Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for July 1996) OVERVIEW The YOHKOH Mission is a program of the Japanese Institute of Space and Astronautical Science (ISAS) with collaboration by the U. S. National Aeronautics and Space Administration and the U. K. Science and Engineering Research Council. The YOHKOH satellite was launched on 30 August 1991 from Kagoshima Space Center (KSC) in Japan. The purpose of this mission is to study high energy phenomena in solar flares and the Sun's corona. Under an international cooperative agreement, Lockheed, under NASA contract, is providing a scientific investigation using the Soft X-ray Telescope (SXT), one of the primary experiments of the mission. The SXT was developed at the Lockheed Palo Alto Research Laboratory in cooperation with the National Astronomical Observatory of Japan, and the Institute for Astronomy of the University of Tokyo. MAJOR PROGRAMMATIC ACTIVITIES IN THE MONTH Maintaining an effective program with high scientific output is our current challenge. Various materials are being prepared that will highlight the achievements to date and their basis for new discoveries in the increasing activity level of the solar cycle. A short video and a folio of relevant data sheets are currently in preparation. << Solar Activity >> Solar activity was low for most of the month except for a period of enhanced activity from AR 7978. This region produced the first X-class flare in a long time on 9 July 1996. Because of the timing with respect to the Yohkoh satellite night, it was not observed, but good observations were made of an M-class flare and smaller flares. Hal Zirin (BBSO) has pointed out that this region is an old-cycle region and that in general we are observing surprisingly few new-cycle regions. AR 7978 developed sunspots with had an area of more than 400 millionths, and a delta magnetic configuration. It disappeared suddenly at the W limb, implying a low-lying soft X-ray structure. It also reappeared suddenly on 25-July (as AR 1981) at about the same level (but thus far without the flares). This was a good opportunity to study an isolated major active region. << Campaigns >> There were several mini-campaigns conducted with SOHO during the month, Page 2 but some had to be postponed because of the strong activity from AR 7978. A plan for deep off-pointed exposures is being prepared in collaboration with SOHO JOP 045. In general there are now many opportunities for Yohkoh and SOHO to work together, and we would like to stay as closely in touch as possible. For Yohkoh operations, there is a text file accessible with "finger campaign@isass0.solar.isas.ac.jp | more" or the Web at "http://www.space.lockheed.com/SXT/homepage.html" which also lists the current SXT Chief Observer. << Science >> Hugh Hudson has pointed out that a good science question emerges from the data acquired during the previous month. If one takes into account the X-flare that was observed on 9-July-1996, then the GOES light curve demonstrated a four decade variation in one month and a very lopsided solar corona. If the Sun can show an X-ray swing of four decades in one month, how come other stellar X-ray sources do not do this? James Lemen spent two weeks at ISAS where he assisted in SXT operations and finished preparations for his talk at the Western Pacific Geophysics Meeting, which was held in Brisbane, Australia. He spoke about two coronal dimming events: 21-Feb-92 and 28-Aug-92. Both events show evidence of dimming that is consistent with about 10^14 g being ejected out of the corona, and therefore, could be associated with the chromospheric mass ejection that is observed by whitelight coronagraphs. Lemen also worked with Alphonse Sterling at ISAS on his Te vs sqrt(EM) paper which is ready to be re-submitted to ApJ Supp soon. Tom Metcalf continued to work with G. Fisher and D. Longcope on the SoHO mini campaign comparing SoHO and SXT image with photospheric vector magnetograms. The project's goal is to study transient brightenings. He has started analyzing the IVM data from the first campaign. No results yet, but the IVM data look good. In the meantime, we had another campaign this month, but neither the weather in Hawaii nor the Sun cooperated nearly as well as for the first campaign. Metcalf also has been working on MEM and pixon HXT light curves for the 1992 January 13 limb flare. He concentrated on simulations designed to optimize the pixon code and to give me a handle on how the code behaves when there are both bright and faint sources in the field of view. A report on the simulation results will appear soon. Metcalf is working with Jing Li (UH) on the comparison of photospheric current density and soft and hard x-ray coronal emission and a paper is being prepared. Tom Metcalf, Don Mickey (UH) and Jean-Pierre, are working on an improved error analysis for the Mees H-alpha polarization paper which they plan to resubmit soon. Nariaki Nitta submitted his Bath conference papers entitled "A Study of Major Flares Observed by Yohkoh" which addresses frequent occurrences Page 3 of eruptions and hot regions, and casts doubt on interpreting double hard X-ray sources as coming from footpoints. While attending the SPD meeting in Madison, Nitta was able to have detailed discussions with Adriana Silva in order to complete the work for their APJ paper "Imaging the Chromospheric Evaporation of the 1994 June 30 Solar Flare" by Adriana V. R. Silva, Haimin Wang, Dale E. Gary, Nariaki Nitta and Harold Zirin. The paper has been submitted. Nitta is continuing work on his superhot flare paper. Serge Savy attended the COSPAR meeting which was held in Birmingham and spoke about new results on chromospheric evaporation. Serge Savy, Nariaki Nitta and Greg Slater continued their collaborative work with Jingxiu Wang, from Beijing, China. Wang has been at ISAS for three months. Just before returning to his home he gave a seminar at ISAS on 8 August 1996 entitled "Shrinkage of X-Ray Loops in AR7420". << Public Use of SXT Images >> We are continuing to make Yohkoh/SXT images available for a variety of uses. Efforts continue to make selected images available on the Lockheed SXT WWW homepage (http://www.space.lockheed.com/SXT/). We continue to receive requests for the Yohkoh posters (#2 and #3) by way of the form on the SXT homepage. Currently we receive requests via our homepage at the rate of 2 or 3 per day. The WEB access statistics in July were 38900 accesses and 805 Mbytes transferred, which represents about a 20% increase over the statistics for May and June. As a part of the YPOP (Yohkoh Public Outreach Project) Sam Freeland has put on line an enhanced IDL WWW movie making program that enables anyone to obtain a move of the last 30 days of full-disk SXT observations and recent partial frame observing regions. Plans are going forward to make a new video. This effort is being led by Keith Strong, Greg Slater, and Gary Linford. It will focus on various aspects of the solar cycle. David Alexander and James Lemen while at ISAS spent a week working on pages of a briefing package that is designed to highlight scientific results from the first five years of the Yohkoh mission. Many useful comments have been received which are now being incorporated in the preparation of the package. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. There has been no further increase in the SXT stray light since 16-Aug-1995. The quiet patrol image has been changed to Al/Mg (DPE=17) to try to improve the performance of the active region selection algorithm for times when the Page 4 Sun is very quiet. Yohkoh was not able to observe for a couple of days when a typhoon which went over Kagoshima prevented operation of the 20- meter antenna. On another occasion, SXT was also not operated for about one day as the result of a operation error at KSC. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT seu error 17-Jul-96 Pass 1: 960716-1237 recovered in pass 3 (9600716-1444) SXT bitmap error 19-Jul-96 Pass 1: 960619-1135 recovered in the same pass SXT seu error 29-Jul-96 Pass 1: 960729-0824 recovered in pass 2 (960729-0928) SXT bitmap error 30-Jul-96 Pass 5: 960730-1135 recovered in the same pass Page 5 << Data Flow >> ------------------------------------------------------------------------------ Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Apr-94 209277 95665 894583 305776 1200359 468764 27.76 May-94 7070 2679 25260 3040 28300 10862 27.74 Jun-94 7417 2738 36795 1996 38791 15760 28.89 Jul-94 7488 2941 50540 3275 53815 24153 30.98 Aug-94 7370 2337 35067 3993 39060 13485 25.66 Sep-94 7079 2552 25131 2855 27986 10677 27.62 Oct-94 7244 2497 25868 5884 31752 10319 24.53 Nov-94 6569 1941 26243 1956 28199 9293 24.79 Dec-94 6429 2456 26763 2583 29346 11904 28.86 Jan-95 6870 2349 26103 1699 27802 10211 26.86 Feb-95 6556 2545 23635 3825 27460 10111 26.91 Mar-95 5915 2082 21485 3448 24933 8485 25.39 Apr-95 6244 2266 22946 4493 27439 9688 26.09 May-95 7084 2884 29617 2647 32264 15331 32.21 Jun-95 7210 3087 25251 307 25558 12045 32.03 Jul-95 6418 4145 21180 1639 22819 15109 39.84 Aug-95 7683 2597 26115 2181 28296 10537 27.13 Sep-95 6546 2853 22006 1753 23759 10433 30.51 Oct-95 6937 3502 22177 3853 26030 13044 33.38 Nov-95 5745 2944 21252 517 21769 12119 35.76 Dec-95 6163 2615 24059 901 24960 11652 31.83 Jan-96 6474 2530 27015 1708 28723 14151 33.01 Feb-96 6200 2581 21380 890 22270 10773 32.60 Mar-96 6908 2869 25437 1460 26897 12274 31.33 Apr-96 7172 2124 45445 671 46116 18848 29.01 May-96 6925 2426 30272 1089 31361 12367 28.28 Jun-96 5804 1961 20849 950 21799 8106 27.11 Jul-96 0 0 0 0 0 0 0.00 Aug-96 0 0 0 0 0 0 0.00 Total 384797 164166 1602474 365389 1967863 790501 28.66 Number of Full Frame Images Received: 384797 Number of Observing Region Images Received: 1967863 Total: 2352660 Approximate Number of Shutter Moves/CCD Readouts: 4112151 NOTES: * The loss of images is mainly due to BDR overwrites, but there are also occasional DSN dumps which are lost. * It is common to have observing regions which contain more than 64 lines, which requires multiple exposures to make a single observing region image. This is why the number of shutter moves is larger than the number of images received plus those lost. Page 6 -------------------------------------------------------------------------------- Month Avg Dark Level # of Dark Spikes CCD Warmings Front Optical (DN) (e/sec) Over 48 Over 64 High / # Support Trans Temp /Days Temp (%) May-94 46.25 590.3 45476 3557 18.3 N/A Jun-94 45.83 574.6 39340 3547 17.8 N/A Jul-94 46.76 609.5 53417 3990 18.2 N/A Aug-94 46.98 617.6 57624 4050 25.2 / 3 18.2 N/A Sep-94 47.07 620.9 58580 4028 18.3 N/A Oct-94 47.34 631.3 64974 4346 19.0 N/A Nov-94 47.64 642.4 70877 4703 20.4 N/A Dec-94 47.82 649.1 74246 4917 21.5 N/A Jan-95 48.55 676.7 89758 5457 20.0 N/A Feb-95 48.70 682.1 92457 5781 25.2 / 3 20.5 N/A Mar-95 48.35 668.9 85527 5271 19.4 N/A Apr-95 48.72 682.8 93904 5627 19.1 N/A May-95 48.73 683.4 94000 5820 18.8 N/A Jun-95 49.08 696.3 100780 6281 19.6 N/A Jul-95 49.34 706.2 106408 6628 18.1 N/A Aug-95 49.72 720.4 114414 7101 19.5 N/A Sep-95 49.79 723.1 115165 7222 19.6 N/A Oct-95 50.29 741.9 126452 7911 20.2 N/A Nov-95 50.11 735.1 122163 7814 25.2 / 2 20.3 N/A Dec-95 50.19 737.9 123705 7927 22.6 N/A Jan-96 50.81 761.3 136197 8888 21.5 N/A Feb-96 50.67 755.8 133263 8705 22.5 / 2 21.5 N/A Mar-96 50.85 762.9 136982 8973 20.3 N/A Apr-96 51.14 773.6 142250 9500 19.9 N/A May-96 51.16 774.4 140697 10018 19.1 N/A Jun-96 51.45 785.3 145739 10476 21.3 N/A Jul-96 N/A N/A N/A N/A 0.0 N/A Aug-96 N/A N/A N/A N/A 0.0 N/A NOTES: * The dark current calculations are using full half resolution 2.668 sec images not taken in during the SAA. The dark current rate assumes a "fat zero" of 30.5 DN and a gain of 100 e/DN. * The entrance filter failure of 13-Nov-92 eliminated the capability of taking optical images, so the optical transmission is not available after Nov-92. It also caused an increase in the dark current signal, however some of the increase shown here is an increase in the readout noise and is not a function of exposure duration. Page 7 << Personnel Travel >> SXT Foreign Travel between 1-JUL-96 and 31-JUL-96 ALEXANDER 1-JUL-96 * 20-JUL-96 20 (total of 20 days) HUDSON 1-JUL-96 * 21-JUL-96 21 29-JUL-96 31-JUL-96 * 3 (total of 24 days) LEMEN 8-JUL-96 31-JUL-96 * 24 (total of 24 days) SAVY 1-JUL-96 * 10-JUL-96 10 24-JUL-96 31-JUL-96 * 8 (total of 18 days) WEBER 1-JUL-96 * 1-JUL-96 1 (total of 1 days) ---------------------------------------------------------------- Grand Total of 87 days for 5 people NOTE: The "*" signifies travel that actually ends after 31-JUL-96 SXT Foreign Travel between 1-AUG-96 and 31-AUG-96 HUDSON 1-AUG-96 * 9-AUG-96 9 17-AUG-96 31-AUG-96 * 15 (total of 24 days) SAVY 1-AUG-96 * 31-AUG-96 * 31 (total of 31 days) JIAO 1-AUG-96 31-AUG-96 31 (total of 31 days) ---------------------------------------------------------------- Grand Total of 86 days for 3 people NOTE: The "*" signifies travel that actually ends after 31-AUG-96 Respectfully submitted, James R. Lemen Frank M. Friedlaender Page 8 ================================================================= Montana State Univ Activity Report for June 1996-July 1996 ================================================================= MAJOR ACTIVITIES FOR JUNE AND JULY During the report period the MSU group supported Yohkoh operations, analyzed Yohkoh and ground-based data, presented results at scientific meetings, submitted manuscripts for publication, welcomed new personnel, and prepared for the Chapman Conference at MSU. Significant personnel changes took place. Alexander resigned from MSU to work for Lockheed-Martin as part of their Yohkoh and Yohkoh Public Outreach Program teams and SoHO/EIT research. Canfield resigned from Hawaii to join the MSU group to carry out observational research and analysis on the role of the solar dynamo and the convection zone in structuring coronal magnetic fields and current systems. Graduate student Meredith Wills finished her batchelor's degree at Harvard and arrived at MSU to begin graduate study. She will work with Acton on inter-comparison of X-ray irradiance measurements from various spacecraft. The MSU group supported Yohkoh operations in various ways. Weber spent one month at ISAS to help with SXT Chief Observer duties. Alexander spent three to help with SXT Chief Observer duties. Canfield served for one week as Mees Yohkoh Duty Scientist. Acton worked on software to model the accuracy with which we can convert SXT signals into solar irradiance in various wavelength bands. This is necessary for both SXT research and for publication of SXT data for the aeronomy community. He corresponded with Benz about an appropriate SXT sequence table for his next VLA campaign on fine structure of X-ray and radio emission from the quiet corona. He worked extensively on preparations for the Chapman conference, on preparations for the Yohkoh 5th anniversary, and on being a grandfather. Andrew Conway of the University of Glasgow visited to work with Alexander on hard X-ray coronal emission using kinetic theory of bremsstrahlung production from a range of injected electron distributions. Alexander continued to work with Giovanni Peres and MSU graduate student David Weston on soft X-ray line-of-sight effects in flares, taking into account 3-D effects as well as time dependence. They found that it is possible to produce loop-top sources in the SXT Be 119 filter using standard loop models, given the SXT temperature sensitivity and loop orientation effects. MSU graduate student Brian Welsch, working with Alexander, studied DEM distributions and their effect on inferred line widths. He found that a hot component at 30 MK does not have a significant effect on the line width determination. Together with Lemen, he put together the bulk of the Yohkoh fifth-anniversary briefing package. He worked on large-scale eruptive events for the Brisbane conference. He started the organization of a CDAW on HXT to be held early January at Lockheed-Martin. Page 9 Bargatze made two versions of wide field coronal images and investigated issues concerning data quality. He also finished delivery of images to Dan Baker of the University of Colorado and Joe Allen of the National Geophysical Data Center as part of their collaboration on space weather studies. Canfield worked on infrastructure matters associated with his relocation from Hawaii. He participated in the Solar Magnetism Initiative meeting at HAO in Boulder. Major components of SMI will modeling, observation, and analysis of the solar dynamo, near-surface structure, and the corona. Although the new instrumentation aspects are focussed on NSO's SOLIS project and full-disk vector magnetograms, the initiative will have many indirect benefits for Yohkoh and NASA space research. He continued to work with Jing Li on the second draft of "What is the Spatial Relationship Between Hard X-Ray Footpoints and Vertical Electrical Currents in Solar Flares", with Metcalf, Wuelser, and Kosugi. He worked on magnetic reconnection, magnetic twist, and solar coronal eruptions with Pevtsov and Reardon. Handy presented a talk at the Madison SPD meeting comparing various features of the SXT and SoHO/EIT data from the 7 March 1996 Polar Plume JOP. He worked with fellow graduate students Michael Kellen and Stephen Guimond to develop the capability at MSU to write optical CDs and got several new workstations, transferred from Hawaii, in operation with IDL and unix software. Handy spent a fair part of July studying coronal holes, in preparation for adopting a study of this phenomenon for a thesis topic. Weber spent the month of June at ISAS. In addition to performing SXT Chief Observer duties, he studied the straylight/terminator situation with Hudson, discovering orbital pointing drift since Acton's last analysis. He began analysis of the May-19 glitch, including lost data periods and open-shutter time estimates. Finally, he continued to provide remote assistance for the Chapman conference by coordinating development of the web page. In July Weber worked heavily on the Chapman conference and made some progress on analyzing recent "artifacts" of the SXT to consider susceptibility of the CCD to degradation. PLANS FOR AUGUST AND SEPTEMBER Acton will support the Chapman Conference and public outreach and manage the MSU SXT contract. Acton and Wills work on the inter-comparison of irradiance measurements from various spacecraft. Alexander will continue the collaborations with Khan, Welsch, and Weston, and will relocate to Lockheed Martin, effective September 16. Canfield will work on photospheric and coronal measurements of twist in magnetic fields and coronal structures and on the relationship between photospheric and sub-photospheric motions, on the one hand, and photospheric and coronal magnetic morphology, on the other. Weber will work on differential rotation of the soft x-ray corona and on a thesis plan. Page 10 PUBLICATIONS AND PRESENTATIONS DURING JUNE AND JULY Papers submitted "Magnetic Chirality and Coronal Reconnection", Richard C. Canfield, Alexei A. Pevtsov, and Alexander N. McClymont, Yohkoh Conference Proceedings, Bath meeting. Papers accepted "Reconnection and Helicity in a Solar Flare", by Alexei A. Pevtsov, Richard C. Canfield, & H. Zirin, ApJ., December 10 issue. Papers published "H-Alpha Surges and X-ray Jets in AR 7260", Richard C. Canfield, Kevin P. Reardon, K. D. Leka, K. Shibata, T. Yokoyama, & M. Shimojo, ApJ 464, 1016, 1996. Abstracts Submitted and Presentations "Large-Scale Eruptive Events", David Alexander, Western Pacific Geophysics meeting, Brisbane, July. "Loop-Top X-Ray Sources", David Alexander, ISAS seminar, July. Page 11 ======================================================================= Univ of Calif, Berkeley Activity Report for June 1996-July 1996 ======================================================================= J. McTiernan spent most of the last two months looking into the scattering of Xray photons by the ND filter, and exposure time effects in SXT flare images. Previously we had determined that the presence of the ND filter, on average, causes an increase in the width of the radial profile of flare sources of the order of 0.1 FR pixels. For equal corrected exposure times, The ND filter can also cause a reduction in the brightness in the brightest pixels by a few percent, with different values for different flares. There are also two exposure time effects, which systematically reduce the brightnesses observed for short exposures (which include ND filter images). The first was mentioned in the last bi-monthly report; back- ground pixels are more likely to be negative for shorter exposures. Some of the difference between background levels for long and short exposures is due to scattered X-rays from the source (there are more of these for longer exposures) but the difference does not typically show the flare time profile; there seems to be non-flare X-ray emission present, which is not accounted for by dark current subtraction. Also the compression and decompression algorithms systematically under- estimate the values of the brightness in dim pixels; those with original Data Numbers less than 64. This can be a major effect; for the flare of 17-feb-1992, near the flare maximum, 30 of the total emission is in pixels with DN<64 for the shortest exposures (0.07 msec). This causes an underestimation of the total brightness by 3 to 5% for those images. We are currently preparing a report in the form of a tutorial IDL program to illustrate these effects. This will be online by 10-Aug-96. J. McTiernan attended the AAS/SPD meeting in Madison, WI from June 9 to 16, and presented a paper titled "The Low Energy Cutoff of Nonthermal Electrons in Solar Flares Inferred from YOHKOH and GOES Observations". This work used SXT and GOES data to obtain the Differential Emission Measure early in the impulsive phase, and then used HXT data to look for a cutoff in the Hard X-ray profile, after the thermal emission into the HXT-LO channel was subtracted. It was determined that non-thermal emission is present in the HXT-LO channel during the impulsive phase, but that the cutoff in the electron spectrum is much higher than the cutoff in the photon spectrum. Further work on the DEM will include BCS data, and has been put on hold until the completion of the ND filter/ exposure time work. S.R. Kane attended the COSPAR meeting in Birmingham, England in July, and presented a paper on stereoscopic Hard X-ray observations using HXS, HXT and Ulysses. The results from this work indicated that there is no evidence for anisotropy in the HXR emission below 100 keV. In the same vein, S.R. Kane and J. McTiernan are collaborating with H. Nakajima of Nobeyama Observatory, comparing HXT and Ulysses results for the giant flare of 2-November-1992. Page 12 ============================================================= Univ of Hawaii Activity Report for June 1996-July 1996 ============================================================= MAJOR ACTIVITIES FOR JUNE AND JULY Our activities included support of Yohkoh operations and data analysis at ISAS, coordinated ground-based data acquisition (including designated Yohkoh campaigns) at Mees, collaborative analysis of Yohkoh/Mees data, and preparation of manuscripts. Operational support for SXT was provided by Nitta at Mees, by Jiao, and LaBonte in Manoa. Our colleagues Mickey at Manoa, Canfield at Montana State University, Wuelser and Metcalf at Lockheed, and Hudson at Solar Physics Research Corporation aided in advice and oversight of Mees operations. LaBonte worked with K. Reardon on a paper using the SXT to measure the energies of individual photons. This method is common in astrophysics and can provide measurements of coronal temperatures with only a single filter. He also worked with L. Acton, J. Lemen, and M. Morrison on understanding the on-orbit properties of the SXT CCD camera. He reduced some test observations made with SXT in April 1996 to verify the CCD gain constant. He restored the software environment of the UH workstation at ISAS to permit that machine to be used effectively. Jiao continued 3-D reconstruction of solar coronal magnetic fields (CMF) in AR6919, AR7220_7222, AR7123, AR7216, AR7123 and AR7321. For AR6919, Jiao tested computations based on data from only one polarity and compared the result based on data from the whole magnetogram. For AR7220_7222, Jiao tested reconstruction from several different boundary condition (BC) data sets. For example, the boundary data set can be composed from magnetograms of different pixel sizes; this will help to explore the convergence problem in calculation. The SXT images are taken for the AR7222, Jiao built up CMF based on vector magnetograms for AR7222, or combination of vector magnetograms for AR7222 and AR7220, or vector magnetograms for AR7222 and LOF magnetogram for AR7220. To study such results from different boundary magnetogram combinations will help to understand the behavior of code in sensitivity, error tolerance etc. to the BC. Delays in obtaining a visa have postponed until later in the year his visit ISAS for collaborative research, scientific presentations, and SSOC toban duty. PLANS FOR AUGUST AND SEPTEMBER LaBonte will complete the paper on single filter temperature measurements with K. Reardon. He will work with Hudson on the statistical description of the flare activity in the recent AR7891. Page 13 Jiao will continue his thesis work, under the guidance of A. McClymont, R. Canfield, and Z. Mikic, on three dimensional reconstruction of solar coronal magnetic field. He will try to study a few more ARs, if not all his datasets, in the next 2 months and do some analysis write-ups. PUBLICATIONS AND PRESENTATIONS DURING JUNE AND JULY Papers submitted RECONSTRUCTION OF THE THREE-DIMENSIONAL CORONAL MAGNETIC FIELD L. Jiao, A. N. McClymont, R.C. Canfield and Z. Mikic. Solar Physics. PROBLEMS AND PROGRESS IN COMPUTING THREE-DIMENSIONAL CORONAL ACTIVE REGION MAGNETIC FIELDS FROM BOUNDARY DATA A. N. McClymont, L. Jiao and Z. Mikic. Solar Physics. Papers accepted "The Imaging Vector Magnetograph at Haleakala", Mickey, D.L., Canfield, R.C., LaBonte, B.J., Leka, K.D., Waterson, M.F., and Weber, H.M., Solar Physics Papers published "The Prospects for Asteroseismology from Ground-Based Sites", 1996 Heasley, J.N., Janes, K., LaBonte, B.J., Guenther, D., Mickey, D.L., and Demarque, P., Pub. Astr. Soc. Pacific, 108, 385. Page 14 ============================================================ Stanford Univ Activity Report for June 1996-July 1996 ============================================================ Stanford Group Yohkoh Report for June and July 1996 The Sun exhibits many puzzling periodicities, including the quasi-biennial, and Rieger periodicities. These may represent global phenomena rather than phenomena localized in the convection zone, since there is some evidence that the neutrino flux exhibits the quasi-biennial periodicity, and since solar diameter measurements exhibit the Rieger periodicity. Peter Sturrock has proposed that these periodicities may be understood by a model of the solar core which is non-steady and non-spherically symmetric, so that nuclear burning drives hydrodynamic flows and flows in turn modulate nuclear burning. In order to explain the Rieger and quasi-biennial periodicities, a specific model with two interacting dynamical components is proposed. Specifically, an outer region of the core rotates with a period close to the Carrington sidereal period (25.4 days), and an inner region rotates with a period in the range 21-22.5 days. In collaboration with Gunther Walther of the Statistics Department at Stanford, Peter has searched for evidence of 21-22.5 day periodicity in data from the Homestake neutrino experiment, and has found evidence for a period of 21.3 days. Spectrum analysis of data from the more recent Gallax and Kamiokande solar neutrino experiments appears to confirm the reality of this finding. Peter Sturrock has submitted two papers to Nature, one on the theoretical model, and the other on the statistical analysis of the neutrino data. Roumeliotis has continued work on an improved method of vector magnetic field reconstruction of force free-fields on the solar corona. His approach is a novel variational method, which has given promising results in 2-D simulations performed for comparison with analytically calculable fields. A paper is being prepared on this topic. Mike Wheatland has drafted a paper describing the results of his collaboration with Peter Sturrock and Loren Acton on an analysis of SXT observations of two regions of extended, diffuse corona, and its implications for coronal heating in the quiet corona. He has also been working towards a theoretical understanding of the flare frequency-energy distribution, in particular what it reveals about energy storage and release in the solar corona. Page 15 =========================================================================== Solar Physics Research Corp. Activity Report for June 1996-July 1996 =========================================================================== Activities during this reporting period have been directed toward: Karen L. Harvey: (1) On June 1, 1996, Hugh Hudson joined SPRC. He will continue his work for Yohkoh in Japan as before. (2) During July, we attended A InterAgency Consultative Group Campaign IV (IACG-C4) Workshop on "Open and Closed Solar Fields and the Solar Wind" was held in Bern, Switzerland July 8-12. The workshop was organized by Hugh Hudson, Toni Galvin, Ruedi von Steiger, Karen Harvey and hosted by the International Space Science Institute (ISSI). This workshop provided a forum and an opportunity for members of the Solar Physics and Space Physics communities to interact in informal and congenial surroundings. It was organized around four subtopics that combine and compare solar observations by Yohkoh, the newly commissioned SOHO, and ground-based solar observatories with in-situ polar hole solar wind measurements by Ulysses and near-equatorial coronal hole solar wind measurements by WIND and IMP. Four specific topics for the workshop were considered through tutorials and hands-on comparison of a multitude data sets. * Empirical definitions of coronal holes Coronal holes may seem different at different wavelengths. For almost any research program that one could imagine, it would be nice to have working empirical definitions. At this workshop we can intercompare various kinds of data - 10830, EIT, Yohkoh - and perhaps learn how to do this. The definition based on He I 10830 observations can be found at http://flare25.solar.isas.ac.jp/~yohkoh/ISSI/ch_definitions. In addition, we compared the coronal hole boundaries determined from NSO/KP He I 10830 spectroheliograms with those deduced from the four EIT images. Our results can be found (thanks to Hugh) in the same WWW pages. * Physics of the flow The new LASCO data show fascinating details of structural development in the outer corona. UVCS is showing broad line profiles for heavy ions (order of 1000 km/s?) - what does this imply for the evolution of the thermodynamic properties, particle distribution functions, turbulent motions, etc.? * Coronal-hole temporal development on short time scales There is a great deal of new material coming from Yohkoh and now SoHO on transient disturbances. Dave Webb, for example, suggests that there Page 16 are four kinds of signatures in the X-ray counterparts of coronal mass ejections, all of them of course associated with arcade formation. Coronal mass-loss events often involve temporary or long-lived changes in the apparent boundaries of coronal holes. * Evolution of magnetic connectivity between the corona and the solar wind How good are the models, what physics is needed, can we now improve on the elementary method currently used to track interplanetary observations back to the Sun? Current models for solar-wind flow actually seem to work, but much work in identifying solar sources is still done using really simple approximations such as that of constant-velocity flow. With all this wonderful new data, and with the new modeling capabilities, can't we do better than that? A report of the workshop, which includes will be published in the form of WWW pages at and printed in the ISSI Reports series. A second workshop is planned for spring 1997. (3) Continued analysis of observations of XBPs obtained though a collaboration of several ground-based observatories and the Yohkoh SXT instrument, and SOHO in early April and late May 1996. In particular, during these two runs, the line profiles of He I 10830 and a nearby Si I line were recorded for every pixel in the scan area (512 x 512 arc-sec) at a cadence of 5 minutes using the NSO/KP spectromagnetograph. We are in the process of fitting the He I 10830 and Si I line profiles, using software developed by Matt Penn and Harry Jones, to deduce the chromospheric and photospheric velocity, the equivalent width, and line depth. These results will be compared with data from the SOHO CDS and SUMER instruments in the over 150 XBPs observed during these two campaigns. (4) Preparation of NSO/KP full-disk magnetograms and He I 10830 spectromagnetograms for SXT investigators for studies of the magnetic field and He I 10830 structures associated with X-ray structures. (5) Continued collection and updating of the bibliography of Yohkoh papers. Hugh Hudson: H. Hudson participated in Yohkoh operations at ISAS and spent most of his research time on the general subject area of the large-scale corona, including some help with the work of ISAS visitor Jingxiu Wang on shrinking structures in active regions. He attended the June AAS/SPD meeting in Madison, Wisconsin, and reported there on the SXT observations of soft X-rays related to the Type II bursts of 13 and 20 October, 1995. The successful detection of Type II bursts would almost complete the inventory of meter-wave coronal dynamical processes in soft X-rays. Much related work has been done by Kundu and his group and colleagues at Nancay, where the only meter-wave imaging observations. Hudson also helped to organize a small IACG-sponsored workshop on open and closed field lines in coronal holes. This workshop brought interplanetary and solar observers together at ISSI (Bern) for a week-long comparison of data. Hudson also gave a lecture on the "space parasol" concept Page 17 and continued to organize the Yohkoh weekly seminar at ISAS. Plans for August and September H. Hudson will attend the Chapman Conference on CMEs in Bozeman and carry out related research activities. This topic has been a main theme for Yohkoh research recently. SOHO has now been launched and is successfully operating (and producing spectacular coronal observations); in addition there are interplanetary observations from SOHO, Wind, and of course Ulysses. The period of overlapping data is rapidly becoming an ideal calibration interval for the calibration of solar coronal and interplanetary effects. The Chapman conference will no doubt generate many homework items in this area, and completing some of them will take top priority. Other Hudson research activities include the Type II bursts mentioned above, the "superhot flare" signatures, and time-series analysis of flare occurrence patterns. --------------------------------- Papers in submitted: --------------------------------- K. L. Harvey, "Observations of X-Ray Bright Points", in The Proceedings of `Observations of Magnetic Reconnection in the Solar Atmosphere', R.D.B. Bentley and J.T. Mariska (eds.), held March 20-22, 1996, Bath, UK (1996). Page 18 ------------------------------------------------------------------------------- NASA REPORT DOCUMENTATION PAGE (IN LIEU OF NASA FORM 1626) --------------------|--------------------------|------------------------------- 1. REPORT NO. | 2. GOVERNMENT | 3. RECIPIENT'S DR-01 | ACCESSION NO. | CATALOG NO. --------------------|--------------------------|------------------------------- 4. TITLE AND SUBTITLE | 5. REPORT DATE Monthly progress report - for the month of | 10 August 1996 July 1996 |------------------------------- | 6. PERFORMING ORG | CODE: O/91-30 -----------------------------------------------|------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- J. R. Lemen | TION REPORT NO: F. M. Friedlaender | |------------------------------- -----------------------------------------------|10. WORK UNIT NO. 9. PERFORMING ORGANIZATION NAME AND ADDRESS | Lockheed Palo Alto Research Labs B/252 |------------------------------- Solar & Astrophysics Laboratory O/91-30 |11. CONTRACT OR GRANT NO. 3251 Hanover Street, Palo Alto Ca. 94304 | NAS8 - 40801 -----------------------------------------------|------------------------------- 12. SPONSORING AGENCY NAME AND ADDRESS |13. TYPE OF REPORT AND Marshall Space Flight Center (Explorer Program)| PERIOD COVERED Huntsville Alabama 35812 | Progress report for the month | of July 1996 |------------------------------- |14. SPONSORING AGENCY | CODE MSFC / AP32 -----------------------------------------------|------------------------------- 15. SUPPLEMENTARY NOTES ------------------------------------------------------------------------------- 16. ABSTRACT The SOLAR-A Mission is a program of the Institute of Space and Astronautical Science (ISAS), the Japanese agency for scientific space activity. The SOLAR-A satellite was launched on August 30, 1991, to study high energy phenomena in solar flares. As an international cooperative agreement, Lockheed, under NASA contract, is providing a scientific investigation and has prepared the Soft X-ray Telescope (SXT), one of the two primary experiments of the mission. --------------------------------------|---------------------------------------- 17. KEY WORDS (SUGGESTED BY | 18. DISTRIBUTION STATEMENT AUTHOR(S)) Solar-A, X-ray, CCD, | Space Science, Solar Physics ------------------------|-------------|----------|-----------------|----------- 19. SECURITY CLASSIF. | 20. SECURITY CLASSIF. | 21. NO OF PAGES |22. PRICE (OF THIS REPORT) | (OF THIS PAGE) | | None | None | 18 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office