Version 2: The Major Programmatic Activities section was not updated correctly for this month in the previous mailing. Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for September 1998) 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 Martin, 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 Martin Solar and Astrophysics 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 Plans are being initiated for FY'99 operations. All indications are that operations can be maintained at their current levels next year. Under the present contractual arrangements a proposal will have to be prepared by LM against an RFQ provided by the government for this activity. << Solar Activity >> In early September, there were more than 10 regions present, including bright regions AR 8323 and 8319. During the first week of September, the level of solar activity was quite high, with four M-class flares. Activity declined as AR 8319 disappeared over the west limb and AR 8323 stabilized. A variety of phenomena, including a prominence eruption, a plasma cloud ejection, and a flare loop formation on the limb were observed. A CME was reported on 4-Sep-98 and was probably associated with AR 8319 (on the basis of its position angle). In the latter half of September, the GOES background level hovered around the mid-B level. There were no X flares, but two M flares including one (Sep. 23) nicely predicted by McIntosh on the basis of flux emergence in AR 8340. This flare led to a major magnetic storm. The Sun showed off lots of interesting features including active regions at extreme latitudes; interconnecting transequatorial loops; a remarkably aloof "anemone" region almost totally surrounded by AR 8340 and its henchmen; and a beautiful faint sigmoid. Finally, SXT observed an M flare over the NW limb on 30-Sep. This was observed by SXT PFIs and TRACE in the late phase, and in Yohkoh flare mode during the event itself. << Campaigns >> Page 2 In early September SXT participated in a Tenerife campaign, sponsored by the French group, to observe filaments. SXT also participated in a TRACE/Norikura campaign organized by Karin Muglach and Louise Harra. The Norikura observations were hampered by rain, but the last day of the run at Norikura had clear skies. Both TRACE and Yohkoh data are available, and there were a number of interesting phenomena in the region being observed. << Science >> Aschwanden, Alexander and Fletcher began a joint TRACE - Yohkoh/SXT study of an oscillating loop observed during the of flare 1998 Jul 14, 1255 UT. This discovery perhaps represents the first direct imaging of an oscillating loop in the solar corona. The loop oscillation lasts about an hour into the postflare phase, but seems also to be present at least an hour before the flare. The oscillating loop, with a length of L=120,000 km, shows transverse displacements with an amplitude of <5500 km and a period of 288 s. No phase shift is found along the loop, suggesting a standing wave that oscillates in the central loop segment. The loop oscillation is only prominent in the temperature range of T=1.0-1.5 MK. The loop is rooted on one side near the flare site, and on the other side near the penumbra of the leading sunspot. Yohkoh/SXT clearly shows that the oscillating loop is not directly connected with the flare plasma. The flare does not trigger the loop oscillation, but improves the brightness contrast of the oscillating loop with respect to the ambient plasma, probably by ejection of hot and cool plasma in front of the oscillating loop. The fast kink mode is the most likely MHD mode responsible for the observed period. Because the observed loop period is comparable with the chromospheric 5-minute oscillation period we suggest that chromospheric 5-min oscillations wiggle the footpoints of coronal loops and excite coronal loop oscillations in the case of a double resonance with the MHD kink mode. Based on statistical parameters we estimate that <12% of loops with temperatures of T=1.0-1.5 MK are in resonance with the 5-min period. The detection probability is likely to be lower, and seems to be optimum after a flare, when material is ejected from the line-of-sight to the oscillating loop. << 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 LMSAL SXT WWW homepage (http://www.lmsal.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 60638 accesses and 3435 Mbytes transferred. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. Page 3 SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT Bitmap error 07-September-98 Pass 5: 980907-0826 recovered in the same pass. SXT Bitmap error 09-September-98 Pass 1: 980909-0310 recovered in the same pass. SXT Bitmap error 09-September-98 Pass 4: 980909-0620 recovered in the same pass. SXT Bitmap error 17-September-98 Pass 1: 980917-0204. recovered in the same pass. In September, Wuelser updated the Yohkoh pointing solution. We use a combination of IRU (gyroscope) and HXA (limb sensor) data to derive this information. Since Fall 1997, the continuing degradation of the HXA data caused the following problems: 1. The accuracy of the pointing solution became worse than one SXT pixel. 2. The (ground) software increasingly failed to derive a pointing solution because of HXA limb address data that fell outside of the expected range of values. Wuelser changed the software to take into account the increased scatter of the data and re-processed the pointing solution data base (ATT files) back to the Fall of 1997. The new database has now very few instances of pointing solution failure. Some analysis showed that the accuracy problems could be overcome by using HXA intensity data instead of limb address data. This data is available much less frequently, but the gaps could potentially be bridged with data from the IRU sensors. Initial tests with fitting a limb-darkening model to the HXA intensity data yielded promising results. The scatter appears to be much smaller than for the limb address data. Page 4 << Data Flow >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Jul-96 392460 166925 1643461 370744 2014205 809345 28.58 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 7001 2296 24292 5395 29687 9340 23.93 Dec-96 7144 2643 25331 2087 27418 10412 27.52 Jan-97 7186 2747 21126 1257 22383 9915 30.70 Feb-97 6016 2034 22097 1072 23169 8961 27.89 Mar-97 7152 1300 26991 1209 28200 6394 18.48 Apr-97 6018 1055 23639 3890 27529 5349 16.27 May-97 7703 1455 29574 3783 33357 7121 17.59 Jun-97 7671 1557 25649 1396 27045 8045 22.93 Jul-97 8614 1385 32503 431 32934 6559 16.61 Aug-97 7316 987 23136 3519 26655 4990 15.77 Sep-97 7051 1479 33646 9596 43242 8887 17.05 Oct-97 7023 1134 26813 1827 28640 6043 17.42 Nov-97 6691 1376 26297 15306 41603 7131 14.63 Dec-97 6806 1013 28472 2136 30608 5263 14.67 Jan-98 5715 1803 23479 3232 26711 9918 27.08 Feb-98 6606 1644 25257 3606 28863 8989 23.75 Mar-98 6043 2056 23029 10399 33428 10939 24.66 Apr-98 6537 1103 22656 8087 30743 6339 17.09 May-98 7569 1838 28292 19018 47310 9868 17.26 Jun-98 6463 1638 24990 5618 30608 9051 22.82 Jul-98 6594 1852 25791 7357 33148 9712 22.66 Aug-98 5824 1960 22978 14126 37104 3764018 99.02 Sep-98 2796 478 8298 5775 14073 2642 15.81 Oct-98 0 0 0 0 0 0 NaNQ Nov-98 0 0 0 0 0 0 NaNQ Total 567522 212239 2285353 504618 2789971 4775815 63.12 Number of Full Frame Images Received: 567522 Number of Observing Region Images Received: 2789971 Total: 3357493 Approximate Number of Shutter Moves/CCD Readouts: 7276359 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 5 << Engineering Summary Table > Month Avg Dark Level # of Dark Spikes CCD Warmings Front Optical (DN) (e/sec) Over 48 Over 64 High / # Support Trans Temp /Days Temp (%) Aug-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 52.45 822.9 161683 12534 21.9 N/A Dec-96 53.08 846.2 171224 13860 22.9 N/A Jan-97 52.35 818.9 164785 11354 23.8 / 7 23.3 N/A Feb-97 51.95 803.9 159426 10346 21.1 N/A Mar-97 55.99 955.6 158428 12190 21.2 N/A Apr-97 53.14 848.4 176207 13265 20.8 N/A May-97 52.96 841.7 172052 13094 20.7 N/A Jun-97 53.71 869.8 182715 14910 19.8 N/A Jul-97 54.44 897.3 184518 20173 22.5 / 2 21.1 N/A Aug-97 54.06 883.1 188485 15549 20.1 N/A Sep-97 54.77 909.7 196501 17757 21.0 N/A Oct-97 54.85 912.8 198157 17857 21.5 N/A Nov-97 55.17 924.8 202153 18993 22.5 / 2 23.1 N/A Dec-97 55.51 937.6 206194 20219 21.9 N/A Jan-98 56.06 958.0 212189 22121 23.9 N/A Feb-98 55.94 953.7 209254 22122 23.8 / 2 22.6 N/A Mar-98 56.29 966.6 213519 23249 21.8 N/A Apr-98 56.44 972.1 214676 23890 20.8 N/A May-98 56.90 989.4 215651 26905 21.4 N/A Jun-98 57.11 997.5 216285 28223 20.1 N/A Jul-98 57.05 995.1 215628 27690 21.4 N/A Aug-98 57.36 1006.7 217355 29544 18.2 N/A Sep-98 57.14 998.4 215837 28118 20.4 N/A Oct-98 N/A N/A N/A N/A 0.0 N/A Nov-98 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-SEP-98 and 30-SEP-98 HUDSON 1-SEP-98 * 30-SEP-98 30 (total of 30 days) NITTA 1-SEP-98 * 20-SEP-98 20 (total of 20 days) SLATER 16-SEP-98 30-SEP-98 * 15 (total of 15 days) WUELSER 7-SEP-98 30-SEP-98 * 24 (total of 24 days) ---------------------------------------------------------------- Grand Total of 89 days for 4 people NOTE: The "*" signifies travel that actually ends after 30-SEP-98 SXT Foreign Travel between 1-OCT-98 and 31-OCT-98 CANFIELD 31-OCT-98 31-OCT-98 * 1 (total of 1 days) FREELAND 20-OCT-98 30-OCT-98 11 (total of 11 days) HUDSON 10-OCT-98 26-OCT-98 17 31-OCT-98 31-OCT-98 * 1 (total of 18 days) MCKENZIE 1-OCT-98 31-OCT-98 * 31 (total of 31 days) SLATER 1-OCT-98 * 21-OCT-98 21 (total of 21 days) WUELSER 1-OCT-98 * 2-OCT-98 2 (total of 2 days) ---------------------------------------------------------------- Grand Total of 84 days for 6 people NOTE: The "*" signifies travel that actually ends after 31-OCT-98 Respectfully submitted, Thomas R. Metcalf Frank M. Friedlaender Page 7 7 ================================================================= Montana State Univ Activity Report for August 1998-September 1998 ================================================================= (A. Davey) Operations: Canfield served one week as Yohkoh duty scientist at Mees, during the Whole Sun Fortnight. Mees got good observations of a prominence eruption on 14 August, with the MCCD, IVM, and WLC. Science: Acton prepared an overlay of the 5-Oct-96 CME from the LASCO C2 coronagraph and an SXT deep-exposure difference image prepared by Hugh Hudson. (The images were from one of the science nuggets.) The SXT difference image shows a coronal depletion at the equator and enhanced emission north and south of that. The extent of the enhancement corresponds roughly to the north and south boundaries of the CME "bubble." This is a very large-volume phenomena and deserves further study and interpretation and more events. If you'd like to see the overlay take a look at cme_overlay.gif which is in Acton's home directories at MSU, SAG, and ISASS0. Acton began work on a paper on a "temperature image" of the whole sun from the 26-Aug-92 long (120 sec in each thin filter) exposure images. Preliminary work on this was given at the Yoyogi meeting and published as an extended abstract. He also began another project with Jing Li on joint UVCS/SXT observations of 23/24 March 1998. Acton started a new collaboration with Jing Li and John Raymond looking at SXT and UVCS data on the SW limb on 23-24 March 1998. Unfortunately, even the short-exposure FFIs are somewhat saturated -- but the PFI coverage is outstanding! Four filters (Al.1, AlMg, Al12 and Be) are used and all have good signals. Acton prepared an SXT image from the long exposure August '92 offpoints, to use on the front cover of the alumni magazine, the Montana Collegian. He plans to use this same dataset, pre-filter-failure and with excellent statistics, for a paper on the global temperature structure of the entire corona. A preliminary version of this work was presented at the Yoyogi meeting a couple of years ago. Canfield worked with Alex Pevtsov on the book "On Magnetic Helicity in Laboratory and Space Plasmas". He also started working with Sean Sandborgh on a manuscript on large-scale structures in the corona. Canfield also worked with Charles Kankelborg on a TRACE flare; unfortunately, it took place after HXT was shut off for SAA. He also worked with Dave McKenzie and Hugh Hudson on sigmoidal structure and eruptions using the SXT data for 1993 and 1997 and worked to revise Hudson's draft manuscript for a paper on the topic. He gave revisions to Tonooka san for a paper on Page 8 eruptive filaments as seen in H-alpha (Mees coronagraph) and SXT. Mckenzie updated software for searching SXT light curves for periodic brightness. Mckenzie and Dermott Mullan (Bartol Research Institute) have a small SR&T grant for an analysis project similar to his thesis work. Mckenzie spent two weeks at Bartol so that he and Dermott could work out an efficient scheme for transferring data, performing analysis, etc, as well as setting up the programs at BRI and giving Dermott an intensive "refresher course". Next summer Dermott will come out to MSU for a short visit, to wrap up the project. Mckenzie Worked with Christine Halas of Harvard to prepare some images and temperatures from SXT's observations of the 26-feb-98 eclipse; she has spectra from Sac Peak and UVCS, and plans to complement them with SXT data. Mckenzie worked a little with data from JOP 080 (13-may-98) to answer some questions for David Berghmans; he is looking at active region transient brightenings. Mckenzie spent a few days reviewing the numbered active regions from 1993; revisiting Samantha Allen's work from this summer, Canfield, Hudson, and attempting to form a statistical basis for the claim that "S" shaped active regions are more likely to erupt than "potential" regions. Weber Finished a short project to do linear force-free field modeling with 3D graphical output; it was a good learning experience. Weber met with Peter Sturrock to discuss differential rotation project and thesis work. Sturrock's own work with time-series analysis may dovetail with his. Other Activities: Canfield participated in a review panel for NASA, reviewed two manuscripts for Solar Physics and one for ApJ. Canfield wrote an article for EOS on the highlights of the Chapman conference "Magnetic Helicity in Space and Laboratory Plasmas" held in Boulder in late July. He is now working with Alex Pevtsov and Mike Brown (Swarthmore) on the book based on the conference. Visitors: During August and September the solar group were visited by a number of people. In August it was Piet Martens and his wife. Piet gave a superb physics colloquium. In September visitors included Sam Freeland, Tom Metcalf and Peter Sturrock. Work with Sam and Tom focused on efforts to complete the tools for making the new mission-long SXT composite-image science movie. Sturrock talked to us about some ideas on coronal mass flux and heating driven by reconnection events in the temperature minimum region and chromosphere -- where the resistivity is high enough for reconnection to be easy. He also gave a colloquium on his recent work looking for periodicities in the solar neutrino data that relate to R-waves (analogous to Rossby waves in the earth's atmosphere) in the solar radiative core. Personnel: Page 9 The group welcomed an undergraduate physics major, Angela Colman, to make MCCD CDR's for Wuelser's list of eruptive flares well observed by the MCCD and Yohkoh. When that's done, she'll make CDR's for the preflare data, as well, to check for preflare "tether cutting" signatures. Computing: During the last two months the upgrade and homogenization of the solar group's systems have continued. A doubling of available user space will come online within a week. Plans to upgrade the network infrastructure are underway along with investigations of the feasibility of using the VBNS network, which should be live at MSU midway through November, for spacecraft operations. The CD jukebox at MSU died at a most unfortunate time and was unavailable for three weeks. This is now back on line and the Yohkoh CD's are once again accessible. Public Outreach: The MSU solar physics program is to be featured this fall on the alumni magazine, the Montana Collegian, as well as the MSU annual research report. An SXT image prepared from the long exposure August '92 offpoints will be on the cover of the Collegian. Manuscripts and Publications: Acton edited galley proofs of "PHYSICAL STRUCTURE OF A CORONAL STREAMER IN THE CLOSED-FIELD REGION AS OBSERVED FROM UVCS/SOHO AND SXT/YOHKOH" which is to appear in ApJ, v506 (1998 Oct 10). Acton submitted revised manuscript of "SUPER-X: A SOFT X-RAY TELESCOPE FOR SOLAR-B" for publication in SPIE Proceedings, "Missions to the Sun II" from the July 1998 meeting in San Diego, CA. Revised and submitted the paper "SOLAR X-RAY RADIANCE FROM YOHKOH" by Acton, Weston and Bruner to JGR-Space Physics. "Bringing Physics of the Sun to the Public", T.F.Slater, M.B.Larson, D.E.McKenzie, accepted by "Technological Horizons in Education (THE) Special Issue on: Partnerships: Industry/Education Success Stories", to appear October 1998. "Magnetic Helicity in Space and Laboratory Plasmas", Richard C. Canfield and Alexei A. Pevtsov, EOS, submitted. ============================================================= Univ of Hawaii Activity Report for August 1998-September 1998 ============================================================= (B. LaBonte) Our activities included support of Yohkoh operations and data analysis at ISAS, coordinated ground-based data acquisition (including designated Yohkoh Page 10 campaigns) at Mees, collaborative analysis of Yohkoh/Mees data, and preparation of manuscripts. Operational support for SXT was provided by Nitta at Mees 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. Weather was good during August, declining in September. All instruments are working well. The IVM is regularly taking magnetogram movies throughout the observing day. Mees participated in the the Whole Sun Fortnight observing campaign. The Imaging Vector Magnetograph observed the Na I D line to measure chromospheric vector magnetic fields. The Haleakala Stokes Polarimeter continued to observe photospheric fields. We observed several major flares (M, X class) during the interval. LaBonte has begun work on analyzing AR8227, the target region for the upcoming YOHKOH/SOHO/TRACE Coordinated Data Analysis Workshop. Mees has good coverage of this region over its disk passage. ============================================================ Stanford Univ Activity Report for August 1998-September 1998 ============================================================ (P. Sturrock) We announce with pleasure that Rich Wolfson, Professor of Physics at Middlebury College, has recently arrived to spend his sabbatical at Stanford where he will be collaborating in our Yohkoh research. Colin Roald and Peter Sturrock are continuing their investigation of the coronal heating theory mentioned in the previous report, in which the key process is magnetic reconnection at the chromospheric level. This model leads to a close relationship between the energy input into the corona, the mass input into the corona, and the rate of emergence and submergence of magnetic flux at the photosphere. Since the rates of emergence and submergence are not well known, we are developing a model for these processes so that we may compare the coronal energy flux with the photospheric magnetic flux itself. Our model involves the emergence of magnetic bipoles within supergranulation cells, the migration of magnetic elements into the network, and "collisions" of elements of opposite polarity (leading to "cancellation") in the network. An analytical treatment shows that the coronal energy flux will vary approximately as a power law function of photospheric magnetic flux, the power law index decreasing from 2 for weak fields to 1 for strong fields. This result appears to be consistent with similar relationships that have been inferred from observational data by Acton (whose data give n = 2), by Hara (who finds n = 1.4) and, more recently, by Fisher, Longcope, Metcalf and Page 11 Pevtsov (who find n = 1.2). However, our model is being developed from processes that are believed to occur in quiet regions, whereas Hara and Fisher et al. were investigating active regions. In order to pursue these studies, Roald is investigating processes in quiet regions in more detail by developing a computational model, and Sturrock is seeking to develop an analytical model of magnetic-flux processes in active regions along the lines of our model for such processes in quiet regions. We are also continuing our collaborative investigation with Sasha Kosovichev and Rick Bogart of the Stanford University SOHO/MDI team concerning the relationship between the soft X-ray luminosity of the solar corona and the photospheric magnetic flux. For a 3 or 4 month period, Bogart and Kosovichev will produce daily averages of the absolute value of the magnetic field for a small region at Sun center, and Roald will produce daily average values of the X-ray flux, as measured by Yohkoh, over the same region for the same time interval. This procedure is very similar to one also being pursued by Mark Webber and Loren Acton at MSU. In 1996 and 1997, Wheatland, Sturrock and Acton analyzed SXT data for a diffuse region on the limb, and found that the temperature and emission measure are consistent with a model in which the magnetic field is open, and the corona is heated by a downward heat flux. Since the region shows some loop-like structure, one is faced with the question of whether a suitable ensemble of loops could lead to the observed temperature and emission-measure profiles. If the answer is yes, it is likely that such diffuse regions are comprised only of closed magnetic structures. If the answer is no, it is likely that such structures contain a combination of both closed and open magnetic flux. In order to answer this question, Wolfson and Sturrock are analyzing a model comprised of such a sequence of loops, in which the state of the plasma in each loop is determined by the Vesecky-Antiochos-Underwood scaling-law model. We will investigate whether any distribution of energy input into such a set of loops can duplicate the temperature and emission-measure profiles of the diffuse region. Following up a suggestion of Roumeliotis, Wheatland has been investigating a procedure for constructing nonlinear force-free magnetic-field configurations from photospheric vector-magnetograph data. This procedure is in essence a variational procedure for minimizing a function formed from (div B)^2 and (j x B)^2 for prescribed boundary conditions. By investigating a known nonlinear force-free-field configuration and using the boundary conditions on all surfaces, Wheatland has found that the procedure does indeed converge to the correct configuration. The remaining problem is how to proceed when we are only given the conditions on one surface (the photosphere). Wheatland (now at the University of Sydney) continues to examine this problem, and it is also being taken up by Wolfson. One possibility that they are examining is that of adopting, as the condition on the remaining surfaces, the field computed from a simple current-free calculation. Another possibility that they are considering is to include another term in the variational procedure that would have the effect of seeking the configuration that is force-free, is consistent with the photospheric boundary condition, and falls off most rapidly with distance from the photospheric source. Alex Pevtsov of MSU has kindly agreed to collaborate in this project by identifying a target region, supplying Page 12 vector-magnetograph data, and comparing the calculated field with that inferred from SXT images. =========================================================================== Solar Physics Research Corp. Activity Report for August 1998-September 1998 =========================================================================== (Karen L. Harvey and Hugh S. Hudson) KAREN L. HARVEY: Activities for August and September: (1) Writing up results of study with Hugh Hudson on the evolution of the magnetic field and coronal holes associated with the active region complex which occurred during several rotations in the summer 1996 for publication in the proceedings of the COSPAR meeting in Nagoya in July. (2) Began analysis of data taken in collaboration with NSO/KP, Yohkoh/SXT, SOHO, TRACE, BBSO during observing program May 4-6, 1998 studying the behavior of magnetic flux in quiet sun canceling bipoles. Worked with K. Schrijver to put together the TRACE and SOHO/MDI data for 12 hours on early 4 May 1998. (3) Preparation of NSO/KP full-disk magnetograms and He I 10830 spectro- heliograms for SXT investigators for studies of the magnetic field and He I 10830 structures associated with X-ray structures. Planned Activities for October and November The analysis of the magnetic fields and coronal holes related to the 1996 activity complex and the large scale field patterns will continue and will be written up for publication in a referred journal. This includes determining the how the coronal connections using the SXT data develop relative to the photospheric magnetic field evolution over several months related to this complex and the new cycle regions. The analysis of the XBP data collected during several observing campaigns, concentrating on the more recent runs with the computer intensive reduction of the zonal scans (line profiles) in the Ca II 8542 and Fe I 8538 lines made during the 4-6 May and very successful 14-17 June 1998 runs and their relation to the XBP observed by SXT. HUGH S. HUDSON Activities in August and September H. Hudson's principal scientific activity in August and September consisted of CME-related work, some of it with ISAS visitor George Simnett. He showed us one remarkable set of data from about a week before SOHO's rest period - a coronal mass ejection flowing INTO THE SUN. For reasons unknown, this remarkable observation has not yet been published, so it's worth mentioning Page 13 here at least. For several consecutive C2 images, more than enough to ensure that physical motion was the cause, one side of a CME fell inwards towards the sun from a projected radial distance of about 4 R_sun. Nobody's theory covers this! In terms of Yohkoh/SXT operations, there was a solar eclipse in August (see ftp://isass0.solar.isas.ac.jp/pub/sxt_co/980829.html) which produced beautiful data but also caused a spacecraft safehold situation, which took a while to recover. Worse yet, half of the data successfully taken were lost due to a DSN error, but the half that we got were quite good. Because these affairs are not central to anybody's research right now, and since they always cause stress, we now intend to avoid eclipses in the future! Plans for October and November The main scientific efforts center on two meetings: the Nobeyama meeting (late October), and the fourth CDAW (early November in Palo Alto, see http://diapason.lmsal.com/~cdaw/). This CDAW will be different from earlier ones, in that it is sharply focused on a specific problem: the interpretation of image data in terms of 3D structure in the corona. The premise is that the X-ray and EUV structures show the field directions, which do not change rapidly unless a disruption occurs; there may be variations of illumination (heating), but these have no obvious effect on the structure. If we can determine the directions to 10%, the logic runs, we will have determined the field to 10% modulo a one-point calibration. This sounds almost too good to be true, since it does not depend at all on the Zeeman effect except at one point, and also does not depend in any way whatsoever on Green's functions! PUBLICATIONS Papers Submitted H. Hudson and R. Schwenn, "Hot cores in filament cavities" COSPAR 1998 Papers Accepted H. Hudson, L. Acton, K. Harvey, D. McKenzie: 1998, "A Stable Filament Cavity with a Hot Core", Ap. J. (Lett). =========================================================================== Naval Research Laboratory Activity Report for August 1998-September 1998 =========================================================================== (J. Lean) Magnetic Modulation of the Global Solar X-Ray Corona Page 14 During the past two months we have modified Yi-Ming Wang's potential field model extrapolation program to calculate simulated full disk coronal intensity images and disk-integrated fluxes for successive days throughout individual Carrington rotations. We have made these simulations thus far for two periods -- high solar activity in Carrington rotation 1851 (early 1992) and low solar activity in Carrington rotation 1925 (mid 1997)-- using Carrington magnetic field maps from both the Wilcox Solar Observatory and the National Solar Observatory. The simulations assumed an average coronal temperature of 2.5E6, and a linear relationship between magnetic field strength and coronal brightness. During 1992, agreement between the variations of the simulated disk-integrated fluxes and the Yohkoh SXT fluxes is fair for the NSO maps. The simulated fluxes track the overall rotational modulation evident in the observed fluxes during what was probably the strongest recorded rotational modulation for the entire mission (thus far). However, differences in intensity can be as much as 50% at some times. Using the WSO data, the agreement of the simulated and observed flux variations is poor, possibly because of the lower resolution and poorer seeing (in early 1992) for these data. Further studies are planned with maps from both observatories, over longer time periods, using different coronal temperatures, and with different assumptions about the relationship between magnetic fields and brightness. We discusses various of these possible assumptions with L. Acton, during his recent visit to NRL. =========================================================================== University of California Activity Report for August 1998-September 1998 =========================================================================== (G. Fisher) During the last two months, PI for the Berkeley subcontract from Lockheed-Martin was transferred from Prof. Kinsey Anderson to Dr. George Fisher. Berkeley personnel involved with Yohkoh research over the past 2 months include Jim McTiernan and George Fisher. McTiernan has revised and resubmitted a paper to the Astrophysical Journal on the evolution of the soft X-ray differential emission measure and its relationship to the Neupert effect during solar flares. McTiernan is also collaborating with Dr. Davin Larson and Prof. R. Lin of SSL in the comparison of SXT images of the Sun with data from NASA's WIND Mission on solar wind outflows, coronal mass ejections, and magnetic clouds. Fisher is working on comparing relationships between the magnetic field in active regions, as measured with the Haleakala Stokes Polarimeter, with coronal heating determined from X-ray radiances, measured with SXT. He has acquired a new set of reduced vector magnetograms for active regions observed between 1991 and 1996. Dr. Fisher is collaborating with Dr. Tom Metcalf of Lockheed Martin, and Dr. Alex Pevtsov of Montana State University on this problem. Fisher and Metcalf have written new software to extract the needed SXT data from the jukebox system at Lockheed so that the entire SXT dataset necessary to do this problem can be stored on disk, rather than having to go through the time consuming process of reading the data from many different Page 15 exabyte tapes. Fisher and McTiernan are discussing plans to compare the vector magnetogram data with SXT and GOES soft X-ray flare rates to determine which magnetic properties of active regions are statistically most correlated to high rates of flaring. Page 16 ------------------------------------------------------------------------------- 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 October 1998 September 1998 |------------------------------- | 6. PERFORMING ORG | CODE: O/H1-12 -----------------------------------------------|------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- T. R. Metcalf | TION REPORT NO: F. M. Friedlaender | |------------------------------- -----------------------------------------------|10. WORK UNIT NO. 9. PERFORMING ORGANIZATION NAME AND ADDRESS | Lockheed Martin Missiles and Space |------------------------------- Advanced Technology Center, O/H1-12, B/252 |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 Contact: John Owens | of September 1998 |------------------------------- |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 | 16 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office