Time filter

Source Type

Flagstaff, AZ, United States

Ryan K.K.,New Mexico Institute of Mining and Technology | Jorgensen A.M.,New Mexico Institute of Mining and Technology | Hall T.,New Mexico Institute of Mining and Technology | Armstrong J.T.,U.S. Navy | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

The Navy Precision Optical Interferometer (NPOI) has now been recording astronomical observations for the better part of two decades. During that time period hundreds of thousands of observations have been obtained, with a total data volume of multiple terabytes. Additionally, in the next few years the data rate from the NPOI is expected to increase significantly. To make it easier for NPOI users to search the NPOI observations and to make it easier for them to obtain data, we have constructed a easily accessible and searchable database of observations. The database is based on a MySQL server and uses standard query language (SQL). In this paper we will describe the database table layout and show examples of possible database queries. © 2012 SPIE. Source

Brown M.F.D.,New Mexico Institute of Mining and Technology | Jorgensen A.M.,New Mexico Institute of Mining and Technology | Buschmann T.,AZ Embedded Systems | Huter D.J.,Naval Observatory | Armstrong J.T.,U.S. Navy
Proceedings of SPIE - The International Society for Optical Engineering

A new hardware system is being implemented at The Navy Precision Optical Interferometer (NPOI) to vastly increase the data recording capabilities of the observatory. NPOI has three spectrographs each with 32 channels ranging the visible spectrum. Siderostat path lengths are modulated at 500 Hz strokes to create fringe patterns. The new system will be able to record and use all of the data generated, unlike the existing system. Utilizing parallel architecture of FPGA"s, all channels are processed simultaneously and piped to a host computer via DMA such that an entire stroke"s data is made available before the start of the next stroke. This is expected to increase the amount of scientific data from the NPOI by an order of magnitude over the current system. Furthermore, this data can also be used to provide feedback to the delay lines to close the fringe tracking loop. In this paper we discuss the hardware and software components of the new system and current progress. © 2012 SPIE. Source

Crawled News Article
Site: http://www.techtimes.com/rss/sections/internet.xml

The clocks turned back an hour on Sunday, Nov. 1, while many of us were still out celebrating Halloween. While we should be happy that we gained an hour of sleep, it's hard to ignore the fact that this comes at a price. With the end of Daylight Savings Time — when we push our clocks an hour ahead in the spring — it will be darker earlier now, a sign that winter is just around the the corner. This means many of you will be leaving for work pre-dawn and coming back home sans the sun. However, while it might feel like we are continuously living in darkness, how much daylight is really left after the day that time falls back? Keith Collins from Quartz put together this handy interactive visual, using data from the Astronomical Applications Department of the U.S. Naval Observatory to show just that. The data assumes you are located in New York, but Collins says that there are slight differences across the U.S. The visual shows how much light is present in blue and darkness in a dark gray, revealing that that today, there are only 10.40 hours of daylight. Users can scroll throughout the graph to see how much light there is year round. You can also enter in what time you wake up and what time you go to bed to see how much of the sun you will get to see. If you wake up at 6:30 a.m. and fall asleep by 11:30 p.m., you still only get a little more than 10 hours of light, although if you work in an office, it may seem like you never see the sun. June appears to provide the most sunlight, so we can keep dreaming of the months ahead. Check out how much Daylight Savings Time has an impact on you by clicking the link here.

Hall T.,New Mexico Institute of Mining and Technology | Jorgensen A.M.,New Mexico Institute of Mining and Technology | Mozurkewich D.,Seabrook Engineering | Armstrong J.T.,U.S. Navy | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

Coherent integration is an analysis approach which, can greatly increase the SNR of optical interferometric visibilities compared to those computed by the traditional squared visibility power spectrum technique. Co- herent integration relies on phase-referencing, optimally through post-processing fringe-tracking, to effectively create long coherent integrations of the fringe. At the Navy Precision Optical Interferometer (NPOI) this phase- referencing is achieved by a combination of wavelength bootstrapping and baseline bootstrapping. The result is that the complex visibility with full phase information is retrieved and that the poor noise associated with the power spectrum approach is greatly reduced. For small visibilities, which are most important in resolving objects, the SNR can be improved sometimes by orders of magnitudes, sometimes making the difference between easy and practically impossible observations. The fringe-tracking portion of coherent integration is limited by the SNR of the tracking signal and the noise of that causes some fringe smearing which must be calibrated. In this paper we develop a theoretical model of the resulting fringe smearing and its correction. We then demonstrated its validity through simulation and on observations from the NPOI. © 2012 SPIE. Source

Jorgensen A.M.,New Mexico Institute of Mining and Technology | Schmitt H.R.,Computational Physics, Inc. | Van Belle G.T.,Lowell Observatory | Mozurkewich D.,Seabrook Engineering | And 5 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

Optical Interferometry has long been limited by low SNR making it nearly impossible to measure the small visibilities required to make resolved images. Although the SNR exists in the raw data, much SNR is lost in the conventional squared-visibility processing. In modern interferometers fringes are recorded simultaneously at many wavelengths and baselines. This makes phase-referencing possible, which is the key to coherent integration, which in turns can greatly improve the SNR of measurements, making small-amplitude resolving measurements possible. In this paper we will detail the theory of coherent integration. We will also explain why coherent integration should, in most cases, be carried out during post-processing in software rather than in real-time in hardware. We will then compare it to conventional processing approaches for some data from the Navy Optical Interferometer. We will demonstrate how coherent integration can improve the accuracy of observations. © 2012 SPIE. Source

Discover hidden collaborations