Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for November 1996) OVERVIEW The YOHKOH Mission is a program of the Japanese Institute of Space and Astronautical Science (ISAS) with collaboration by the U. S. National Aeronautics and Space Administration and the U. K. Science and Engineering Research Council. The YOHKOH satellite was launched on 30 August 1991 from Kagoshima Space Center (KSC) in Japan. The purpose of this mission is to study high energy phenomena in solar flares and the Sun's corona. Under an international cooperative agreement, Lockheed, under NASA contract, is providing a scientific investigation using the Soft X-ray Telescope (SXT), one of the primary experiments of the mission. The SXT was developed at the Lockheed Palo Alto Research Laboratory in cooperation with the National Astronomical Observatory of Japan, and the Institute for Astronomy of the University of Tokyo. MAJOR PROGRAMMATIC ACTIVITIES IN THE MONTH Operations at ISAS are currently covered through January 27, 1997. An option to extend the operations for another year is in the contractual arrangements but has not yet been implemented. Additional funding is also expected to continue operations and data analysis in 1997. << Solar Activity >> For the past few months the main source of X-ray activity has been a single complex of activity that began in April and (as AR 7978) produced an X flare in July. This region made its fifth rotation this month. On 5 October last month it produced a splendid CME event. In the second half of November AR 7999 came onto the disk (on Nov 21) and this region continued to grow and became more active as it crossed to the west; it raised the general X-ray background flux by nearly two decades at one point and provided a flurry of C-class events, and even an M-class event. The passage of AR 7999 beyond the west limb allowed the solar X-ray flux to drop to its previous depressed levels. At the W limb passage Yohkoh adjusted its pointing to watch the W limb corona in hopes of another nice CME like the Oct. 5 event. During the other times the disk was mostly covered with bright points and faint emission. There are polar holes at both poles. << Campaigns >> SXT obtained context images of AR 7994 for SERTS, which unfortunately was launched during Yohkoh night (13-NOV-96 18:30 UT). It turned out that it was not possible to reschedule the SERTS launch time to allow Yohkoh to make coordinated observations. A campaign with SOHO JOP 003 to observe CME onsets ended on November 20, 1996. SXT observed large-scale loops associated with a many-rotation-old active region, but nothing happened (unfortunately) to extend the success stories of 25 September and 5 October. The two events from September and October are the first for which we know that we have simultaneous Yohkoh and SOHO observations of CMEs. We note again that the current low level of solar activity seems to be a help since the X-ray signatures of CMEs may be quite faint. On November 21, we were able to accommodate a late request from the SOHO/MDI team to observe AR 7997 for one day. We continued to track the active region for a day or so after that on our own initiative. Several SOHO-related campaigns of scientific interest to Yohkoh took place, including JOP03 (CME onset), JOP33 (jets), and observations aimed at loop structure. For Yohkoh operations, there is a text file accessible on the Web at http://www.space.lockheed.com/SXT/html2/First_Light.html which also lists the current SXT Chief Observer, or the unix command: # finger campaign@isass0.solar.isas.ac.jp | more The SOHO target planning is available from: http://sohowww.nascom.nasa.gov/operations/targets/today << Science >> David Alexander and Tom Metcalf have nearly finished a paper about the "Masuda event" (1992 January 13 limb flare) using Pixon and MEM analyses. The figures are currently being completed. This is a fascinating study since the pixon results differ from the MEM results. They believe that the pixon images have better photometry and they are using the improved light curves to study the thermal/non-thermal nature of the loop top source. Alexander also continued to arrange the Coordinated Data Analysis Workshop (CDAW) which is being organized along the lines of the successful series of Yohkoh CDAWs that were held at the University of Hawaii over the past few years. Pseudo HXT data has been distributed to the relevant participants in order to access the currently available reconstruction techniques. Alexander also made a presentation at NRL entitled "Hard X-ray Image Reconstruction: The search for loop-top sources." Tom Metcalf completed his part of Longcope and Fisher's 1996-Jun-6 SOHO mini-campaign comparing SOHO and SXT image with photospheric vector magnetograms. The project's goal is to study transient brightenings. He obtained good coalignment between the IVM data and SXT data despite the lack of MWLT data. Nariaki Nitta was at ISAS for much of November. He attended the 5th anniversary conference in downtown Tokyo, in Yoyogi, which is very close to the stadium that was used in the 1964 Olympic games. There were 96 participants and the conference was scientifically a success, with many substantial discussions. Nitta presented a talk on superhot flares. Nitta also presented a Yohkoh seminar at ISAS to report on nonthermal hard X-ray emission from active region transient brightenings. Interactions with Masuda and Brigitte Schmieder (who attended the Yoyogi meeting and visited ISAS afterwards) have been fruitful. Nitta also worked as the SXT duty scientist during part of his visit to ISAS. Greg Slater was at ISAS during the first three weeks of November. While he was there he continued to do the tasks associated with Yohkoh data reformatting and archive generation and he assisted visiting scientists at ISAS with various software and data analysis questions. Slater also presented a talk at the Yohkoh Fifth Anniversary Meeting in Yoyogi, Tokyo. Finally, he prepared a special Yohkoh movie sequence for NHK TV broadcast on the 1997 solar eclipse. Serge Savy in Japan worked with Franta Farnik from the Czech republic who is visiting ISAS. They are working on preflare X-ray brightenings observed 4-22 November 1992. Savy presented a poster on this topic at the Yoyogi meeting. Finally, this month there was a meeting of the Yohkoh Public Outreach (YPOP) Creative Development and Design Team that include Alexander, Lemen, Freeland, Metcalf, Linford and Friedlaender from LMPARL and Tim Slater, Michelle Larson from MSU and David McKenzie from the Bartol Institute. The YPOP effort is one year old and the plans for the web page have progressed significantly during this time. We plan to implement a "visit to a movie theater" theme for the web page in order to show off Yohkoh/SXT movies. We are planning to obtain a small amount of help from a Lockheed Martin graphic artist to design the initial page. << Public Use of SXT Images >> We are continuing to make Yohkoh/SXT images available for a variety of uses. Efforts continue to make selected images available on the Lockheed SXT WWW homepage (http://www.space.lockheed.com/SXT/). We receive requests for the Yohkoh posters (#2 and #3) by way of the form on the SXT homepage. Currently we receive requests via our homepage at the rate of 2 or 3 per day. The WEB access statistics in September were 40538 accesses and 978 Mbytes transferred. Work has intensified on the preparations for both the briefing package and the new SXT video. The briefing package was printed during the first week of December in time to be distributed at the Fall meeting of the AGU. For the video, the Sunnyvale Lockheed Martin video department recorded some sequences off of our Sony laser player and directly off the workstation. Gary Linford is coordinating the production of the video. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. There has been no further increase in straylight since 25 August 1996. 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. Prof Ogawara recently reported that the ISAS aerodynamics department estimates that the orbital life of Yohkoh is good until June, 2002, if an average solar activity for the coming maximum is assumed. The error of this estimation is approximately +/- 2 years depending upon the actual solar activity. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT SYNC1 error 18-Nov-96 Pass 3: 961118-0824 recovered in pass 4. Page 5 << Data Flow >> ------------------------------------------------------------------------------ Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Aug-94 238622 106360 1042245 318080 1360325 533024 27.82 Sep-94 7079 2552 25131 2855 27986 10677 27.62 Oct-94 7244 2497 25868 5884 31752 10319 24.53 Nov-94 6569 1941 26243 1956 28199 9293 24.79 Dec-94 6429 2456 26763 2583 29346 11904 28.86 Jan-95 6870 2349 26103 1699 27802 10211 26.86 Feb-95 6556 2545 23635 3825 27460 10111 26.91 Mar-95 5915 2082 21485 3448 24933 8485 25.39 Apr-95 6244 2266 22946 4493 27439 9688 26.09 May-95 7084 2884 29617 2647 32264 15331 32.21 Jun-95 7210 3087 25251 307 25558 12045 32.03 Jul-95 6418 4145 21180 1639 22819 15109 39.84 Aug-95 7683 2597 26115 2181 28296 10537 27.13 Sep-95 6546 2853 22006 1753 23759 10433 30.51 Oct-95 6937 3502 22177 3853 26030 13044 33.38 Nov-95 5745 2944 21252 517 21769 12119 35.76 Dec-95 6163 2615 24059 901 24960 11652 31.83 Jan-96 6474 2530 27015 1708 28723 14151 33.01 Feb-96 6200 2581 21380 890 22270 10773 32.60 Mar-96 6908 2869 25437 1460 26897 12274 31.33 Apr-96 7172 2124 45445 671 46116 18848 29.01 May-96 6925 2426 30272 1089 31361 12367 28.28 Jun-96 7522 2716 31984 1536 33520 14489 30.18 Jul-96 5954 1995 29886 4769 34655 12427 26.39 Aug-96 7214 3010 21187 1607 22794 9887 30.25 Sep-96 6904 2618 29906 303 30209 12663 29.54 Oct-96 7405 2853 16463 1842 18305 8034 30.50 Nov-96 3854 1171 14740 896 15636 4976 24.14 Dec-96 0 0 0 0 0 0 0.00 Total 417846 176568 1725791 375392 2101183 844871 28.68 Number of Full Frame Images Received: 417846 Number of Observing Region Images Received: 2101183 Total: 2519029 Approximate Number of Shutter Moves/CCD Readouts: 4406800 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 (%) Sep-94 47.07 620.9 58580 4028 18.3 N/A Oct-94 47.34 631.3 64974 4346 19.0 N/A Nov-94 47.64 642.4 70877 4703 20.4 N/A Dec-94 47.82 649.1 74246 4917 21.5 N/A Jan-95 48.55 676.7 89758 5457 20.0 N/A Feb-95 48.70 682.1 92457 5781 25.2 / 3 20.5 N/A Mar-95 48.35 668.9 85527 5271 19.4 N/A Apr-95 48.72 682.8 93904 5627 19.1 N/A May-95 48.73 683.4 94000 5820 18.8 N/A Jun-95 49.08 696.3 100780 6281 19.6 N/A Jul-95 49.34 706.2 106408 6628 18.1 N/A Aug-95 49.72 720.4 114414 7101 19.5 N/A Sep-95 49.79 723.1 115165 7222 19.6 N/A Oct-95 50.29 741.9 126452 7911 20.2 N/A Nov-95 50.11 735.1 122163 7814 25.2 / 2 20.3 N/A Dec-95 50.19 737.9 123705 7927 22.6 N/A Jan-96 50.81 761.3 136197 8888 21.5 N/A Feb-96 50.67 755.8 133263 8705 22.5 / 2 21.5 N/A Mar-96 50.85 762.9 136982 8973 20.3 N/A Apr-96 51.14 773.6 142250 9500 19.9 N/A May-96 51.16 774.4 140697 10018 19.1 N/A Jun-96 51.56 789.2 147705 10634 20.7 N/A Jul-96 57.45 1010.2 146293 12228 19.8 N/A Aug-96 52.58 827.5 165676 12393 19.6 N/A Sep-96 52.47 823.3 162784 12350 20.0 N/A Oct-96 52.21 813.8 157689 12047 22.5 / 2 21.3 N/A Nov-96 52.13 810.7 157004 11775 21.6 N/A Dec-96 N/A N/A N/A N/A 0.0 N/A NOTES: * The dark current calculations are using full half resolution 2.668 sec images not taken in during the SAA. The dark current rate assumes a "fat zero" of 30.5 DN and a gain of 100 e/DN. * The entrance filter failure of 13-Nov-92 eliminated the capability of taking optical images, so the optical transmission is not available after Nov-92. It also caused an increase in the dark current signal, however some of the increase shown here is an increase in the readout noise and is not a function of exposure duration. Page 6 << Personnel Travel >> SXT Foreign Travel between 1-NOV-96 and 30-NOV-96 ACTON 1-NOV-96 * 5-NOV-96 5 (total of 5 days) HUDSON 1-NOV-96 * 5-NOV-96 5 9-NOV-96 18-NOV-96 10 25-NOV-96 30-NOV-96 * 6 (total of 21 days) NITTA 9-NOV-96 30-NOV-96 * 22 (total of 22 days) SAVY 1-NOV-96 * 30-NOV-96 * 30 (total of 30 days) SLATER 1-NOV-96 * 5-NOV-96 5 9-NOV-96 25-NOV-96 17 (total of 22 days) WEBER 20-NOV-96 30-NOV-96 * 11 (total of 11 days) ---------------------------------------------------------------- Grand Total of 111 days for 6 people NOTE: The "*" signifies travel that actually ends after 30-NOV-96 SXT Foreign Travel between 1-DEC-96 and 31-DEC-96 HUDSON 1-DEC-96 * 8-DEC-96 8 13-DEC-96 14-DEC-96 2 28-DEC-96 31-DEC-96 * 4 (total of 14 days) NITTA 1-DEC-96 * 5-DEC-96 5 (total of 5 days) SAVY 1-DEC-96 * 31-DEC-96 * 31 (total of 31 days) WEBER 1-DEC-96 * 25-DEC-96 25 (total of 25 days) ---------------------------------------------------------------- Grand Total of 75 days for 4 people NOTE: The "*" signifies travel that actually ends after 31-DEC-96 Respectfully submitted, James R. Lemen Frank M. Friedlaender Page 8 ================================================================= Montana State Univ Activity Report for October 1996-November 1996 ================================================================= (L ACTON) SCIENTIFIC ANALYSIS and PUBLICATIONS: Canfield, Pevtsov, Longcope and undergraduate Sean Sandborgh worked on problems in solar magnetic helicity. Large scale flux systems are under investigation with SXT imagery. The physics of twist, torsion and writhe in flux ropes is a continuing study. A paper, "On the Sub-Photospheric Origin of Coronal Electric Currents" with Pevtsov and McClymont was submitted to ApJ. The paper "Reconnection and Helicity in a Solar Flare", by A. A. Pevtsov, R. C. Canfield, and H. Zirin is through the proof stage and will soon appear in ApJ. Acton worked on studies of large-scale coronal temperature structure and problems of converting SXT full-disk signals to spectral radiance. Weber continues his work on coronal differential rotation. OUTREACH and SERVICE: The Yohkoh Public Outreach Project (YPOP) is moving rapidly following a very successful meeting at Lockheed Martin in November. David McKenzie will come to MSU in January to work on YPOP with Tim Slater of the MSU NetTeachTalent group and graduate student Michelle Larson. Longcope, Canfield and Acton refereed papers for Solar Physics, Astrophysical Journal, Astronomy and Astrophysics, Journal of Geophysical Research, Physics of Plasmas, and the Chapman Conference Proceedings. Canfield and Acton participated in a Solar-B science definition team meeting at MSFC in mid-November. In early November Acton gave assemblies at 3 middle schools in Great Falls, MT, a middle school and elementary school in Choteau, MT, and an elementary school in Bozeman. VISITORS: We enjoyed a brief visit and colloquium by Prof. Peter Sturrock of Stanford University. David McKenzie, who is finishing his doctorate at the Univ. of Delaware has accepted a post-doctoral appointment at MSU to work on the Yohkoh and YPOP programs. He visited MSU following the YPOP meeting in CA to get acquainted and find housing in Bozeman. MEETINGS: Canfield, Longcope and Acton attended the symposium OBSERVATIONAL PLASMA ASTROPHYSICS: FIVE YEARS OF YOHKOH AND BEYOND which was held in Tokyo in celebration of the 5th anniversary of the Yohkoh launch. Acton presented, "Studies of Coronal Temperature" by L. Acton, J. L. Culhane, C. Foley P. Sturrock, and M. Wheatland. In the paper "On the Origin of Helicity in Active Region Magnetic Fields" Pevtsov and Canfield used the relationship between active region twist and tilt to conclude that the observed twist is created below the convection zone. Longcope presented the paper, "Current Sheet Formation and Reconnection on Separator Field Lines." The conference proceedings will be published in 1997. MSU INFRASTRUCTURE: During the reporting period the MSU Physics Department, including the solar group, moved into the new Engineering and Physical Science Building. This structure, the most costly public building ever constructed in the state of Montana, is reputed to be state-of-the-art in technical and communications aspects. All e-mail and mailing addresses and telephone numbers remain the same. The solar group is one of the heavy Internet users on campus and we are helping prepare a proposal to include MSU on NSFNET's very high bandwidth network system (vBNS). ISAS SUPPORT: Acton spent 5 weeks in Tokyo during the bimester in support of Yohkoh/SXT operations and SXT software improvements. The latter aimed towards the generation of a mission-long SXT movie with improved quantitative accuracy. Weber departed for Japan in November and will serve as SXT Chief Observer until just before Christmas. Page 8 ======================================================================= Univ of Calif, Berkeley Activity Report for October 1996-November 1996 ======================================================================= J. McTiernan attended the Yohkoh 5th Anniversary Symposium in Tokyo, in early November, and presented a poster on the "Limits on the Temperature of Impulsive Phase Solar Flare Hard X-ray Emission, and the Amount of Thermal X-rays Present in the Yohkoh HXT-LO (14-24 keV) Channel". In this work we compare the thermal emission observed by the BCS, with that seen by the HXT in the impulsive phase. It was concluded that the lack of FeXXVI line emission during the impulsive phase suggests that there can only be a small amount of higher temperature (30 to 60 MK) plasma present so that either (1) the impulsive emission seen in the HXT-LO channel is nonthermal, or (2) the HXT-LO emission is due to a very high temperature plasma (70 to 100 MK). If this is the case then the emission seen in the higher energy channels is also due to thermal bremsstrahlung. Thus we can say with some certainty that the impulsive HXT-LO emission comes from the same source as the higher energy emission. We are now continuing this work, and will use differential emission measures obtained using the BCS, SXT, and GOES for this purpose, and also in extending our previous work on the decay phase of soft X-ray flares. McTiernan has been collaborating with Fabio Reale, from the Istituto ed Osservatorio Astronomico, in Palermo, Italy, on other work relating to the flare decay phase. A paper entitled "Determination of the length of coronal loops from the decay of X-ray flares", by F.Reale, R.Betta, G.Peres, S.Serio, and J.McTiernan, has recently been submitted to Astronomy and Astrophysics. A paper titled "Stereoscopic Observations of Solar Hard X-ray Flares Made by Ulysses and Yohkoh" by S.R.Kane, K.Hurley, J.McTiernan, M.Boer, M.Neil, T.Kosugi, and M.Yoshimori is being submitted for publication. In this paper, we compare X-ray data obtained using the Ulysses spectrometer and the HXS and HXT. Since Ulysses has a different view angle, we can look for directivity in the energy range from 25 to 150 keV. Due to large uncertainties in the Ulysses flux, we do not find any. Page 8 ============================================================= Univ of Hawaii Activity Report for August 1996-November 1996 ============================================================= (B. LABONTE) Our activities included support of Yohkoh operations and data analysis at ISAS, coordinated ground-based data acquisition (including designated Yohkoh campaigns) at Mees, collaborative analysis of Yohkoh/Mees data, and preparation of manuscripts. Operational support for SXT was provided by Nitta at Mees, by Jiao, and LaBonte in Manoa. Our colleagues Mickey at Manoa, Canfield at Montana State University, Wuelser and Metcalf at Lockheed, and Hudson at Solar Physics Research Corporation aided in advice and oversight of Mees operations. The Mees CCD imaging spectrograph was returned to operation after failures in the guider and image monitor through the efforts of Mickey and graduate student R. Kupke. Work is in progress to repair the Stokes polarimeter which failed in the detector section at about the same time. The increasing pace of joint Yohkoh/SOHO campaigns has kept the observing schedule busy despite the low level of solar activity. LaBonte and K. Reardon finished their paper using SXT to measure coronal temperatures from the average energy of photons received through single filters. The manuscript has been submitted to Solar Physics. LaBonte, H. Hudson, A. Sterling, and T. Watanabe have continued work on the isolated active regions AR 7978/7981 from July and August 1996. This region is very interesting because its appearance on an otherwise blank Sun makes it a "test particle" for understanding the nature of its activity and its effects on the global corona. Statistical study of the soft x-ray events is the primary focus of this study. The flares of this region show no indication of obeying a relaxation oscillator. LaBonte and graduate student K. Blais have used the SXT images for a subset of her x-ray selected flares to determine the relative contribution of the flaring volume to the global coronal soft x-ray flux, in the preflare state. This settles an issue in the background correction of nonimaging GOES data for the complete sample in her PhD thesis. Her flares are generally small, and an interesting evolution of the flare/disk ratio is seen as the solar cycle declines and the number of active regions decreases from 1991 to 1993. Jiao continued his thesis work, under the guidance of A. McClymont, R. Canfield, and Z. Mikic, on three dimensional reconstruction of solar coronal magnetic field. His paper with Dr. A. McClymont, Dr. R. Canfield and Z. Mikic., "RECONSTRUCTION OF THE THREE-DIMENSIONAL CORONAL MAGNETIC FIELD" was highly praised by referee of Solar Physics. Based on the suggestion by referee, he worked with his advisors to modify the paper and reanalyze the data. He applied Pixon image reconstruction technique to one of the SXT soft X-ray image for AR7222, July 13, 1992. The resultant image quality has been improved incredibly, and Jiao will reanalyze the reconstructed three dimensional solar coronal magnetic field for it. Jiao continued work on Mees Stokes Data at SDSC. In studying some of the computational results in 3-dimensions graphically, he found the ambiguity resolution of the magnetogram sometimes plays an important role in leading to the stable state. The ambiguity correction method relies to some extent on comparing the measurements with the computed potential field or linear force-free field, which is not good in case the fluxes do not balance within the magnetogram field of view. Currently, he is testing how to reduce the sensitivity. When applying methods such as embedding Mees Stokes vector magnetogram into Kitt Peak LOS magnetogram to balance flux, some spurious currents will be introduced around the edges of the insertion; such problems are must be investigated. The new super computing season at SDSC begins and Jiao will resume the computation at Cray for a few new ARs. PUBLICATIONS AND PRESENTATIONS DURING AUGUST THROUGH NOVEMBER Papers submitted: "X-ray Photon Spectroscopy with the Yohkoh Soft X-ray Telescope", B. LaBonte and K. Reardon, Solar Physics. Presentations given: "NOAA 7978: the last best old-cycle region", H. Hudson (SPRC), B. LaBonte (U. Hawaii), A. Sterling (NRL), and T. Watanabe (NAOJ) YOHKOH 5th Anniversary Meeting, Yoyogi, November 1996. Page 8 ============================================================ Stanford Univ Activity Report for October 1996-November 1996 ============================================================ During the reporting period, we were pleased to have Clare Parnell join our group as a Post-Doctoral research fellow. Clare has been working at St Andrews on the theory of three-dimensional magnetic reconnection, with the aim of developing improved models of X-ray bright points. Bright points are among the smallest soft X-ray features observed on the Sun, and are most visible at times of low activity. The present observing period is an excellent time to study these events, because of the low activity and also because of the possibility of concurrent observations by the SXT and by instruments on SOHO. Clare hopes to make measurements to test the predictions of a two-dimensional bright point model that she developed with Eric Priest of St Andrews University. Clare will also continue to work on reconnection in the solar atmosphere, as well as pursuing a number of Peter Sturrock's ideas on solar activity. Clare is keen to increase the degree of interaction between the Stanford group and the solar group at Lockheed, and a series of informal meetings of the two groups has been organized. Peter Sturrock has continued to work with Mike Wheatland and Guenther Walther (of the statistics department at Stanford) on an analysis of the available solar neutrino data. The aim of this investigation is to decide whether the neutrino flux is constant or time-varying. A time varying neutrino flux could be produced, for example, by a rotational modulation of the underlying (constant) flux by magnetic fields in the radiative zone. We have searched for periodicities in the range of radiative zone rotation frequencies derived from helio-seismology, using periodograms constructed to incorporate the solar neutrino collection process. Guenther Walther has also formulated a more general test for stationarity of the Homestake neutrino data, which suggests that the neutrino flux does vary in time. George Roumeliotis has continued work on a novel variational method for reconstructing force free-fields in the solar corona, which has shown promise in initial simulations. A student has been employed to work on a three-dimensional implementation of the method. Papers accepted: * Roumeliotis, "Smoothness Maps: A new method for solving inverse problems involving sharp gradients," accepted for publication in IEEE Proceedings on Signal Processing Page 8 =========================================================================== Solar Physics Research Corp. Activity Report for October 1996-November 1996 =========================================================================== (Karen L. Harvey and Hugh S. Hudson) Karen L. Harvey: (1) Detailed analysis of activity complex 7958/7979 with Hugh Hudson in order to trace the sites and occurrences of magnetic flux emergence and the dispersal of the active region remnant fields. The history of this complex was traced from its first emerged in late April 1996 to its October 1996 disk passage. A total of seven major active regions emerged within the boundaries of the complex during a four month interval. Six coronal holes formed in association with this complex, only two of which lasted for more than one solar rotation. Plans are to continue this analysis adding the Yohkoh/SXT data to determine the development of the magnetic field connections as this complex evolved and dispersed. A poster paper with H. Hudson as co-author was presented at the Yoyogi meeting in early November. (2) Continuing to develop and refine IDL program to draw the irregular coronal hole boundaries on the NSO/KP He I 10830 spectroheliograms. The program is being adapted to the high- and med-resolution data to improve the limb detection necessary in doing the HeI 1083 nm equivalent width and magnetic flux measurements. The program will soon be implemented on the current daily NSO/KP observations and then to extend the coronal holes maps through the Yohkoh period (late 1991 to fall 1996 to provide an extensive data base for direct comparison of coronal hole boundaries seen in the SXT images and He I 10830 spectroheliograms. (3) Analysis of observations of XBPs obtained though a collaboration of several ground-based observatories and the Yohkoh SXT instrument, and SOHO in early April and late May 1996. Initial comparisons of the Yohkoh/SXT, HeI 10830 line depth, MDI magnetograms, CDS intensity images in HeI 584 and Mg X 625 A were presented at a meeting on "Advances in the Physics of Sunspots" (held October 2-6, 1996 at Tenerife, Spain) in a session on the Coordination of SOHO and ground-based observations. Plans are to complete the data analysis of the 150 XBPS observed in the spring 1996 campaigns working with Ted Tarbell (MDI), A. Fludra (CDS), D. Hassler (SUMER), and D. Moses (EIT). (4) Continued analysis of the collaborative observations of XBPs obtained in the several XBP campaigns between Yohkoh/SXT, NSO/KP, MSO, BBSO, HAO, SOONSPOT. Plan is to complete by early next year a paper presenting the results of the association of XBPs with the evolution of the magnetic fields and chromospheric structures. (5) XBP campaign scheduled late October 1996 took place during 2 days in conjunction with SOHO JOP 033. For this run, NSO/KP obtained high-spatial and temporal magnetograms in the chromosphere for comparison with XBPs. (6) 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. Paper presented: "Coordinated Satellite and Ground-Based Observations of X-ray Bright Points", K. L. Harvey, presented at a meeting on `Advances in the Physics of Sunspots', held October 2-6, 1996 at Tenerife, Spain. HUGH HUDSON: H. Hudson studied the "last best" active region centering on AR7978 in preparation for the Yoyogi meeting, and presented some results there. One interesting possibility is that this kind of situation - an isolated activity complex - might show stronger tendencies towards "relaxation oscillator" behavior than a more complex situation would. This, if found, would be excellent progress because it would confirm the whole energy build-up scenario and also say interesting things about AR structure. Alas, the first survey was a null result. This survey did not make use of the Yohkoh data, though, just GOES, so there is clearly a lot of improvement possible for the future work, e.g. before the manuscript deadline. This activity complex was interesting in many other ways, including the interaction with a new-cycle region (K. Harvey poster at Yoyogi) and the launching of two well-observed CMEs (25 September and 5 October). These latter have been chosen as the theme for the first SOHO/Yohkoh CDAW, to be held at GSFC March 3-7. Hudson also prepared some material on these and other CME-related events to support Dave Webb's poster presentation at AGU. Although spatially quite large, the occultation profiles on Oct. 15 and other limb passages were strikingly abrupt. This seems to confirm the idea that the loop population itself has a kind of exponential falloff. Hudson worked with A. Sterling on comparing the GOES, SXT, and BCS views of this. PLANS FOR DECEMBER AND JANUARY Hudson intends to continue pursuing the collaboration with Dave Webb on dimming signatures, CMEs, and the like. It is also a high priority to write a paper on the two CMEs Yohkoh has observed in collaboration with SOHO, since these are the first really good examples that let us see what the X-ray counterpart of a coronagraph CME looks like. They are quite different, even though both involved the activity complex mentioned above, and both quite interesting. It is also still a high priority to work up the material on flare-related dimming in Feb. 21 and Aug. 28 1992 events (Lemen, Webb). Hudson also intends to do some preparatory work for the hard X-ray imaging CDAW in Palo Alto Jan. 13. Papers published: "Yohkoh observations of coronal mass ejections", H. S. Hudson, in Y. Uchida et al. (eds.), `Magnetodynamic Phenomena in the Solar Atmosphere - Prototypes of Stellar Activity' (Kluwer), pp. 89-96, 1996. Page 8 ------------------------------------------------------------------------------- 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 December 1996 November 1996 |------------------------------- | 6. PERFORMING ORG | CODE: O/91-30 -----------------------------------------------|------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- J. R. Lemen | TION REPORT NO: F. M. Friedlaender | |------------------------------- -----------------------------------------------|10. WORK UNIT NO. 9. PERFORMING ORGANIZATION NAME AND ADDRESS | Lockheed Palo Alto Research Labs B/252 |------------------------------- Solar & Astrophysics Laboratory O/91-30 |11. CONTRACT OR GRANT NO. 3251 Hanover Street, Palo Alto Ca. 94304 | NAS8 - 40801 -----------------------------------------------|------------------------------- 12. SPONSORING AGENCY NAME AND ADDRESS |13. TYPE OF REPORT AND Marshall Space Flight Center (Explorer Program)| PERIOD COVERED Huntsville Alabama 35812 | Progress report for the month | of November 1996 |------------------------------- |14. SPONSORING AGENCY | CODE MSFC / AP32 -----------------------------------------------|------------------------------- 15. SUPPLEMENTARY NOTES ------------------------------------------------------------------------------- 16. ABSTRACT The SOLAR-A Mission is a program of the Institute of Space and Astronautical Science (ISAS), the Japanese agency for scientific space activity. The SOLAR-A satellite was launched on August 30, 1991, to study high energy phenomena in solar flares. As an international cooperative agreement, Lockheed, under NASA contract, is providing a scientific investigation and has prepared the Soft X-ray Telescope (SXT), one of the two primary experiments of the mission. --------------------------------------|---------------------------------------- 17. KEY WORDS (SUGGESTED BY | 18. DISTRIBUTION STATEMENT AUTHOR(S)) Solar-A, X-ray, CCD, | Space Science, Solar Physics ------------------------|-------------|----------|-----------------|----------- 19. SECURITY CLASSIF. | 20. SECURITY CLASSIF. | 21. NO OF PAGES |22. PRICE (OF THIS REPORT) | (OF THIS PAGE) | | None | None | 17 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office