Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for January 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 This report marks the formal end of the original SXT contract (NAS8-37334). The Extended Mission Effort has now been negotiated but the definitive contract has not yet been implemented. It is in the process of being defined and approved. No funding has consequently been made made available and the contractor is using his own funds to support all activities including the Co-I's. << Solar Activity >> Solar activity was low for the month of January. There was a C1 flare on 3-Jan-96 at 17:10 UT. However, the flare occurred during the Yohkoh operations New Year's holiday. Although the spacecraft was operated, there were a limited number of telemetry downlinks during this time and this flare was not observed. Yohkoh traced active regions NOAA 7939, 7943 and 7944. << Campaigns >> SXT supported Dave Rust's Flare Genesis balloon payload which was launched from the South Pole on 7 January 1996. The balloon launch was successful and the pointing appeared to work very well, but some difficulties with balloon payload did occur during the mission. As a result, the balloon telescope was pointed at Sun center for much of the mission. During times of low solar activity, plans were made to direct Page 2 the SXT partial field-of-view to the north solar limb to try to observe plume activity in coordination with the Mees observatory's cardinal stripes program. There were no filament targets during most of the month. << Science >> The SXT science program has reached a very mature stage in the course of the mission. The range of topics that are being investigated with Yohkoh data continues to be broad and increasingly quantitative. The science reports from the co-investigators includes topics ranging from flare studies to diffuse coronal emission studies, and Loren Acton's recently submitted solar activity paper submitted to the Coolstar 9 proceedings. Lemen spent the month of January at ISAS. He worked as the SXT Chief Observer for three weeks and worked with Hugh Hudson as the Yohkoh SSOC (Duty Scientist) one week. The operations are going very well at ISAS, but are still somewhat labor intensive, owing to the nature of the ground operations of the Yohkoh mission. January was a very nice month to be at ISAS because of the overlap with several other visitors. Richard Schwartz (GSFC) was present for three weeks to analyze the HXT data from the 13 Oct 1995 flare during which HXT was operated in calibration mode, and thus, obtained higher spectral resolution data, instead of high-time resolution spatial data. Richard has submitted a paper to upcoming HEAD meeting. Other visitors included Richard Canfield (U of Hawaii), Robert Rosner, Vinay Kashyap, Christof Litwin (U of Hawaii), and David Webb (Hanscome AF). Lemen worked with Hudson and Webb on the 21 Feb 1992 and the 28 Dec 1992 large scale eruption events, which are likely to be the X-ray signatures of a CME. An abstract has been prepared for the Bath meeting. Nariaki Nitta continues to analyze superhot flares. He is analyzing 50 flares that have hard X-ray spectra extending to 100 keV. He plans to compare the results with less energetic events. Nitta has submitted an abstract to the Bath meeting. Jean-Pierre Wuelser continues to work as the Mees duty scientist for about one week per month. He is working on a paper that describes the Yohkoh pointing and the transit of Mercury. The Mercury transit provided a rare opportunity to calibrate the relationships between the SXT, HXT and Yohkoh spacecraft coordinate systems. The first draft is being modified according to feed back from co-authors Hudson, Kosugi, Nishio, Masuda, and Morrison. Gary Linford spent the month of January in Japan and accomplished a very important rearrangement of the databases. Because of the size of certain supporting databases, the files are distributed on several different NFS mounted disks at ISAS. Gary managed to simplify and consolidate the databases, which should make the system more tolerant to failure and will provide for easier expansion and management. Greg Slater continues his synoptic map data analysis project. He also supported Yohkoh operations Page 3 remotely on a routine basis. Greg also supervised the distribution of the new Yohkoh poster, which appears to be in high demand. << Publications>> Karen Harvey recently updated the publication list. We had intended to include it in this report, but given the length of the current report, we intend to append it to the February report. The refereed list currently contains 227 references. << 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). Plans are being made to include a web form that will allow interested people to order Yohkoh posters through the homepage. The new Yohkoh poster appears to be very popular. A few hundred posters were handed out at the American Physics Teachers conference in Reno, NV. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. There has been no further increase in the SXT straylight 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 Sun is very quiet. On 2-3 February a 24-hour CCD Bakeout was performed. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT bitmap error 06-Jan-96 Pass 3; 960106-1032 recovered in the same pass SXT bitmap error 22-Jan-96 Pass 1; 960122-0412 recovered in the same pass SXT bitmap error 31-Jan-96 Pass 1; 960131-0104 recovered in the same pass Page 4 << Data Flow >> ------------------------------------------------------------------------------ Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Oct-93 167063 77742 686934 262728 949662 363062 27.38 Nov-93 8504 3864 42953 5849 48802 23896 32.87 Dec-93 5898 3047 21128 13297 34425 13001 27.41 Jan-94 6934 2804 28567 10960 39527 13746 25.80 Feb-94 7000 2840 23021 5819 28840 11257 28.07 Mar-94 7736 2627 69273 3733 73006 31464 30.12 Apr-94 6142 2741 22707 3390 26097 12338 32.10 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 5549 2120 23768 1506 25274 12723 33.48 Feb-96 0 0 0 0 0 0 0.00 Total 350863 151795 1455844 360127 1815971 726705 28.58 Number of Full Frame Images Received: 350863 Number of Observing Region Images Received: 1815971 Total: 2166834 Approximate Number of Shutter Moves/CCD Readouts: 3807056 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 Page 5 than the number of images received plus those lost. Page 6 << Engineering Summary Table >> -------------------------------------------------------------------------------- Month Avg Dark Level # of Dark Spikes CCD Warmings Front Optical (DN) (e/sec) Over 48 Over 64 High / # Support Trans Temp /Days Temp (%) Nov-93 45.33 555.8 32047 3210 23.8 / 3 19.7 N/A e Dec-93 45.92 578.1 38515 3101 19.2 N/A Jan-94 46.00 580.9 39074 3088 22.5 / 2 20.3 N/A Feb-94 46.03 582.1 40449 3246 19.3 N/A Mar-94 45.92 578.0 39715 3420 18.2 N/A Apr-94 45.97 579.9 41302 3721 25.2 / 3 17.8 N/A 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 50.85 762.7 137531 8827 21.3 N/A Feb-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-JAN-96 and 31-JAN-96 HUDSON 1-JAN-96 * 1-JAN-96 1 2-JAN-96 31-JAN-96 * 30 (total of 31 days) LEMEN 8-JAN-96 31-JAN-96 * 24 (total of 24 days) LINFORD 2-JAN-96 31-JAN-96 30 (total of 30 days) SAVY 1-JAN-96 * 31-JAN-96 * 31 (total of 31 days) CANFIELD 17-JAN-96 31-JAN-96 * 15 (total of 15 days) ---------------------------------------------------------------- Grand Total of 131 days for 5 people NOTE: The "*" signifies travel that actually ends after 31-JAN-96 SXT Foreign Travel between 1-FEB-96 and 29-FEB-96 HUDSON 1-FEB-96 * 29-FEB-96 * 29 (total of 29 days) LEMEN 1-FEB-96 * 7-FEB-96 7 (total of 7 days) NITTA 10-FEB-96 29-FEB-96 * 20 (total of 20 days) SAVY 1-FEB-96 * 29-FEB-96 * 29 (total of 29 days) CANFIELD 1-FEB-96 * 2-FEB-96 2 (total of 2 days) ---------------------------------------------------------------- Grand Total of 87 days for 5 people NOTE: The "*" signifies travel that actually ends after 29-FEB-96 Respectfully submitted, James R. Lemen Frank M. Friedlaender Page 8 ================================================================= Montana State Univ Activity Report for November 1995-January 1995 ================================================================= This was a busy and productive trimester for the MSU solar group. One highlight occurred in November when Daniel Goldin, the NASA administrator, visited Montana State University, accompanied by Senator Conrad Burns of Montana. A presentation was made by David Alexander on YOHKOH which was well appreciated by the administrator -- who carried away an SXT video. Loren Acton spent November at ISAS and worked on several items to improve the ability to correct SXT images for observational artifacts -- including the increased stray visible light produced by the August 1995 entrance filter failure. He noted that the filter ruptures have appreciably increased the SXT sensitivity at longer wavelengths, a benefit for observing the fainter corona of solar minimum. In December and January, Acton concentrated on further analysis of the temperature structure of the diffuse corona for papers with Sturrock and with Culhane and Foley, as well as processing long-term solar x-ray radiance data for several research efforts. He has discovered remarkably tight correlations between total SXT x-ray radiance and parameters, such as Ca-K, 10.7cm emission, and active regions fields -- parameters that emphasize active regions. The correlation with, e.g., full disk fields is considerably poorer. One very interesting result is that the mean coronal temperature, determined from SXT filter ratios, for the 53 Carrington rotations (4 years) varied from 1.9 to 3.3 MK but does not decrease systematically over the period. There is no correlation between temperature and any other parameter. However, a pseudo pressure from the temperature times the square root of the emission measure correlates strongly with x-ray flux and other activity parameters. David Alexander has continued work on large-scale eruptive events, non-thermal line broadening and gamma-ray studies, and 3-D projection of x-ray loops. He attended the first Solar Magnetic Initiative Workshop at the High Altitude Observatory in December. On an extended trip to the UK, Alexander worked at MSSL on the analysis of SXV and SXT data over the lifetime of the Yohkoh mission, looking at the correspondences between heating events in SXT with those seen in SXV over the long term. During a visit to the Rutherford Appleton Laboratory TRACE/SoHO/Yohkoh collaborations were discussed. As a result, the CDS planning software is to be installed at MSU to design CDS experiments. During the period Alexander gave talks at MSU and MSSL and co-founded an Astrophysical Journal Club at MSU. November saw the initiation of the Yohkoh Public Outreach Project (YPOP) at MSU under the leadership of David Alexander and Dave Thomas, Professor of Mathematics with a kickoff meeting of the YPOP Creative Design and Definition Team. We are quite excited about the opportunity to collaborate with our Lockheed colleagues on this 3 year program to Page 9 make the SXT results accessible to educators and the public over the Internet and in other forms. Physics graduate student Michelle Larson will be the key person in implementation of this program, as part of her doctorate in physics education. Dr. Lee Bargatze accepted a temporary appointment with the MSU solar group to work on creation and study of SXT "wide-field" images. These are to be prepared from the YOHKOH/SXT offpoint observations of 1993 and 1994. The MSU students involved in the solar program have been active as follows: Brian Handy (thesis student): Continues to work on the TRACE program at Lockheed Palo Alto, is defining his thesis topic, and provides computer systems assistance for the solar group. Mark Weber (thesis student): Visited HAO for study of coronal effects of CMEs, continuing study of differential rotation of the corona, working on a paper with Bai of Stanford on coronal holes and solar wind, accepted position of deputy chairman of the local organizing committee for the Chapman Conference on CMEs which will take place at MSU in August '96. David Weston: Worked with Acton on paper for Solar Physics on spectral averaging of the SXT point spread function parameters and another paper on SXT response to model solar differential emission measures. The latter work is intended to permit estimation of improved formal uncertainties on SXT x-ray irradiance. Brian Welsch: Working with David Alexander on studies of filling factors of the solar transition region. Michelle Larson: Gave a paper on YPOP at teacher's convention in Reno and attended the "CAN" PI meeting in West Virginia -- a meeting of those involved in this NASA internet access program. Michael Kellen: Working with Loren Acton on SXT dark frame correction statistics and helps with computer systems work. Kevin Wright: Undergraduate student working with David Alexander on simulation of solar convection. Adina Ragenovich: Computer science major using the sun for a master's degree project on computer visualization of physical processes. Papers submitted during the contract period: "Spectral averaging of the point spread function for Yohkoh's SXT", D. C. Weston and L. W. Acton, submitted to Solar Physics. (Jan 1996) Page 10 "A long-duration solar flare with mass ejection and global consequences", H.S. Hudson, L.W. Acton, and S.L. Freeland, submitted to The Astrophysical Journal. (Dec 1995) "Interpretation of SXT data concerning the diffuse corona", P.A. Sturrock, M.S. Wheatland, and L.W. Acton, submitted to The Astrophysical Journal. (Dec 1995) "X-ray and other Solar Activity Parameters for November 1991 to November 1995", L. W. Acton, to be published in Proceedings of the 9th Coolstar Workshop, Florence, Italy, October 1995. Page 11 ======================================================================= Univ of Calif, Berkeley Activity Report for November 1995-December 1995 ======================================================================= At UCB work is continuing on the variation of the temperature and emission measure in the decay phase of flares. In addition to the work on the variation of average temperature and total emission measure, we have been modeling the DEM, or differential emission measure, using GOES and SXT data. The DEM is calculated in three different ways: (1) Forward-fitting, using parameterized models and minimizing Chi^2 to obtain the appropriate parameters, (2) 2nd-order regularization, which inverts the temperature response integatsion to find a smoothed DEM, and (3) using SXT only to find a spatial DEM, assuming that each pixel is isothermal, and binning the emission measures. Each method has its advantages and disadvantages, and only the forward-fitting method fits the data as well as could be hoped for. It will be necessary to include BCS data to get a better DEM. The results for all of these methods are qualitatively similar; higher temperature plasma cools faster than lower temperature plasma. This is true if the dominant cooling mechanism is conduction. For radiative cooling the decay time is longer for higher temperatures. We can estimate the variation of the cooling time as a function of temperature, and we find that it is not consistent with either pure conductive or radiative cooling. It may be a mixture of both types of cooling, or cooling plus extended heating of the plasma. Some of the results of this study were presented at the Fall AGU meeting in San Francisco on 15 December, 1995, a paper is being written, and further results of this work will be presented at the reconnection workshop in England in March. Page 12 ============================================================= Univ of Hawaii Activity Report for November 1995-January 1995 ============================================================= 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 enabled by travel to Japan, presentation of results at meetings, and preparation of manuscripts. Operational support for SXT and campaigns was provided by Hudson at ISAS, by Nitta and Douglass at Mees, and by Canfield, Jiao, LaBonte, and Metcalf in Manoa. Wuelser relocated to Lockheed so that his critical skills were still available to the SXT project. Reardon left to go to graduate school in Italy. Significant campaigns supported during the reporting period include the Flare Genesis balloon flight from 7-26 January. Wuelser worked on putting MCCD and MWLT quality control data on-line. Reardon, as part of his study of eruptive and quasi-eruptive events in H-alpha and soft-x-rays with Shibata and Tonooka, digitized the H-alpha coronagraph data for several more events that were well observed by the Mees Patrol Coronagraph. This data will be coaligned with the Yohkoh/SXT data to study the different dynamics of the hot and cool plasma in various types of eruptions. Reardon also improved his software for measuring velocities from quiet H-alpha line profiles. This IDL software will be used by Shimojo in Japan, who is analyzing Mees MCCD H-alpha data for several active regions that showed a large number of x-ray jets. Reardon also continued working on measuring long-term properties of bright-points in the quiet Sun by using Carrington de-rotated data. Reardon plans to continue this work with Karen Harvey using a five day series of derotated data from March '95. Jiao finished preparation of short SXT images movies and co-registered SXT Partial Frame optical images and soft X-ray images related to about 70 magnetograms. He also received all related Kitt Peak magnetograms and brightness maps. He improved his IDL codes which co-align SXT images and magnetic field data. His proposal for San Diego Supercomputer allocation for 1996 was approved. He also re-wrote IDL codes to produce magnetic data relating to the hight of formation of the spectral line. Metcalf continued to work with J. Li, Canfield, and Wuelser on a study of the spatial relationship between hard x-ray emission during flares and photospheric current systems. The study confirms that HXR emission normally occurs at the edges of photospheric currents. He worked with G. Fisher on a project comparing SXT non-flare images and photospheric vector magnetograms. The study will look for correlations between SXR intensity and various measures of non-potentiality in the magnetograms in an effort to understand the mechanisms of coronal heating. He continued work on the new WWW Home page for Mees Observatory. As well Page 13 as providing archival data, the system allows interested people to access the Mees data at URL http://www.solar.ifa.hawaii.edu/mees.html in near real time. He collaborated with B. Schmieder and L. van Driel-Gesztelyi on vector magnetograms for AR 7205 (June 1992). The study examines the evolution of the active region in the photosphere and corona, using full-disc white-light observations from Debrecen, vector magnetograms from Mees Observatory, and soft and hard X-ray observations from Yohkoh. He began a project with Hudson, comparing MEM and pixon HXT light curves for the 1992 January 13 limb flare. They are looking at differences in the light curve for the loop top source computed with the two reconstruction algorithms. Finally, he worked on the IVM H-alpha linear polarization study, and the paper is near completion. Hudson continued to accumulate information on the remarkable M-class flares that occurred 1995 13 and 20 October, which provided some of Yohkoh's best observations of metric and longer-wavelength type II bursts. These observations may help significantly in defining the propagation of the responsible disturbance very near the impulsive core of a flare; radio observations of course do not have sufficient angular resolution to study this region. He also completed the paper on superhot flares presented at the Goddard conference in August. He helped several visitors to ISAS, including Ron Moore, Dave Webb, Vinay Kashyap, Christof Litwin, and Bob Rosner. Moore and Webb in particular are interested in eruptive events (20 October is a fine example), and we hope that their efforts will help to bring the SXT "coronal dimming" observations to public view. Canfield worked on a paper with A. Pevtsov on the role of magnetic reconnection and helicity in the Yohkoh flare of 08 May, 1992. He worked at ISAS during the last half of January, gave a paper at the Hitachi meeting, and gave an ISAS seminar. PLANS FOR FEBRUARY AND MARCH Jiao will begin to use his supercomuter time to study one or more active regions in preparation for the Huntsville meeting. Metcalf will submit the IVM H-alpha polarization paper to co-authors and to the Astrophysical Journal. He will start work on a new version of the SXT pixon code. He will continue work on the new Mees WWW home page. He will continue collaborations with J. Li, H. Hudson, B. Schmieder, L. van Driel-Gesztelyi, and G. Fisher. Hudson's top priorities will be (a) to assist Franta Farnik in his study of hard-spectrum events, and (b) to work on a review paper co-authored with L. Culhane. He will also present the "anti-reconnection" point of view on flare development (not really an enviable task!) at the Yohkoh magnetic reconnection meeting in Bath, England (March), along with a poster paper on coronal dimming. He will also describe Yohkoh observations of coronal mass ejections at the Chapman conference on magnetic storms (February). Page 14 Canfield plans to finish the paper with A. Pevtsov on the role of magnetic reconnection and helicity in the Yohkoh flare of 08 May, 1992. He will work on the paper with Jing Li and Metcalf on the spatial relationship between hard X-ray footpoints and vertical electric currents, and on two papers with Pevtsov on the magnetic helicity of photospheric fields and coronal structures. PUBLICATIONS AND PRESENTATIONS DURING NOVEMBER, DECEMBER, AND JANUARY Papers submitted "Yohkoh observations of flares with superhot properties", H.S. Hudson and N. Nitta, Proceedings of GSFC Conference on High-Energy Solar Physics. "Comparison and relation of HeI 10830 nm two-ribbon flares and large-scale coronal arcades observed by Yohkoh," K.L. Harvey, A. McAllister, H. Hudson, D. Alexander, J.R. Lemen, and H.P. Jones, Solar Wind 8. "What is the Spatial Relationship between Hard X-Ray Footpoints and Vertical Electric Currents?", Jing LI, Thomas r. Metcalf, Richard C. Canfield, Jean-Pierre Wuelser, and Takeo Kosubi, submitted to Proceedings of GSFC conference on high-energy solar physics. Papers accepted "Pixon-Based Multiresolution Image Reconstruction for Yohkoh's Hard X-Ray Telescope", Thomas R. Metcalf, Hugh S. Hudson, Takeo Kosugi, R. C. Puetter, and R. K. Pina, Astrophys. J. (July 20, 1996) "A Test of a New Flare Loop Scaling Law Using Yohkoh SXT and GOES Observations", Thomas R. Metcalf and George H. Fisher, Astrophys. J. (May 10, 1996) "Energetic particles and coronal mass ejections in the high latitude heliosphere: Ulysses-LET observations", V. Bothmer, R.G. Marsden, T.R. Sanderson, K.J. Trattner, K.-P. Wenzel, A. Balogh, R.J. Forsyth, B.E. Goldstein, Y. Uchida, and H.S. Hudson, Geophysics Research Letters. "H-alpha Surges and X-Ray Jets in AR7260", Richard C. Canfield, Kevin P. Reardon, K. D. Leka, K. Shibata, T. Yokoyama, and M. Shmimojo, Astrophys. J (June 20, 1996). Papers published "Large-scale coronal active phenomena in Yohkoh SXT images, I", Z. Svestka, F. Farnik, H.S. Hudson, Y. Uchida, P. Hick, and J.R. Lemen, Solar Phys., 161, 331-363 (1995). "Solar flares: no myth", Hugh S. Hudson, EOS Transactions 76, 405 (1995). "X-Ray Bright Point Flares Due to Magnetic Reconnection", Page 15 van Driel-Gesztelyi, L., Schmieder, B., Cauzzi, G., Mein, N., Hofmann, A., Nitta, N., Kurokawa, H., Mein, P., and Staiger, J. Solar Phys., 163, 145 (1996). Presentations given "Pixon-Based Multiresolution Image Reconstruction for Yohkoh's Hard X-Ray Telescope", Thomas R. Metcalf, LPARL Colloquium, November 5, 1995. "Signatures of Convection in the Helicity of Solar Magnetic Fields" R.C. Canfield, ISAS Seminar, January 31. "Magnetic Reconnection, Magnetic Helicity, and Solar Coronal Eruptions", Richard C. Canfield, Kevin P. Reardon, and Alexei A. Pevtsov, Workshop on Solar Flares and Related Disturbances, January 23, 1996 Abstracts submitted "EVOLUTION OF A DELTA--GROUP IN THE PHOTOSPHERE AND CORONA", G. Csepura, L. van Driel-Gesztelyi, B. Schmieder, and T. Metcalf, 8th European Conference on Solar Physics, Thessaloniki, Greece, 12-18 May 1996. "3-D Active Region Magnetic Fields", L. Jiao, A. N. McClymont, R. C. Canfield, and z. Mikic, for MHD Workshop, Huntsville, April 1996. "Observational Problems for Standard Flare Models based on Magnetic Reconnection", Hugh S. Hudson and Josef I. Khan, submitted to submitted to Yohkoh Conference on Observations of Magnetic Reconnection in the Solar Atmosphere, Bath. "The High Energy Solar Spectroscopic Imager - HESSI", B.R. Dennis, R.P. Lin, R.C. Canfield, C.J. Crannell, A.G. Emslie, G.D. Holman, G.H. Hurford, J.C. Ling, N.W. Madden, and R. Ramaty, submitted to S.P.I.E., 1996. "Yohkoh Soft X-ray Observations of Coronal Depletion and Ejection", submitted to Yohkoh Conference on Observations of Magnetic Reconnection in the Solar Atmosphere, Bath. "Coronal Dimming in Soft X-rays", Hugh S. Hudson, James R. Lemen, and David F. Webb, submitted to Yohkoh Conference on Observations of Magnetic Reconnection in the Solar Atmosphere, Bath. "Magnetic Chirality and Coronal Reconnection", R.C. Canfield, A.A. Pevtsov, and A.N. McClymont, submitted to Yohkoh Conference on Observations of Magnetic Reconnection in the Solar Atmosphere, Bath. Page 16 ============================================================ Stanford Univ Activity Report for November 1995-January 1995 ============================================================ In collaboration with Sturrock and Acton, Wheatland has continued on the analysis of SXT data for a region of diffuse (quiet) corona observed on May 9, 1992. An Abel inversion procedure is used to derive the radial temperature profile for the region, under the assumption of spherical symmetry. The results show that the non-thermal energy responsible for heating this region is deposited beyond 1.5 solar radii (the limit of the observations). Sturrock finds it significant that the heat flux, derived from the temperature profile, is related to the estimated pressure at the base of the region according to pressure-heat-flux relation obtained some time ago by Moore and Fung (Solar Physics, 23, 78, 1972). Sturrock has also been thinking over the implication that nonthermal energy is released at the tops of the magnetic loops. A possible interpretation is that heating is due to high-frequency standing Alfven waves on the flux tubes that make up the region. The transverse amplitude of these oscillations would be greatest at the loop top. The transverse oscillations would excite sound waves that rapidly damp. Wheatland also continued work on a study of the avalanche model of solar flares. The idea is that avalanche models reproduce the statistics of flare occurrence for a single active region (AR) on the Sun. To compare the model with observations, it is necessary to integrate over the distribution of ARs. This calculation is performed using observationally derived AR size distributions. The resulting model distribution of flare frequency as a function of energy is a power law at low energies, but steepens with energy. This result is being compared with the `observed' distribution derived from ISEE-3/ICE data (courtesy Jim McTiernan). A reasonable agreement may be obtained, although the observed distribution is better represented as a simple power law. Roumeliotis continued work on an adaptive smoothing algorithm that performs signal reconstruction without artificially smoothing sharp transitions in the actual signal. One application of this algorithm will be the recovery of smoothed X-ray images from noisy SXT images, while preserving the sharp edges associated with coronal loops. During the reporting period, Jim Klimchuk began to model the structure of twisted flux tubes using his 3D force-free magnetic field code. He is attempting to verify his earlier conjecture that twist is responsible for the uniform thicknesses observed in coronal loops. His paper with Lisa Porter on the dependence of pressure, temperature, and heating rate on loop length appearing in the Astrophysical Journal (1995, ApJ, 454, 499). Graduate student Slava Glukhov has obtained temperature and density data for the coronal helmet streamer observed by SXT on Jan. 24, 1992. The Page 17 data are compared with a thermodynamic equilibrium model. A geometrical model of the helmet, which can explain the discrepancy between the data and the equilibrium model, has been identified. Taeil Bai, in collaboration with Acton and others, confirmed that a persistent coronal hole was responsible for quasi-periodic variations observed by Ulysses. The Ulysses spacecraft discovered that solar wind speed, energetic particle fluxes, and the interplanetary magnetic field varied quasi-periodically with a period of about 26 days during the spacecraft's mid latitude passage south of the ecliptic plane in 1992P1993. The origin of the variation has been attributed to the 26-day period of a stable corotating interaction region and the heliospheric current sheet. The actual sidereal period was estimated to be 26.4 days, after correcting for the effect of the approach of Ulysses toward the Sun. The corresponding synodic period, 28.5 days, is much longer than the rotation periods of features in the activity belts. Since high-speed solar winds originate from coronal holes, the existence of a stable coronal hole lasting for more than two years can be inferred from the Ulysses data, but it has not been verified until now. By analyzing soft X-ray data observed by the Yohkoh satellite, we have confirmed the existence of a stable coronal hole in the southern hemisphere. Stackplots of synoptic maps of Yohkoh soft X-ray brightness show that a lobe protruding from the southern polar coronal hole persisted since 1992 until now (the middle of 1995). Its synodic rotation period was 28.5 days during the Ulysses observation of the "26-day" periodicity, but it has been shortened recently. Page 18 =========================================================================== Solar Physics Research Corp. Activity Report for November 1995-January 1995 =========================================================================== Activities in the last three months are as follows: (1) Analysis of data obtained during several XBP collaborative campaigns. The preliminary results of this analysis will be presented at a meeting on `Observations of Magnetic Reconnection in the Solar Atmosphere' in March 1996 as an invited talk on "Observations of X-ray Bright Points". Aspects of the analysis currently planned to be included in this talk are the time scales of variabililty of XBP, quantifying their association with structures and changes in the underlying photospheric magnetic fields, and their association with HeI 1083 nm dark points and H-alpha structures. (2) Continuation study with Alan McAllister, Hugh Hudson, David Alexander, and Jim Lemen of the comparison and association of the large-scale coronal arcades and two-ribbon flares observed in the NSO/KP He I 10830 data. Current work involves an investigation of the evolution of transient coronal holes associated with the X-ray arcades that follow the eruption of a filament. A paper on the results of a detailed study of the transient coronal holes, deduced from both HeI 1083 nm spectroheliograms and the Yohkoh SXT images, for two events, 21 March 1993 and 14 April 1994, was completed and submitted for publication in The Proceedings of the 16th National Solar Observatory/Sacramento Peak Summer Workshop on `Solar Drivers of Interplanetary and Terrestrial Disturbances'. The several-year video of SXT FFI images is now being surveyed to locate other transient coronal hole events for further study combining with the HeI 1083 nm spectroheliograms. Objectives of this study are to determine the nature of coronal hole change (enlargement, formation, contraction), the timing of coronal hole changes relative to the X-ray arcade formation, and evolution of the transient coronal hole. Events located at disk positions located within about 30 degrees of disk center are being considered for this study, as they will give the best estimates of the positions of coronal hole boundaries both before and during the events. In many cases the events are partially obstructed by overlying coronal structures, so techniques are being developed that will allow an establishing the coronal hole boundaries hidden under brighter coronal structures. A second paper, "Coronal Structures Deduced from Photospheric Magnetic Field and He I 10830 Observations", was finalized, following referee comments, and submitted for publication in Geophys. Res. Let. as part of the Proceedings of the SolWind 8 meeting held in June 1095. (3) Preparation of NSO/KP full-disk magnetograms and He I 10830 spectro- magnetograms for SXT investigators for studies of the magnetic field and He I 10830 structures associated with X-ray structures. (4) Continued collection and updating of the bibliography of Yohkoh papers. Page 19 --------------------------------- Papers accepted for publication: --------------------------------- "Coronal Structures Deduced from Photospheric Magnetic Field and He I 1083 Observations": K. L. Harvey, Geophys. Res. Let., in press (1996). "Comparison and Relation of He I 1083 nm Two-Ribbon Flares and Large-Scale Coronal Arcades Observed by Yohkoh SXT": K. L. Harvey, A. McAllister, H. Hudson, D. Alexander, J. R. Lemen, and H. P. Jones, in R. Smartt, S. Keil, K.S. Balasubramaniam (eds.), The Proceedings of the 16th National Solar Observatory/Sacramento Peak Summer Workshop on `Solar Drivers of Interplanetary and Terrestrial Disturbances', held at NSO/SP October 16-20, 1995, in press. Page 20 ------------------------------------------------------------------------------- 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 February 1996 January 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 - 37334 -----------------------------------------------|------------------------------- 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 January 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 | 20 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office