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MIT Haystack Observatory
Summer Research Program:
Abstracts and Presentations

Research Experiences for Undergraduates (REU)
August 12, 2016

 

2016 REUs

 

 

Evolution of Star Formation of Dwarf Galaxies within Extragalactic Cluster Substructures
Haylee Archer, University of North Dakota (Presentation)

Galaxy clusters form the largest structures in the universe and provide an environment to study galaxy evolution. In particular, dwarf galaxies with low mass are highly susceptible to external influences. Therefore, to understand the star formation history of dwarf galaxies, effects from the environment need to be identified and separated. To address this prob- lem, we examine a sample of galaxies from the Sloan Digital Sky Survey (SDSS). A key part is the characterization of galaxy clusters and cluster substructures, which we address using VariantDBSCAN, an algorithmic technique extending the well-known Density-Based Spatial Clustering of Applications with Noise (DBSCAN). Our approach can vary clustering pa- rameters that each lead to alternative clustering models of galaxy clusters with potentially different shapes and densities. Scientists can thus gen- erate and explore potential evolutionary histories in an semi-automated way.

PyCloudPath
Cory Cotter, University of Wisconsin–Madison (Presentation)

Pycloudpath allows for simple creation of a multiprocessing, multimachine pipeline in Python. This module modifies and extends code from the mpipe module for creating mutltiprocessing pipelines in Python. Pycloudpath aims to extend the pipeline framework to have greater scalability, run in a cloud environment, and allow the user to fully interact with the pipeline while it runs.

Low Frequency Solar Imaging Using the Murchison Widefield Array and CASA
Meagan Crowley, University of Massachusetts (Presentation)

Radio images of the Sun from an event of high solar activity on November 4, 2015 are presented using interferometric data from the Murchison Widefield Array (MWA). The MWA is a low frequency, high resolution phased array radio telescope spanning 3 km in the radio quiet Australian Golden Outback, making it particularly suitable for radio imaging of the Sun. Low frequency, high resolution solar observations provide key insights about the structure and spectra of solar emissions and allow for superior modeling and prediction of space weather. Methods of producing solar images using the imaging program CASA, developed by the National Radio Astronomy Observatory (NRAO) are discussed, as well as the success of the results and their interpretations. The advancement of solar radio imaging with the aid of the pioneering technology of the MWA has opened the door to enhanced solar activity predictions and modeling and has broadened the capabilities of low frequency interferometry. The images shown will provide a case for the continuing advancement of low frequency solar imaging.

What Happens in the Thermosphere if the Stratosphere is Strongly Disturbed?
Jolene Fong, Wellesley College (Presentation)

We investigate the possible stratosphere-thermosphere coupling at high latitudes, where the cusp of the Earth’s magnetic fields lie, using Sondrestrom Winter Ionosphere Model (SWIM) and Sondrestrom Incoherent Scatter Radar (ISR) data from the last 15 winters (2001-2016). This position is of particular interest because of the ionosphere’s strong dependency on solar and geomagnetic activity, as well as its proximity to the stratospheric polar vortex. After using the model to remove daily variations, seasonal variations, and variations due to solar flux and geomagnetic activity, anomalies in the data were compared to anomalies in stratospheric winds and temperatures. Our results so far show a possible dependency between ion temperature and stratospheric winds, with higher correlations found during the daytime. This dependency is intensified during years of Sudden Stratospheric Warnings (SSWs), where sudden changes in the winter hemisphere westerly winds can result in an increase in stratospheric temperatures and sometimes even reversal of the polar vortex. Studying the connection between these anomalies can help us link stratospheric events to ionospheric disturbances, and therefore help us predict the state of the ionosphere using meteorological events, which we currently know up to several days in advance.

Dust Is Everywhere: Opportunistic High Power UHF Radar Measurements of Meteoroid Properties
Christina Migliore, Northeastern University (Presentation)

Meteoroids entering the atmosphere help to provide insight into the behavior of the iono- sphere. The radar scattering from a dense ball of plasma around an ablating meteor, known as meteor head echo, is key to the study of meteoroid properties. Ultra high frequency (UHF) radar measurements of meteor head echoes and their properties are frequently only collected as a dedicated meteor experiment, but detection is possible in the majority of radar experiments if the right processing is applied. A meteor data pipeline was created in order to detect and processes meteors on all data collected by the radar. In order to provide a higher SNR and reduced range ambiguity, this pipeline correlates the received signal to the transmitted signal by using a matched filter. To account for the velocities of the meteoroids the data is Doppler corrected by Discrete Fourier Transform (DFT). Meteor head echoes are identified and clustered into individual events based on signal-to-noise ratio (SNR), time, range, and velocity, which are then saved for statistical analysis. This pipeline additionally plots histograms of range, range rate, duration, and SNR. An experiment on July 26, 2016 using the UHF Millstone Hill radar in Westford, Massachusetts found 272 meteors between 7 am to 11 am roughly at a rate of 96 meteors per hour with the peak at 7 am. Comparing these results to other past meteor experiments found that the meteor trends agree. This data pipeline will help to create an abundance of statistics on meteors in order to provide a better platform for meteor science.

Investigating Dual Frequency Software GPS Signal Processing for Geodetic-Quality Positioning
Manuel Paul, California State University (Presentation)

Generally used for basic civilian positioning, the Global Positioning System (GPS) has been pushed beyond its original design and has become a powerful tool for high-precision geodetic applications in geosciences, and beyond. Current dual frequency GPS hardware receivers can provide sub-millimeter level precision, but their closed designs, limited interfaces, and high prices can become a limitation to their applicability. Software receivers are an alternative, but, to the best of our knowledge, available implementations are limited to single frequency receiving systems. We will present our first steps on digital signal processing techniques and algorithms towards converting GPS software receivers from single to dual frequency systems.

A Fully Automated Scanning RFI Monitoring System for VGOS Site Surveys
Cadence Payne, Morehead State University (Presentation)

MIT Haystack Observatory has established itself as a renowned leader in the field of Very Long Baseline Interferometry, VLBI. Haystack is leading the development of a wideband signal chain for the VLBI Global Observing System (VGOS) component of NASA’s Space Geodesy Project. With the deployment of these new wideband VGOS stations there exists the threat of radio frequency interference. This interference, both naturally formulated and manmade, poses degradation to the sensitivity of the station’s instrumentation and can result in the disruption of a station’s ability to conduct successful VGOS observations. This threat motivated engineers to design a fully automated scanning RFI monitoring system to observe and characterize these unwanted signals at prospective sites prior to the construction of these VGOS stations. The current project’s responsibility involves improving the current design of said system. Before beginning the designing process, the previously developed system underwent testing and analysis to provide a better understanding of its functionality and of the general realm of radio frequency interference. With the help of Haystack engineers and technical staff, a refined design for the previously composed scanning system is underway. The design works to incorporate a smarter motor for simpler maneuvering, utilize software development for instrument control, and integrate a more portable and powerful spectrum analyzer capable of capturing observed spectra in real time. Other improvements to system simplicity and functionality are under consideration.

Studying Earth Surface Deformations with InSAR and GPS
Juliet Pilewskie, University of Colorado (Presentation)

Remote sensing techniques, such as Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR), are important for measuring and modeling the deformation of the Earth’s surface. GPS gathers precise, real-time measurements with high temporal resolution, while InSAR provides accurate measurements over large spatial regions. Ongoing work continues to face difficulties in combining the two tech- niques in order to utilize the superior time resolution from GPS and the higher spatial resolution of InSAR. In this project, we explore poten- tial methods to fuse the two data sets using InSAR data from two dif- ferent sources, Uninhabited Aerial Vehicle SAR (UAVSAR) and ASAR- ENVISAT. We generate interferograms from Single Look Complex (SLC) stacks provided by UAVSAR to study surface deformations due to ground- water changes in California, and examine InSAR images from ASAR- ENVISAT to explore volcanic activity in the region surrounding the Ki- lauea volcano in Hawaii. Building on the ASAR-ENVISAT data, we focus on Kilauea and incorporate simultaneously recorded GPS data. These two data sets can be incorporated into a data processing pipeline that allows for efficient exploration of many-dimensional parameter space with the hopes of increasing the level of precision and reliability of both surface deformation patterns and volcanic expansion centers.

Super-resolution Polarimetric Imaging of Black Holes Using the Event Horizon Telescope
Mollie Pleau, Smith College (Presentation)

Black holes are thought to reside in the centers of many galaxies; however, due to their diminutive size, we have yet to directly detect and image a black hole. The Event Horizon Telescope (EHT), a global array for 1.3mm very long baseline interferometry (VLBI), has been designed to observe and image the supermassive black hole in the center of the Milky Way (Sagittarius A*), as well as the one in the center of the nearby giant elliptical galaxy M87. The nominal resolution of the EHT is around 30 μas, comparable to the size of the black hole’s event horizon. For this reason, we require super-resolution to accurately reconstruct images in total intensity and linear polarization. High fidelity polarimetric imaging can be used to test general relativity and to characterize the magnetic field structure surrounding black holes, which is important for understanding its role in mediating the innermost accretion and outflow region. We employ new sparse imaging techniques based on compressed sensing for linear polarimetry. Using synthetic data of M87 observations with the EHT, we find that our new techniques improve upon the standard CLEAN by a factor of ten regardless of resolution, as measured by the differences in mean squared error (MSE). We conclude that compressed sensing proves to be an effective method for linear polarimetric imaging.

Towards Understanding the Data from the Next-Generation Geodetic VLBI Systems
Shelby Price, Morehead State University (Presentation)

This project involved data analysis of geodetic VLBI experiments using the Vienna VLBI Software (VieVS). This report explains what progress was made and what the next person to work on this project will need to do. The paper includes hyperlinks to helpful websites throughout, which are also available at the end of the report as a reference section.

Intelligent Baseline Selection for Radio Interferometric Imaging
Sasha Safonova, University of Arizona (Presentation)

This project develops an algorithmic method for incrementally selecting VLBI baselines under con- straints such as reducing the number of required correlations while aiming to preserve salient features in the image. We show preliminary results using a genetic algorithm approach and case study ex- amples using point source, nebula, and other images. We compare the structural similarity index (SSIM) of the approximated image with the full resolution image to evaluate result quality as well as the contribution of selected baselines. Initial results indicate that our method has the potential to preserve key features of astronomical images while reducing the data size needed for correlation. In the future, this method will provide image specific correlation processing that can reduce correlation time using an approximate set of baselines or produce full resolution images that utilize the complete set of baselines. Scientists will be able to utilize this method to decide the amount of approximation appropriate for different types of astronomical objects.

Posters

The Resurrection and Repurposing of the VLG-10 (P2) Hydrogen Maser
Cadence Payne, Morehead State University (Poster)

The task of resurrecting MIT Haystack’s VLG-10 (P2) Hydrogen MASER was conquered. The MASER, previously housed at the SMA observatory in Mauna Kea, sat stagnant at MIT Haystack. The MASER successfully powered back on and currently sits, happily stabilized, in house at the observatory. It will relocate to Morehead State University in Kentucky with its primary purpose being the time standard for the university’s 21m dish as it undergoes integration into NASA’s DSN. P2 underwent Allan Deviation testing in comparison with the NR7 MASER that also resides at MIT Haystack, and has proven itself capable of meeting the frequency stability specifications required for the DSN. The P2’s Hydrogen bottle sits at a significantly low PSI, resulting in the design of a new configuration for the bottle replacement prior to it being delivered to Morehead State.

Super-resolution Polarimetric Imaging of Black Holes Using the Event Horizon Telescope
Mollie Pleau, Smith College (Poster)

Black holes are thought to reside in the centers of many galaxies; however, due to their diminutive size, we have yet to directly detect and image a black hole. The Event Horizon Telescope (EHT), a global array for 1.3mm very long baseline interferometry (VLBI), has been designed to observe and image the supermassive black hole in the center of the Milky Way (Sagittarius A*), as well as the one in the center of the nearby giant elliptical galaxy M87. The nominal resolution of the EHT is around 30 μas, comparable to the size of the black hole’s event horizon. For this reason, we require super-resolution to accurately reconstruct images in total intensity and linear polarization. High fidelity polarimetric imaging can be used to test general relativity and to characterize the magnetic field structure surrounding black holes, which is important for understanding its role in mediating the innermost accretion and outflow region. We employ new sparse imaging techniques based on compressed sensing for linear polarimetry. Using synthetic data of M87 observations with the EHT, we find that our new techniques improve upon the standard CLEAN by a factor of ten regardless of resolution, as measured by the differences in mean squared error (MSE). We conclude that compressed sensing proves to be an effective method for linear polarimetric imaging.

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