Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography: leaves 60-62. / M.S.

<p dir="ltr">Advancements in astronomical imaging all-sky surveys are revolutionising the field of time domain astronomy. However, the immense volume of alert data presents a critical bottleneck in maximizing scientific returns from these surveys. Effectively analyzing alert streams to discover transients in unexplored physical parameter spaces is crucial for enhancing scientific output. Building robust infrastructure to identify, prioritize, and execute efficient follow-up strategies on alert streams from all-sky surveys becomes critical. My thesis confronts this challenge through a multidisciplinary approach, by integrating statistical methods, machine learning algorithms, and hydrodynamical simulations to constrain transient explosion properties and motivate effective follow-up initiatives. </p><p dir="ltr">I analyze a sample of 45 Type II supernovae from the Zwicky Transient Facility (ZTF) public survey using a grid of hydrodynamical models in order to assess whether theoretically driven forecasts can intelligently guide follow-up observations supporting all-sky survey alert streams. I estimate several progenitor properties and explosion physics parameters, including zero-age main-sequence (ZAMS) mass, mass-loss rate, kinetic energy, ⁵⁶Ni mass synthesized, host extinction, and the time of the explosion. This work involves simulations of real-time of evolving incomplete light curves of the sample (∆t < 25 days, ∆t < 50 days, all data) leading to the conclusion that certain physical parameters exhibit greater reliability as indicators of true values during early epochs. This study emphasises the vital role of real-time modeling of transients, supported by multi-band synthetic light curves tailored to survey passbands, for identifying interesting transients based on their progenitor and explosion properties and determining critical epochs for follow-up observations.</p><p dir="ltr">In my thesis, I report multi wavelength observations and characterization of the ultraluminous transient AT 2021lwx (ZTF20abrbeie; aka“Barbie”) identified in the ZTF alert stream, that was flagged as an anomaly by the Recommender Engine For Intelligent Transient Track-ing (REFITT). From a spectroscopically measured redshift of 0.9945, and slowly fading g and r light curves spanning over 1000 observer-frame days that peak with an absolute magnitude of Mr = −25.7 mag, AT 2021lwx has an extraordinary peak pseudo-bolometric luminosity of log (Lmax/[erg/s]) = 45.7. The total radiative energy is over 10⁵³ erg, and as of today, the transient continues to decline slowly following a t^−5/3 power-law. Modeling available photometry with MOSFiT suggests that AT 2021lwx is a tidal disruption event (TDE) candidate involving a ≈ 14 or 15 solar mass star accreting onto a supermassive black hole (SMBH) with mass M_BH ≈ 10⁸ solar mass. But, intriguingly, no host galaxy associated with the theorized SMBH is detected yet. The Pan-STARRS non-detections do not definitively exclude the existence of a galaxy hosting AT 2021lwx. Utilizing EzGal, upper limits on the stellar mass for different stellar population models were determined. These upper limits suggest that a 10¹⁰ solar mass host galaxy cannot be ruled out.</p><p dir="ltr">The enhanced sensitivity of upcoming large-scale all-sky surveys enables the early detection of transients, providing unique insights into their progenitor systems, an example being detection of shock cooling emission (SCE) in light curves of stripped-envelope supernovae(SESNe). Leveraging a statistically significant sample of these events with early detections from all-sky surveys presents an invaluable opportunity to constrain their environments, pro-genitors, and explosion properties. In my final study contributing to this thesis, I analyze a sample of 16 SESNe identified from the ZTF survey, characterised by prominent shock cooling emission features in their light curves. By modeling the SCE and the radioactive peak in these transients, I derive estimates of progenitor radius, mass of the extended envelope and explosion properties of SESNe. This analysis yields upper limits and ranges for the compactness and envelope structures of the SESN progenitors that exhibit SCE in their light curves. I conclude my thesis with a summary of the findings and their future applications.</p>

The design of the flexure mount recently submitted to NASA Ames for the structural support of the primary mirror of the Space Infrared Telescope Facility (SIRTF) is presented. The flexure system must passively accommodate the differential thermal contraction between the glass mirror and the aluminum structure of the telescope during cryogenic cooldown. Further, it must support the one meter diameter, 116 kilogram (258 pound) primary mirror during a severe launch to orbit. Procedures used to establish the required radial compliance using computer programs NASTRAN and FRINGE are discussed. The parametric design program developed to study early concepts is presented. Methods of combining modal responses resulting from a displacement response spectrum analysis are discussed, and a combination scheme called MRSS, Modified Root of Sum of Squares, is presented. Modal combination schemes using MRSS, SRSS, and ABS are compared to the results of a Modal Frequency Response analysis.

Ng Yat Chiu Patrick. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 1997-98, design report." / Includes bibliographical references (leaves 112-113). / Synopsis / Existing State / Background of Hong Kong --- p.2-3 / Background of Astronomy --- p.4-7 / Astronomy in Hong Kong --- p.8 / Client Profile & Users Group --- p.9-11 / Site Selection --- p.12 / Site Analysis --- p.13-18 / Constraints --- p.19 / Opportunities --- p.20-21 / Discussion of Issues --- p.22-24 / Future State / Formulatoin of Program --- p.25-33 / List of Activities --- p.34 / Schedule of Accommodation --- p.35-36 / Design Proposal / Design Philosophy --- p.37 / Site Aspect --- p.38-41 / Design Development --- p.42-66 / Final Design / Site Approach --- p.67 / Site Zoning --- p.68 / Site Setting out --- p.69 / Museum Sequence --- p.70 / Modern Astronomy & Space Science Museum --- p.71 / Star Odyssey --- p.72 / Myth and Legend --- p.73 / Zodiac --- p.74 / Ancient Astronomical Instrument --- p.75 / Cosmology and Observatory --- p.76 / Reservoir and Water Edge --- p.77 / "Cafeteria, Internet Cafe & Contemporary Interest Topic" --- p.78 / Astronomical Observatory & Star Gazing Classroom --- p.79-80 / Environmental / Use of Energy --- p.81-86 / Lighting --- p.87-88 / Natural Ventilation --- p.89 / HVAC System --- p.90-91 / Plumping & Drainage --- p.92-93 / Life Safety / Means of Escape --- p.94-95 / Construction / General Structure --- p.96 / Special Structure --- p.97-98 / Construction Sequence --- p.99-101 / Cost Analysis Appendices --- p.102-103 / Appendices / Precedents Studies --- p.104-111 / Bibliography --- p.112-113 / Acknowledgement --- p.114

This thesis deals with testing of astronomical measurement system MAAS-1, which was developed at the Institute of Geodesy, Faculty of Civil Engineering, Brno University of Technology. Several reference measurements were done on the terrace of B building Faculty of Civil Engineering during this testing. The data obtained were processed into astronomical geographic coordinates and . These coordinates, as well as atmospheric conditions and calibration measurements, are basis for evaluation. In this test I try to detect the influence of the CCD sensor mounting of the accuracy on the final data and to assess if the construction needs to be modified.

This thesis deals with use of astronomical-geodetic and gravimetric leveling to calculate quasigeoid profile. The main input data in the calculation are gravimetric vertical deviations on point of profile. The aim of this thesis is the processing and calculating of the profile of relativ quasigeoid with three different methods and then comparing the calculation results with gravimetric quasigeoid and GPS/leveling.

For 20 years now, gravitational microlensing observations towards the Galactic bulge have provided us with a wealth of information about the stellar and planetary content of our Galaxy, which is inaccessible via other current methods. This thesis summarises work on two research topics that arose in the context of exoplanetary microlensing, but we take a step back and consider ways of increasing our understanding of more fundamental phenomena: firstly, stellar microlenses in our Galaxy that were stereoscopically observed and, secondly, the morphological variety of binary-lens light curves. In autumn 2008, the ESA Rosetta spacecraft surveyed the Galactic bulge for microlensing events. With a baseline of ∼1.6 AU between the spacecraft and ground observations, significant parallax effects can be expected. We develop a photometry pipeline to deal with a severely undersampled point spread function in the crowded fields of the Galactic bulge, making use of complementary ground observations. Comparison of Rosetta and OGLE light curves provides the microlens parallax π[subscript{E}] , which constrains the mass and distance of the observed lenses. The lens mass could be fully determined if future proper motion measurements were obtained, whereas the lens distance additionally requires the determination of the source distance. In the second project, we present a detailed study of microlensing light curve morphologies. We provide a complete morphological classification for the case of the equal-mass binary lens, which makes use of the realisation that any microlensing peak can be categorised as one of only four types: cusp-grazing, cusp-crossing, fold-crossing or fold-grazing. As a means for this classification, we develop a caustic feature notation, which can be universally applied to binary lens caustics. Ultimately, this study aims to refine light curve modelling approaches by providing an optimal choice of initial parameter sets, while ensuring complete coverage of the relevant parameter space.

Detection of earth-size exoplanets using the astrometric signal of the host star requires sub-microarcsecond measurement precision. One major challenge in achieving this precision using a medium-size (< 2-m) space telescope is the calibration of dynamic distortions. A diffractive pupil can be used to generate polychromatic diffraction spikes in the focal plane, which encode the distortions in the optical system and may be used to calibrate astrometric measurements. The first half of this dissertation discusses the design and construction of a laboratory to test this concept. The main components of the system are a high stability star simulator, a diffraction limited off-axis optical system, and the data reduction algorithms to obtain the distortion map calibration. Currently, the laboratory is operational and first tests of distortion measurements have been done validating this concept to improve the astrometric accuracy of a telescope. The second part of this dissertation describes the use of the multi-laser guide star (LGS) system available at the 6.5 m MMT telescope to characterize GLAO performance and advance Laser Tomography Adaptive Optics (LTAO) technology. The system uses five range-gated and dynamically refocused Rayleigh laser beacons to sense the atmospheric wavefront aberration. Corrections are then applied to the wavefront using the 336-actuator adaptive secondary mirror of the telescope. So far, the system has demonstrated successful control of ground-layer aberration over a field of view (FoV) substantially wider than is delivered by conventional adaptive optics, yielding reduction in the width of the on-axis point-spread function from 1.07" to < 0.2" in H band. Both techniques can be combined to improve the astrometric accuracy of ground based telescopes, especially when using Multi-Conjugated Adaptive Optics (MCAO). A diffractive pupil can be used to calibrate the distortions induced by multiple Deformable Mirrors (DM), which is the main limitation to use this kind of AO system for high precision astrometric measurements.

Mount Graham, in Southern Arizona supports valuable, ecological communities and at least one endangered species, the Mt. Graham red squirrel. The area is managed by the U.S. Forest Service. Elevation, dryness, sky clarity and freedom from light pollution at Mt. Graham make it a desirable site for astronomy. The University of Arizona presented a proposal to the Forest Service for the development of a multi-telescope observatory on the mountain. This has generated much controversy due to the opposition of environmentalists who fear the potential impacts of development on the mountain. Eleven potential sites for astrophysical development have been identified, with varying impacts on the ecosystem. They are ranked according to their suitability for development, using multiple criteria decision making techniques. The results are very consistent and robust, both within and across techniques and can be useful for decision support and conflict management purposes.

Several next generation astronomical telescopes or large optical systems utilize aspheric/freeform optics for creating a segmented optical system. Multiple mirrors can be combined to form a larger optical surface or used as a single surface to avoid obscurations. In this paper, we demonstrate a specific case of the Daniel K. Inouye Solar Telescope (DKIST). This optic is a 4.2 m in diameter off-axis primary mirror using ZERODUR thin substrate, and has been successfully completed in the Optical Engineering and Fabrication Facility (OEFF) at the University of Arizona, in 2016. As the telescope looks at the brightest object in the sky, our own Sun, the primary mirror surface quality meets extreme specifications covering a wide range of spatial frequency errors. In manufacturing the DKIST mirror, metrology systems have been studied, developed and applied to measure low-to-mid-to-high spatial frequency surface shape information in the 4.2 m super-polished optical surface. In this paper, measurements from these systems are converted to Power Spectral Density (PSD) plots and combined in the spatial frequency domain. Results cover 5 orders of magnitude in spatial frequencies and meet or exceed specifications for this large aspheric mirror. Precision manufacturing of the super-polished DKIST mirror enables a new level of solar science.