Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for October 1995) 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 The contract will now be extended to the end of December in order to accommodate the various funding and other administrative considerations.The new contract will then be concurrent with a calendar year schedule. << Solar Activity >> The first and last weeks of the month were marked by relatively low solar activity. However, during the middle two weeks of the month, Yohkoh observed NOAA 7912 which produced three M-class flares and eight flares above C5. The region itself was either a low-latitude new-cycle region or a reversed polarity Cycle-22 region. The M4.8 flare which occurred on 13 October at 05:10 was well observed from the beginning by Yohkoh and by BATSE. In addition, the HXT was being operated in CAL mode at the time, so this will produce good energy-resolved data from HXT. The event was also a type II burst, as reported at Hiraiso and at Culgoora. The SXT images show an unusual double ejection. << Campaigns >> There was a coordinated observing campaign called the "Chromospheric Activity and Coronal Loops" during 17-26 October which was organized by Brigitte Schmieder and Lidia van Driel-Gesztelyi. Yohkoh participated in this campaign and the SXT Chief Observer was involved in the selection of the target. Ground-based observers included Mees, Big Bear, Meudon, the Tenerife (the MSDP instrument), VLA (Rob Wilson), and Page 2 Irkutsk. Yohkoh was unable to participate for the last two days because of the Eclipse campaign. The solar eclipse on 24 October that was observed in central and south- east Asia was also observed as a partial eclipse during two orbits from the Yohkoh spacecraft. Many members of the Yohkoh team worked to plan for the special observations. Two graduate students, R. Kano and T. Yoshida, worked especially hard to plan and prepare the spacecraft table command loads. The observations were very successful and mpeg movies of the SXT data may be viewed at from the Lockheed homepage: http://www.space.lockheed.com/SXT/eclipse.html. Joe Gurman quickly copied the SXT movies of the eclipse to the Solar Data Analysis Center homepage and NBC picked up an early version of the movie and included it as a part of the NightlyNews coverage of the solar eclipse. Although the eclipse observations were very successful, a combination of factors having to do with the eclipse caused the attitude control system to transfer to safehold mode, even though this situation had been anticipated. The subsequent recovery required four days in total, during which routine SXT observations were interrupted. << Science >> The M-class flares of 13 October and 20 October, both extremely well-observed by Yohkoh, both produced Type II bursts observed by radiospectrographs at Culgoora and at Hiraiso. The soft X-ray observations, contrary to expectation, do not show concentric wave-like excitation radiating from the flare core resulting from adiabatic compression. The fast ejecta from the flares are instead anisotropic and complex in structure, apparently consisting of rapidly expelled magnetic loops. This suggests that Type II burst excitation, which extended to >400 MHz (density >3 x 10^9 cm^-3) in the 13 October event, may not require the formation of a shock wave near the source. B.V. Jackson (UCSD and STELab) and H. Watanabe (STELab) gave the Yohkoh seminar on 18 October. Their work deals with the increasing evidence that active regions produce direct effects on the solar wind, as observed by the IPS technique. The Yohkoh data are very helpful in elucidating any such connection. The traditional coronal green line and red line observations do not respond so well to the higher temperatures of active regions. The seminar caused a great deal of useful discussion, especially regarding the active-region expanding loops noted by Uchida et al. from the initial Yohkoh movie representations. Dr Ronald Moore, NASA-MSFC, continued his work on the filament eruption work. He has now identified seven events that will be included in a paper that he is beginning to prepare. Ron will be be at ISAS through the end of November funded by the ISAS visiting Professor program. << Publications>> Page 3 The following is an incomplete listing of work in progress on papers and presentations that include scientists that are supported by the NASA SXT contract. - Papers Published (2) - "A Novel Maximum Likelihood Method for Image Reconstruction with Increased Sampling", Roumeliotis, G., 1195, ApJ, 452, 944. "The Scaling of Heating Rates in Solar Coronal Loops", Klimchuk, J. A., and Porter, L. J., 1995, Nature, 377, 131. - Papers accepted (4) - "The Large-scale Eruptive Event of 1994 April 14", D. Alexander, K.L. Harvey, H. Hudson, J.T. Hoeksema and X. Zhao, accepted for publication in Geophysical research Letters (Solwind8 proceedings). "Coronal X-ray Jets Observed with Yohkoh/SXT": M. Shimojo, K. Shibata, T. Hirayama, L. Acton, H. Hudson, Publ. Astron. Soc. Japan, accepted. "Evidence for Current-Carrying Emerging Flux", K. D. Leka, R. C. Canfield, A. N. McClymont, L. van Driel-Gesztelyi, ApJ. submitted 1995 "Pixon-Based Multiresolution Image Reconstruction for Yohkoh's Hard-Ray Telescope", Thomas R. Metcalf, Hugh S. Hudson, Takeo Kosugi, R. C. Puetter, and R. K. Pina, Proceedings of the MaxEnt '95 Workshop, Sante Fe, July 31 - August 4, 1995. - Papers Submitted (7) - "Geometrical Considerations in Imaging the Solar Corona", D. Alexander and S. Katsev submitted to Solar Physics. "Coronal Structures, Local And Global", L. Acton submitted to for publication of Proceedings of IAU symposium 155. "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. "A Test of the Hawley et al Flare Loop Length Relationship", Thomas R. Metcalf and George H. Fisher, Astrophys. J. "Yohkoh SXT Observations of Prominence Eruption and Disappearance H. Tonooka, R. Matsumoto, S. Miyaji, S.F. Martin, R.C. Canfield, K. Reardon, to Magnetodynamic Phenomena in the Solar Atmosphere: Prototypes of Stellar Magnetic Activity, Makuhari, Japan (IAU 153). "A Long-Duration Solar Flare with Mass Ejection and Global Consequences", H.S. Hudson, L.W. Acton, S.L. Freeland, ApJ. Page 4 "Yohkoh Soft X-ray Observations of CMEs", H.S. Hudson, in Magnetodynamic Phenomena in the Solar Atmosphere: Prototypes of Stellar Magnetic Activity, Makuhari, Japan (IAU 153). - Presentations (5) - "Observations of Active Region Current Systems in the Photosphere and their Relationship to Solar Flares", Thomas R. Metcalf, The Origins of Solar Flares Revisited, Workshop, Irvine, October 23-25, "Hard X-ray Observations the Early Phases of Solar Flares", H.S. Hudson in NASA Workshop on Solar Flares (Irvine, California, Oct. 1995). "The Maximum Temperatures of Solar Flare Plasmas", H.S. Hudson, ISAS Seminar, 20 September 1995. "Magnetic Helicity: Kinky Business", R. C. Canfield, Colloquium, Dept. of Physics, Montana State University, 13 October 1995. "Signatures of Convection in the Helicity of Photospheric Magnetic Fields" A. A. Pevtsov, R. C. Canfield, G. A. Glatzmaier, Geophysical and Astrophysical Convection, Boulder, 10-13 October, 1995. - Abstracts submitted(3) - "Helicity Loading in the Eruptive Flare of 15:12 UT, 8 May 1992", A. A. Pevtsov and R. C. Canfield, American Geophysical Union meeting, San Francisco, 11-15 December 1995. "Signatures of Convection in the Helicity of Photospheric Magnetic Fields" R. C. Canfield and A. A. Pevtsov American Geophysical Union meeting, San Francisco, 11-15 December 1995. "The Yohkoh Data Analysis System", S. L. Freeland, M. D. Morrison, J. R. Lemen, Invited poster to the American Geophysical Union meeting, San Francisco, 11-15 December 1995. << 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. During the month of September over 14,000 Yohkoh files on the Lockheed homepage were accessed from over 900 sites. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. During the eclipse operations the spacecraft went into safehold because of a slight error in the planning. Then, a commanding error led to the need to reload some of the spacecraft software. Routine observations were interrupted for four days while the software was reloaded and the pointing system Page 5 checked. 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. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT bitmap error 06-Oct-95 Pass 1; 951006-0617 recovered in the same pass Page 6 << Data Flow >> ------------------------------------------------------------------------------ Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Jul-93 145086 67548 599750 246017 845767 314270 26.83 Aug-93 7628 3638 30705 3563 34268 17436 33.72 Sep-93 6875 2899 22697 5600 28297 11252 28.45 Oct-93 7474 3657 33782 7548 41330 20104 32.72 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 1472 855 4842 949 5791 3229 35.80 Nov-95 0 0 0 0 0 0 0.00 Total 327941 141469 1369430 354299 1723729 680396 28.30 Number of Full Frame Images Received: 327941 Number of Observing Region Images Received: 1723729 Total: 2051670 Approximate Number of Shutter Moves/CCD Readouts: 3602894 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 7 << 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 (%) Aug-93 44.20 513.6 21319 2598 25.2 / 3 17.2 N/A Sep-93 45.07 546.2 27469 2745 17.5 N/A Oct-93 45.40 558.6 31684 2982 17.7 N/A Nov-93 45.33 555.8 32047 3210 23.8 / 3 19.7 N/A 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 50.41 746.4 129286 8038 19.7 N/A Nov-95 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 8 << Personnel Travel >> SXT Foreign Travel between 1-OCT-95 and 31-OCT-95 List was Generated: 10-Nov-1995 08:00:34.00 PR_TRAV_SUMM Ver 1.0 29-Apr-92 ACTON 28-OCT-95 31-OCT-95 * 4 (total of 4 days) FREELAND 1-OCT-95 * 2-OCT-95 2 (total of 2 days) HUDSON 11-OCT-95 31-OCT-95 * 21 (total of 21 days) LEMEN 1-OCT-95 * 30-OCT-95 30 (total of 30 days) SAVY 1-OCT-95 * 31-OCT-95 * 31 (total of 31 days) SHING 1-OCT-95 * 31-OCT-95 * 31 (total of 31 days) SLATER 1-OCT-95 * 2-OCT-95 2 (total of 2 days) ---------------------------------------------------------------- Grand Total of 121 days for 7 people NOTE: The "*" signifies travel that actually ends after 31-OCT-95 SXT Foreign Travel between 1-NOV-95 and 30-NOV-95 List was Generated: 10-Nov-1995 08:00:40.00 PR_TRAV_SUMM Ver 1.0 29-Apr-92 ACTON 1-NOV-95 * 30-NOV-95 * 30 (total of 30 days) HUDSON 1-NOV-95 * 30-NOV-95 * 30 (total of 30 days) NITTA 13-NOV-95 30-NOV-95 * 18 (total of 18 days) SAVY 1-NOV-95 * 30-NOV-95 * 30 (total of 30 days) SHING 1-NOV-95 * 3-NOV-95 3 (total of 3 days) ---------------------------------------------------------------- Grand Total of 111 days for 5 people NOTE: The "*" signifies travel that actually ends after 30-NOV-95 Respectfully submitted, James R. Lemen Frank M. Friedlaender Page 9 ================================================================= Montana State Univ Activity Report for September and October 1995 ================================================================= The MSU group has been busy this bimester with work at ISAS, travel to meetings, organizing the Yohkoh Public Outreach Project, and scientific research. Alexander has completed and submitted for publication his work with Katsev on effect of thermal loop structure and viewing angle on SXT images. He is now concentrating on wrapping up his work on eruptive events. Acton is completing two review papers and is well along on the investigation of the temperature structure of the diffuse corona. He is working with Weston on a letter presenting the variation of the SXT point spread function parameters with temperature. Weber has provided information on coronal rotation during the south polar passage of Ulysses to Bai. This collaborative paper will shortly be ready for submission. The following bullets summarize the activities and status of solar work at MSU during the reporting period. SCIENTIFIC MEETINGS: Acton - Inter-Agency Consultative Group, Sapporo, Hokaido, Japan. The Structure and Dynamics of the Solar Atmosphere -- The BBSO Legacy, Big Bear Solar Observatory, CA. 9th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, Florence, Italy. Micro-workshop on Flares and CMEs, High Altitude Observatory, Boulder, CO Weber - Micro-workshop on Flares and CMEs, High Altitude Observatory, Boulder, CO SCIENTIFIC VISITORS: Dr.Craig DeForest, Stanford University Dr. Toshifumi Shimizu, HAO and NAOJ Ms. Meredith Wills, Harvard University Prof. Richard Canfield, University of Hawaii PUBLIC LECTURES: Acton- 5th graders of Emily Dickinson School, Bozeman. Alexander- Two Adult and Continuing Education classes on "Our Star the Sun" General solar talk to the Bozeman Astronomical Society. Talk on solar physics research at MSU to freshman Physics Majors. YOHKOH PUBLIC OUTREACH PROJECT (YPOP) Despite not yet having received funding for this project the YPOP Creative Design and Definition Team has been formed and the first meeting planned for 20 November. Michelle Larson will present talks on the MSU YPOP plans at a teachers meeting in Elko, NV, and at the meeting Page 10 of NASA "Cooperative Agreement Notice" principal investigators in WV. PUBLICATIONS "The Effects of Geometry in the Solar Corona", S. Katsev and D. Alexander, Journal of Undergraduate Research, 2, 157, (1995). "The Large-scale Eruptive Event of 1994 April 14", D. Alexander, K.L. Harvey, H. Hudson, J.T. Hoeksema and X. Zhao, accepted for publication in Geophysical research Letters (Solwind8 proceedings). "Geometrical Considerations in Imaging the Solar Corona", D. Alexander and S. Katsev submitted to Solar Physics. "Coronal X-ray Jets Observed with Yohkoh/SXT": M. Shimojo, K. Shibata, T. Hirayama, L. Acton, H. Hudson, Publ. Astron. Soc. Japan, accepted. "Coronal Structures, Local And Global", L. Acton submitted to for publication of Proceedings of IAU symposium 155. Paper on eruptive flare of 13 Nov 94 by H. Hudson, L. Acton and S. Freeland submitted to The Astrophysical Journal. MSU STUDENTS INVOLVED IN SOLAR RESEARCH Brian Handy, PhD student working on TRACE instrument development. Mark Weber, PhD student working on SXT data analysis. Michelle Larson, Phd student working on Yohkoh Public Outreach Project Adina Ragenovich, MS student working on computer visualization. David Weston, graduate research assistant. Brian Welsch, graduate research assistant. Michael Kellen, half time graduate research assistant. Kevin Wright, undergraduate working on modeling of solar convection WORK IN PROGRESS Acton - Review paper for proceedings of 9th Cool Star Workshop. Coronal temperature structure. Solar x-ray irradiance. MISCELLANEOUS David Alexander gave a well-received talk on solar programs at MSU to the NASA Administrator and Senator Conrad Burns in early November. Page 11 ====================================================================== Univ of Calif, Berkeley Activity Report for September and October 1995 ====================================================================== Here at UCB we are continuing work on the variation of the temperature and emission measure in the decay phase of flares. Previously we had noted that for SXT, plots of Log(T) vs. Log(EM)/2 (log(n) for constant Volume) have slopes of about 0.45 in the decay phase, with a FWHM of about 0.6; a slope of 0.5 would result from loop scaling laws. We have now compared the SXT curves with GOES curves for the same events and find that the GOES data shows different behavior; the peak GOES temperature is higher that the peak SXT temperature, and the GOES emission measure decays faster. Plots of Log(T) vs. Log(EM)/2 for GOES are much steeper in the decay phase than those for SXT, with slopes that are typically two or three times as large. Higher temperature plasma cools much faster than lower temperature plasma, this is true if the dominant cooling mechanism is heat conduction. For radiative cooling the decay time is longer for higher temperatures. We have written an IDL routine that will do combined fits for spectra from SXT, GOES and HXT (if thermal HXT-LO emission is present), and are using it to fit models of the emission measure that are power laws in temperature. This will enable us to obtain the energy loss time scale as a function of temperature. The results of this study will be presented at the upcoming Fall AGU meeting in San Francisco on 15 December, 1995. Page 12 ============================================================= Univ of Hawaii Activity Report for September and October 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 Judd, Nitta, and Douglass at Mees, and by Canfield, Jiao, LaBonte, Metcalf, Reardon, and Wuelser in Manoa. Funding ended for Judd at the end of October, leaving operation of the telescopes at Mees to Nitta and Douglass. Significant campaigns supported during the reporting period include the SPARTAN 201 - 3 Mission, the X-ray bright point and filament campaign, the Meudon-Yokhoh Chromospheric Observation campaign, and the October 24th eclipse. Reardon spent three weeks at ISAS in September working on a variety of Yohkoh topics. His primary objective was to work with Shibata and Tonooka on comparing eruptive prominences observed at the limb with the Mees H-alpha coronagraph and coincident full-disk SXT observations. This work made some good progress during this time, with some interesting cases of H-alpha and SXT emission seeming to come from the same volume of plasma. Based on a small sample of events, it appears that quasi-eruptives don't show the soft x-ray coronal dimming seen preceding eruptive events. Also during his stay at ISAS, Reardon, with the generous aid of LaBonte, performed a co-registration between Yohkoh/SXT quiet-sun observations and Ca II K full-disk observations in order to look for correlations in the network patterns in the two different levels of the solar atmosphere. The comparison of the two images is interesting, with some chromospheric network features showing up as enhancements in soft x-rays. But there is certainly not a one-to-one correspondence and it is impossible to predict the appearance of an image in one wavelength from an image the other wavelength. Reardon also began working with Koutchmy, Hara, and others on deep exposures of polar coronal holes. The goal of this work is to look for a connection between polar plumes and soft x-ray features in order to better understand what drives the high-speed solar wind at the poles. One interesting discovery from a series of data taken at the beginning of September was a series of several very faint x-ray jets that came from small polar x-ray bright points. These jets are extremely faint (~1 x-ray photon per 30 second exposure) and are only visible because of the almost non-existent x-ray background in the coronal hole. One wonders whether impulsive events such as these could be the source of the seemingly static polar plumes. To follow up on this finding Reardon, along with Hudson and Koutchmy and the rest of the eclipse committee, planned a series of observations for Page 13 the total solar eclipse of 24 October, 1995. During the eclipse, ground-based observers in the path of totality took white-light photographs that will allow the polar plumes to be well delineated. At the same time, Yohkoh/SXT took thirty-second exposures of both the north and south polar regions (latitudes above ~60 degrees). Comparison of the ground-based and Yohkoh data sets will attempt to see if there is a statistical correlation between the extrapolated footpoints of the white-light streamers and locations of transient brightenings in soft x-rays. A quick look at the SXT data shows that the coronal hole was well placed, making the background was very low again, and there are at least several x-ray bright points visible at the poles. Reardon also began developing a technique to measure the temperature of the coronal plasma from images through only one soft x-ray filter using statistical analysis. He collaborated with Shimojo, providing him with Mees MCCD H-alpha data for several active regions in which a large number of jets were seen. Using software provided by Reardon, Shimojo will derive H-alpha velocities from the H-alpha spectra. Finally, Reardon and Slater, in tribute to Yohkoh's fourth anniversary, prepared a large-scale display of the famous 8 May, 1992 Yohkoh/SXT image. The mural, measuring 15 feet by 10 feet, with the Sun over 8 feet in diameter, hangs in D-toh at ISAS. Jiao continued to prepare a short SXT animation and a co-registered SXT partial-frame optical image and soft X-ray image related to about 100 Mees magnetograms. He applied the pixon image reconstruction algorithm to some SXT images. The reconstructed image has some negative pixel values (unlike Maximum Entropy processing result) which may be large in magnitude while the initial image requires positive values. The new image generally needs to be further histogram-equalized or subjected to logarithm filters to look better. Overall, the pixon method removes the background cloud and reveals the underlying finer loop structures which are crucial for his later comparison of SXT images to theoretical magnetic field calculations. Working with S. McClymont, Jiao studied the multitasking environment and multitasking analysis tools at NCAR supercomputer center. Finally, working with Canfield and McClymont, Jiao also finished a proposal for San Diego Supercomputer time for 1996. Metcalf continued to work with Li and Canfield 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. Metcalf completed a collaboration with H. Nakajima on the 1992 June 28 and 1992 Nov 2 limb flares. Metcalf used the pixons method to compute HXT images for alignment with Nobeyama data for the event. Metcalf completed a collaboration with G. Fisher testing the Hawley-Fisher coronal loop scaling law using SXT data. This scaling law relates the coronal loop length to the flare rise time, decay time and the loop temperature. They have determined that the scaling law works well. Metcalf completed writing a paper on the HXT pixon reconstruction algorithm. Finally, Metcalf and Mickey worked on the new WWW Home page for Mees Observatory. We now have placed on line most of the HSP magnetograms from 1991 to the present. As well as providing Page 14 archival data, the system allows interested people to access the Mees data in near real time. The URL is http://www.solar.ifa.hawaii.edu/mees.html. Wuelser, with Hudson, Nishio, and Kosugi prepared a manuscript that covers the efforts in finding the best possible post-facto Yohkoh pointing information. The paper also includes the Mercury transit observations which were used to determine the SXT roll angle. Accurate pointing information is crucial for accurate SXT temperature observations, for co-aligning time series of Yohkoh images, and for co-alignment with a variety of ground-based imaging observations from radio interferometers, magnetographs, and other optical telescopes. Hudson, with Acton and Freeland, finished his study of the "aurora solaris" event of 13-Nov-95. This was a long-duration flare event for which a large volume of coronal mass clearly was ejected outwards at the beginning of the event. Although no coronagraph observations are available for this event, they believe (because of motions involved, as well as the reasonable estimated mass) that this represented a direct observation of the launch of a coronal mass ejection - the first such observation in X-rays, other than the "dimming" signature. This and related subjects were discussed at a CDAW-type meeting in Boulder, Oct. 24-26. In other activity Hudson presented a discussion of hard X-ray observations of flare onset at a workshop in Irvine, California, and also worked on the 3 October 1993 flare with F. Farnik. PLANS FOR NOVEMBER and DECEMBER Reardon will leave UH in mid-November, and will take up a position in Italy. He will be missed greatly, but we hope for continued contact via the WWW! Jiao will request Kitt Peak full disk magnetograms to match Mees data for 1991 and 1992 and finish up remaining SXT data processing of images to be compared with theoretical models. Metcalf plans to continue the analysis of the IVM H-alpha polarization data and will continue to write up the study. He will start work on a new version of the SXT pixon code. He will also continue to work on the new Mees Observatory WWW home page. Finally, he will continue collaborations with J. Li and R. Canfield on electron precipitation sites relative to regions of high current density and will begin a collaboration with G. FIsher studying the relationship between photospheric currents and coronal heating. Canfield will respond to referee's comments on the "surges and jets in AR 7260" paper with Reardon, Leka, Shibata and resubmit the revised manuscript and will work with Reardon on a manuscript about evidence for preflare "tether cutting" before the Nov 15 filament eruption. Hudson's major activity will be centered on the visit to ISAS by Len Culhane in the middle of November (review paper on "Solar X-rays") and on preparation for an AGU meeting in December and a Chapman Conference in Page 15 January. For the former, the subject matter may include the remarkable M-class flares that occurred on 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 disturbance very near the impulsive core of the flare; radio observations of course do not have sufficient angular resolution to study this region. Wuelser will move to the Lockheed SXT group in early November, and will continue to work on SXT and Mees data from California. PUBLICATIONS AND PRESENTATIONS DURING JULY and AUGUST Papers submitted "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. "A Test of the Hawley et al Flare Loop Length Relationship", Thomas R. Metcalf and George H. Fisher, Astrophys. J. "Yohkoh SXT Observations of Prominence Eruption and Disappearance H. Tonooka, R. Matsumoto, S. Miyaji, S.F. Martin, R.C. Canfield, K. Reardon, to Magnetodynamic Phenomena in the Solar Atmosphere: Prototypes of Stellar Magnetic Activity, Makuhari, Japan (IAU 153). "A Long-Duration Solar Flare with Mass Ejection and Global Consequences", H.S. Hudson, L.W. Acton, S.L. Freeland, ApJ. "Yohkoh Soft X-ray Observations of CMEs", H.S. Hudson, in Magnetodynamic Phenomena in the Solar Atmosphere: Prototypes of Stellar Magnetic Activity, Makuhari, Japan (IAU 153). Papers accepted "Evidence for Current-Carrying Emerging Flux", K. D. Leka, R. C. Canfield, A. N. McClymont, L. van Driel-Gesztelyi, ApJ. submitted 1995 "Pixon-Based Multiresolution Image Reconstruction for Yohkoh's Hard-Ray Telescope", Thomas R. Metcalf, Hugh S. Hudson, Takeo Kosugi, R. C. Puetter, and R. K. Pina, Proceedings of the MaxEnt '95 Workshop, Sante Fe, July 31 - August 4, 1995. Presentations given "Observations of Active Region Current Systems in the Photosphere and their Relationship to Solar Flares", Thomas R. Metcalf, The Origins of Solar Flares Revisited, Workshop, Irvine, October 23-25, "Hard X-ray Observations the Early Phases of Solar Flares", H.S. Hudson in NAS Workshop on Solar Flares (Irvine, California, Oct. 1995). Page 16 "The Maximum Temperatures of Solar Flare Plasmas", H.S. Hudson, ISAS Seminar, 20 September 1995. "Magnetic Helicity: Kinky Business", R. C. Canfield, Colloquium, Dept. of Physics, Montana State University, 13 October 1995. "Signatures of Convection in the Helicity of Photospheric Magnetic Fields" A. A. Pevtsov, R. C. Canfield, G. A. Glatzmaier, Geophysical and Astrophysical Convection, Boulder, 10-13 October, 1995. Abstracts submitted "Helicity Loading in the Eruptive Flare of 15:12 UT, 8 May 1992", A. A. Pevtsov and R. C. Canfield, American Geophysical Union meeting, San Francisco, 11-15 December 1995. "Signatures of Convection in the Helicity of Photospheric Magnetic Fields" R. C. Canfield and A. A. Pevtsov American Geophysical Union meeting, San Francisco, 11-15 December 1995. Page 17 ============================================================ Stanford Univ Activity Report for September and October 1995 ============================================================ Sturrock and Wheatland, in collaboration with Acton, have continued their analysis of SXT data for a region of diffuse (quiet) corona observed on May 9, 1992. An Abel inversion procedure has been used to derive the radial variation of electron number density and temperature for the region, assuming spherical symmetry. The results clearly demonstrate that the non-thermal energy responsible for coronal heating is being deposited at a greater height than half a solar radius (the limit of the observations). Two papers are in preparation. Sturrock and Wheatland have initiated a theoretical study of the avalanche model of solar flares. The motivation of the study is the following. Avalanche models are capable of reproducing the (power-law) energy distribution of flares, but this distribution is produced for a single avalanche system, which must be identified with a single active region (AR) on the Sun. The actual flare energy distribution for the avalanche model is the convolution of the individual AR power-laws with the energy distribution of ARs. This calculation is being performed subject to some reasonable assumptions and published statistics of AR distributions. Preliminary results suggest that the resulting model distributions maintain a power-law over several decades, but perhaps not the four decades or more necessary to match observations. Roumeliotis continued to develop and test algorithms for performing image reconstructions using several SXT images taken at high cadence, with imprecisely known registration. The additional information provided by several images yields more reliable image reconstructions. Roumeliotis has also been testing different ways of smoothing SXT images before taking the ratio of two images to determine the temperature and emission measure map. In particular, an algorithm has been developed which smoothes images at all locations except near sharp edges such as the borders of coronal loops. The article "A Novel Maximum Likelihood Method for Image Reconstruction with Increased Sampling" was published in the October 20 issue of The Astrophysical Journal. During this reporting period, Jim Klimchuk produced probability density functions (distributions) of coronal loop pressure, temperature, density, width, and length using the SXT measurements of 47 loops that he had made previously with Lisa Porter. He used the kernel method to extract the maximum amount of information from the sparse data. This method produces smooth functions rather than coarse, discontinuous histograms. An interesting result of the analysis is that the loops appear to have a bimodal nature. The significance of this result is still being investigated. Klimchuk also continued his work on using post eruption arcades to detect the occurrence of Earthward directed CMEs. He has begun to examine solar wind data in the OMNI Database in order to test the apparent detections made with the Yohkoh data. It is hoped that this Page 18 work will eventually lead to an operational space weather tool, and Klimchuk attended two space weather workshops to discuss the project with the "user community" -- a one day workshop at Philips Lab in Boston and a one week workshop sponsored by NRL and held in Washington. The responses were encouraging. Klimchuk's paper with Lisa Porter on "The Scaling of Heating Rates in Solar Coronal Loops" was published in Nature. News articles about the work have subsequently appeared in Science News, Physics World, and Labstracts. A related Yohkoh image with a rather humorous description also appeared in the News and Views section of the Nature issue! Page 19 =========================================================================== Solar Physics Research Corp. Activity Report for September and October 1995 =========================================================================== Activities in the last two months are as follows: (1) revised paper for the Proceedings of the SolWind 8 meeting held at the end of June 1995. Title: "Coronal Structures Deduced from Photospheric Magnetic Field and He I 10830 Observations". This paper discusses the interpretation of structures observed in the NSO/KP HeI spectroheliograms in terms of coronal structures and their comparison with structures observed in the Yohkoh SXT data. (2) Visited Lockheed to work with K. Strong on the solar cycle variation of X-Ray Bright Points observed with the Yohkoh SXT. I repeated some of the analysis done by Keith, verifying his analysis technique. We also planned out the work needed for publication of this work. (3) Completed a reasonably successful collaborative XBP campaign during the interval 15-23 September 1995 with the help of N. Nitta at ISAS. This run included several observatories and instruments: Yohkoh SXT, MSO, NSO/KP, BBSO, NSO/SP, and HAO. The objective of this campaign was to obtain He I 10830 and magnetic field observations simultaneously with the high spatial and temporal SXT X-ray observations. We had a very quiet Sun; poor weather conditions prevailed at most of the sites in the early part of the run, but changed to reasonably good conditions thereafter. HAO joined our collaboration at the last minute, providing full-disk HeI 1083 nm observations with 2 arc-second pixels. (4) Continued 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. This included a detailed investigation of the development of the transient coronal holes deduced from HeI 1083 nm spectroheliograms and from the Yohkoh SXT images during two events: 21 March 1993 and 14 April 1994. Both of these events occurred along the polarity inversion (neutral line) surrounding the polar fields. The transient coronal holes appeared as extensions of pre-existing coronal holes located on either side of the polarity inversion. The extent of the transient coronal hole changes, when overlaid on the pre-existing holes, indicates that the closed fields connecting across the polarity inversion in fact had opened at the time of the first sign of the formation of the large-scale X-Ray arcade. This work was presented as a poster paper at the National Solar Observatory/Sacramento Peak Summer Workshop on `Solar Drivers of Interplanetary and Terrestrial Disturbances' and is currently being written up for inclusion in the Proceedings of this meeting. Title of the paper: Comparison and Relation of He I 1083 nm Two-Ribbon Flares and Large-Scale Coronal Arcades Observed by Yohkoh SXT. Authors: K. L. Harvey, A. McAllister, H. Hudson, D. Alexander, J. R. Lemen, and H. P. Jones. Page 20 (5) 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. (6) Continued collection and updating of the bibliography of Yohkoh papers. Page 21 ------------------------------------------------------------------------------- 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 November 1995 October 1995 |------------------------------- | 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 October 1995 |------------------------------- |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 | 21 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office