Precision surfaces of optical grade have been in great demand for various applications such as high-power laser systems, astronomical reflecting telescopes glass mirrors, folding mirrors of avionics displays, reflectors, guides for transmission of hot and cold neutron beams for neutron exploration setups, electronic substrate, display covers and substrates for biomedical imaging and sensing, etc. Generation of such surfaces has been a challenge; particularly the polishing operation of optical fabrication process is quite critical which determines the final surface quality. To achieve the required optical surface parameters, a good control and systematic understanding of polishing process and its parameters are required. However, the conventional or full aperture optical polishing process still depends on operator's skills to achieve the target surface quality. To exploit the process to the extent, it is must to have a scientific understanding of material removal behavior of the polishing process, which will lead to the process becoming deterministic. This article has attempted to address this issue. Authors have summarized different material removal theories and discussed various mathematical models as proposed by researchers so far. Attempt has been made to come up with knowledge gaps which are required to be bridged in future. [ABSTRACT FROM AUTHOR]
Venkatakrishnan, P., Mathew, Shibu K., Srivastava, Nandita, Bayanna, A. R., Kumar, Brajesh, Ramya, Bireddy, Jain, Naresh, and Saradava, Mukesh
Current Science (00113891). 8/25/2017, Vol. 113 Issue 4, p686-690. 5p.
SOLAR telescopes, ADAPTIVE optics, SOLAR chromosphere, REFLECTING telescopes, EQUIPMENT & supplies, TELESCOPE design & construction, UDAIPUR (India), and SOLAR photosphere spectra
Multi Application Solar Telescope (MAST), a telescope for the detailed study of solar activity, was operationalized at the Udaipur Solar Observatory (USO) of Physical Research Laboratory (PRL), on 16 June 2015. This article traces the history of the conceptualization to realization of MAST and describes its salient features. MAST is an off-axis Gregorian-Coudé telescope with a 50 cm aperture. The first light backend instruments include a narrow band polarimetric imager to map the photospheric and chromospheric magnetic fields and a multi-slit spectro-polarimeter. An adaptive optics system is also being developed for the on-line corrections of the image distortions produced by atmospheric seeing. The main objective of MAST is to obtain high spatial and temporal resolution observations of solar photospheric and chromospheric activity, with the ultimate goal of predicting space weather. [ABSTRACT FROM AUTHOR]
Astronomy. May2017, Vol. 45 Issue 5, p28-33. 6p. 2 Color Photographs, 5 Black and White Photographs.
TELESCOPES, ASTRONOMICAL instruments, and REFLECTING telescopes
The article discusses the history of Hooker Telescope at Mount Wilson Observatory located in in Los Angeles County, California that was established by American astronomer George Ellery Hale in 1917 for astronomical discoveries. It mentions the working of Hale with assistant Walter Adams and John D. Hooker for the development of Hooker Telescope. It also mentions that Hooker Telescope is a reflecting telescope.
The article offers information on mathematician and physicist Isaac Newton. Topics discussed include his publication of the book "Philosophiæ Naturalis Principia Mathematica" or "Principia"; his research on gravity, development of reflecting telescopes, and alchemy; and appointment to be Warden of the Mint in London, England and introducing ridged coins.
Astavin, A., Kovalev, V., Komaev, R., Moisheev, A., Tsvelev, V., and Serebrennikov, V.
Solar System Research. Dec2015, Vol. 49 Issue 7, p604-609. 6p.
RADIO telescopes, REFLECTING telescopes, THERMAL stability, DEFORMATIONS (Mechanics), and SPACE telescopes
The paper presents methods for the design and engineering concepts, which made it possible to develop and manufacture the space radio telescope with a large size and high accuracy of the effective reflector area and focal assembly position. [ABSTRACT FROM AUTHOR]
Journal of the British Astronomical Association. Oct2015, Vol. 125 Issue 5, p281-284. 4p.
CASSEGRAINIAN telescopes, REFLECTING telescopes, CURVATURE, MIRRORS, and OPTICAL instruments
The article discusses the steps for kitchen table collimation of a Cassegrain-type reflector. The steps discussed include arranging the telescope horizontally on a flat surface facing the collimation target such that the distance between the two can be varied easily by sliding the telescope, determining the centre of curvature of the primary mirror by looking into the telescope and moving closer or further away and checking the target is still reasonably square to the telescope.
The article evaluates several equipment used for astronomical research including the VMC95L 3.7" Reflector Telescope from Vixen Co. Ltd.; the Sirius Plössl Telescope Eyepieces from Orion Telescopes & Binoculars; and the AstroMaster 70AZ refractor telescope from Celestron LLC.
Monthly Notices of the Royal Astronomical Society. Dec2018, Vol. 481 Issue 2, p2148-2167. 20p.
LARGE Synoptic Survey Telescope, REFLECTING telescopes, GAUSSIAN function, and ASTROMETRY
Faint, hidden contaminants in the point spread functions (PSFs) of stars cause shifts to their measured positions. Wilson & Naylor showed failing to account for these shifts can lead to a drastic decrease in the number of returned catalogue matches in crowded fields. Here, we highlight the effect these perturbations have on cross-matching, for matches between Gaia DR2 and Wide-field Infrared Survey Explorer (WISE) stars in a crowded Galactic plane region. Applying the uncertainties as quoted to Gaussian-based astrometric uncertainty functions (AUFs) can lead, in dense Galactic fields, to only matching 55 per cent of the counterparts. We describe the construction of empirical descriptions for AUFs, building on the cross-matching method of Wilson & Naylor, utilizing the magnitudes of both catalogues to discriminate between true and false counterparts. We apply the improved cross-matching method to the Galactic plane | b | ≤ 10. We provide the most likely counterpart matches and their respective probabilities. We also analyse several cases to verify the robustness of the results, highlighting some important caveats and considerations. Finally, we discuss the effect that PSF resolution has by comparing the intra-catalogue nearest neighbour separation distributions of a sample of likely contaminated WISE objects and their corresponding Spitzer counterpart. We show that some WISE contaminants are resolved in Spitzer, with smaller intra-catalogue separations. We have highlighted the effect contaminant stars have on WISE, but it is important for all photometric catalogues, playing an important role in the next generation of surveys, such as the Large Synoptic Survey Telescope. [ABSTRACT FROM AUTHOR]
Catadioptric telescopes (CATs) such as the Schmidt Cassegrains remain popular among amateur astronomers for their ability to reveal thousands of beautiful deep-space wonders. Additionally, their computer-assisted capabilities allow them to automatically point to and track celestial objects, making astronomy accessible to more people than ever before. However, selecting the right one and learning how to use it can be difficult for stargazers both old and new. That's where this book comes in. The first edition, published in 2009, has remained the standard reference for mastering these popular instruments. This revised edition brings the material completely up to date, with several extensively rewritten chapters covering the most recent developments in telescope and camera equipment as well as computer software.Through the author's 45 years of experience with catadioptric telescopes, readers will learn to decide which catadioptric telescope is right for them, to choose a specific make and model, and finally, to use the telescope in the field. Covered in other chapters are: Solar System and deep-sky observations; astrophotography and computer control of CATs; and troubleshooting and maintaining your equipment.If you dream of owning a telescope or are frustrated by the telescope you already own, this is the book for you!
The article focuses on aligning one's reflector's mirrors to get best view along with keeping Newtonian telescope clean and mentions need for regular collimation for reflector. Topics discussed include Cheshire eyepiece which makes easier by constricting diameter of the reference circle, screws in adjusters and primary mirror adjustment which will have screws that pull and push.
Monthly Notices of the Royal Astronomical Society. Feb2018, Vol. 474 Issue 2, p2612-2616. 5p.
SUPERNOVAE, CATACLYSMIC variable stars, LARGE Synoptic Survey Telescope, REFLECTING telescopes, and GALACTIC X-ray sources
In the coming Large Synoptic Survey Telescope era, we will observe O(100) of lensed supernovae (SNe). In this paper, we investigate the possibility for predicting time and sky position of an SN using strong lensing. We find that it will be possible to predict the time and position of the fourth image of SNe which produce four images by strong lensing, with combined information from the three previous images. It is useful to perform multimessenger observations of the very early phase of SN explosions including the shock breakout. [ABSTRACT FROM AUTHOR]
ECLIPSING binaries, PHOTOMETRY, REFLECTING telescopes, LIGHT curves, and HOT spots (Astronomy)
VZ Psc is a W-type contact binary system with a short period of 0.26125897 days. B, V, R c and I c light curves of the eclipsing binary system were obtained by using the 1.0 m reflecting telescope at Weihai Observatory of Shandong University. By collecting 136 times of minimum light, we studied the orbital period change of VZ Psc. A sinusoidal variation was discovered in the O − C diagram, and the amplitude of 0. d 0023 and the period of 17.7 year were obtained. This can be caused by Applegate mechanism or light-time effect. Both the mechanisms are suited according to our investigation, but we prefer the latter that the light-time effect due to the presence of a third body results in the cyclic variation. By using the W-D program, we analyzed the four color light curves. Because of the asymmetric light curves and the possible third body, we used the spot mode of W-D program with and without L 3 . We found that a hot spot on the primary component with the third light leads to the best result. A very high filling factor of 94.4% ± 2.8% and orbit inclination of 53.2° were obtained. [ABSTRACT FROM AUTHOR]
OPTICAL scanners, ESTIMATION theory, FOCAL length, RADIO telescopes, REFLECTING telescopes, and PARABOLIC reflectors
Due to gravitation, the main reflector of a radio telescope underlies a deformation that causes a change in focal length depending on the variations of the elevation angle of the telescope. To estimate these gravity dependent deformations of the main reflector of the 100-m radio telescope at Effelsberg, Germany, this study proposes a measurement concept based on a laser scanner being mounted upside down on the subreflector. The measurements that have been performed at seven different elevations between 90 and 7.5° are used to estimate the focal length variation of the main reflector parameterized by a rotational paraboloid. To guarantee reliability of the adjustment, this study uses an orthogonal distance regression (ODR) rather than a classical least squares adjustment in a Gauss-Helmert model and formulates the independence of the focal length estimation from the absolute position and orientation of the main reflector in space as a requirement for a reliable adjustment approach. This investigation attests that the ODR has superior reliability with regard to this criterion. A three-step adjustment procedure based on an alteration of the ODR and several outlier eliminations is used to determine the variations of the focal length due to gravitation. The estimated focal length decreases by a maximum of 12.6 mm when tilting the reflector from 90 to 7.5° elevation angle. The postfit discrepancies between the best-fit paraboloid and the reflector's surface are Gaussian distributed within the accuracy of the measurements. This face supports the assumption of a homologous deformation of the main reflector. [ABSTRACT FROM AUTHOR]