Matthew B. James, Graeme L. White, Roderick R. Letchford, Stephen G. Bosi
Presented here is list of 50 pairs quasi-evenly spaced over the northern sky, and that have Separations and Position Angles accurate at the milli-arcsec, and milli-degree level. These pairs are suggested as calibration pairs for lucky imaging observations. This paper is a follow-up to our previous paper regarding southern sky calibration pairs.
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Accurate measures of double stars require accurate calibration of the instrument. Here we present a list of 50 pairs, that are quasi-evenly spaced over the southern sky, and that have Separations and Position Angles accurate at the milli-arcsec, and milli-degree level. These wide angle pairs are suggested as calibration pairs for lucky imaging observations.
We present a method for calibrating the flux density scale for images generated by the Amsterdam ASTRON Radio Transient Facility And Analysis Centre (AARTFAAC). AARTFAAC produces a stream of all-sky images at a rate of one second in order to survey the Northern Hemisphere for short duration, low frequency transients, such as the prompt EM counterpart to gravitational wave events, magnetar flares, blazars, and other as of yet unobserved phenomena. Therefore, an independent flux density scaling solution per image is calculated via bootstrapping, comparing the measured apparent brightness of sour…
Regular large-scale polarimetric observations in Crimean astrophysical observatory began in the early 1960s. In 2002 - 2017 the single-channel aperture photometer-polarimeter with a quarter-wave plate at the 2.6-m Shajn mirror telescope (SMT) was used. We accumulated a large homogeneous data set of polarimetric observations of different types of objects that are to be published separately. Correct polarimetric data processing requires high polarization standards and zero-polarization stars. We aim to improve the data reduction and calibration process to obtain further results with highest poss…
LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of the low-frequency radio sky. At the same time LOFAR also provides excellent short baseline coverage to map diffuse extended emission. However, producing high-quality deep images is challenging due to the presence of direction dependent calibration errors, caused by imperfect knowledge of the station beam shapes and the ionosphere. Furthermore, the large data volume and presence of station clock errors present additional difficulties. In …
ANTARES is a deep-sea, large volume Mediterranean neutrino telescope installed off the Coast of Toulon, France. It is taking data in its complete configuration since May 2008 with nearly 900 photomultipliers installed on 12 lines. It is today the largest high energy neutrino telescope of the northern hemisphere. The charge calibration and threshold tuning of the photomultipliers and their associated front-end electronics is of primary importance. It indeed enables to translate signal amplitudes into number of photo-electrons which is the relevant information for track and energy reconstruction…
The atmospheric monitoring devices for the planned calibration system of the Cherenkov Telescope Array (CTA) are undergoing intensive development, prototyping and testing. The All-Sky Cameras, the Sun/Moon Photometers and the FRAM telescopes have been gradually deployed at the future CTA sites with the primary goal of site characterization, simultaneously allowing the assessment of their operational reliability in realistic environmental conditions. All three devices have shown the ability to work smoothly in both the extreme dryness and the large temperature variations of the southern site as…
We present descriptions of the alignment and calibration tests of the Pathfinder, which achieved first light during our 2013 commissioning campaign at the LBT. The full LINC-NIRVANA instrument is a Fizeau interferometric imager with fringe tracking and 2-layer natural guide star multi-conjugate adaptive optics (MCAO) systems on each eye of the LBT. The MCAO correction for each side is achieved using a ground layer wavefront sensor that drives the LBT adaptive secondary mirror and a mid-high layer wavefront sensor that drives a Xinetics 349 actuator DM conjugated to an altitude of 7.1 km. When …
A key challenge of high contrast imaging (HCI) is to differentiate a speckle from an exoplanet signal. The sources of speckles are a combination of atmospheric residuals and aberrations in the non-common path. Those non-common path aberrations (NCPA) are particularly challenging to compensate for as they are not directly measured, and because they include static, quasi-static and dynamic components. The proposed method directly addresses the challenge of compensating the NCPA. The algorithm DrWHO - Direct Reinforcement Wavefront Heuristic Optimisation - is a quasi-real-time compensation of sta…
UNIONS: The Ultraviolet Near-Infrared Optical Northern Survey
UNIONS整合CFHT、Pan-STARRS与Subaru开展北天6250平方度$ugriz$多波段深场巡天，服务暗物质、结构形成、银河系研究，并支撑Rubin与Euclid科学。
In April 2019, the Baikal-GVD collaboration finished the installation of the fourth and fifth clusters of the neutrino telescope Baikal-GVD. Momentarily, 1440 Optical Modules (OM) are installed in the largest and deepest freshwater lake in the world, Lake Baikal, instrumenting 0.25 cubic km of sensitive volume. The Baikal-GVD is thus the largest neutrino telescope on the Northern Hemisphere. The first phase of the detector construction is going to be finished in 2021 with 9 clusters, 2592 OMs in total, however the already installed clusters are stand-alone units which are independently operati…
GroundBIRD: First On-Sky Responsivity Calibration at the Teide Observatory
GroundBIRD实验旨在测量CMB大角度尺度各向异性以约束再电离光学深度。通过对木星重复观测，得出首个天空响应度校准模型，建立并验证校准方法，表征探测器响应度与PWV关系，为扩展校准方法至整个焦平面奠定基础。
[abridged] The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ~2,000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 MHz, although this is technically and logistically challenging. Here we present a calibration strategy that builds on previous high-resolution work with LOFAR. We give an overview of the calibration strategy and discuss the special challenges inherent to enacting high-resolution imaging with LOFAR, and describe the pipeline, which is publicly available, in detail. W…
LOFAR is the only radio telescope that is presently capable of high-sensitivity, high-resolution (<1 mJy/b and <15") observations at ultra-low frequencies (<100 MHz). To utilise these capabilities, the LOFAR Surveys Key Science Project is undertaking a large survey to cover the entire northern sky with Low Band Antenna (LBA) observations. The LOFAR LBA Sky Survey (LoLSS) aims to cover the entire northern sky with 3170 pointings in the frequency range 42-66 MHz, at a resolution of 15 arcsec and at a sensitivity of 1 mJy/b. Here we outline the survey strategy, the observational status, the curre…
The Keck Planet Imager and Characterizer (KPIC) is a purpose-built instrument to demonstrate new technological and instrumental concepts initially developed for the exoplanet direct imaging field. Located downstream of the current Keck II adaptive optic system, KPIC contains a fiber injection unit (FIU) capable of combining the high-contrast imaging capability of the adaptive optics system with the high dispersion spectroscopy capability of the current Keck high resolution infrared spectrograph (NIRSPEC). Deployed at Keck in September 2018, this instrument has already been used to acquire high…
Direct Imaging and Gradient-Based Analysis of the 12 August 2026 Partial Solar Eclipse from a Freely Rotating High-Altitude Balloon
本研究通过自由旋转高空气球搭载Insta360 ONE RS相机对日偏食观测，用二维梯度法分析图像获定量食分，验证被动旋转可实现半定量日食观测并定义校准策略。
We describe a new instrument that forms the core of a long-term high contrast imaging program at the 200-inch Hale Telescope at Palomar Observatory. The primary scientific thrust is to obtain images and low-resolution spectroscopy of brown dwarfs and young Jovian mass exoplanets in the vicinity of stars within 50 parsecs of the Sun. The instrument is a microlens-based integral field spectrograph integrated with a diffraction limited, apodized-pupil Lyot coronagraph, mounted behind the Palomar adaptive optics system. The spectrograph obtains imaging in 23 channels across the J and H bands (1.06…
The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient to produce ~5arcsec resolution images with a sensitivity of ~0.1mJy/beam and accomplish the main scientific aims of the survey which are to explore the formation and evolution of massive black holes, galaxies, clusters of galaxies and large-scale structure. Due to the compact core and long baselines of LOFAR, the images provide excellent sensitivity to both highly extende…
The Murchison Widefield Array (MWA) is a new low-frequency, wide field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory (MRO) in Western Australia. We have used a 32-element MWA prototype interferometer (MWA-32T) to observe two 50-degree diameter fields in the southern sky in the 110 MHz to 200 MHz band in order to evaluate the performance of the MWA-32T, to develop techniques for epoch of reionization experiments, and to make measurements of astronomical foregrounds. We developed a calibration and imaging pipeline for the MWA-32T, and used it to prod…
The LOFAR Two-metre Sky Survey: VII. Third Data Release
LOFAR双米天空调查第三次数据发布，通过高分辨率图像发现大量天体源，验证了其对无线电源群体的约束能力。
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