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Pasachoff J.M.,Williams College | Pasachoff J.M.,California Institute of Technology | Rusin V.,Slovak Academy of Sciences | Saniga M.,Slovak Academy of Sciences | And 10 more authors.
Astrophysical Journal | Year: 2015

Continuing our series of observations of coronal motion and dynamics over the solar-activity cycle, we observed from sites in Queensland, Australia, during the 2012 November 13 (UT)/14 (local time) total solar eclipse. The corona took the low-ellipticity shape typical of solar maximum (flattening index ε = 0.01), a change from the composite coronal images we observed and analyzed in this journal and elsewhere for the 2006 and 2008-2010 eclipses. After crossing the northeast Australian coast, the path of totality was over the ocean, so further totality was seen only by shipborne observers. Our results include velocities of a coronal mass ejection (CME; during the 36 minutes of passage from the Queensland coast to a ship north of New Zealand, we measured 413 km s-1) and we analyze its dynamics. We discuss the shapes and positions of several types of coronal features seen on our higher-resolution composite Queensland coronal images, including many helmet streamers, very faint bright and dark loops at the bases of helmet streamers, voids, and radially oriented thin streamers. We compare our eclipse observations with models of the magnetic field, confirming the validity of the predictions, and relate the eclipse phenomenology seen with the near-simultaneous images from NASA's Solar Dynamics Observatory (SDO/AIA), NASA's Extreme Ultraviolet Imager on Solar Terrestrial Relations Observatory, ESA/Royal Observatory of Belgium's Sun Watcher with Active Pixels and Image Processing (SWAP) on PROBA2, and Naval Research Laboratory's Large Angle and Spectrometric Coronagraph Experiment on ESA's Solar and Heliospheric Observatory. For example, the southeastern CME is related to the solar flare whose origin we trace with a SWAP series of images. © 2015. The American Astronomical Society. All rights reserved.


Kozubal M.J.,Clay Center Observatory | Gasdia F.W.,Clay Center Observatory | Dantowitz R.F.,Clay Center Observatory | Scheirich P.,Academy of Sciences of the Czech Republic | Harris A.W.,Space Science Institute
Meteoritics and Planetary Science | Year: 2011

A calibrated lightcurve is presented of the near-Earth asteroid 2008 TC 3, obtained before it impacted Earth on October 7, 2008. The asteroid was observed in unfiltered images from the end of astronomical twilight until the object entered Earth's shadow about 2h later. The observations covered a wide range of phase angles from 14.79° to 2.93°, during which the asteroid ranged from 82,000km to 29,000km distance from the observer. A method is presented for obtaining photometrically filtered brightness values for the asteroid using unfiltered imaging techniques. Over 1,700 images of the asteroid produce a lightcurve with a peak-to-peak variation in V of 0.76 magnitude. Analysis of the lightcurve yields values for H=30.86±0.01 and G=0.33±0.03. Combined with other constraints on the kinetic energy and diameter of the asteroid, which suggest a low 1.8gcm -3 density and albedo 0.05±0.01, the value of H implies an asteroid of about 4.1m in diameter, 28m 3 in volume, and 51,000kg in mass. The determined value of G is out of range for normal, larger asteroids of albedo 0.05-0.15. © The Meteoritical Society, 2011.


Scheirich P.,Academy of Sciences of the Czech Republic | Durech J.,Charles University | Pravec P.,Academy of Sciences of the Czech Republic | Kozubal M.,Clay Center Observatory | And 7 more authors.
Meteoritics and Planetary Science | Year: 2010

On October 6, 2008, a small F-class asteroid 2008 TC3 was discovered by Catalina Sky Survey telescope, and exploded 20-hr later in the Earth's atmosphere at 37-km altitude. We analyzed available photometric data taken from 6 October 21:10 to 7 October 01:46-UT, and created a numerical model of a shape and rotation state of the asteroid. The asteroid was in excited rotational state. We found two approximately mirror solutions of orientation of its angular momentum vector. Rotational and precession periods are 99.20 and 97.00-s (errors of the rotational period for the two solutions are 0.03 and 0.04-s; of the precession period are 0.05-s for both solutions). The volume of the convex model and the length of the longest axis of the dynamically equivalent, equal volume ellipsoid are and, where pV is surface geometric albedo. Assuming a mean albedo value for F taxonomic class, 0.049-±-0.010, the volume is (25-±-10)-m3 and the longest axis is (6.7-±-0.8)-m. This volume of the convex model is an upper limit on a real volume of the asteroid, which may be less by up to 20% due to concavities. © The Meteoritical Society, 2010.


Snively J.B.,Utah State University | Snively J.B.,Embry - Riddle Aeronautical University | Taylor M.J.,Utah State University | Jenniskens P.,Search for Extraterrestrial Intelligence Institute | And 4 more authors.
50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition | Year: 2012

During the 2010 NASA / JAXA Hayabusa re-entry observational campaign, a system of four co-located cameras was deployed by Utah State University on the NASA DC-8 Airborne Laboratory to track and measure the spacecraft fragmentation and sample return capsule descent. These instruments included an intensified video camera for narrow-field tracking, an intensified video camera for visible and near-infrared spectral measurements from 400 to 900 nm, and a near-infrared InGaAs spectrograph for high resolution measurements from 980 to 1080 nm. The latter was configured to monitor the capsule emissions' spectral evolution during descent, seeking evidence of possible carbon signatures due to ablation of the heat shield. Data complement previous Stardust capsule observations where distinct 1069 nm emission signatures were measured, likely associated with carbon ablation from the Phenolic Impregnated Carbon Ablator (PICA) heat shield. The Hayabusa capsule spectra also exhibit 1069 nm line emissions, appearing intermittently at ∼13:52:05, persisting from ∼13:52:10-13:52:20 as the capsule approached peak heating, and weakening to undetectable levels after ∼13:52:20. Continuum emission and nitrogen line emissions were detected simultaneously. The evolutions of these signatures over the course of re-entry are investigated, in comparison with model predictions and complementary campaign data. © 2012 by the American Institute of Aeronautics and Astronautics, Inc.


Snively J.B.,Utah State University | Snively J.B.,Embry - Riddle Aeronautical University | Taylor M.J.,Utah State University | Jenniskens P.,Search for Extraterrestrial Intelligence Institute | And 4 more authors.
Journal of Spacecraft and Rockets | Year: 2014

As part of the 2010 airborne observational campaign for the Hayabusa capsule reentry, a system of four colocated cameras was deployed to track and measure the spacecraft fragmentation and sample return capsule descents. These instruments included an intensified video camera for narrow-field tracking, an intensified video camera for visible and near-infrared spectral measurements from 400 to 900 nm, and a near-infrared spectrograph for high-resolution measurements from 980 to 1080 nm. The latter was configured to monitor the spectral evolution of capsule emissions during descent, seeking evidence of possible carbon signatures due to ablation of the heat shield. The data complement previous Stardust capsule observations in which distinct 1069 nm emission signatures were measured, likely associated with carbon ablation from the Phenolic Impregnated Carbon Ablator heat shield. The Hayabusa capsule spectra also exhibited 1069nmline emissions, appearing intermittently at ~13:52:05, persisting from approximately 13:52:10 to 13:52:20 as the capsule approached peak heating, and weakening to undetectable levels after ~13:52:20. Continuum emission and nitrogen line emissions were detected simultaneously. The evolutions of these signatures over the course of reentry are investigated, in comparison with model predictions and complementary campaign data. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc.

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