivalent collecting area equivalent to that of a telescope with 56cm aperture (25.4% larger than that of the current ATLAS) with a field of view of 7,37 deg2 and a 1.25 “/pix plate scale. Considering the slightly lower sensitivity of the QHY cameras respect to ACAM the ATLAS module should detect objects of V=19.5-20 in 30s exposures. Figure 1- Schematic drawing of an ATLAS module. To cover a similar sky area of the ATLAS units, ATLAS-Teide will consist of four ATLAS building blocks (16 OTAs RASA 11 in total) installed in a building with a roll-off roof structure. This design provides a similar sensitivity and sky coverage with a better plate scale. Moreover, it has several advantages: (i) its cost is a fraction of the cost of the old ones; (ii) it is much more flexible, allowing e.g. to point the four modules to the same field going 0.75 mag deeper; (iii) it is more efficient as in case some of its part fail the other modules can continue operating while the failed component is rapidly replaced, thus, if the COTS parts behave as promised, it is cheaper and easier to maintain and operate. We are building the first ATLAS “building block” that will be operational before the end of 2022. It will be used to test its capabilities, develop all the needed software (control and image reduction) and the integration of the system into the ATLAS network. The main aim is to complete the four modules of ATLAS-Teide by the end of 2023 and have it fully integrated in the ATLAS network early 2024. Acknowledgements. This project has received funding from the “Subprograma Estatal de Infraestructuras de Investigación y Equipamiento Científico Técnico (Ref. EQC2021-007122-P)”

We describe results of a planetary defense exercise conducted during the close approach to Earth by the near-Earth asteroid (99942) Apophis during 2020 December–2021 March. The planetary defense community has been conducting observational campaigns since 2017 to test the operational readiness of the global planetary defense capabilities. These community-led global exercises were carried out with the support of NASA’s Planetary Defense Coordination Office and the International Asteroid Warning Network. The Apophis campaign is the third in our series of planetary defense exercises. The goal of this campaign was to recover, track, and characterize Apophis as a potential impactor to exercise the planetary defense system including observations, hypothetical risk assessment and risk prediction, and hazard communication. Based on the campaign results, we present lessons learned about our ability to observe and model a potential impactor. Data products derived from astrometric observations were available for inclusion in our risk assessment model almost immediately, allowing real-time updates to the impact probability calculation and possible impact locations. An early NEOWISE diameter measurement provided a significant improvement in the uncertainty on the range of hypothetical impact outcomes. The availability of different characterization methods such as photometry, spectroscopy, and radar provided robustness to our ability to assess the potential impact risk.

The main features of SG-WAS (SkyGlow Wireless Autonomous Sensor), a low-cost device for measuring Night Sky Brightness (NSB), are presented. SG-WAS is based on the TSL237 sensor --like the Unihedron Sky Quality Meter (SQM) or the STARS4ALL Telescope Encoder and Sky Sensor (TESS)--, with wireless communication (LoRa, WiFi, or LTE-M) and solar-powered rechargeable batteries. Field tests have been performed on its autonomy, proving that it can go up to 20 days without direct solar irradiance and remain hibernating after that for at least \mbox{4 months}, returning to operation once re-illuminated. A new approach to the acquisition of average NSB measurements and their instrumental uncertainty (of the order of thousandths of a magnitude) is presented. In addition, the results of a new Sky Integrating Sphere (SIS) method have shown the possibility of performing mass device calibration with uncertainties below 0.02 mag/arcsec$^2$. SG-WAS is the first fully autonomous and wireless low-cost NSB sensor to be used as an independent or networked device in remote locations without any additional infrastructure., 15 pages, 9 figures

In 2018, Solar Cycle 24 entered into a solar minimum phase. During this period, 11 million zenithal night sky brightness (NSB) data were collected at different dark sites around the planet, including astronomical observatories and natural protected areas, with identical broadband Telescope Encoder and Sky Sensor photometers (based on the Unihedron Sky Quality Meter TSL237 sensor). A detailed observational review of the multiple effects that contribute to the NSB measurement has been conducted with optimal filters designed to avoid brightening effects by the Sun, the Moon, clouds, and other astronomical sources (the Galaxy and zodiacal light). The natural NSB has been calculated from the percentiles for 44 different photometers by applying these new filters. The pristine night sky was measured to change with an amplitude of 0.1 mag/arcsec$^2$ in all the photometers, which is suggested to be due to NSB variations on scales of up to months and to be compatible with semiannual oscillations. We report the systematic observation of short-time variations in NSB on the vast majority of the nights and find these to be related to airglow events forming above the mesosphere., Comment: 22 pages, 16 figures, 3 tables, 1 appendix