Multi-parameter study for a new Ground-Based telescope in Egypt
Mohamed S. Darwish, Hazem Badreldin, Nasser M. Ahmed, Mostafa Morsy, E. E. Kohil, Hany M. Hassan, I. Helmy, Ahmed shokry, M. A. Hassan, S. M. Saad, G. M. Hamed,… 展开作者
Mohamed S. Darwish, Hazem Badreldin, Nasser M. Ahmed, Mostafa Morsy, E. E. Kohil, Hany M. Hassan, I. Helmy, Ahmed shokry, M. A. Hassan, S. M. Saad, G. M. Hamed, Z. F. Ghatass, S. A. Ata
本研究开展了多参数分析,以评估气象参数、夜空亮度和地震灾害对埃及新型光学/红外天文望远镜拟建台址的影响。研究采用ERA5再分析数据集获取以下气象参数:总云量分数、可降水量、相对湿度、风速与风向以及气温。为估算气溶胶光学厚度,我们使用了现代研究与应用回顾分析第2版(Modern-Era Retrospective analysis for Research and Applications version 2, MERRA-2)。候选台址的光污染通过可见光红外成像辐射仪套件(Visible Infrared Imaging Radiometer Suite, VIIRS)昼夜波段(Day Night Band, DNB)进行测量。研究采用基于物理的地震动方法计算了以最大加速度和反应谱表示的地震输入,以评估地震灾害,进而为拟建台址确定抗震结构的设计,从而能够评估候选台址的地震灾害。在7个提名台址中,有2个台址的测量结果最佳,可被视为埃及新型天文望远镜的未来台址。第一个台址位于西奈半岛南部,第二个台址位于红海山脉地区。
英文摘要:
A multi-parameter analysis was conducted to evaluate the impact of meteorological parameters, night sky brightness and seismic hazard on proposed sites for the new optical/infrared Egyptian astronomical telescope. The ERA5 reanalysis data set is used to get the following meteorological parameters: Total cloud coverage fraction, precipitable water vapor, relative humidity, wind speed & direction and Air temperature. To estimate the aerosol optical depth we used the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2). Light pollution over the candidate sites was measured from Visible Infrared Imaging Radiometer Suite (VIIRS) Day Night Band (DNB). The seismic input in terms of maximum acceleration and response spectra were computed using a physics-based ground motion approach to assess the seismic hazards and consequently the designation of seismic resistant structure for the proposed sites to be able to assess the seismic hazards for the candidate sites. Of the seven nominated sites, two sites are found to have the best measurements and might be considered future sites for the new Egyptian Astronomical telescope. The first site is located in the south of the Sinai peninsula, while the second one is located in the Red Sea mountains region.
The Critical, Strategic Importance of Adaptive Optics-Assisted Ground-Based Telescopes for the Success of Future NASA Exoplanet Direct Imaging Missions
Modern large ground-based solar telescopes are invariably equipped with adaptive optics systems to enhance the high angular resolution imaging and spectroscopic capabilities in the presence of the Earth's atmospheric turbulence. The quality of the images obtained from these telescopes can not be quantified with the Strehl ratio or other metrics that are used for nighttime astronomical telescopes directly. In this paper, we propose to use the root mean square (rms) granulation contrast as a metric to quantify the image quality of ground-based solar telescopes. We obtain semi-logarithmic plots i…
More than 5,000 exoplanets have been confirmed and among them almost 4,000 were discovered by the transit method. However, few transiting exoplanets have an orbital period greater than 100 days. Here we report a transit detection of Kepler-167 e, a "Jupiter analog" exoplanet orbiting a K4 star with a period of 1,071 days, using the Unistellar ground-based telescope network. From 2021 November 18 to 20, citizen astronomers located in nine different countries gathered 43 observations, covering the 16 hour long transit. Using a nested sampling approach to combine and fit the observations, we dete…
Microwave telescopes require an ever-increasing control of experimental systematics in their quest to measure the Cosmic Microwave Background (CMB) to exquisite levels of precision. One important systematic for ground and balloon-borne experiments is ground pickup, where beam sidelobes detect the thermal emission of the much warmer ground while the main beam is scanning the sky. This generates scan-synchronous noise in experiment timestreams, which is difficult to filter out without also deleting some of the signal from the sky. Therefore, efficient modelling of pickup can help guide the desig…
Accurate optical modeling is important for the design and characterisation of current and next-generation experiments studying the Cosmic Microwave Background (CMB). Geometrical Optics (GO) cannot model diffractive effects. In this work, we discuss two methods that incorporate diffraction, Physical Optics (PO) and the Geometrical Theory of Diffraction (GTD). We simulate the optical response of a ground-based two-lens refractor design shielded by a ground screen with time-reversed simulations. In particular, we use GTD to determine the interplay between the design of the refractor's forebaffle …
AOLI: Near-diffraction limited imaging in the visible on large ground-based telescopes
幸运成像与低阶自适应光学系统的结合在近10年前在帕洛马5米望远镜上得到了非常成功的证明。它仍然是唯一一个在地面望远镜上对微弱的天文目标提供可见光或近红外高分辨率图像的系统。本文将介绍AOLI最初部署在加那利群岛拉帕尔马WHT 4.2米望远镜上的情况。特别是,我们将研究我们的低阶曲率波前传感器的设计和状态,该传感器已被简化以使其更有效,确保覆盖大部分天空,以自然引导星作为参考对象。AOLI使用光学对接的电子倍增CCD来提供2000 x 2000像素的成像阵列。
In the 70s of the last century, the stratospheric solar observatory "Saturn" with a 100cm telescope was launched at Pulkovo Observatory. The photographs and spectra obtained on it for more than 45 years remained record-breaking in angular resolution. Then, for ground-based observations of Sun fine structure in Pamir at an altitude of 4.5 km, a 50 cm open-type Pulkovo mobile telescope was installed. Photographs and spectra obtained with the Saturn telescope for the visible range were an important step in the development of high spatial resolution technologies in heliophysics. However, to date, …
Meter-sized ground-based telescopes are frequently used today for the follow-up of extrasolar planet candidates. While the transit signal of a Jupiter-sized object can typically be detected to a high level of confidence with small telescope apertures as well, the shallow transit dips of planets with the size of Neptune and smaller are more challenging to reveal. We employ new observational data to illustrate the photometric follow-up capabilities of meter-sized telescopes for shallow exoplanet transits. We describe in detail the capability of distinguishing the photometric signal of an exoplan…
High-Resolution Imaging in the Visible on Large Ground-Based Telescopes
“幸运成像”与低阶自适应光学系统相结合,提供了有史以来在可见光或近红外波段拍摄的微弱天体的最高分辨率图像。本文介绍了一种新的仪器,已经部署在拉帕尔马的WHT 4.2米望远镜,特别强调的光学设计和预测的系统性能。采用光子计数CCD探测器和多平面曲率波前传感器的低阶波前传感器的新设计将使微弱的自然导航星几乎覆盖整个天空。AOLI拥有1024 x 1024个光子计数EMCCD的2 x 2阵列,是新一代高灵敏度、近衍射极限成像系统中的第一个,在地面可见光范围内的分辨率比迄今为止从太空获得的分辨率更高。
The Kilodegree Extremely Little Telescope: Searching for Transiting Exoplanets in the Northern and Southern Sky
Kilodegree Extremely Little Telescope(KELT)是一个地面计划,旨在寻找围绕相对明亮恒星运行的系外行星。为了实现这一目标,KELT科学小组运营着两个行星设施-位于亚利桑那州维纳天文台的KELT-North和位于南非天文台的KELT-South。这些天文台使用的望远镜具有特别宽的视野,使KELT能够研究大量潜在的系外行星宿主恒星。瞄准明亮恒星的主要优势之一是,分布在世界各地的小型地面观测站可以很容易地跟踪检测到的系外行星候选者。本文将简要概述KELT-北和KELT-南调查,KELT后续合作进行的后续观测,以及迄今为止确认的系外行星发现,最后简要讨论KELT计划的未来。