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The Prominence Magnetometer (ProMag) is a dual-channel, dual-beam spectro-polarimeter designed by the High Altitude Observatory at the National Center for Atmospheric Research (HAO/NCAR) for the study of the magnetism of solar prominences and filaments with the ultimate goal of predicting prominence activation and eruptions. It was deployed in August 2009 at the 40-cm coronagraph of the Evans Solar Facility (ESF) of the National Solar Observatory on Sacramento Peak (NSO/SP). For two years HAO staff operated the instrument in campaign mode , in which a two week observing campaign ran once per quarter. The Air Force Office of Scientific Research funded a three-year program to run the instrument in synoptic mode , in which data is taken daily on many prominences. In this report we summarize progress towards the goals of this three-year program. Dr. J. Lewis Fox became the ProMag Observing Scientist in residence at Sacramento Peak, August 2011 as a postdoctoral research associate funded through the AFOSR program and employed by the National Solar Observatory. Since that time Dr. Fox has completed a redesign of the instrument. Data reduction software, including polarimetric calibration is now nearly complete. He has carried out two years of routine observations, resulting in the observation of hundreds of prominences and filaments and trained two observers to carry out ProMag observations independently., The original document contains color images.

On 2011 February 14, the ISOON telescope at the National Solar Observatory at Sacramento Peak recorded a Moreton wave associated with a 1B flare (GOES class M2 with a 1 8 maximum at 17:26 UT). The solar event was well observed by the STEREO spacecraft (both in quadrature from Earth) and SDO. The Moreton wave was first observed at 17:25 UT and propagated away from the flare site in a north-easterly direction at a speed of 730 km s 1. It displayed a characteristic down up vertical velocity pattern and lagged slightly (4 x 10000 km) behind an EUV wave observed by the Atmospheric Imaging Assembly on SDO to be travelling with essentially the same speed and trajectory. STEREO EUVI and COR1 data indicate that the fast wave was associated with the northward lateral expansion of a coronal mass ejection (CME). The radial CME speed deduced from STEREO A observations was only 580 km s 1, but STEREO EUV observations of the low corona indicate an initial lateral speed of 700 km s 1 near the time of wave onset, with the coronal portion significantly leading the surface response. A distance vs. time plot of the EUV wave along its main trajectory shows an initial fast bright wave that has a constant speed over 6 x 100000 km and reflects off an active region within its angular span, followed by a slower bright wave that becomes stationary., The original document contains color images.

Carley, et al., (2013) link together the key elements for acceleration of particles by magnetohydrodynamic shocks at the Sun for an eruptive event on 22 September 2011. In brief, in this event the lateral expansion of a coronal mass ejection drove a quasi-perpendicular shock wave that accelerated electrons in intermittent bursts, with the intermittency attributed to the rippled or wavy surface of the shock front. The history of research on large-scale solar waves is reviewed. Such waves were discovered by radio means in 1947. Recent progress has been primarily based on high-cadence images of such waves at extreme ultra-violet wavelengths., The original document contains color images. Published in Nature Physics, 6 Oct 2013.

Solar Cycle 24 is having a historically long and weak start. Observations of the Fe XIV corona from the Sacramento Peak site of the National Solar Observatory show an abnormal pattern of emission compared to observations of Cycles 21, 22, and 23 from the same instrument. The previous three cycles have shown a strong, rapid Rush to the Poles (previously observed in polar crown prominences and earlier coronal observations) in the parameter N(t, l, dt) (average number of Fe XIV emission features per day over dt days at time t and latitude l). Cycle 24 displays a weak, intermittent, and slow Rush that is apparent only in the northern hemisphere. If the northern Rush persists at its current rate, evidence from the Rushes in previous cycles indicates that solar maximum will occur in early 2013 or late 2012, at least in the northern hemisphere. At lower latitudes, solar maximum previously occurred when the time maximum of N(t, l, 365) reached approximately 20 latitude. Currently, this parameter is at or below 30 and decreasing in latitude. Unfortunately, it is difficult at this time to calculate the rate of decrease in N(t, l, 365). However, the southern hemisphere could reach 20 in 2011. Nonetheless, considering the levels of activity so far, there is a possibility that the maximum could be indiscernible., The original document contains color images. Pub on line Solar Phys, DOI 10.1007/s11207-011-9714-9 23 Feb 2011.

We have recently noticed cellular features in Fe xii 193 A images of the 1.2 MK corona. They occur in regions bounded by a coronal hole and a filament channel, and are centered on flux elements of the photospheric magnetic network. Like their neighboring coronal holes, these regions have minority-polarity flux that is 0.1-0.3 times their flux of majority polarity. Consequently, the minority-polarity flux is ?grabbed? by the majority-polarity flux to form low-lying loops, and the remainder of the network flux escapes to connect with its opposite-polarity counterpart in distant active regions of the Sun. As these regions are carried toward the limb by solar rotation, the cells disappear and are replaced by linear plumes projecting toward the limb. In simultaneous views from the Solar Terrestrial Relations Observatory and Solar Dynamics Observatory spacecraft, these plumes project in opposite directions extending away from the coronal hole in one view and toward the hole in the other view, suggesting that they are sky-plane projections of the same radial structures. We conclude that these regions are composed of closely spaced radial plumes, extending upward like candles on a birthday cake and visible as cells when seen from above. We suppose that a coronal hole has this same discrete, cellular magnetic structure, but that it is not seen until the encroachment of opposite-polarity flux closes part or all of the hole., Pub. in The Astrophysical Journal, v749 n40, p1-14, 10 April 2012.

We describe the status of current ground-based solar spectroscopic and imaging instruments used in solar observations. We describe the advantages and disadvantages of using these two classes of instruments with examples drawn from the Improved Solar Optical Observing Network (ISOON) and Synoptic Long Term Investigations of the Sun (SOLIS) Network. Besides instrumental requirements and lessons learned from existing ground-based instruments, this talk also focuses on the future needs and requirements of ground-based solar optical observations., The original document contains color images.

This study consists of a quantitative comparison of H-alpha solar flare area and brightness as recorded by the Solar Observing Optical Network (SOON) and the Global Oscillation Network Group (GONG) from March 11 through November 30, 2011. The Air Force utilizes the three-site SOON network for H-alpha flare monitoring, while the six-site GONG network, managed by the National Solar Observatory, provides backup H alpha flare monitoring for SOON. A total of 1000 flares were observed and 100 of these were rated larger or brighter than the 0-F category. In the SOON network, 8% of flares observed by two sites had a difference in area or brightness category, or both. In the GONG network, with up to four sites viewing the same flare, 44% of flares observed by multiple sites had at least one site with differences in area, brightness, or both. Of these cases, the GONG site that rated the flare as having the largest or brightest rating also had the highest sharpness 95% of the time. Of the 84 flares larger or brighter than 0 F observed by both networks, area and brightness category ratings were the same 35% of the time. The GONG rating was one category larger or brighter than SOON 26% of the time and the SOON rating was one category larger or brighter than GONG 39% of the time. There was only one case with a two category difference between networks this was attributed to clouds at one site. GONG observed all 9 of SOON?s event-level flares while observing three additional that SOON did not observe. Ultimately, GONG observed all SOON flares with the same variability noted when comparing flares observed within the SOON network, and is a reliable source for H-alpha flare observations., The original document contains color images.

We present CCD photometric distance estimates of 100 SCR (SuperCOSMOS RECONS) systems with mu >= 0".18/yr, 29 of which are new discoveries previously unpublished in this series of papers. These distances are estimated using a combination of new VRI photometry acquired at CTIO and JHK magnitudes extracted from 2MASS. The estimates are improvements over those determined using photographic plate BRI magnitudes from SuperCOSMOS plus JHK, as presented in the original discovery papers. In total, 77 of the 100 systems investigated are predicted to be within 25 pc. If all 77 systems are confirmed to have pi(sub trig) >= 40 mas, this sample would represent a 23% increase in M dwarf systems nearer than 25 pc in the southern sky., Published in The Astronomical Journal, v141 n21 p1-11, 2011. Issue No. 1. Prepared in collaboration with Georgia State University, Atlanta, GA; Cerro Tololo Inter-American Observatory, La Serena, Chile; and University of Edinburgh, UK. The original document contains color images.

We present trigonometric parallaxes of 64 stellar systems with proper motions between 0".5 yr(exp -1)and 1".0 yr(exp -1) from the ongoing Research Consortium On Nearby Stars parallax program at the Cerro Tololo Inter-American Observatory. All of the systems are south of decl. = +30, and 58 had no previous trigonometric parallaxes. In addition to parallaxes for the systems, we present proper motions, Johnson-Kron-Cousins VRI photometry, variability measurements, and spectral types. Nine of the systems are multiple; we present results for their components, three of which are new astrometric detections. Of the 64 systems, 56 are within 25 pc of the Sun and 52 of those are in the southern hemisphere, comprising 5.7% of the total number of known southern 25 pc systems., Published in The Astronomical Journal, v140 n3 p897-911, September 2010. Prepared in collaboration with Georgia State University, Atlanta, GA; Cerro Tololo Inter-American Observatory (CTIO), La Serena, Chile; University of Virginia, Charlottesville, VA; and Universidad de Chile, Santiago, Chile. The original document contains color images.

We discuss how simultaneous observations by multiple heliospheric imagers can provide some important information about the azimuthal properties of Coronal Mass Ejections (CMEs) in the heliosphere. We propose two simple models of CME geometry that can be used to derive information about the azimuthal deflection and the azimuthal expansion of CMEs from SECCHI/HI observations. We apply these two models to four CMEs well-observed by both STEREO spacecraft during the year 2008. We find that in three cases, the joint STEREO-A and B observations are consistent with CMEs moving radially outward. In some cases, we are able to derive the azimuthal cross-section of the CME fronts, and we are able to measure the deviation from self-similar evolution. The results from this analysis show the importance of having multiple satellites dedicated to space weather forecasting, for example in orbits at the Lagrangian L4 and L5 points., Published in The Astrophysical Journal (preprint), 2010. Prepared in cooperation with Universidad de los Andes, Bogota, Colombia; STFC Rutherford Appleton Laboratory, Didcot, UK; and the Naval Research Laboratory, Washington, DC. Sponsored in part by NASA, NRL, and others.

We are constructing a spectro-polarimeter using the 4 0-cm coronagraph at the Evans Solar Facility of the National Solar Observatory in Sunspot, NM for the purpose of measuring the vector magnetic filed in prominences and filaments. The Prominence Magnetometer (ProMag) is comprised of a polarization modulation package and a spectrograph. The modulation optics are located at the prime focus of the coronagraph along with calibration optics and a beamsplitter that creates two beams of orthogonal Stokes states. The spectrograph resides at the coude focus of the coronagraph. The polarizations of the two chromospheric lines of neutral helium, at 587.6 cm and 1083.0 nm, are to be observed simultaneously. We present details of the design of the spectro-polarimeter., The original document contains color images. All DTIC reproductions will be in black and white. Published in the Proceedings of the SPIE, v7014, 2008 from Ground-based and Airborne Instrumentation for Astronomy II.

Coronal mass ejections (CMEs) are massive outflows of material from the Sun's corona, traveling into the surrounding heliosphere at speeds up to 1000-2000 kilometers per second. When directed toward the Earth, CMEs can result in damage to satellites, enhanced auroral displays, blackouts of power grids on Earth, and interference with surface radio communications. The first CME detected from space was observed by an NRL coronagraph onboard the Seventh Orbiting Solar Observatory (OSO-7) in December 1971. Much of our recent knowledge of CMEs has been obtained from an NRL visible-light coronagraph (LASCO, the Large Angle Spectroscopic Coronagraph(2)) on the Solar and Heliospheric Observatory (SOHO) spacecraft, launched in 1995. But SOHO observes from only one viewpoint, leaving three-dimensional structure ambiguous for individual CMEs. The next step beyond SOHO is the Solar Terrestrial Relations Observatory (STEREO) mission, consisting of two spacecraft observing the Sun from two different viewpoints, allowing a three-dimensional view of the initiation of CMEs and their propagation outwards. In addition, STEREO will carry a new type of heliospheric coronagraph that is off-pointed from the solar disk, and can observe from the side the Sun-Earth line all the way out to Earth. The STEREO mission is meant to increase our understanding of such topics as solar structures and their properties involved in CME initiation; threedimensional structure and kinematics of CMEs; three-dimensional structure of active regions, coronal loops, and streamers; propagation of CMEs into the corona and interplanetary medium; and the effects of CMEs through the heliosphere to the Earth., Published in the Naval Research Laboratory (NRL) Review, p227-229, 2007. Sponsored in part by the National Aeronautics and Space Administration (NASA).

The Solar Mass Ejection imager experiment launched 6 January 2003 on Coriolis continues to detect and track Coronal Mass Ejections (CMEs) A proof-of-concept experiment, SMEI has outlived its planned 2-3 year lifetime and amassed a database of full-sky images with a 102 minute cadence recorded for almost five years. After its first year of operation control of Coriolis was transferred from the Air Force Space Test Program to the Navy who operates the spacecraft today and provides SMEI data to AFRL as well as executing routine operations such as calibrations mask uploads resets etc at no charge to the Air Force Research Laboratory. The Navy plans to operate Coriolis for as long as its experiment Windsat is functional. Because of an irrecoverable failure on its A-side redundant electronics (March 2006) SMEI has been switched to B-side, which is operating nominally Camera 3 (closest to the Sun) has run above predicted/planned for temperatures and performance continually degrades with accumulated radiation dose. In addition to periodic anneals to help alleviate this problem we have instituted a severe on-board masking of hot pixels in Camera 3 since 2006. Despite these problems SMEI has amassed a wealth of detailed Images of coronal mass ejections (CMEs) as well as other phenomena such as high altitudes auroras variable stars zodiacal dust, Gegenschein and comet tail interactions with the heliosphere, SMEI has demonstrated that such an instrument can accomplish a 30% and greater improvement in space weather forecasts At the time of this report the SMEI team is working with the Air Force Space Weather Agency to incorporate SMEI data into their operational forecasts. A workshop on future heliospheric imaging missions to meet DoD needs was held in April 2007 at the Air Force facilities at the National Solar Observatory at Sunspot NM, at which the Air Force and Navy agreed to work together to field the next heliospheric imager.

This report results from a contract tasking Astrophysical Institute Potsdam as follows: Grantee will upgrade radio spectrometers allow collection of CME signature data it the 693-741 MHz and 316-337 MHz frequency ranges. This data will then be analyzed and compared to CME data from satellite collection systems. Known CME data from the satellite systems will help researchers determine if CME signatures can be detected from radio astronomical methods alone, without having to correlate the data with the satellites (14 to 48 hours after lift off from the corona). In effect, this will allow detection of CMEs 14 to 48 hours more quickly than current methods., Text in both English and German. The original document contains color images.

The first Heliophysical Year International SCINDA Workshop was held at Sal, Cape Verde, during the period of July 10-14, 2006. This 5-day workshop was organized by Air Force Research Laboratory, NC A&T State University, the and Instituto Nacional De Metereologica E Geofisica Republico De Cabo Verde (INMG). Representatives from Nigeria, Ethiopia, Cape-Verde, Cote D Ivoire, Malaysia and Congo Brazzaville participated in the workshop. The overall goals of the workshop were to establish space science expertise and to install Scintillation Network Decision Aid (SCINDA) across Africa following the geomagnetic equator. SCINDA is a real-time, data driven communication outage forecast and alert system developed for the United States Air Force Space Command by the Air Force Research Laboratory (AFRL), Ionospheric Hazards Specification and Forecast Team, Hanscom AFB. Its purpose is to aid in the specification and prediction of satellite communication degradation due to ionospheric scintillation in the equatorial region. Ionospheric disturbances can cause rapid phase and amplitude fluctuations of satellite signals observed at or near the earth's surface; these fluctuations are known as scintillation. The workshop has provided instructions on the deployment, operation and interpretation of data from SCINDA sensors. These instructions were accompanied by talks by the participating scientists, and meal time discussions on how to advance space science research and education in Africa in the future. At the end of the workshop, the participants learned to setup a GPS TEC/scintillation system on-line at their home institution. This report supplies a summary of the contributed talks., Summary of the Heliophysical Year International SCINDA (Scintillation Network Decision Aid) Workshop held Sal, Cape Verde on 10-14 Jul 2006. The original document contains color images.

This report results from a contract tasking Radio Physical Research Institute (NIRFI) as follows: The contractor will investigate the use of powerful HF radars to detect coronal mass ejections from the sun.

The Large Angle Spectrometric Coronagraph (LASCO) on board SOHO provided unprecedented views of the solar corona since January 1996. This instrument contains three individual coronagraphs C1, C2, and C3, described in detail in Brueckner et al (1995). The C1 coronagraph acquires high resolution images (11" and higher) of the lower corona from 1.1 R to 3.0 R, thereby providing a close link to the disk observations of other instruments in the SOHO complement. The C2 and C3 images have lower resolution (23" and about 2' respectively), however they provide a unique view of the extended corona up to 32 R. During the past year we carried out a study of the morphology and dynamical evolution of various structures in the solar corona as observed by LASCO and EIT. In the following, we summarize the results of this studies.

The Large Angle Spectrometric Coronagraph (LASCO) onboard SOHO provides unprecedented views of the solar corona since January 1996. During the past year we carried out a study of the morphology and dynamical evolution of various structures in the solar corona including coronal mass ejections, and polar jets. We highlight in this report two examples of our analysis of CMEs (from 1997 April 30 and 1997 February 23), and the results of our testing of the viability of an MHD model of expanding flux rope developed by Chen et al. (1997). We also highlight results from our ongoing study of the dynamical evolution of structures in the solar polar regions. Our study was focused on a series of three compact jets of material ejected on 1997 March 22 from a point near the north pole. The results show evidence for substantial deceleration. The estimated initial ejection velocity is slightly below the Sun's escape velocity of 619 km/s. We conclude that the dynamical evolution of these jets is different from that of coronal mass ejections, which generally show continuous acceleration below 3-4 R solar radius.

The magnetic field of the Sun determines the structure of the corona and the interplanetary medium. Observations of the solar field made at the Wilcox Solar Observatory at Stanford from 1976 to the present have been used to model the field patterns in the corona, the source of the heliospheric magnetic field. The IMF polarity at Earth can be predicted with about 80% reliability throughout the solar cycle. However, the field in the ecliptic is just one slice of a three-dimensional structure that changes greatly during the solar cycle. Near solar minimum the heliospheric current sheet is confined to the Sun's equatorial region. As the polar fields decay and reverse near solar maximum, the geometry of the heliospheric field becomes much more complex. Model coronal fields can also be used to estimate the solar wind velocity, determine the solar origin of interplanetary structures, and predict the out-of-ecliptic component of the IMF at Earth.

Two dimensional maps of the longitudinal magnetic field can be readily calculated for small-scale magnetic regions. Here we use a one hour time sequence of high spatial resolution (0.75 arc sec) filtergrams, obtained at the Sacramento Peak Vacuum Tower Telescope with the universal filter (UBF) in the wings of the magnetically sensitive lambda 6103 CaI line. The time difference between two magnetic maps is 32 sec. The measurements of the magnetic field in the blue wing are about 40% higher than in the red wing., Pub. in Proceedings of the National Solar Observatory on Solar Polarimetry (11th), p257-262, 27-31 Aug 1990.

An extensive collaborative study of the maximum-type solar corona at the July 22, 1990 eclipse has been performed after collecting data from the ground and from an aircraft. The study provides photometric quality data and structural analysis on the electron corona. Synoptic data are used from the Emission-Line Coronal Photometer of the National Solar Observatory/Sacramento Peak. The activity of the low corona at the time of the eclipse is first discussed. Noticeable is a large nearby polar hole at the SSW limb well-observed on both synoptic green-line data and eclipse data. Strong activity is seen at the E and W limbs and numerous faint prominences are recorded all around the limb. The photometry of the White-Light corona has been performed with selected pictures from the French Falcon-20 aircraft experiment flown above Finland. Isophote maps are given as well as azimuthal scans in absolute units of average solar brightness. The standard flattening index is computed using the values determined for different radial distances. A few scans are compared with Fe XIV 530.3nm scans, and show great similarity when prominence emissions are excluded. The structural analysis is based on the excellent radially-filtered eclipse pictures obtained from the ground with one of the standard multi-station experiments placed along the path of totality in the USSR. Both the inner parts and especially the outer parts of the plasma corona are analyzed., Pub. in Astronomy and Astrophysics, Supplement Series 96, p169-182, 11 Nov 1992.

This report documents, a study of the differences in the climatological probabilities of a cloud-free line-of-sight (CFLOS) at the Palehua, Hawaii, Solar Optical Observatory and the Barbers Point Naval Air Station, about 5 miles southeast of Palehua. The study shows that sunny line-of- sight probabilities (SLOS--cloud-free line-of-sight from an observer to the Sun) are typically about 10 percent lower at Palehua (elevation about 1,700 feet) than at Barbers Point (34 feet). The study compared 17 years of actual weather observations from Barbers Point and 5 years Palehua solar optical site status reports (Surface weather observations are not available from Palehua). The results of this study suggest that the Stanford Research Institute technique for relating fractional sky-cover and viewing angle to CFLOS probability (described by Malick, et al., 1979) is valid for use in Hawaii.

We have used the NOAO 58 x 62 InSb array and the National Solar Observatory McMath telescope to image the deepest photospheric layers of three active regions at the 1.63 micron opacity minimum. At 1.63 microns, faculae are darker than the photosphere, with a measured contrast of at least 2% at positions on the disk between approx. 0.75

Observations of solar active regions with the Very Large Array (VLA) and with the Solar Maximum Mission (SMM) satellite are providing new insights to the origin and prediction of solar activity. This activity includes bursts or flares that can disrupt the tracking of satellites, distort communication systems, and interfere with high-flying aircraft. These bursts originate in coronal loops that are uniquely studied with the VLA (at 20 cm wavelength) and with the SMM (at X-ray wavelengths). The research summarized includes discussions of coronal diagnostics, solar burst precursors, and energy build-up in coronal loops. We also discuss novel discoveries of coherent burst mechanisms on nearby active stars other than the sun. VLA observations of a solar noise storm (at 92-cm wavelength) have resolved the sources of storm radiation for the first time. Future VLA observations with the new 92-cm system will provide new information about the unknown processes that trigger and continually excite solar noise storms, while also providing insights to the unknown triggering mechanisms for decimetric bursts and coronal mass ejections. This report includes reprints, preprints or abstracts of articles prepared under this grant, Keywords: Solar radio radiation, Solar X rays; Preburst heating; Magnetic triggering of solar bursts; Compact variable sources; Coronal diagnostics; Solar noise storms; High-resolution microwave observations.

Observations of low degree modes of solar oscillation have been made at The Wilcox Solar Observatory for more than a decade. The set of observations from 1977 through 1986 are currently being examined. First test the stability of the p mode frequencies for modes of degree l=2-5 in each year. A marginally significant trend of a decrease in p mode frequencies of 0.06 microHz per year. Examined the continuity of the observed signal at 160.01 minutes. The previously reported phase stability is no longer present. However, due to uncertainties in calibration one can not exclude the reality of the reported signal.

The solar-terrestrial environment is monitored by a wide variety of scientific sensors located throughout the world and on space platforms. This second edition of the Directory of Solar-Terrestrial Physics Monitoring Stations presents detailed information for 1163 sensors used to monitor this environment. The scientific disciplines covered are solar and interplanetary phenomena, ionospheric phenomena, flare-associated events, geomagnetic variations, aurora, cosmic rays, airglow, and miscellaneous related phenomena such as atmospheric ozone. The following summary station tables are also given: master station list, alternate name list, listing by subdiscipline, and a list of stations closed since the first directory was published in 1977. In addition, a status report summarizes the relative decrease in solar-terrestrial physics monitoring activities since 1976. Keywords: Solar-terrestrial physics; Solar phenomena; Solar activity; Cosmic rays; Aurora; Geomagnetic activity; Ionospheric phenomena; Solar-terrestrial data; Solar-terrestrial monitoring; Interplanetary phenomena; Solar flares; and Airglow.

A description of the new Lockheed 57-actuator segmented active mirror is given. Observational results from four observing runs at Sac Peak with the active mirror are presented, along with a Fourier analysis of these results. The active mirror is shown to be capable of producing near-diffraction limited results in average seeing conditions. Keywords: Solar observatories; Segmented mirrors; Active mirrors; Adaptive optics; Wavefront sensor.

Research accomplishments include: 1) Research on 'flaring arches'; 2) A collaborative paper on 'Anomalously Dense Flare Loops' was published; 3) The footprints of the 'giant arches' previously discovered by Z. Svestka were found in hydrogen alpha observations from the Big Bear Solar Observatory and the Udaipur Solar Observatory, 4) Several sets of new observations showing a relationship between cancelling magnetic fields and flares were acquired and analyzed; 5) A new hypothesis is advanced that cancelling magnetic fields are necessary condition for the energy build-up to solar flares

We describe a powerful cross-correlation technique for the precise measurement of the proper motion of tracers seen on successive images of a time series of solar granulation. The cross correlation is defined as a function of position in the image, within a spatially localized apodization window. The time average of the spatially localized cross correlation gives a measure of the displacement that is not biased by atmospheric seeing. The window size and the seeing define the effective resolution of the vector displacement determination. We use this cross-correlation technique to analyze an 80 minute run of white- light observations made at the Sacramento Peak Vacuum Tower Telescope. Even though geometric distortion due to atmospheric seeing is instantaneously at least 10-20 times larger than the observed scale of the large-scale solar displacements, 100-1000 m/s , its net contribution to the 80 minute average of proper motions is RMS < 20 m/s. The measured vector displacement clearly show solar mesogranulation and super-granulation flows having spatial scales from 10 min to 40 min. The measured amplitude of these flows is significantly larger than the RMS 100 m/s noise which we attribute principally to solar granulation evolution. Keywords: Solar atmospheric motion. Reprints., Pub. in the Astrophysical Jnl., v333 n1 part 1 p427-442, 1 Oct 1988.

There have been two major gains in this period: First, the completion and analysis of round-the-clock observations in cooperation with the Huairou Observatory in the People's Republic of china, which enabled us to obtained the first longterm observations of weak solar magnetic fields, and the application of the magneto-optic filter to the measurement of magnetic fields. The observations in collaboration with China have enabled us to make observations for as long as seven days of solar magnetic regions, with only short interruptions when the sun could not be seen from the U.S. and China. The stronger elements of the chromospheric network are rather long lived, lasting about 70 hours. In fact, it is possible that they last longer, because although the shape changes it is often possible to still identify a magnetic entity. The second important result was that one could find definite evidence of magnetic field cancellation occurring after solar flares. The increased time coverage enabled us to check the evolution of the magnetic fields during this period. The other development, the use of the magneto-optic filter, is full of promise for the future. This filter is made by using a glass tube filled with potassium which is placed in a strong magnetic field. It enables us to obtain a passband of about 30 milliAngstroms at the potassium resonance line at 7699 Angstroms. This filter will take magnetograms of sensitivity higher than that obtained before; the only limitation is on the position of the passband which is fixed until we obtain an electromagnet to vary the magnetic field strength. The magneto-optic filter will enable us to go much further in the measurement of solar magnetic fields.

Multiple Wavelength Observations of Flaring Active Regions; Very Large Array Observations of Solar Active Regions III. Multiple Wavelength Observations. High-Resolution Observations of Solar Radio Bursts at 2, 6, and 20 cm Wavelength; The Circularly Polarized Sun at 12.6 cm Wavelength; Bright, Rapid, Highly Polarized Radio Spikes from the M Dwarf AD. Leonis; Possible Detection of Thermal Cyclotron Lines from Small Sources within Solar Active Regions. Observations of Preburst Heating and Magnetic Field Changes in a 20 cm Loop; The Structure of a Solar Active Region from RATAN-600 and Very Large Array Observations; The Solar-Stellar Connection; Short Term Prediction of Solar Bursts - Radio Wavelength Precursors; VLA Observations of Flare Build Up in Coronal Loops on the Sun and Solar Type Stars; VLA Observations of Narrow-Band Decimetric Burst Emission; VLA Observations of Solar Active Regions at Closely Spaced Frequencies: Evidence for Thermal Cyclotron Line Emission; VLA observations of Compact, Variable Sources on the Sun; Flare Stars and Solar Bursts; High Resolution In Time and Frequency; Coronal Plasmas On The Sun and Nearby Stars; Coronal Diagnostics; Narrow-Band; Millisecond Radio Spikes From the Dwarf M Flare Star AD Leonis; VLA Observations of a Solar Noise Storm., Appendix to rept. no., ADA203873.

This paper is organized as follows. First we discuss the historical background before the SMM (Solar Maximum Mission) launch. Next we discuss the recent developments made by observations with SMM, Hinotori, and other contemporary satellites and ground-based observatories. Based on these observations, we classify solar flares into the following five classes: thermal hard X-ray flares, nonthermal hard X-ray flares, impulsive gamma-ray/proton flares, gradual gamma-ray/proton flares, and quiescent filament-eruption flares. We also discuss the roles of filament eruptions in flare development. Finally we discuss theoretical ideas related to processes occurring in different classes of flares., Also supported by NASA.

Investigations have included observations and analysis of the solar and interplanetary quantities relevant to geomagnetic activity. The operation of the Wilcox Solar Observatory and analysis of the synoptic observations of magnetic fields has constituted a significant part of the effort. Emphasis has been to attempt to understand the timing and severity of geomagnetic disturbances by understanding the solar mechanisms responsible for the origin of solar wind variations. Keywords: Large scale magnetic fields, Solar corona, Spectroscopic analysis, Solar, Cycle.

During most of solar cycle 21 the large-scale photospheric field rotated more rapidly in the northern hemisphere than in the southern. the large- scale northern field rotated with a 26.9 day period (synodic), was centered at 15 degress N, and covered a latitude zone about 24 degrees wide. The large-scale southern field rotated with a periodicity of 28.1 days, was centered at 26 degrees s, and covered a latitude zone about 32 degrees wide. Our analysis showed rotational power at only a few discrete latitudes and frequencies in each hemisphere. The center of each peak lies near the sunspot differential rotation curve. The largest scale field contributes to the configuration of the coronal and interplanetary magnetic field (IMF). The strength of the first harmonic of the northern field suggests that this structure may be related to the 4-sector pattern observed in the IMF polarity. The southern field had much lower power at the first harmonic of the solar rotation rate and so would contribute only to a 2-sector structure in the IMF. These results were discovered in Fourier analysis of photospheric synoptic charts obtained at the Wilcox Solar Observatory from 1976 - 1986 and confirmed a higher resolution maps from the National Solar Observatory. Mt. Wilson magnetic field measurements from solar cycle 20 show a similar north-south asymmetry. Keywords: Solar rotation; Solar magnetic field; Solar asymmetry. (JHD)

Global convective flows in the solar convection zone have been predicted by theoretical interpretations of the global-scale ordering of magnetic fields and activity centers and by theoretical analyses of rotating convection zones. Direct evidence of these flows in the photosphere has not previously been found despite several long-term efforts. The signatures of such flows have now been detected by analyzing the daily series of low-resolution Dopplergrams obtained at the Wilcox Solar Observatory at Stanford Univ. The signatures are patterns of alternating east and west flows with amplitudes on the order of 25 m/s and longitudinal extent of about 30 degrees. The patterns move across the solar disc at approximately the solar rotation rate and have lifetimes of at least several rotations. Boundaries of the fast and slow flows are often associated with large magnetic active regions.

Ephemeral active regions (ER) have been identified and counted for selected periods from 1970 to mid-1984 using the daily, full-disk photospheric magnetograms taken by the National Solar Observatory. The number of ephemeral regions varies nearly in phase with the solar cycle. At solar minimum, ER are distributed almost uniformly in latitude; by solar maximum, peaks in the latitude distribution are observed in the sunspot zones and in higher latitude bands. In the quiet sun, 37% of the He I lambda 10830 'dark points', used as a proxy for X-ray bright points (XBP), are associated with ER; 63% overlie bipoles that appear to be the chance encounter of opposite polarity network. The percentages are somewhat different in coronal holes; 21% of the dark points in He I are associated with ephemeral regions and 79% with bipoles that apparently result from chance encounters of flux. The dark points observed in the quiet sun and in coronal holes, vary anti-correlated with the solar cycle. Little relations was found between the areal density of He I dark points and ephemeral regions within the boundaries of coronal holes and parameters of the high speed solar wind streams associated with coronal holes. This study suggests that (1) ephemeral regions are not small active regions and that they may be primarily a surface phenomena, possibly resulting from convection interacting with sub-photospheric fields, and (2) He I 'dark points', and therefore, XBP, are more often associated with the encounter of existing opposite polarity network flux, the occurrence of which is related to the amount of mixed polarity areas which varies inversely with the solar cycle. (Author)

The problem of imaging the solar surface is considered. A theoretical study is presented that indicates that traditional adaptive optic techniques are of limited usefulness for solar imaging. A new method for adaptive optic image sharpening for extended sources is described. The incoming wavefront has added to it controlled amounts of various aberrations. The image quality is sensed and an error signal derived that allows iterative corrections to the wavefront to be determined. The measure of the image quality that is used is an integrated power spectrum of the image plane distribution. It is shown that quantity is maximized for an unaberrated input wave. Results sharpening under conditions of moderately severe turbulence.

Observations of solar active regions with the Very Large Array (V.L.A.) led to a new understanding of the origin and prediction of the solar bursts which disrupt communication systems and interfere with high-flying aircraft. The V.L.A. was used to delineate the temperature and magnetic structure at different heights in coronal loops, and the magnetic field strength was also determined. Much of the visible solar disk was resolved at 20 cm wavelength with 2.6 in. angular resolution. Snapshot maps at intervals of 3 seconds were used to specify changes in the temperature and the magnetic field before and during solar bursts. These snapshot maps were used to investigate the flow of plasma within coronal loops during solar bursts. Postflare loop systems were similarly investigated. Our V.L.A. observations provided new information on coronal heating and emerging magnetic loops that may trigger the emission of solar bursts. Keywords include:Coronal loops - Radio radiation, Polarization, Evolution, Temperature, Density, Magnetic field, Thermal cyclotron lines, Very large array, Solar bursts - Origin, Prediction, Preburst heating, Changing magnetic fields, Coherent maser-like emission, Flare build-up, Nearby stars - Coronae, Bursts, Slowly varying emission, International ultraviolet explorer satellite.

Structure and evolution of large scale photospheric and coronal magnetic fields in the interval 1976-1983 were studied using observations from the Stanford Solar Observatory and a potential field model. The solar wind in the heliosphere is organized into large regions in which the magnetic field has a componenet either toward or away from the sun. The model predicts the location of the current sheet separating these regions. Near solar minimum, in 1976, the current sheet lay within a few degrees of the solar equator having two extensions north and south of the equator. Soon after minimum the latitudinal extent began to increase. The sheet reached to at least 50 deg from 1978 through 1983. The complex structure near maximum occasionally included multiple current sheets. Large scale structures persist for up to two years during the entire interval. To minimize errors in determining the structure of the heliospheric field particular attention was paid to decreasing the distorting effects of rapid field evolution, finding the optimum source surface radius, determining the correction to the sun's polar field, and handling missing data. The predicted structure agrees with direct interplanetary field measurements taken near the ecliptic and with coronameter and interplanetary scintillation measurements which infer the three dimensional interplanetary magnetic structure. During most of the solar cycle the heliospheric field cannot be adequately described as a dipole., Sponsored in part by Grants NGR-05-020-559 and NSF-ATM77-20580.

Spectrometric airglow measurements during the solar eclipse of 26 February 1979 have yielded first-of-a-kind residual airglow spectra during the total phase of the eclipse. The temporal variations of the O2 infrared atmospheric features and the He multiplet at 1.083 microns are consistent with current excitation/emission models; however, the OH Meinel emission levels decreased almost monotonically by totality, in contrast with expectations based on most code predictions. Twilight transition, nightglow and auroral data were also acquired to characterize airflow conditions during the general timeframe of the eclipse. The twilight-transition results compare favorably with similar earlier measurement by other investigators. (Author)

In the last few years it was learned that the solar corona and the solar wind are three-dimensional. That is, the deviations from spherical or even cylindrical symmetry and first-order effects, that are important for our basic description and indeed physical understanding of the coronal expansion. The recognition of this simple fact has been a slow process; perhaps because it complicates the mathematical treatment. Even a quick look at the solar corona reveals a highly structured medium with large density gradients. It has long- almost for a century as a matter of fact (Bigelow, 1889)- been suggested that magnetic fields are the fundamental agent that controls the shape of the corona and determines the inner boundary conditions for the solar wind escape. Only recently have we recognized how dominant is the role of large-scale magnetic fields in determining the global structure of the solar wind. The highly successful 'SKYLAB Workshop on Coronal Holes' that was conducted last year has been important for the general acceptance of the new three-dimensional description of the structure of the corona and the interplanetary magnetic field. Zirker (1977) and Hundhausen (1977) have aptly summarized the insight resulting from this work. The present review will attempt a further synthesis based on a broader database than that available to the Workshop. We will attempt to provide a unified viewpoint recognizing that such an attempt is usually associated with a certain degree of oversimplification.

PROPHET denotes a class of radio propagation forecast terminals which represent the culmination of an 11-year development effort at the Naval Ocean Systems Center (NOSC) under the SOLRAD satellite program. The system is unique in that it provides a real-time link between Navy operations personnel and a worldwide network of ground-based and satellite-borne solar-terrestrial environment monitors. This link is used to generate - via distributed data processing - electromagnetic system performance predictions in formats specially tailored to meet the operational requirements of the user. An initial implementation of PROPHET has provided - over a 3-year period - highly successful hf frequency/antenna management support to the Technical Control Facility of the Naval Communication Station at Stockton, CA. This executive summary provides a concise overview of the evolution, structure, function, and accomplishments of PROPHET, together with recommendations for ways in which the PROPHET technology can be applied to recognized operational requirements fo the Navy. Technical details are elaborated in volume II. (Author)

A daily radio patrol was maintained at Manila Observatory. The cm sun was monitored at discrete frequencies: 8800, 4995, 2695, 1415 and 606 MHz, while the dekameter sun was monitored by a sweep frequency interferometer in the band 24-48 MHz. Microwave bursts accompanying six proton events are shown. (Author)

Major flare eruptions in solar active regions create geophysical disturbances which may seriously disrupt Air Force communication and surveillance systems. This report discusses interferometric observations of solar active regions which show that small-scale, highly circularly polarized sources dominate solar emission at radio wavelengths. The small-scale sources emit intense circularly polarized radiation immediately prior to and during the eruption of solar flares, whereas the circularly polarized emission remains at a lower, constant level whenever the active regions are quiescent and not erupting. The circular polarization of the flare precursors indicates a direct connection with changing magnetic fields in the solar active regions. The precursors reflect changing magnetic fields which may trigger subsequent flare eruptions, and these trigger sources may serve as reliable flare predictors. Studies of the changes in circularly polarized emission during the flare eruptions suggest that the flare eruption process is also the result of changes in magnetic fields. This report further discusses the synthesis mapping technique in which simultaneous solar observations with as many as 55 different interferometer pairs have been used to produce radio wavelength maps of active regions with second of arc angular resolution.