Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for August 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 forth anniversary of the launch of Yohkoh occurred this month. Operations continue to go smoothly despite an increase in the SXT straylight signal (see further details below). The proposal for the extended mission was submitted to MSFC this month. An evaluation of the proposal has already been initiated and several questions have been asked and answered. The start date for the extended mission is 1 November 1995. The program will benefit in this extended period by having an experienced and dedicated team. The extended operations will offer a unique opportunity to study the high-temperature coronal and the solar magnetic evolution at the time of the transition between solar cycles. << Solar Activity >> The solar activity has remained on average in the mid GOES-A range for most of the month. AR7901 and 7902 produced a few C-class flares. In the middle of the month it was reported that new-cycle regions were beginning to appear, although this interpretation is not accepted universally. As has been the pattern for the past few months, there is generally one active region present at any one time. Many bright points are discernible in the X-ray images. << Campaigns >> The coordinated filament watch campaign, which specifically involves Mees and Page 2 and Yohkoh, was attempted this month again. Most of the campaign activity was concentrated on preparations for Spartan flight which was delayed until early September. << Science >> A early draft of the pixon paper by Tom Metcalf, Hugh Hudson and co-authors shows an HXT for the Feb 21 1992 event the SXT observations of which have been extensively studied by S. Tsuneta. This is a nice result, since the pixon method was able to synthesize the HXT image whereas the MEM reconstruction could not cope with the low hard X-ray count rates for this particular event. Preliminary analyses indicate that the HXT LO channel sources found using the pixon method matches the locations of the high temperature regions detected by SXT. << Publications>> 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. There will be a few more AGU abstracts listed next month as these were being prepared at the end of the month. - Papers Published (1) - "A Comparison of Active Region Temperatures and Emission Measures Observed in Soft X-Rays and Microwaves and Implications for Coronal Heating," Klimchuk, J. A., and Gary, D. E. 1995, ApJ, 448, 925. - Papers accepted (7) - "Scaling of Heating Rates in Solar Coronal Loops," Klimchuk, J. A., and Porter, L. J., Nature, in press (September). "The effects of geometry in the solar corona" - S. Katsev and D. Alexander, Journal of Undergraduate Research "Reconnection and field line shrinkage in solar flares" - T. Forbes and L. Acton, Astrophysical Journal. "Metric type III bursts associated with soft X-ray jets", J.P. Raulin, M.R. Kundu, H.S. Hudson, N. Nitta, and A. Raoult, ApJ. "A Search for Asymmetric Flows in Young Active Regions", G. Cauzzi, R. C. Canfield and G. H. Fisher, ApJ. "Solar Flares: No Myth", H.S. Hudson, E.O.S. "A novel maximum likelihood method for image deconvolution with resampling", Roumeliotis, G., ApJ, in press (October). - Papers Submitted (11) - Page 3 "A Super-hot Flare Observed by Yohkoh," Nariaki Nitta and Kentaro Yaji (ApJ Letters). "The Heating of Soft X-Ray Coronal Loops," Klimchuk, J. A., and Porter, L. J., in Proceedings of IAU Colloquium #153. "Temperature Structure of the Diffuse Corona" - C.R. Foley, L.W. Acton, J.L. Culhane, J.R.Lemen, (extended abstract) submitted to Proc. of IAU Colloq. #153. "Interpretation of SXT data concerning the diffuse corona" - P.A. Sturrock, M.S. Wheatland, L.W. Acton, (extended abstract) submitted to Proc. of IAU Colloq. #153. "The large-scale eruptive event of April 14 1994" - D. Alexander, K.L. Harvey, H.S. HUdson, J.T. Hoeksema, X.Zhao, submitted to Proc. of Solwind 8 "The Solar Origins of Two High-Latitude Interplanetary Disturbances" - H.S. Hudson, L.W. Acton, D. Alexander, K.L. Harvey, S.W. Kahler, H. Kurokawa, J.R. Lemen, submitted to Proc. of Solwind 8 "Yohkoh/SXT Soft X-ray Observations of Sudden Mass Loss from the Solar Corona" - H.S. Hudson, L.W. Acton, D. Alexander, S.L. Freeland, J.R. Lemen, K.L. Harvey, submitted to Proc. of Solwind 8 "Solar Identification of Solar-Wind Disturbances observed at Ulysses" - J.R. Lemen, L.W. Acton, D. Alexander, A.B. Galvin, K.L. Harvey, J.T. Hoeksema, X. Zhao, H.S. Hudson, submitted to Proc. of Solwind 8 "Electron Time-of-Flight Measurements During the Masuda Flare 1992 Jan 13", M. Aschwanden, H.S. Hudson, and R. Schwartz, ApJ. "Evidence for Current-Carrying Emerging Flux", K.D. Leka, R.C. Canfield, A.N. McClymont, L. van Driel-Gesztelyi, ApJ. "H-alpha Surges and X-ray Jets in AR7260", R.C. Canfield, K.P. Reardon, K.D. Leka, K. Shibata, T. Yokoyama, and M. Shimojo, ApJ. - Presentations (4) - "Conditions for Energetic Flares" presented at the High Energy Solar Physics Workshop at GSFC during 16-18 August, Nariaki Nitta. "Fractal Pixon Image Reconstruction for HXT", Metcalf, T. R., Hudson, H. S., Kosugi, T., Puetter, R. C., Pina, R. K., MaxEnt95 Workshop, Sante Fe, July 31 - August 4, 1995 "Yohkoh Observations of Flares with Superhot Properties", H.S. Hudson, High Energy Solar Flare Workshop, Goddard Space Flight Center, August 16-18 Page 4 "Electrical Currents and Solar Flares: Dispelling the Myth", R.C. Canfield, High Energy Solar Flare Workshop, Goddard Space Flight Center, August 16-18 (invited) - Abstracts submitted(2) - "Yohkoh Observations of Superhot Flares," N. Nitta and H. S. Hudson, abstract for the AGU 1995 Fall Meeting. "The Yohkoh Data Analysis System," S. L. Freeland, M. D. Morrison, J. R. Lemen, abstract for the AGU 1995 Fall Meeting. << 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. We expect this effort to be enhanced when funding is started for the Yohkoh Public Outreach Project (YPOP) CAN program. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. There was a factor of three increase in the straylight level in the SXT which occurred on 16-Aug-1995. The straylight level has been nearly constant since the first entrance filter segment failed in November 1992. We have no means to understand the failure mechanism. Loren Acton reported in his memo on 30 August 1995 the following: "It is my opinion that the cause is puncture by micro-meteorites or space debris. It is the nature of these thin plastic films that a puncture is usually followed by catastrophic rupture. MSFC informed us back in 1992, following the first failure, that their experience indicated that we could expect about one particle contact per square cm per year in the Yohkoh orbit. We have roughly 45 square cm of entrance filter exposed but the solid angle is limited by an aluminum thermal shield. Roughly, the Yohkoh experience is consistent with the MSFC predictions." The ISAS operations team immediately acquired and processed new terminator images, so called because they are acquired at the time of the day/night terminator and provide visible light images without X-ray emission. These images are used to subtract the straylight from the X-ray images. The impact on SXT observations and operations is small, but the additional straylight signal will make faint-object observations more difficult. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT bitmap error Aug 25 Pass 1; 950825-0310 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 May-93 129487 61309 487644 228126 715770 263758 26.68 Jun-93 7340 2589 64545 12539 77084 26299 25.44 Jul-93 8259 3650 47561 5352 52913 24213 31.39 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 6403 1966 22452 1625 24077 8252 25.53 Sep-95 0 0 0 0 0 0 0.00 Total 318643 137130 1338919 351041 1689960 664449 28.22 Number of Full Frame Images Received: 318643 Number of Observing Region Images Received: 1689960 Total: 2008603 Approximate Number of Shutter Moves/CCD Readouts: 3521594 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 << 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 (%) Jun-93 44.03 507.2 20037 2531 16.3 N/A Jul-93 44.46 523.4 23020 2600 22.5 / 2 17.7 N/A 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 49.75 721.5 115052 7145 19.6 N/A Sep-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 7 << Personnel Travel >> SXT Foreign Travel between 1-AUG-95 and 31-AUG-95 ALEXANDER 1-AUG-95 * 2-AUG-95 2 (total of 2 days) HUDSON 1-AUG-95 * 7-AUG-95 7 23-AUG-95 31-AUG-95 * 9 (total of 16 days) NITTA 25-AUG-95 31-AUG-95 * 7 (total of 7 days) SLATER 14-AUG-95 31-AUG-95 * 18 (total of 18 days) WEBER 1-AUG-95 * 31-AUG-95 * 31 (total of 31 days) JIAO 1-AUG-95 28-AUG-95 28 (total of 28 days) ---------------------------------------------------------------- Grand Total of 102 days for 6 people NOTE: The "*" signifies travel that actually ends after 31-AUG-95 SXT Foreign Travel between 1-SEP-95 and 30-SEP-95 FREELAND 18-SEP-95 30-SEP-95 * 13 (total of 13 days) HUDSON 1-SEP-95 * 30-SEP-95 30 (total of 30 days) LEMEN 30-SEP-95 30-SEP-95 * 1 (total of 1 days) NITTA 1-SEP-95 * 23-SEP-95 23 (total of 23 days) SHING 25-SEP-95 30-SEP-95 * 6 (total of 6 days) SLATER 1-SEP-95 * 13-SEP-95 13 (total of 13 days) WEBER 1-SEP-95 * 23-SEP-95 23 (total of 23 days) ---------------------------------------------------------------- Grand Total of 109 days for 7 people NOTE: The "*" signifies travel that actually ends after 30-SEP-95 Respectfully submitted, James R. Lemen Frank M. Friedlaender Page 8 =========================================================== Montana State Univ Activity Report for July and August 1995 =========================================================== During the last bimester the MSU solar group has been busy with SXT operations, proposal writing, SXT data analysis and educational outreach. Acton spent a lot of the last two months working on proposals for the new SXT contract, for the Yohkoh Public Outreach Program and for SR&T funding ("Coronal Processes and the Solar Dynamo"). He also presented an invited talk on Yohkoh at the IAGA/IUGG meeting in Boulder, Colorado. In addition, Acton served on a NASA panel review and spent a lot of time working on the recent SXT entrance filter problem. Alexander spent the month of July as SXT Chief Observer working on a filament observing campaign with the University of Hawaii and carried out a quiet corona study. While at ISAS, Alexander worked on the preparation of a paper discussing the effects of geometry on the interpretation of SXT images, studied loop top sources in solar flares using Metcalf's pixon reconstruction algorithm and started a study on non-thermal velocities in solar flares with Khan, Harra-Murnion and Matthews. These studies were continued through August on his return to MSU. Alexander presented a 1 hour talk on general solar physics to a class of Native American high school students. Weber assisted Bai and Acton in producing stackplots of SXT data (an example can be found in show_pix). This provides a nice complement to his Fourier analysis study of solar rotation as observed in the corona. Weber spent August as SXT Chief Observer at ISAS, continuing the Hawaii filament campaign, carrying out observations of polar regions with Hara and Koutchmy and planning for coordination with the Spartan observations. On the science front, Weber discovered a possible 300-day period in the time-series analysis of coronal data as he continued to pursue the coronal rotation project. Handy continues to work on UV channel issues for the TRACE project as well as working on the calibration of SPDE data. Weston is making good progress with the characterisation of the scattering within SXT. Katsev ended his time at MSU by completing our movie-making ability (a project started by Handy and Weber). Katsev returned to Belarus to continue his studies. A new graduate student, Brian Welsch, joined the solar group at MSU to work with Alexander. Papers accepted --------------- Page 9 "The effects of geometry in the solar corona" - S. Katsev and D. Alexander, Journal of Undergraduate Research "Reconnection and field line shrinkage in solar flares" - T. Forbes and L. Acton, Astrophysical Journal. Papers submitted ---------------- "Temperature Structure of the Diffuse Corona" - C.R. Foley, L.W. Acton, J.L. Culhane, J.R.Lemen, (extended abstract) submitted to Proc. of IAU Colloq. #153. "Interpretation of SXT data concerning the diffuse corona" - P.A. Sturrock, M.S. Wheatland, L.W. Acton, (extended abstract) submitted to Proc. of IAU Colloq. #153. "The large-scale eruptive event of April 14 1994" - D. Alexander, K.L. Harvey, H.S. HUdson, J.T. Hoeksema, X.Zhao, submitted to Proc. of Solwind 8 "The Solar Origins of Two High-Latitude Interplanetary Disturbances" - H.S. Hudson, L.W. Acton, D. Alexander, K.L. Harvey, S.W. Kahler, H. Kurokawa, J.R. Lemen, submitted to Proc. of Solwind 8 "Yohkoh/SXT Soft X-ray Observations of Sudden Mass Loss from the Solar Corona" - H.S. Hudson, L.W. Acton, D. Alexander, S.L. Freeland, J.R. Lemen, K.L. Harvey, submitted to Proc. of Solwind 8 "Solar Identification of Solar-Wind Disturbances observed at Ulysses" - J.R. Lemen, L.W. Acton, D. Alexander, A.B. Galvin, K.L. Harvey, J.T. Hoeksema, X. Zhao, H.S. Hudson, submitted to Proc. of Solwind 8 Page 10 ================================================================ Univ of Calif, Berkeley Activity Report for July and August 1995 ================================================================ YOHKOH/SXT PROGRESS REPORT (2-SEP-1995) For the past two months, work at UCB has concentrated on two projects. The first is a translation of George Roumelotis' IRIS (Image Reconstruction with Increased Sampling) code for SXT image deconvolution from FORTRAN into IDL. A preliminary version works well, and is faster than the Fortran routine, due to the magic of IDL. Testing is continuing, and a debugged version should be put online this month. This code should be useful in the current work we are doing regarding impulsive SXT footpoint emission; the size of the footpoint is an important consideration. Back in February, J.McTiernan travelled to Japan and obtained temperatures and emission measures using the flare-mode Be119-Al12 filter observations for all SXT flares. From this sample we have been calculating the variation of T and EM in the decay phase. Out of about 1200 flares, about 200 give flare modes that are long enough to get the EM to decrease by a factor of 4. Plots of Log(T) vs. Log(EM)/2 (log(n) for constant Volume) have slopes of about 0.45, (with lots of scatter, a FWHM of about 0.6); a slope of 0.5 would result from loop scaling laws. Some similar behavior was found for some SMM flares by Sylwester, et.al., (Astron. Astrophys. 267, 586-594 (1993)). However, they also found events which had very steep slopes (1.5 or so) which are not seen in the SXT data. Right now we are working on selection effects, and will also compare to the GOES data for the selected flares. We hope to present this work at the upcoming Fall AGU meeting in San Francisco in December. Page 11 ======================================================= Univ of Hawaii Activity Report for July and August 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. In addition to extensive vector magnetogram coverage, the filament campaign was a mainstay of coordinated Mees/Yohkoh observations during the month; another near miss took place as a filament erupted just an hour before uploading of a filament table to SXT. Finally, polar vector magnetogram observations were begun in anticipation of the Spartan 201 experiment on the shuttle. K.D. Leka, Canfield, A.N. McClymont, and L. van Driel-Gesztelyi finished the second of two papers from Leka's thesis, adding new measurements of currents carried by moving magnetic bipoles to the arguments that new flux emerged in AR7260 already carrying current, which was not generated by photospheric motions, as is often supposed. Collaborating with K.D. Leka, K. Shibata, T. Yokoyama, and M. Shimojo, Canfield and Reardon finished their work on H-alpha surges (Mees) and X-ray jets (SXT) in AR7260, in which IVM data were used to measure currents and demonstrate quantitatively that surges and jets are due to magnetic reconnection. New data from Leka on currents in moving magnetic bipoles showed clearly that their twisted reconnecting fields contain both the correct sign and correct amount of stored twist to drive the total spin of the observed surges. Finally, Pevtsov and Canfield studied large-scale patterns of chirality from Yohkoh images, and uncovered several unambiguous cases of trans-equatorial connections of active regions, thanks to the simple conditions seen on the Sun in recent months. Hudson devoted most of July and August to Yohkoh observations related to CMEs, in support of the Solar Wind 8 meeting. Other work included a survey of flares with the "superhot" property, in preparation for the High Energy Solar Physics workshop. The latter work was inspired by the Nitta and Yaji paper on one of the AR 7620 flares, which showed an interesting morphological property: an early relatively cool Neupert-like loop, followed by a late longer superhot loop. How often does this happen? How often do superhot properties occur? Is this some of the missing evidence for the popular but difficult-to-prove loop-loop reconnection? With these questions in mind a preliminary survey based on D. Pike's list of FeXXVI flares was carried out, with several interesting results - for example, the survey showed up several events for which the HXT temperatures exceed the FeXXVI temperatures and agree with each other. This latter point confirms the original conclusion of Lin et al. on "isothermality", now interpretable as a sharp upper cutoff in the differential emission measure distribution. Page 12 Wuelser started writing up his work on the Yohkoh pointing, for publication in a technical journal. This includes the analysis of the Mercury transit observations with Nishio, Kosugi, and Hudson. The Mercury observations led to a more accurate value of the SXT roll angle, and a new independent determination of the SXT pixel size. Wuelser also analyzed a few more events for his study of the structure and evolution of eruptive flares. 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 long-lived active region vertical current systems. The results call into question an earlier conclusion, based on ground-based H-alpha profiles rather than HXT image reconstructions, that flare nonthermal electron precipitation normally occurs at the edges of photospheric currents. Metcalf continued a collaboration with H. Nakajima on the 1992 June 28 and 1992 Nov 2 limb flares. HXT data are being aligned with Nobeyama data for the event. Metcalf continued 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 and the result is being written up. Finally, Metcalf's paper on the HXT pixon reconstruction algorithm is nearing completion. He is also preparing an abbreviated version of the paper for the proceedings of the MaxEnt95 workshop. Jiao applied two 180-degree ambiguity-resolution methods (continuity-dominant and simulated annealing) to more than 300 Mees vector magnetograms. He also produced two versions of scripts to automatically handle such processes. By comparing with the Kitt Peak database and SXT database he established before, studying the qualities of each of the above magnetograms, he extracted about 100 as primary targets for computation of 3-D coronal magnetic fields. He also coded an IDL program to be able to animate a series of images regardless of their image sizes and their color properties (pseudo or true color) in a widget-driven environment. Having completed the paper on surges and jets observed in H-alpha and soft X-rays, Reardon and Canfield moved back to the topic of tether cutting seen in the 15 November, 1991 flare. Reardon completed most of the figures for a paper on this subject. As a result of the work on reconnection in surges and jets, an improved understanding of the role of tether cutting has been developed, including new ideas about the role of reconnection with current-carrying emerging flux in filament destabilization (helicity loading). Reardon began a three week stay in Japan to work with K. Shibata on simultaneous observations of prominence eruptions with SXT and the Mees H-alpha coronagraph. The goal of this study is to determine the behaviour of soft x-rays during a variety of different H-alpha prominence eruptions (eruptive, quasi-eruptive, and disappearing). Reardon also plans to work with Hudson on disk filament eruptions observed in soft x-rays and on studies of the quiet corona. Finally, Reardon helped the Montana State University group finish the development of their video recording and display system. Page 13 PLANS FOR SEPTEMBER AND OCTOBER Canfield will concentrate his efforts on his work with Reardon on the role of reconnection in the filament eruption that preceded the 15 Nov 1991 flare and with Pevtsov on the 8 May 1992 flare. As well, he will continue to work on flare HXR images and current maps with J. Li, Metcalf, and Wuelser. The top priorities for Hudson are to help F. Farnik with his analysis of the remarkable 3 Oct. 1993 events and to finish the long-awaited paper on the CME flare of 13 Nov. 1994 with Acton and Freeland. Other than this, there will be little time for other research work than the review of "Solar X-rays" being written with J.L. Culhane. This is due in November. Hudson will also attend a small seminar in Boulder, Oct. 24-26, to work with Acton, Gosling, and Hundhausen on CME and flare relationships. Finally, Hudson will set up the Yohkoh observations of the October 1995 total solar eclipse. Excellent coverage is expected and tentative plans are to devote the opportunity to a beautiful movie mainly for educational purposes. Wuelser plans to finish the manuscript on the Yohkoh pointing, and then start writing up the results from the eruptive flare study. Metcalf plans to continue the analysis of the IVM H-alpha polarization data and will continue to write up the study. He will complete the HXT pixon image reconstruction paper, and. will start work on a new version of the SXT pixon code. Finally, he will continue collaborations with J. Li, G. Fisher, and H. Nakajima. Jiao will prepare a short SXT images animation and co-registered SXT partial frame optical image and soft X-ray loop image for each targeted magnetogram in the database discussed above. Reardon will finish his stay at ISAS, with hopes of returning home with a preliminary manuscript for the prominence eruption work with Shibata. Reardon and Canfield will continue to work on the manuscript for the 15 November, 1991 pre-flare tether-cutting events. Reardon plans to give a talk on this subject at the meeting at ISAS in September in honor of the retirement of Prof. T. Hirayama. PUBLICATIONS AND PRESENTATIONS DURING JULY and AUGUST Papers accepted "Metric type III bursts associated with soft X-ray jets", J.P. Raulin, M.R. Kundu, H.S. Hudson, N. Nitta, and A. Raoult, ApJ. "A Search for Asymmetric Flows in Young Active Regions", G. Cauzzi, R. C. Canfield and G. H. Fisher, ApJ. "Solar Flares: No Myth", H.S. Hudson, E.O.S. Page 14 Papers submitted "Electron Time-of-Flight Measurements During the Masuda Flare 1992 Jan 13", M. Aschwanden, H.S. Hudson, and R. Schwartz, ApJ. "Yohkoh/SXT Soft X-ray Observations of Sudden Mass Loss from the Solar Corona", H.S. Hudson, L. W. Acton, D. Alexander, S. L. Freeland, J. R. Lemen, K. L. Harvey, Solar Wind 8. "The Solar Origins of Two High-Latitude Interplanetary Disturbances", H.S. Hudson, L.W. Acton, D. Alexander, K.L. Harvey, S.W. Kahler, H. Kurokawa, and J.R. Lemen, Solar Wind 8. "Solar Identification of Solar-Wind Disturbances observed at Ulysses", J.R. Lemen, L. W. Acton, D. Alexander, A.B. Galvin, K.L. Harvey, J. T. Hoeksema and X. Zhao, Solar Wind 8. "Evidence for Current-Carrying Emerging Flux", K.D. Leka, R.C. Canfield, A.N. McClymont, L. van Driel-Gesztelyi, ApJ. "H-alpha Surges and X-ray Jets in AR7260", R.C. Canfield, K.P. Reardon, K.D. Leka, K. Shibata, T. Yokoyama, and M. Shimojo, ApJ. Presentations given "Fractal Pixon Image Reconstruction for HXT", Metcalf, T. R., Hudson, H. S., Kosugi, T., Puetter, R. C., Pina, R. K., MaxEnt95 Workshop, Sante Fe, July 31 - August 4, 1995 "Yohkoh Observations of Flares with Superhot Properties", H.S. Hudson, High Energy Solar Flare Workshop, Goddard Space Flight Center, August 16-18 "Electrical Currents and Solar Flares: Dispelling the Myth", R.C. Canfield, High Energy Solar Flare Workshop, Goddard Space Flight Center, August 16-18 (invited) Page 15 ====================================================== Stanford Univ Activity Report for July and August 1995 ====================================================== During this reporting period, Sturrock continued his work in which SXT observations of the diffuse corona were matched to the predictions of a spherically symmetric model. In an earlier phase of this work, it was found that the temperature of the diffuse corona increases out to 1.5 solar radii, implying that the non-thermal energy input responsible for coronal heating is deposited at even greater heights. Although a spherically symmetric model was adopted, it should be emphasized that the coronal region that was analyzed appears to be composed of loops that extend to quite large radii. It appears that below 1.5 solar radii, the atmosphere is approximately spherically symmetric. If the analysis of other regions also shows that nonthermal energy deposition in coronal loops is typically localized close to the top of the loops, this fact would provide a significant constraint on theories of coronal heating. In collaboration with Wheatland, the spherically symmetric model continues to be refined, primarily through the inclusion of more realistic assumptions concerning the radiative loss and thermal conductivity in the lower transition region. Roumeliotis continued his work on image reconstruction using SXT observations. A framework has been established for exploiting the jitter of the instrument to effectively increase the spatial sampling rate. Images taken at high cadence in quiet mode often do not change substantially over the observation period. However, the axis of the telescope drifts between observations, so that the different images are offset by an amount that is not precisely known. A Bayesian approach has been developed to simultaneously determine the optimal reconstructed image and the offsets. Initial application of the method to the famous limb flare of January 13, 1992 results in a remarkable sharpening of the inner edge of the flare, while leaving the outer edge diffuse and filamentary. It is clear that this event was not a "simple loop flare". Other events are currently being analyzed with a view to gaining insight into this important class of events that are characterized by bright, long-lived sources of X-rays high in the corona. During this reporting period, Klimchuk continued his work with Peter Cargill in which they are comparing nanoflare coronal heating simulations with soft X-ray loops observed by Yohkoh. Klimchuk is also developing an operational algorithm for detecting the occurrence of earth-bound coronal mass ejections based on sequences of soft X-ray images. Page 16 Papers submitted: "The heating of soft X-ray coronal loops", Klimchuk, J. A., and Porter, L. J., in Proceedings of the IAU Colloquium 153 Papers accepted: "Scaling of heating rates in solar coronal loops", Klimchuk, J. A., and Porter, L. J., Nature, in press (September) "A novel maximum likelihood method for image deconvolution with resampling", Roumeliotis, G., ApJ, in press (October) Papers published: "A comparison of active region temperature and emission measures observed in soft X-rays and microwaves and implications for coronal heating", Klimchuk, J. A., and Gary, D. E. 1995, ApJ, 448, 925 Page 17 ===================================================================== Solar Physics Research Corp. Activity Report for May and June 1995 ===================================================================== (Karen L. Harvey) Activities the last two months are as follows: (1) Prepared and submitted a written version of invited talk presented at the SolWind 8 meeting in late June 1995. Title: "Coronal Structures Deduced from Photospheric Magnetic Field and He I 10830 Observations". This paper, to be published as part of the meeting proceedings, discusses the interpretation of structures observed in the NSO/KP He I spectroheliograms in terms of coronal structures and their comparison with structures observed in the Yohkoh SXT data. (2) Requested an collaborative XBP campaign for the interval 15-23 September 1995. This run will involve several observatories and instruments: Yohkoh SXT, MSO, NSO/KP, BBSO, NSO/SP, and Udipar Observatory. The objective of this campaign is to obtain He I 10830 and magnetic field observations simultaneously with the high spatial and temporal SXT X-ray observations. NSO/SP will be taking high resolution H-alpha spectra and CN spectroheliograms of the selected target. (3) 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. Reviewed the development of He I 10830 structures, i.e. coronal holes, two-ribbon flares, in association with several selected events under study. (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. 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 | 9 August 1995 August 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 August 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 | 18 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office