Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for June 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 Mission operations and data analysis activities are continuing in their well established modes. Preparations are continuing for the impending RFP for the mission extension. << Solar Activity >> The GOES x-ray level was about A or low-B level for most of the month. However, there was usually at least one active region present at all times. During the early part of the month AR7877 produced a few B flares and provided a target for the Pic du Midi campaign. Later in the month there was one major active region, AR7882, that traversed the solar disk. Two GOES C-class flares were observed from NOAA7874 (June 6 21:41 UT and June 6 14:30 UT). Given the low activity level, it was a good month for solar minimum observing programs. << Campaigns >> The filament watch campaign was run on several occasions in coordination with Mees Observatory and the SOON system. A filamentary structure and the formation of a large loop on the limb was observed in full disk images. The loop formation was apparently coincident with a CME that was observed at Mauna Loa. There was a combined XBP campaign involving Kitt Peak organized by Karen Harvey and a chromospheric campaign involving Pic du Midi, organized by Page 2 Brigitte Schmieder. Nariaki Nitta worked hard to support these two campaigns. The chromospheric campaign traced AR 7877 for several days. It did not produce any major flares, but there were many small brightenings. It will be interesting to compare the Yohkoh and Pic du Midi data. In one XBP run, a XBP in a coronal hole channel was observed to flare. The campaigns also included Alan Kiplinger's involvement. The use of e-mail and the Web really makes these kinds of campaigns much more feasible. The SXT chief observer was able to communicate by e-mail with the campaign participants at Kitt Peak, Pic du Midi, Mees and the Soon locations by e-mail and to consult various SOON H-alpha images using Mosaic. Spartan 201-03 is scheduled for launch on 3 August, followed by deployment 24.5 hours later. It will observe the solar corona for 43.5 hours. The Yohkoh team is coordinating observing plans with Leonard Strachan (Harvard). The Spartan mission will be supporting the north polar passage of Ulysses and they want Yohkoh to also point as far north as possible during this time period. Future plans include campaigns to observe filaments and XBP campaigns. << Science >> The past month included a large number of presentations by Yohkoh team members at the Makuhari meeting in Japan, the AGU in Baltimore, the SPD in Memphis and the SolWind 8 meeting in Dana Point, Ca. A partial listing of the presentations is given below. The Dana Point meeting was attended by Hugh Hudson and Greg Slater. Greg drove to the meeting and took the Sony and Panasonic laser disk players to use in conjunction with the survey poster. One objective of these studies is to determine the solar X-ray counterparts of CMEs and interplanetary bi-directional streaming events in conjunction with Ulysses observations. Tom Metcalf's visit to ISAS was an occasion for him to apply the Pixon reconstruction technique to a variety of HXT events. The Pixon method apparently gives a marked improvement over the MEM technique for many events. << 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. - Papers Published (0) - - Papers accepted (3) - "Yohkoh soft X-ray spectroscopy observations of the bright loop-top kernels of solar flares," J.I. Khan, L.K. Harra-Murnion, H.S. Hudson, J.R. Lemen, and A.C. Sterling (Ap. J. Letters) Page 3 "Soft X-Ray Loops and Coronal Heating," Porter and Klimchuk, Ap. J. "Solar Rotation Stereoscopy in Microwaves," Aschwanden, Lim, Gary, and Klimchuk, Ap. J. - Papers Submitted (2) - "The effects of geometry in the solar corona," S. Katsev and D. Alexander, submitted to Journal of Undergraduate Research. "Geometrical Considerations in the Solar Corona," D. Alexander and S. Katsev, in preparation for submission to Solar Physics - Presentations (>14) - (there were more than the list below indicates) "Analysis of Impulsive Soft X-ray and Hard X-ray Emission from Footpoint Sources," Solar Physics Division meeting, Memphis, Tennessee, June 1995. "H-alpha Surges and X-Ray Jets in AR 7260", R. C. Canfield, K. P. Reardon, K. D. Leka, K. Shibata, T. Yokoyama, M. Shimojo, in Magnetodynamic Phenomena in the Solar Atmosphere: Prototypes of Stellar Magnetic Activity, Makuhari, May 22-26, 1995. "Yohkoh Observations: Magnetic Reconnection in the Solar Atmosphere", R. C. Canfield, American Geophysical Union meeting, Baltimore, May 30-June 2 1995 (invited). "Helicity of Active Regions in the Photosphere and Corona" R. C. Canfield, A. A. Pevtsov, and L. W. Acton, American Geophysical Union meeting, Baltimore, May 30-June 2 1995 "Yohkoh Soft X-ray Observations of CMEs", H.S. Hudson, in Magnetodynamic Phenomena in the Solar Atmosphere: Prototypes of Stellar Magnetic Activity, Makuhari, May 22-26, 1995 (invited). "The Non-Thermality of Flares", H.S. Hudson, Yohkoh seminar (ISAS), 17 May 1995 "Detection of Mass Loss in the 24 Jan. 1992 CME -- Visions of Bugles" Yohkoh seminar (ISAS), H.S. Hudson, 7 June 1995 "Fractal Pixon Image Reconstruction for HXT", Metcalf, T. R., Hudson, H. S., Kosugi, T., Puetter, R. C., Pina, R. K., Solar Physics Division Meeting, Memphis, June 8, 1995 "Fractal Pixon Image Reconstruction for HXT", Metcalf, T. R., Hudson, H. S., Kosugi, T., Puetter, R. C., Pina, R. K., ISAS Yohkoh Seminar, ISAS, June 21, 1995. "Coordinated X-ray and H-alpha Observations of Eruptive Flares", J.-P. Wuelser, R.C. Canfield, T. Sakao, L.W. Acton, 26th Solar Page 4 Physics Division Meeting, Memphis, Tennessee, June 4-8, 1995. "The energetics of solar eruptive events," Alexander, D., AGU invited talk, Baltimore, 31-May-95. "Yohkoh/SXT Soft X-ray Observations of Sudden Mass Loss from the Solar Corona," Hudson et al., poster paper at SolWind8 meeting in Dana Point, CA "The Solar Origins of Two High-Latitude Interplanetary Disturbances," Hudson et al., poster paper at SolWind8 meeting in Dana Point, CA "Comparison of Yohkoh X-ray Coronal Events with Ulysses Interplanetary Events," Lemen et al., poster paper at SolWind8 meeting in Dana Point, CA - Abstracts submitted(0) - << Public Use of SXT Images >> Yohkoh SXT images will be included in a French Canadian College text book entitled, "Astronomie et astrophysique" by Seguin and Villeneuve. The Yohkoh posters continue to be very popular and a new batch was ordered and received at Lockheed during the month. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. No significant degradation in the instrument has occurred since the loss of the front thermal shield in 1992. There were some data transmission problems from JPL/DSN that affected both Yohkoh and ASCA. This concerned data that came from Madrid, Canberra, and Goldstone during June 19-23. This was eventually corrected by JPL and the data were recovered and retransmitted to ISAS. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT bitmap error June 5 (Pass 1; 950605-1239) recovered in the same pass. SXT warm reset error June 15 (Pass 1; 950615-0929) recovered in Pass 3. Since the week of 11 June 1995, Santiago has been regularly used by Yohkoh and the ASCA spacecraft. The Santiago contacts very nicely fill in the gaps that occur when Yohkoh cannot use the KSC contacts because of a conflict with ASCA. Typically, six or seven Santiago contacts are scheduled per week. The combined daily usage of Santiago by Yohkoh and ASCA is not to exceed three hours total, which includes pre-calibration, post-calibration, and post-pass playbacks. This means that ASCA and Yohkoh can share at most, two Santiago station contacts per day. Page 5 << Data Flow >> ------------------------------------------------------------------------------ Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Mar-93 113162 53715 411684 212256 623940 223820 26.30 Apr-93 7754 3644 34128 8352 42480 17967 29.72 May-93 8571 3950 41832 7518 49350 21971 30.81 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 3788 1736 12768 153 12921 6105 32.09 Jul-95 0 0 0 0 0 0 0.00 Total 302400 129668 1282804 347623 1630427 635148 28.03 Number of Full Frame Images Received: 302400 Number of Observing Region Images Received: 1630427 Total: 1932827 Approximate Number of Shutter Moves/CCD Readouts: 3375942 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 (%) Apr-93 43.13 473.4 14304 2146 23.8 / 2 16.9 N/A May-93 43.45 485.3 16405 2357 17.3 N/A 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 49.11 697.4 101416 6293 18.3 N/A Jul-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-JUN-95 and 30-JUN-95 ALEXANDER 4-JUN-95 30-JUN-95 * 27 (total of 27 days) HUDSON 1-JUN-95 * 3-JUN-95 3 10-JUN-95 22-JUN-95 13 (total of 16 days) LINFORD 20-JUN-95 30-JUN-95 * 11 (total of 11 days) NITTA 1-JUN-95 * 23-JUN-95 23 (total of 23 days) SLATER 1-JUN-95 * 5-JUN-95 5 (total of 5 days) METCALF 13-JUN-95 30-JUN-95 * 18 (total of 18 days) ---------------------------------------------------------------- Grand Total of 100 days for 6 people NOTE: The "*" signifies travel that actually ends after 30-JUN-95 SXT Foreign Travel between 1-JUL-95 and 31-JUL-95 ALEXANDER 1-JUL-95 * 31-JUL-95 * 31 (total of 31 days) HUDSON 3-JUL-95 31-JUL-95 * 29 (total of 29 days) LINFORD 1-JUL-95 * 19-JUL-95 19 (total of 19 days) SHING 26-JUL-95 31-JUL-95 * 6 (total of 6 days) WEBER 29-JUL-95 31-JUL-95 * 3 (total of 3 days) METCALF 1-JUL-95 * 6-JUL-95 6 (total of 6 days) ---------------------------------------------------------------- Grand Total of 125 days for 7 people NOTE: The "*" signifies travel that actually ends after 31-JUL-95 Respectfully submitted, James R. Lemen Frank M. Friedlaender Page 8 =========================================================== Montana State Univ Activity Report for May and June 1995 =========================================================== During the last bimester the MSU solar group has been busy with SXT operations, paper preparation and assisting others with use of SXT and SXT data, as well as educational and public outreach activities. Acton spent the entire month of May as SXT Chief Observer at ISAS. During this period the following work was accomplished. Science: 1. Completed the figures for the loop shrinkage paper which T. Forbes has subsequently submitted to ApJ. 2. Prepared and gave an invited talk at IAU153 in Makuhari. 3. Prepared figure for Ulysses paper with Gosling, et al. on the recent fast passage of Ulysses through low solar latitude zone. This paper has now been submitted to GRL. 4. Discussed CMEs a lot with Hudson, McAllister, et al. Hudson has now discovered several events for which the coronal evacuation which must take place in these events can be subtly seen in SXT data. 5. Prepared a processed SXT data set and sent it off to A. Benz for the time of their VLA campaign in February '95. 6. Prepared a processed SXT data set for the SERTS rocketeers. Operations: 1. Did a small amount of filament campaign until the sun got active. 2. Studied the intrinsic variations in straylight intensity. 3. Struggled to develop a better system for tracking and decision- making on terminator images. Revised a lot of software for this purpose which is now in use by SXT Chief Observers. 4. Supported the SERTS rocket flight with composite SXT images and targeting suggestions. In June Acton gave a paper on coronal temperature structure at the SPD meeting in Memphis. It has been agreed that the SPD meeting in 1997 will be held at MSU on 27 June - 1 July. He also prepared and presented (on Independence Day) an invited talk for the IAGA/IUGG meeting in Boulder, CO. David Weston passed his MS comprehensive exams (congratulations, Dave). He is spending the summer on at MSU learning Unix and IDL by working on SXT analysis. At present he's looking at flare "starburst" images to improve our understanding of the SXT x-ray scattering function and how it may vary with pointing, etc. David Alexander presented two invited talks at the Spring AGU in Baltimore, a Yohkoh Seminar at ISAS and collaborated on preparation of four poster papers for the SolWind8 meeting at Dana Point. He completed teaching the course "Physics of Astrophysics" at MSU as well as the x-ray loop geometry project with Sergei Katsev. This program permits modeling the effects of loop geometry, temperature/density structure and observing perspective on SXT observations. This work is to be published in Journal of Undergraduate Page 9 Research and is being submitted for publication in Solar Physics. Alexander, working with Louise Harra, have completed the processing of the non-flare SXV fluxes for the entire mission. These results will be compared with the SXT active region fluxes as a means of gaining better insight into differential emission measure and active region heating. Work on temperature structure of polar crown events continues and is being included in various papers. Alexander spent the latter part of the month of June at ISAS as SXT Chief Observer where he has completed a revision of the Chief Observer's Handbook and continued the filament and quiet corona structure programs. Brian Handy continues to spend most of his time on the TRACE program in Palo Alto but aids the SXT work tremendously by being our remote computer systems manager. The conversion of our primary server to the new internet domain sxt4.physics.montana.edu was a trying experience for him and all of us -- but is now complete and fully functional. Mark Weber attended the SPD Meeting in Memphis under a SPD Studentship Award. He prepared and presented a poster paper on the "Differential Rotation of the Corona", co-authored with Drs. Acton and Alexander. Page 10 ================================================================ Univ of Calif, Berkeley Activity Report for May and June 1995 ================================================================ J. McTiernan presented a paper titled "Analysis of Impulsive Soft X-ray and Hard X-ray Emission from Footpoint Sources" at the Solar Physics Division meeting, which took place in Memphis, Tennessee from 4 June 1995 to 8 June 1995. This was based on work on the impulsive Soft X-ray sources found by SXT in the flares of 2-Nov-91, 13-Jan-92 and 26-Jan-92. The poster compared the emission in the SXT footpoints with HXT footpoint images obtained using a forward fitting method. The conclusions are as follows: (1) The impulsive SXR emission is probably thermal emission, with a low temperature less than 10 MK (loop top emission in SXT sources often approaches 20 MK). (2) The overall peaks for the SXR and HXR emission are not necessarily identical, but they are close. The SXR peak for the 2-Nov-1991 footpoint happens 27 seconds before the HXR peak, but there is a bump in the HXR time profile corresponding to this peak. For the 26-Jan-1992 flare the peaks are within a few seconds of each other (effectively identical given the SXT time resolution), and for the 13-Jan-1992 flare, the SXR peaks lag behind the HXR peaks. (3) The conductive cooling times for the footpoints are shorter than the duration of the peaks. (4) The filling factor is small; this hints at unresolved structure in the sources. (5) There is enough electron energy pumped into the footpoints to account for the SXR plasma energy. For the two large flares (2-Nov-91 and 26-Jan-92) the energy flux is greater than 10^{10} ergs per sec per cm^2, enough to cause chromospheric evaporation. A paper based on this work is being prepared for publication. For the past six months we have had a graduate student visiting from Brazil, Francisco Fernandes, who is currently working on the comparison of radio emission and Yohkoh SXT and HXT emission. He is presently keeping busy gathering the appropriate Yohkoh data for this comparison. Page 11 ======================================================= Univ of Hawaii Activity Report for May and June 1995 ======================================================= Our most important activities included support of Yohkoh operations and data analysis at ISAS, coordinated ground-based data acquisition at Mees, including designated Yohkoh campaigns, analysis of Yohkoh/Mees data, 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. Operational support was provided in May for the SERTS rocket campaign led by Joe Davila (SERTS PI) and in June for an X-Ray bright point campaign led by SXT Co-I Karen Harvey and a chromospheric activity campaign led by Brigitte Schmieder. Metcalf spent most of June at ISAS and served as SSOC tohban for one week. Canfield worked with K. Reardon, K. D. Leka, K. Shibata and T. Yokoyama to finish their manuscript on H-alpha surges and X-ray jets in AR 7260. The most interesting new discovery is that there is an approximate equality between the amount of spin these surges undergo and the amount of twist stored in them above the photosphere, judging from the observed length and helicity density in the related bipoles. He also worked with J. Li on her study (also with Metcalf and Wuelser) on the relationship between active region current systems and flare energetic electron acceleration and heating in six large HXR flares (more than 150 counts in the HXT high-energy channel). The preliminary conclusion is that neither HXR footpoints nor SXR footpoints correspond well to sites of high vertical current density in the photosphere. Hudson finished his work on various aspects of "XME's" (ie, mass ejections seen in X-rays) for the Solar Wind 8 meeting at the end of June. Several interesting things emerged from getting four posters put together (thanks to David Alexander for sharing the burden!). One of them is that, after all, yes SXT does see mass being launched, and quite easily. The list thus far includes three LDE flares and two giant arcade events. The latter are (i) the 31 May 1993 event that became the prototype of the new class of forward/reverse interplanetary shocks noted by Gosling et al; and (ii) the celebrated 24 Jan. 1992 event that was detected as a "true" CME or at least its aftermath, by Hiei et al. (1993). In the 24 Jan. event SXT sees a coronal darkening that probably represents the exact onset of the CME, free of confusion about the invisible zone underneath the occulting edge of the white-light coronagraph. Other results have to do with the beginnings of real analytical work, including comparisons with the ionization temperatures detected Page 12 in the driver gas for high-latitude events by Ulysses/SWICS (little correlation!). Among flare studies, Hudson also continued to participate in Farnik's study of the 3 Oct. 1993 hard-spectrum event. The great leap forward taken by Metcalf with the HXT pixon analysis is giving us better confidence about HXT images. In this case there is an extremely clear non-Neupert behavior, in the sense that the footpoints are quite invisible in SXT, implying only feeble evaporation. Canfield noted that this could be due to the very hard spectrum, which is known from numerical simulations not to drive strong evaporation, and also may have less of an effect because of a high cutoff energy. If so we might explain the Rieger "electron-rich" events, which could be intenser versions of the 3 Oct 93 behavior, as due to a large potential drop or large electric field. Wuelser continued to work on eruptive flares, and included a couple more events in his study. The additional analysis confirms the previous results: the filament eruption starts prior to the impulsive hard X-ray flare, whereas the bright (soft X-ray and sometimes H-alpha) ejecta are associated with the impulsive hard X-ray burst. The material of the erupting filament moves ahead of the material in the soft X-ray ejection. Wuelser presented a poster on this topic at the Solar Physics Division meeting in Memphis, Tennessee. Wuelser also did some experiments in trying to reconstruct the 3-dimensional structure of a filament as it erupts. The idea is to integrate over the measured Doppler velocity, to obtain the filament's spatial location along the line of sight. The first results are promising. Metcalf continued to work on IVM H-alpha data. He also continued writing up the study on linear polarization in H-alpha during flares. He worked 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 does not coincide with peaks in the density of photospheric vertical currents. Metcalf completed the analysis of 5 magnetograms from 3 separate active regions for G. Doschek for his study of flares with strong blueshifts. While at ISAS Metcalf worked with Hudson and N. Nitta on HXT pixon image reconstruction. He also began a collaboration with H. Nakajima on the 1992 June 28 limb flare. HXT data will be aligned with Nobeyama data for the event. He began 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. Finally, Metcalf began writing a paper on the HXT pixon reconstruction algorithm. Page 13 Jiao finished his Teaching Assistant on May 16. From then to the end of June, he processed more than 300 Stokes magnetograms. These data are crucial input into his 3-D theoretical solar coronal magnetic field model. Based on such experience, he wrote a comprehensive script program "auto_unno", which performs automatic retrieving, preparation, and data processing with extensive error-checking and error-handling and can be run under both SunOS 4 and Solaris. He also made some scripts which may be handy for use by the Yohkoh Duty Scientist at Mees. Reardon continued to help coordinate filament observation by Mees and the SXT during times of low activity. In addition Big Bear Observatory, Udaipur Solar Observatory in India, and the entire SOONSPOT four-site network of telescopes are active participants in filament observation campaigns. As solar activity continues to wane toward minimum, filament observations are slowly becoming the default mode for Mees/SXT observations. There were more than a half-dozen separate filament "campaigns" lasting several days each during May and June. One side benefit of the filament observations is that they provide many exposures of the "quiet" corona. A series of images can be summed together and provide a high signal-to- noise image of the quiet corona, even if the intensity is several orders of magnitude lower. Reardon also spent some time developing a new technique for displaying Yohkoh SXT data. By transforming a series of full-disk images onto a Carrington coordinate grid, the effect of the Sun's rotation is removed. This makes following an individual, long-lived feature in a movie much easier and allows images separated by intervals of hours to days to be summed together. A movie of NOAA AR7260's transit across the solar disk in August of 1992 was produced, and it shows quite dramatically the growing complexity of not only the active region, but also the long inter-region loops in the surrounding corona. PLANS FOR JULY AND AUGUST Canfield will work on the surges and jets manuscript with Shibata, Yokoyama, Reardon, et al. He will work with J. Li, Metcalf, and Wuelser on the relationship between photospheric currents and precipitation of nonthermal electrons in flares, using Mees and HXT data. He will present a paper on this topic at the High Energy Solar Physics workshop at Goddard. Hudson's next step in work on CME's is to try to measure velocity fields. One of the flares in the Ulysses/Yohkoh studies (that of 27 Feb. 94) is well-suited for this, because it was observed at the limb in flare mode and there are many clear images of the departing mass. Because the "disappearing corona" syndrome is predicted by the standard reconnection theory, this Page 14 is really a crucial aspect of flare physics. The reconnection theory predicts inflow, of course, and we observe the opposite, but this contradiction may only be superficial - the two velocity fields may be superposed on each other via the line-of-sight effect. Thus a better form of data analysis than just looking at the beautiful fireworks is indubitably called for! Hudson plans to work on "superhot" sources in preparation for the meeting at GSFC in August. Surprisingly little work has been done on the physics of these events in the Yohkoh data. Perhaps only two events (16 Dec. 91; 8 Feb. 92) have been published. There are wonderful data and the pixon imaging for HXT should help a great deal. In another project, Hudson is working with Joe Khan and students (including Katsuma-san) on the automatic characterization of loops. This is a form of pattern-recognition software and (we hope) will tie in well with work done by other people on modeling the geometry of what SXT observes. Wuelser plans to continue the study of eruptive events, and to start writing up the results for publication. He also plans to pursue the 3-dimensional reconstruction of eruptions in H-alpha. 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 continue collaborations with J. Li, G. Fisher, and H. Nakajima. Finally, he plans to complete the paper on the pixon image reconstruction method for HXT. Jiao will finish up the remaining Stokes magnetograms. After that, he will resolve their 180-degree ambiguities and paste related magnetograms into full disk longitudinal-field magnetograms. Reardon plans a trip to ISAS at the end of August to work with Shibata and Hudson on filament and prominence eruptions observed in soft x-rays and H-alpha. Reardon will also finish the reduction of the data on pre-flare "tether-cutting" events on 15 November, 1991, in the hopes of finishing the manuscript on this work. PUBLICATIONS AND PRESENTATIONS DURING MAY AND JUNE Papers accepted "Yohkoh soft X-ray spectroscopy observations of the bright loop-top kernels of solar flares," J.I. Khan, L.K. Harra-Murnion, H.S. Hudson, J.R. Lemen, and A.C. Sterling (Ap. J. Letters) Page 15 Presentations given "H-alpha Surges and X-Ray Jets in AR 7260", R. C. Canfield, K. P. Reardon, K. D. Leka, K. Shibata, T. Yokoyama, M. Shimojo, in Magnetodynamic Phenomena in the Solar Atmosphere: Prototypes of Stellar Magnetic Activity, Makuhari, May 22-26, 1995. "Yohkoh Observations: Magnetic Reconnection in the Solar Atmosphere", R. C. Canfield, American Geophysical Union meeting, Baltimore, May 30-June 2 1995 (invited). "Helicity of Active Regions in the Photosphere and Corona" R. C. Canfield, A. A. Pevtsov, and L. W. Acton, American Geophysical Union meeting, Baltimore, May 30-June 2 1995 "Yohkoh Soft X-ray Observations of CMEs", H.S. Hudson, in Magnetodynamic Phenomena in the Solar Atmosphere: Prototypes of Stellar Magnetic Activity, Makuhari, May 22-26, 1995 (invited). "The Non-Thermality of Flares", H.S. Hudson, Yohkoh seminar (ISAS), 17 May 1995 "Detection of Mass Loss in the 24 Jan. 1992 CME -- Visions of Bugles" Yohkoh seminar (ISAS), H.S. Hudson, 7 June 1995 "Fractal Pixon Image Reconstruction for HXT", Metcalf, T. R., Hudson, H. S., Kosugi, T., Puetter, R. C., Pina, R. K., Solar Physics Division Meeting, Memphis, June 8, 1995 "Fractal Pixon Image Reconstruction for HXT", Metcalf, T. R., Hudson, H. S., Kosugi, T., Puetter, R. C., Pina, R. K., ISAS Yohkoh Seminar, ISAS, June 21, 1995. "Coordinated X-ray and H-alpha Observations of Eruptive Flares", J.-P. Wuelser, R.C. Canfield, T. Sakao, L.W. Acton, 26th Solar Physics Division Meeting, Memphis, Tennessee, June 4-8, 1995. Page 16 ====================================================== Stanford Univ Activity Report for May and June 1995 ====================================================== Peter Sturrock has continued his analysis of data acquired by Loren Acton for the region of diffuse corona observed during 3-15 May 1992. It proves possible to fit the data to a model that is substantially spherically symmetric, and for which nonthermal energy is deposited outside 1.5 R. However, it proves possible to reconcile data for the Al-1 and Al-Mg filters only if we assume that the relative calibration is in error by 15%. Specifically, we suggest that the measured ratio of count rates from the Al-1 filter to count rates from the Al-Mg filter may be too high by 15%. According to this analysis, the inward heat flux is 10^6.7 erg cm^-2 s^-1, and the density at the base of the model is approximately 10^8.8 cm^-3. George Roumeliotis has been investigating whether it is possible to take advantage of the jitter in the position of the SXT axis. The idea is to merge several images of an active region to obtain a single image that is more finely sampled than any of the individual images. It is anticipated that this procedure for producing over-sampled images will be useful for studying the properties of individual coronal loops. Mike Wheatland has continued theoretical work to account for the features seen in hard X-ray images. In particular, he has been investigating the possibility of the confinement of the hard X-ray producing energetic electrons in the acceleration region due to resonant scattering. During this reporting period, Klimchuk presented Yohkoh results at three meetings: "Soft X-Ray Loops and Coronal Heating," IAU Colloquium #153, Makuhari, Japan, May 22; "The Heating of Coronal Loops," Spring AGU Meeting, Baltimore, May 31; and "The Cross-Sectional Properties of Coronal Loops," Annual SPD Meeting, Memphis, June 6. The following two papers which make use of SXT data were accepted for publication in the ASTROPHYSICAL JOURNAL: "Soft X-Ray Loops and Coronal Heating" by Porter and Klimchuk and "Solar Rotation Stereoscopy in Microwaves" by Aschwanden, Lim, Gary, and Klimchuk. Graduate student Nikolai Lehtinen continued his work on a numerical model to determine the differential emission measure that would result from impulsively heated coronal loops. Page 17 ===================================================================== Solar Physics Research Corp. Activity Report for May and June 1995 ===================================================================== (Karen L. Harvey) Activities for the last two months are as follows: (1) Prepared an invited talk that was presented at the SolWind 8 meeting in on 25 June. Title: "Coronal Structures Deduced from Photospheric Magnetic Field and He I 10830 Observations". This paper discussed the interpretation of structures observed in the NSO/KP He I spectroheliograms in terms of coronal structures, such as coronal holes, large-scale two-ribbon flare-like events, and X-ray bright points, and their comparison with the Yohkoh SXT data. It is clear from the response to this talk that much work needs to be done on the study and comparison of the He I 10830 and Yohkoh SXT observations of coronal holes addressing, for example, their formation, evolution, variation with height. (2) Participated in an collaborative XBP campaign from 9 - 16 June 1995 that included involving Yohkoh SXT, MSO, NSO/KP, and possible BBSO. 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. This was run was successful in large part due to N. Nitta, who selected the XBP target and coordinated the campaign with another that was studying the only active region on the Sun. We plan to request another XBP campaign in mid-September. (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. As mentioned in the previous report, the results of this study will be presented at the National Solar Observatory/Sacramento Peak Summer Workshop to be held October 16-20, 1995. Title of paper to be presented this group is "Comparison and Relation of He I 1083nm Two-Ribbon Flares and the Large-Scale Coronal Arcades Observed by Yohkoh SXT". Harry Jones was asked to join this effort; we will be using the NSO/KP full-disk magnetograms to investigate the long-term evolution and motions of the magnetic fields at the sites of the X-ray arcades and comparing the results with sites that have no arcades. (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 Jets and large scale X-ray arcades. (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 | 10 July 1995 June 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 June 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