Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for the month of December 1993) 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 from Kagoshima Space Center (KSC) in Japan, and renamed Yohkoh. The purpose of this mission is to study high energy phenomena in solar flares. 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 by Lockheed in cooperation with the National Astronomical Observatory of Japan, and the Institute for Astronomy of the University of Tokyo. MAJOR ACTIVITIES IN THE MONTH << Monthly Overview>> The program finished 1993 with an instrument that is still providing very high quality data and an ever growing user community. Images from Yohkoh are being requested almost daily from various scientific, educational, and public information sources. It is sometimes very trying to satisfy all of the needs and still perform scientific analysis. It is very encouraging to see that there is such a broad interest in the data and the results of this mission. The extension of the mission will allow the continuation of these highly visible and productive pursuits to continue and expand at very little additional cost. << Solar Activity and Observation Planning >> The solar corona has undergone the most amazing transformation in the last month, it exhibited some of the quietest conditions on 16 and 17 December since solar maximum, but within a week the corona had reverted to near solar maximum activity levels. The Sun produced nine major flares during this high level of activity. A large active region, NOAA 7640, in the northern hemisphere was mainly responsible for this sudden increase in activity. It was the region that emerged into a pre-existing coronal hole late last month but it obviously underwent major growth during the two weeks when it was on the far side of the Sun and returned over the east limb as major flare-producing region. With abundant microflares and emerging flux, this would be another very good region for comparison of occurrence maps with coronal field structure calculated from the vector magnetograms, as proved so interesting at the CDAW meeting on AR 7260. Because there is very little other activity, SXT will have been sitting on the active region before each flare. This is not the only area to have undergone growth. There were two active regions that appeared on the east near the end of the month that have developed significantly since we last saw them on 15 December. The northern region, in particular, had grown rapidly from a small isolated magnetic bipole into a large, complex active region. These active regions have developed an arcade of cross-equatorial loops. Page 2 Observation planning was shared between J. Lemen, H. Hudson, and N. Nitta. Operations were relatively simple this month with no major campaigns or tests. We continued the offpoint program to obtain synoptic images of the large-scale structure of outer corona, and to take a series of "terminator" images for calibration purposes. At the end of the month Yohkoh had to be configured for operation over the New Year's holiday in Japan. << Campaigns >> During the week of 29 Nov - 3 Dec there was a bright point campaign which was organized by Karen Harvey involving Kitt Peak, BBSO, and Mees. Solar activity prevented us from operating the SXT with its special bright point observing table for two days, and a power outage at ISAS prevented us from loading the special table on a third day. Despite this, SXT bright observing mode was used on three days between KSC Passes 2 and 4 on 30 Nov and 1 Dec and between Pass 3 and 4 on 3 Dec. The region that was selected on 30 Nov produced a few bright points. << Science Progress>> We heard the very good news that the HXT/SXT coalignment problem had been solved by HXT graduate student S. Masuda. Essentially he found that the flexure long noted between the two telescopes is mainly in the HXT aspect sensor, not the HXT telescope itself. This cleared the way for a reliable empirical matching of hard and soft X-ray images. Masuda's initial parameters for this have now been checked by Lemen and Farnik and quite extensively in his AR7260 study by Nitta, and they look good. This is a crucial step forward in correctly understanding the non-thermal/thermal physics of solar flares. The coalignment accuracy now is probably as good as one SXT pixel, pending the completion of Masuda-san's thesis, and because of the large number of flares observed there is every reason to think that it can be refined further. Masuda's "home run" science, based upon this breakthrough, is the discovery of hard X-ray cusps, e.g. in a limb loop flare of 13 Jan. 1992. This has now been summarized in a beautiful illustration that is available wherever the Yohkoh software is installed under SHOW_PIX. Another interesting result was discussed at the weekly ISAS seminar organized by H. Hudson and K. Shibata, it was about the remarkable distribution pattern of microflares observed by SXT (Shimizu) in the context of the new MHD-based calculations of the coronal field (McClymont and Mikic). These unexpectedly showed a clear pattern of avoidance of "bald spot" neutral lines, defined as the neutral lines where the inversion-line field lines are concave up (concave down means simple crossing loops). The charm of the microflares is that there are enough of them so that real statistical work can be done, as opposed to big flares which may be beautiful but lonely. Page 3 W. Brown prepared and presented a poster on Sounding Rocket Experiment results from SPDE and the joint observations from SXT. (AGU meeting in SF) The SXT part emphasized the relation between Transition Region Camera images of supergranulation cells and overlying SXT images of x-ray loops. He also supported (with lots of help from MDM, MEB, KTS, DTR, and others) the visit of Luc Dame from Service d'Aeronomie, Verrieres-le-Buisson, France. While mostly focussed on the TRC data from the SPDE rocket, he also obtained access to the SXT data set acquired in the joint experiment. Several attended the Hawaii CDAW (30 Nov - 3 Dec), involved chiefly in the microflare (Toshi Shimizu) and 20-Aug-92 flare (Tim Bastian) sessions. In addition to the Mees Solar Observatory tour, Alan Kiplinger and Nitta visited Palehua Observatory to find out how long it will take the SOON sites to start archiving the data routinely, a plan initiated in 1991. The plan has been treated as part of their upgrading the system on a larger scale, involving introduction of a CCD camera. However, the system as a whole is still not working porperly. According to the USAF people stationed at Palehua, it is hoped that the Holoman site will be able to get the system working in January 1994. We pointed out that we also want to have RSTN data (radio flux) archived together with H-alpha and other optical images. Nitta used the successful alignment routine by Satoshi Masuda to overlay HXT on SXT images again for the 21 flares in AR 7260. The result was very encouraging. Lidia van Driel-Gesztelyi and he finished a draft of the paper to discuss two flares that occurred in similar environments of magnetic field. They are embarking on another paper to deal with the flares in the EFR of AR 7260. Our emphasis is to associate the flare activity with a more global development of the region, specifically paying attention to the existence of the flare loop well before and after the flare. Although some people argue that a flare resulted in a drastic reconfiguration of the magnetic field, there has been no clear evidence for it as far as AR 7260 is concerned. Nitta hopes to present these results at the Cospar meeting in July as a contribution paper. He also worked with Hugh Hudson on a rejected paper by Kazu Shibata, et al. on a gigantic jet in an anemone region. K. Strong has been invited by Physics Reports to write an extended review of Solar X-ray Astronomy which will feature the recent results from Yohkoh and related coordinated observations. He has also been invited to give a review paper on solar active regions at the next COSPAR meeting in Hamberg in July. Several papers and posters were presented at the recent AGU meeting in San Francisco. The Yohkoh posters attracted a lot of attention with their powerful video graphics and stunning images. This provided an opportunity to tell scientists from other related areas of physics about our results. K. Strong attended the Executive Committee Meeting of Space Physics to discuss plans for a joint meeting of the AAS-SPD and AGU at the Spring Meeting in Baltimore. We have managed to arrange an unprecidented five special sessions involving solar physics plus a Union-wide lecture on flares. This is the 75th anniversary of the AGU and should be an excellent opportunity to showcase our results. He will be organizing the intrumental session with Ed Roeloff which will feature at least one Yohkoh review paper and hopefully several contributed papers and posters. Other scientific progress is reported in the individual Co-I reports at the end of this file Page 4 << Public Use of SXT Images >> G. Linford and Keith Strong are providing Sky & Telescope with a monthly article, including an SXT image, about the solar activity seen by Yohkoh. We also gave them an image of the Mercury transit which was included in their January edition. The 18 December 1993 issue of France's popular Figaro Magazine contained a color article about results from Yoko (sic). We supplied much of the material for this article and suggested French scientists who could give the author the article background details. Titled "Unseen secrets of the sun" it is full of language suggesting that the previously unknown mystery is now revealed. We continue to fill a steady stream of requests for SXT videos and posters. At the Fall AGU over 200 "Our Star The Sun" posters were given away to visitors to the two Lockheed posters presented there. A number of requests for our PR video were received and processed. The "Space Physics" poster prepared by TRW to promote the intermediate spacecraft (HESP, TIMED, and IMI) included two Lockheed images, including one from SXT. << Spacecraft and SXT Operations and Health >> There were several ground-system problems during the first week of December. There was a scheduled power outage at ISAS on the first potential day of the campaign, and thus, we were unable to prepare or load SXT tables on that day. During week 48, Yohkoh data received at KSC downlinks on two days were mis-labeled as ASCA data during their transmission to ISAS. As a result, the Sirius temporary files were not created and auto_toban2 could not reformat the data. This situation made it difficult for the SXT Chief Observer to plan the sequences. On 3 Dec, the mainframe # 1 computer at ISAS had to be rebooted during the time of SXT operations, causing the delay in the observing campaign. Page 5 << Data Flow >> ------------------------------------------------------------------------------ Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Sep-91 517 397 21174 3541 24715 5481 18.15 Oct-91 4106 2532 6393 12437 18830 3401 15.30 Nov-91 5291 2475 12149 14696 26845 10952 28.98 Dec-91 4858 3228 4983 16837 21820 6910 24.05 Jan-92 5544 3177 10084 5972 16056 6849 29.90 Feb-92 5305 2803 16932 11382 28314 12019 29.80 Mar-92 6248 2361 20367 2653 23020 9458 29.12 Apr-92 6734 3500 20094 5423 25517 12390 32.69 May-92 7032 3158 25464 4589 30053 13745 31.38 Jun-92 6937 3112 23307 13221 36528 12627 25.69 Jul-92 6345 3275 23941 10510 34451 14717 29.93 Aug-92 6572 2978 24207 11154 35361 13550 27.70 Sep-92 6087 2916 26832 20042 46874 15729 25.12 Oct-92 6743 2589 50985 14709 65694 23687 26.50 Nov-92 6658 2939 24416 14696 39112 12924 24.84 Dec-92 6775 2999 24253 6633 30886 12356 28.57 Jan-93 6888 3351 24067 4861 28928 13069 31.12 Feb-93 6833 3004 24479 18149 42628 12302 22.40 Mar-93 7177 3460 25874 19537 45411 14657 24.40 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 8353 4015 42180 5849 48029 24669 33.93 Dec-93 3509 2116 12440 3900 16340 8635 34.57 Total 178413 84412 739871 271263 1011134 399369 28.31 Number of Full Frame Images Received: 178413 Number of Observing Region Images Received: 1011134 Total: 1189547 Approximate Number of Shutter Moves/CCD Readouts: 2109149 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 (%) Oct-91 31.07 21.3 509 261 10.5 77.8 Nov-91 31.06 20.9 648 277 11.9 64.4 Dec-91 31.04 20.2 804 353 14.0 52.5 Jan-92 31.13 23.6 985 450 0.5 / 2 14.9 38.4 Feb-92 31.32 30.8 1176 544 14.3 31.7 Mar-92 31.47 36.5 1355 626 14.8 25.1 Apr-92 31.44 35.2 1323 610 23.8 / 4 14.6 22.8 May-92 31.65 43.1 1417 653 14.4 20.1 Jun-92 32.12 60.9 2215 880 -2.5 / 3 15.1 17.4 Jul-92 32.22 64.4 1852 832 15.5 14.1 Aug-92 32.21 64.1 1922 886 14.9 13.1 Sep-92 32.38 70.5 2062 954 -1.2 / 3 15.9 12.2 Oct-92 32.64 80.3 2317 1055 16.8 11.5 Nov-92 36.24 215.1 6112 1391 18.0 11.0 Dec-92 42.58 452.8 17390 2024 17.9 N/A Jan-93 42.59 453.1 13006 2034 23.8 / 2 19.2 N/A Feb-93 42.28 441.5 13895 2090 17.7 N/A Mar-93 43.14 473.8 14047 2151 17.7 N/A 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 44.52 525.6 23977 2700 22.5 / 2 17.7 N/A Aug-93 44.24 515.0 21879 2643 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 45.31 554.9 31892 3224 23.8 / 3 19.7 N/A Dec-93 45.84 575.1 37228 3024 19.0 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 travel for the month of December 1993: Freeland 1-Dec-1993 23-Dec-1993 23 days Hudson 5-Dec-1993 22-Dec-1993 26-Dec-1993 31-Dec-1993 24 days Lemen 1-Dec-1993 15-Dec-1993 15 days Nitta 5-Dec-1993 31-Dec-1993 27 days TOTAL 89 days Planned SXT travel for the month of January 1994: Hudson 1-Jan-1994 6-Jan-1994 17-Jan-1994 31-Jan-1994 21 days Nitta 1-Jan-1994 24-Jan-1994 24 days Slater 4-Jan-1994 31-Jan-1994 28 days Canfield 18-Jan-1994 31-Jan-1994 14 days Labonte 5-Jan-1994 31-Jan-1994 26 days TOTAL 113 days In addition to these scheduled trips some combination of Acton, Bruner, Lemen, and Strong will attend the IAGC conference in Easton, MD, at the end of January. Respectfully submitted, Keith Strong Frank Friedlaender Page 8 -------------------------------------------------------------------------------- UNIVERSITY OF HAWAII ACTIVITY REPORT (DR. R. CANFIELD) MAJOR ACTIVITIES FOR THE MONTHS OF NOVEMBER AND DECEMBER Our most important activities included support of Yohkoh operations and data analysis at ISAS, coordinated ground-based data acquisition at Mees, collaborative analysis of Yohkoh/Mees data, preparation of manuscripts for conference proceedings, preparation for and hosting the Hawaii Coordinated Data Analysis Workshop (CDAW) on AR 7260, and major improvements in the cadence of vector magnetograms with the IVM at Mees. During this period operational support for SXT was provided by Hudson and Leka at ISAS, Judd, Nitta, and Douglass at Mees, and Canfield, Jiao, Leka, Metcalf, Mickey, and Wuelser in Manoa. Solar activity was low to moderate, rising in celebration of the holidays. All Hawaii Yohkoh personnel contributed to the CDAW on "Magnetic Flux Emergence and Flares in NOAA AR 7260", whose 30 participants included a large Yohkoh contingent from Japan, many young people, and quite a few participants from the mainland U.S. and Europe. Noteworthy real-time coordinated data-analysis results (greeted by cheers) included the discoveries that X-ray transient brightenings coincide with magnetic neutral lines, but not bald-patch ones, that they occur in coincidence with moving magnetic features, not just emerging flux, and that dynamic H-alpha events (moving blue-shift events) occur in arch filament systems as the emerging flux reconnects with pre-existing coronal fields. Hudson's preparations for the CDAW dealt mainly with the irradiance variations of AR 7260 on longer time scales and did not seem to fit into the CDAW framework very well. This work is now incorporated in his invited review for IAU Colloquium 143 (Boulder). Hence, during the CDAW Hudson participated in the "VLA flare group" centered around the flare of 1700 UT on 20 Aug. 1992. This complicated and interesting flare has abundant observational material, including Mees MCCD and Boulder fast H-alpha observations, as well as VLA and Yohkoh observations. It was Hudson's intention to study the "conjugacy" of footpoint development and hence magnetic interconnectivity in this flare, but the attempt was frustrated by results obtained at the CDAW - the flare has an interesting pattern of compact sources along the magnetic inversion line, but in none of the analysis did simultaneous conjugate footpoints show up clearly. Either this is a bad example or else the concept does not work as well as thought. Hudson completed his review of Yohkoh white-light observations for the Boulder conference and also assisted Lidia van Driel with a poster paper on "black light flares" for the same conference. He also completed a draft of a poster paper for the Kofu conference proceedings on simultaneous mm-wave, white-light, and X-ray gradual bursts in flares. He also led the ISAS/Yohkoh seminar of 13 Dec., which mainly consisted of a discussion of the microflare spatial distribution in AR7260 and the Titov et al. paper on "bald patch" inversion lines. Finally he collaborated with visitor Frantisek Farnik and others (notably Jim Lemen, who used Farnik's visit as an opportunity to strengthen the SXT analysis software) on studies of X-ray precursor events and of a particularly interesting "super-hard" flare in October 1993. Page 9 Metcalf's paper on AR6952 and the surprising lack of any correlation between X-ray brightness, as observed by SXT, and photospheric vertical currents, inferred from Mees magnetograms, was accepted for publication in ApJ. He wrote up his work with Jiao on the height dependence of solar active region magnetic fields using a combination of Na-D and FeI magnetograph data. The manuscript is now being modified in response to comments from co-authors. In preparation for the CDAW, he set up a guest account and freed up disk space on the solar computer system. During the CDAW, he worked with Acton and Alexander on SXT movies to study the interconnections of AR7260 with neighboring regions. Finally, he worked with Hudson on magnetograms for AR7590 In connection with the AR7260 CDAW, Mickey looked into IVM data reduction procedures with an eye to (a) evaluating the effects of stray light and (b) utilizing to the extent possible the redundancy in the measurements. The 7260 data suffer from pretty severe stray light problems, but current data appear to have more tractable stray light. It looks possible to utilize polarization data from several spectral points by fitting low-order polynomials to the Stokes profiles, so that we can reduce the noise level without excessive computational cost. Mickey solved two problems in the IVM observing software, one with the shutter control and the other with camera readout control, which were causing aborted observing sequences. Continuous sequences of observations can now be done without constant monitoring by the operator. During November and December there were several days for which we obtained 45 magnetograms; the total for two months was 1368 magnetograms. As well, Mickey did some timing tests on the IVM observing software, in hopes of eliminating some dead time. First results indicate that the camera readout time is noticeably longer than expected. Leka worked on Yohkoh operations and data analysis at ISAS, and prepared for and participated in the Coordinated Data Analysis Workshop in Honolulu. As one of the resident experts on NOAA AR7260, she provided the CDAW participants with documentation on the emerging flux and magnetic fields and connectivity which she has studied as part of her thesis. At the CDAW she worked primarily with Shimizu, Sakurai, van Driel on the correlation of X-ray transient brightenings with magnetic features in the area. Jiao and Canfield continued to try to understand whether the intriguingly constant cross-sections of X-ray loops found by Klimchuk is related to the density of currents flowing through them. Using Klimchuk's code for quantifying the cross-sectional variation of loops observed by SXT in AR 7260, Jiao and Canfield worked on the relationship between the shapes of well-observed soft X-ray loops and the values of the footpoint photospheric electric current density inferred from the Mees vector magnetograms. While the results are interesting, they do not yet represent a sufficiently large statistical sample to be meaningful. Jiao presented the AR 7260 results at the CDAW. Canfield and Reardon continued their study of the H-alpha blueshift episodes and neutral-line crossing events that occurred during the preflare phase of the well-observed Yohkoh flare of 1991 Nov 15. Thanks to insights picked up during the AR 7260 CDAW, they were finally able to develop a detailed cartoon model of the nature of the reconnections that took place that comprise the destabilization of the filament through "tether cutting". During the CDAW, Canfield and Reardon worked with Yokoyama on reconnection events associated with emerging flux and surges and on velocity gradients in an arch filament system. Page 10 PLANS FOR JANUARY AND FEBRUARY Hudson will attend the AAS meeting in Washington in early January to give a paper on the SXT observations of the Mercury transit and partial eclipse. These unique data give us a head start towards understanding the X-ray emission corona at altitudes above 100,000 km, where the Yohkoh team is actively engaged in comparing data with SPARTAN and ground-based observatories, and looking forward to Ulysses and SOHO as well. As a part of this he is assembling an internal review of the SXT coronal observations, which have proceeded in both routine and special modes since mid-1992. He also plans to finish his contributions to the Kofu conference proceedings - one poster paper and one invited review of the Yohkoh soft X-ray observations. Metcalf will finish and submit the paper with Jiao studying the height dependence of the magnetic field using a combination of Na-D (chromospheric) and FeI (photospheric) magnetograph data. He will continue to work with Hudson on AR7590 magnetograms. He will complete the AR7260 movie on inter-region interconnections for Acton. He will continue the analysis of the IVM H-alpha data, searching for signatures of nonthermal protons in flares. Leka plans to complete applications for postdoctoral positions, as well as finish and submit the "Roadmap" paper for publication and complete the analysis of electric current and sunspot proper motions in NOAA AR7260. Leka will also work on the comparison of the Imaging Vector Magnetograph with the Haleakala Stokes Polarimeter for the IVM instrument paper in progress. Mickey plans to write a paper describing the IVM instrument and its performance. He will continue hardware and software improvements to the instrument in order to enable faster observation sequences, and complete the full-disk mosaic capability. He plans to verify the usefulness of some new data reduction techniques and incorporate them into a standard procedure, testing it on a long sequence of observations which follow the evolution of AR 7618. Jiao and Canfield will expand their study of the longitudinal variation of SXT loop cross-sections and footpoint currents and fields to include regions other than AR 7260. The additional regions will include AR 6919, 6952, and 7522. Canfield will be at ISAS from January 18th - February 11th, excepting absences for travel to the IACG meeting and Kyoto. He plans to work with Shibata and Yokoyama on simultaneous observations of X-ray jets and H-alpha surges. Page 11 -------------------------------------------------------------------------------- UNIVERSITY OF CALIFORNIA AT BERKELEY (DR. S. KANE) J. McTiernan attended the Fall AGU meeting in San Francisco from Dec. 6-10, 1993, and gave a talk titled, "Combined Soft X-ray and Hard X-ray Spectra for Solar Flares Derived from Yohkoh Observations", by J.McTiernan, S.Kane, J.Lemen, D.Zarro, and T.Kosugi. This presentation included spatially resolved, (approximately 10 arcsec resolution) SXT-HXT spectra for the flare of 2 November, 1991, and also results from combined BCS-HXT analysis of the whole flare source. In this analysis, we've identified a combined SXR-HXR impulsive source at a loop footpoint, and a gradual superhot (> 30 MK) source in a region that looks like the intersection of two loops. Analysis of a sample of 12 flares shows that in most cases (10 of 12), the non-thermal hard X-ray emission is dominant in the rise of the impulsive phase for all of the HXT channels. Thermal continuum emission from a plasma with temperature and emission measure determined from BCS FeXXV data, (using the D.Zarro, J.Lemen routine FIT_BSC), can only account for a few percent of the emission seen in the HXT-LO channel. Thus we may reliably push the value of the low energy cutoff of the non-thermal electron spectrum down to approximately 10 keV. Work is also continuuing on the analysis of multi-spacecraft hard X-ray spectra from Yohkoh, Ulysses and GRO/BATSE. This is being done by Terry Slocum, an undergraduate at UCB, under the supervision of S.Kane in collaboration with Richard Schwartz of GSFC. We now have data and scintillator response functions from approximately 20 common Yohkoh-Ulysses-BATSE events. -------------------------------------------------------------------------------- STANFORD UNIVERSITY (DR. P. STURROCK) November/December 1993 During the past two months, Jim Klimchuk and Lisa Porter have continued their study of X-ray coronal loops. The primary aim of the study is to determine the dependence of loop pressure on loop length. For quasi-static loops, this dependence yields useful information on how the energy input to a loop depends on the loop length. Such information places important constraints on theories of coronal heating in loops. Klimchuk and Porter are paying careful attention to the uncertainties in the pressure and length measurements. They have revised their analysis procedure and are about to reanalyze the approximately fifty cases they have identified so far. As part of this analysis, Klimchuk and Porter will determine the pressure time scales of the observed loops and compare these time scales to radiation and thermal conduction cooling time scales to determine whether the loops are heated steadily or episodically. On the theoretical end, Klimchuk has examined several simple ideas concerning coronal heating and has determined how these ideas may be tested with the forthcoming observational results. During the reporting period, Peter Sturrock attended the Yohkoh Coordinated Data Analysis Workshop held in Hawaii in late November, where he presented a summary talk of the workshop results. He also made a trip to Washington, DC to meet with Congressional staffers and with Wes Huntress, NASA Associate Administrator for the Office of Space Science, to discuss the important scientific contributions that Yohkoh has made to date and to point out the need for an extended mission and a guest investigator program. Klimchuk, George Roumeliotis, and Taeil Bai attended the American Geophysical Union meeting held in San Francisco in early December. Page 12 -------------------------------------------------------------------------------- SOLAR PHYSICS RESEARCH CORPORATION (KAREN L. HARVEY) Activity during Novemeber and December 1993 for SPRC are as follows: (1) continued work on the collaborative observing program between SXT/Yohkoh and the NSO/KP magnetograph of XBPs on 9-10 December 1993, 17-21 May 1993, and the most recent successful collaboration during 28 November-3 December 1993. The 28 Nov-3 Dec XBP observing campaign provided very good sequences to study the time variability of XBPs at a cadence of 8 and 16 sec. Magnetic field coverage of the target area came from NSO/KP, Big Bear Solar Observatory, and the Mees Solar Observatory instruments. Though the ground-based sites were often plagued by clouds, the combination of these three observatories gave good coverage of the photospheric magnetic fields. (2) completion of a paper on the variety of associations of X-ray bright points observed with the SXT Yohkoh instrument with magnetic structures found in simultaneous magnetic field observations. This paper will be published in the Proceedings of the 14th Summer Workshop held at the National Solar Observatory/Sacramento Peak 31 August - 3 September 1993. (3) continued update of bibliography of SXT/Yohkoh papers; the bibliography is being restructured for easier access as per conversation with N. Nitta and K. Strong. (4) continuation of plans for multi-observatory collaborative observing programs to study X-ray bright points. The next opportunity for a collaboration will begin around 19 January 1994 for approximately a 10 day period. The The Chief SXT Observer in Japan has been contacted to arrange this collaboration subject to low solar activity. The Big Bear and Mees Solar Observatories also will be contacted for ground-based support along with the National Solar Observatory/Kitt Peak. (5) began study of evolution of the magnetic field structures underlying X-ray jets. This is being done in collaboration with K. Shibata, who provided a list of X-ray jets he found from 1 November 1991 to 30 April 1992. This list was recently updated by Mr. Shimojo, a student at Tokai University. Two events have been studied extensively, those on 12 November 1991 and 7 December 1991. Both events occur at sites where magnetic flux is cancelling; the cancelling bipoles resulted from magnetic flux that emerged earlier, which then encountered adjacent opposite-polarity network. Page 13 -------------------------------------------------------------------------------- MONTANA STATE UNIVERSITY (LOREN ACTON) SUMMARY Primary activities at Montana State University this bimester: a. Arrival of Dr. David Alexander from University of Glasgow who joined the MSU solar physics group as a Research Scientist. b. Participation by Acton and Alexander in a Coordinated Data Analysis Workshop on AR7260 at the University of Hawaii. c. Work on scientific organizing committee of IACG campaign workshop. d. Instalation of PCs and image processing equipment. e. Acton was awarded 3 month Foreign Research Fellowship by ISAS. PUBLIC AFFAIRS - Public lectures (L. Acton): 4-6 Nov 94 Assemblies at eleven junior high schools, Billings, MT. 23 Nov 94 Speaker at Montana Science Olympiad, Bozeman, MT. 23 Nov 94 Manhattan Christian School (8th grade), Churchill, MT - Helped with release of Mercury transit images which were published in Science and Sky & Telescope. - Made contact with science reporter for the New York Times for publication of first appropriate newsworthy item from SXT. OPERATIONS - Completed work and prepared preliminary report on analysis of Al.1 straylight images. The correction algorithm so derived has not yet been tested and implemented in SXT analysis software. - All of the image processing equipment and one of the PCs we had ordered for SXT arrived and were made operational by Brian Handy. We can now print SXT images on the Tektronix printer but have not yet written anything to the Sony laser disk. Considerable difficulty was experienced making the DEC PCs fully functional but these have been largely overcome thanks to the skill and hard work of Handy. - Alexander completed a spread sheet for tracking the MSU SXT budget. He found some bookkeeping errors/misunderstandings and initiated corrective action. SCIENTIFIC WORK - Alexander gave Astrophysics Seminar on coronal heating. - Acton and Alexander prepared material on effects of AR7260 on general coronal structure for Hawaii workshop. It appears that the inter region loops to the east of AR7260 brightened and were sustained by the AR. These loops will be the subject of further study. A TBB item on this project is to be submitted and this work will serve as the basis of a poster paper by Brian Handy at the AGU/SPD meeting. - Acton analyzed the 22-Apr-92 "loop interaction" event that is to be published with Akioka and Hudson. - The written version of the paper "General Structure of the X-ray Corona" by Acton was completed and sent in for publication in the proceedings of IAU Colloquium 144. - Acton helped to organize the IACG Science Campaign Workshop on "Solar Sources of Heliospheric Structure Observed Out of the Ecliptic" which will take place at Easton, MD, on 27-29 January 1994. PLANS FOR NEXT BIMESTER - Attend IACG workshop. - Acton will go to ISAS to begin 3 month stay (Feb-Apr). - Alexander will teach a course in Solar Astrophysics (Physics 570, Individual Problems). - Bring Sony recorder system up to full functionality. Page 14 -------------------------------------------------------------------------------- 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 January 1994 December 1993 |-------------------------------- | 6. PERFORMING ORGANIZATION | CODE: O/91-30 -----------------------------------------------|-------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- K. T. Strong | 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 December 1993 |-------------------------------- |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 | 15 | ------------------------|------------------------|-----------------|------------ For sale by: Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402-0001