Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for May 1999) 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 All contractual and financial aspects of the program are nominal. Effort is continuing for the continuation of the operations and data analysis beyond 1999. SOLAR ACTIVITY Solar activity went through two peaks during May, reflecting the occurrence of major flare activity in multiple regions. In early May, solar activity increased to moderate levels with the GOES background hovering in the low-C range at the end of the period. There were several M flares, including at least two long-duration events on 03-may and 08-may. The biggest event was M7.6 (May 9), which was on the NW limb. The M7.6 flare displayed extremely interesting ejecta. The outward flow persisted for a considerable period along the same path, strongly inclined to the vertical. In mid-May, activity was again high. Four M class events were reported by GOES, one on May 10 and three on May 16. However, in late-May, solar activity moderated with two low-level M-class flares and more than ten C-class flares. One of the M-class flares was observed in real time during the 2nd pass of Yohkoh on 29-May-99(UT). CAMPAIGNS This has been a busy season for observing campaigns. In the last few weeks we have taken part in JOPs 104 (X-ray jets, Davina Innes coord.), 100 (differential emission measures, Jeff Brosius coord.), 103 (TRACE moss, Tom Page 2 Berger coord.), and 017 (arch filament systems, Lidia Van Driel Gesztelyi coord.), in addition to making images in support of the VAULT rocket mission. During JOP 104, SXT followed the target regions hoping to see X-ray jets. We observed many brightening events; SUMER reports line shifts up to 400 - 600 km/s. On 7-may we supported the VAULT rocket-borne observations by making images of AR 8525. The rocket mission was a success. SCIENCE Acton developed a second order straylight correction technique which (as a second pass after sxt_prep) adds or subtracts enough additional SFC straylight image to cause the net signal in a strip across the bottom of the image to be zero. This results in a definite improvement in the gross accuracy of the corrected images in the years around solar minimum when the coronal signal is low. However, when the sun is more active there is actual coronal signal clear to the bottom of the CCD and the assumption that the corrected signal there should be zero breaks down. McKenzie worked on the X-ray voids seen above some flare arcades and did a survey of SXT data for all M and X flares between Jan-1998 and May-1999. He found downwardly mobile X-ray voids above 9 of the arcades. He measured the speeds from SXT and compared their appearances to EIT and TRACE images for the few events jointly observed. They may be blobs of cool material. In addition to these X-ray void events, the survey also turned up some really nice observations of ejecta (complete with twisting motions and apparent eddies) and possible evidence for inflow. Hudson reported on two sigmoidal active regions at similar longitudes north and south of the equator on May 27. Both regions erupted confirming our statistical conclusions that sigmoidal regions tend to produce CME-launching flares. This points to a relatively long lead time in predictive power but the time of the eruption remains enigmatic. Each of the sigmoids produced a relatively weak GOES event, which helps to explain some of the confusion of the earlier literature regarding flare and CME associations - sometimes you can't see the flare well in GOES data. 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 May were 85657 accesses and 4504 Mbytes transferred. YOHKOH OPERATIONS AND HEALTH Yohkoh and the SXT continue to function very well. SXT experienced a normal level of Single Event Upset (SEU) events during the month: Page 3 SXT Bitmap error 31-May-99 Pass 5: 990531-0411 recovered in same pass. Page 4 DATA FLOW Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Mar-97 448482 186426 1830854 385516 2216370 884951 28.43 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 6810 1892 27046 7357 34403 9970 22.47 Aug-98 5823 1960 22978 14126 37104 11167 23.13 Sep-98 6776 1432 21814 11626 33440 7753 18.82 Oct-98 6573 1901 23520 5198 28718 9220 24.30 Nov-98 6442 1695 25124 26948 52072 9920 16.00 Dec-98 5962 2005 21490 15770 37260 10561 22.08 Jan-99 5494 1825 20087 17620 37707 9622 20.33 Feb-99 5729 1525 30802 9798 40600 10630 20.75 Mar-99 6807 1844 24721 12354 37075 10064 21.35 Apr-99 6715 1371 25113 4179 29292 7791 21.01 May-99 3330 1053 24258 8006 32264 9995 23.65 Jun-99 0 0 0 0 0 0 -NaN Jul-99 0 0 0 0 0 0 -NaN Total 618769 226452 2495239 610342 3105581 1106136 26.26 Number of Full Frame Images Received: 618769 Number of Observing Region Images Received: 3105581 Total: 3724350 Approximate Number of Shutter Moves/CCD Readouts: 6395695 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 (%) 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 57.01 993.7 215499 27493 21.4 N/A Aug-98 57.36 1006.7 217355 29544 20.9 N/A Sep-98 57.43 1009.5 218520 29683 20.9 N/A Oct-98 57.59 1015.3 220504 30221 21.3 N/A Nov-98 58.17 1037.0 223755 34614 22.5 / 2 23.4 N/A Dec-98 57.86 1025.5 221918 32420 23.8 N/A Jan-99 58.74 1058.6 227503 38238 23.1 N/A Feb-99 58.44 1047.4 224002 36198 23.2 N/A Mar-99 59.26 1078.1 227900 43051 21.7 N/A Apr-99 58.82 1061.4 225973 38963 23.8 / 1 21.4 N/A May-99 58.42 1046.5 223838 35828 22.5 N/A Jun-99 N/A N/A N/A N/A 0.0 N/A Jul-99 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-MAY-99 and 31-MAY-99 CANFIELD 1-MAY-99 * 7-MAY-99 7 (total of 7 days) HUDSON 1-MAY-99 * 29-MAY-99 29 (total of 29 days) MCKENZIE 1-MAY-99 * 28-MAY-99 28 (total of 28 days) SLATER 26-MAY-99 31-MAY-99 * 6 (total of 6 days) ---------------------------------------------------------------- Grand Total of 70 days for 4 people NOTE: The "*" signifies travel that actually ends after 31-MAY-99 SXT Foreign Travel between 1-JUN-99 and 30-JUN-99 HANDY 26-JUN-99 30-JUN-99 * 5 (total of 5 days) HUDSON 2-JUN-99 30-JUN-99 * 29 (total of 29 days) MARTENS 5-JUN-99 30-JUN-99 * 26 (total of 26 days) SLATER 1-JUN-99 * 25-JUN-99 25 (total of 25 days) ---------------------------------------------------------------- Grand Total of 85 days for 4 people NOTE: The "*" signifies travel that actually ends after 30-JUN-99 Respectfully submitted, Thomas R. Metcalf Frank M. Friedlaender Page 7 ======================================================================= Montana State University Activity Report for April 1999-May 1999 ======================================================================= (D. McKenzie) SCIENCE Pevtsov worked on transequatorial active regions, characterizing geometrical and magnetic properties, and presented same at the AAS meeting. Acton worked on the SXT Science Movie, with Lemen, Metcalf, and Freeland. This database comprises all of the composite or unsaturated medium and long exposure images for the entire mission. These images will include all of the corrections in which we have confidence and will be kept in floating point so that no information is lost by data compression or exclusion of negative noise. Acton also worked with Jing Li on data analysis questions. Canfield worked with Angela Colman, adapting Kevin Reardon's software for velocity measurements prior to eruptive flares; and worked with Sean Sandborgh on his capstone project on large scale structures in the Yohkoh data. McKenzie analyzed observations of downward motion above LDE flare arcades. The initial part of this work formed a paper accepted by ApJL, and was presented at the ISAS solar seminar on Wednesday, April 28, and at AAS in Chicago. Martens and Kankelborg have been working on revising the abundances used in TRACE and SXT analysis software, to be sure the FIP effect is considered appropriately. Weber did research on a correlation between magnetic flux eruptions (at the photosphere) and rotation rates of polar coronal hole extensions in SXT stackplots. TRAVEL & TALKS McKenzie presented the downward motion above arcades at the ISAS solar seminar on April 28. At the ISAS seminar on May 6, Canfield led the "Cusps as Signatures of Eruption" Round Table Discussion. Canfield presented ``Sigmoidal Morphology and Eruptive Solar Activity'' at Space Weather Week, SEC/NOAA, Boulder, April 21-23, 1999. T. Slater presented "Using Real-Time Solar Data to Implement the National Science Education Standards" at the Space Science Institute Workshop for Space Scientists April 10, 1999 in Boulder. Most of the MSU group presented something or other at the Chicago AAS meeting: Canfield - press conference on the coming solar maximum; Canfield - Max Millennium; Noonan - self-organized criticality and magnetic separators; Page 8 Kankelborg - X-ray bright points; Larson - YPOP, and superfluid friction in neutron stars; Longcope - X-ray bright points; Pevtsov - transequatorial active regions; Martens - TRACE "moss"; Welsch - magnetic separators; Slater - YPOP, and science education; McKenzie - plasma motion above LDE flare arcades. YOHKOH OPERATIONS McKenzie and Canfield worked at ISAS as SXT Chief Observer and SSOC Tohban, respectively. The team coordinated observations with a number of JOPs in collaboration with several other observatories. Acton investigated some anomalies in the exposure durations for short-duration SXT dark frames; also examined SXT stray light levels, and the occurrence of a small entrance filter event in late April. SERVICE AND PUBLIC OUTREACH Acton reviewed a paper for Journal of Plasma Physics, and also helped with planning for IAU Symposium 195. Canfield refereed a paper for Solar Physics, flew the flag of the Space Science and Engineering Laboratory with the biologists of greater Bozeman, and worked with various writers on the sigmoids press release (World Book Publishing, Sky and Telescope). Canfield also spoke to the MSU President's advisory committee about the solar program at MSU; and set up summer work on Yohkoh data for summer students from the Montana Apprenticeship Program of American Indian Research Opportunities. Kankelborg reviewed a paper for ApJ. McKenzie prepared SXT images and movies from April 1998 for NASA HQ to be incorporated into a composite with LASCO, showing the sigmoid, CME, and spiky arcade of 20-apr-98. Also provided SXT images to a Japanese TV production. Our high school student from last summer, Samantha Allen, took her sigmoids work to the Montana State Science Fair and was named recipient of the 1999 "Award for the Most Outstanding Eleventh Grade Exhibit in Computer Science, Engineering, Physics, or Chemistry" by Yale Science & Engineering Association, Inc.; she also got "The Student Award for Geoscience Excellence" on the behalf of Association for Women Geoscientists for an outstanding project. Several members of the group worked with the local organizing committee of the IAU meeting in Bozeman this summer: "Highly Energetic Physical Processes and Mechanisms for Emissions from Astrophysical Plasmas" PUBLICATIONS SUBMITTED: "Coronal Heating by Resonant Absorption: the Effects of Chromospheric Coupling", A.J.C. Belien, P.C.H. Martens, and R. Keppens 1999, submitted to Astrophys. J. Page 9 "A Method for Characterizing Rotation Rates in the Soft X-Ray Corona", M.A. Weber, L.W. Acton, D. Alexander, S. Kubo, and H. Hara 1999, submitted to Solar Physics. "Coronal X-Ray Brightness and Photospheric Magnetic Field: A Study in Correlations", R. Wolfson, C. Roald, P.A. Sturrock, and M. Weber. ACCEPTED: "X-Ray Observations of Motions and Structure Above a Solar Flare Arcade", D. E. McKenzie and H. S. Hudson 1999, ApJL, in press. "Nonlinear Dynamics and Wave Heating in Solar Coronal Loops", A.J.C. Belien, P.C.H. Martens, R. Keppens, and G. Toth 1999, in 3rd Advances in Solar Physics Euroconference on: "Solar Magnetic Fields and Oscillations", Eds. B. Schmieder, A. Hofmann, and J. Staude, in press. "The Preflare Phase" (Invited Article) P.C.H. Martens 1999, in: "Encyclopedia of Astronomy and Astrophysics", in press. D. Emerson and E.R. Priest (eds.), The Institute of Physics Publishing ============================================================= Univ of Hawaii Activity Report for April 1999-May 1999 ============================================================= (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 and LaBonte and Li in Manoa. Our colleagues Kupke and 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 at Mees has been good, with some observations on 90% of scheduled days. Changes in the Mees instrument status during this interval include: Imaging Vector Magnetograph in full operation with the new datasystem and cameras. The Hawaii workstation at ISAS, kopiko (isass6) was brought back online with newer hardware and software and has been used successfully by visitors to ISAS and remotely by groups members. LaBonte spent 2 weeks at ISAS in April, including a stint as SSOC tohban. He gave a seminar entitled "Vector Magnetic Fields in NOAA AR 8210". Page 10 Jing has lead the planning of a joint observation among SXT, SOHO UVCS, SUMER, and CDS, and TRACE of the variation of thermodynamic properties in a streamer. The altitude overlap of the instruments will permit a unique comparison of the various diagnostics of temperature, emission measure, and density. SXT leak images for the offpoint position are already in hand thanks to the work of the Chief Observers, Hudson and McKenzie. LaBonte in continuing work on the analysis of AR8210 in April-May 1998. The SXT data for this region show that it dominated an entire quadrant of the Sun, with connections to active regions in both hemispheres. The largest (X-class) flares produced distinct and long-lived cusp structures; at least 2 of those events were preceded by brightenings of structure deep in the region, over the neutral line, of roughly sigmoidal shape. ============================================================ Stanford Univ Activity Report for April 1999-May 1999 ============================================================ (P. Sturrock, C. Roald, and R. Wolfson) 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. 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. Roald has developed a numerical model of this process, and computed power-law dependences of the heating flux on the mean magnetic field over a wide range of values of the principal problem parameters. The power-law index appears to be a robust prediction of the model, being approximately independent of the model's free parameters, characteristically falling in the range 1.9--2.0. A paper describing these calculations has been drafted. Sturrock has developed an analytical model of the magnetic-element kinetics in which elements arise only within the supergranulation cells and annihilate only in the network regions. This leads to a simple analytical relationship between the mean coronal energy flux density and the mean photospheric magnetic flux density. For weak fields, the relationship is approximately quadratic, but for strong fields the relationship is approximately linear; the weak-field limit therefore better corresponds to the behavior of Roald's numerical model. This relationship should be observable given sufficiently high-resolution measurements of the unsigned magnetic field. We intend to investigate the feasibility of comparing Yohkoh SXT heating data to high-resolution magnetograms and/or Ca II K images. Sturrock is continuing his spectrum analysis of an SXT data set kindly provided by Mark Weber of Montana State University, giving daily average values of the SXT flux, as measured by the Al and Dg filters, in nine small regions located at latitudes -60S, -45S ... 45N, 60N. Spectrum analysis of Page 11 this data set has yielded a surprising split in frequencies, with low to mid-latitudes appearing to rotate rigidly at 13.5 yr^-1 while higher latitudes rotate at 12.9 yr^-1. The expected smooth differential rotation profile was not found. The key question is whether the rotational properties of the corona may be understood simply in terms of the photospheric magnetic field, as one would expect. We hope that further study of the SXT data, and a comparison between the SXT data and MDI magnetic-flux data, will shed light on this question. Roald will pursue this question by examining the raw unbinned data. Richard Wolfson has completed his Stanford sabbatical, and is returning to Middlebury College after the AAS/SPD meeting. He spent his last month completing calculations and preparing papers describing results of two Yohkoh investigations, both of which were described in earlier reports. The first, a study of correlations between coronal X-ray fluxes measured with the Yohkoh SXT and photospheric magnetic fields measured with the MDI on SOHO, is coauthored with Roald and Sturrock from Stanford, and with Mark Weber from Montana State University. A version of this work is also being presented at the AAS/SPD meeting. The second paper concerns a discrepancy between Yohkoh SXT and SOHO SUMER determinations of the temperature structure in a region of quiet corona observed in November 1996. After the initial results reported earlier, Wolfson undertook a model-dependent calculation that accounts for the non-isothermal nature of the emitting plasma, and finds that the discrepancy persists. The paper shows that gravitational stratification of iron, as suggested by the SUMER measurements, is not sufficient to account for the temperature discrepancy. This paper is coauthored with Roald and Sturrock, and with J. Lemen and P. Shirts at the Lockheed Martin Solar and Astrophysics Laboratory. Both papers have been submitted to The Astrophysical Journal. Sturrock and Wolfson have begun to develop a model of coronal mass ejections, based on the scenario that a CME is caused basically by the eruption of a long twisted magnetic flux rope constrained by an overlying transverse field. The simplest version, with translational symmetry, is comprised of a flux tube in a force-free (but not potential) state, and an overlying field in a potential state. We anticipate that the equilibrium configuration can be analyzed either by the magnetofrictional method or possibly by a generating-function (Grad-Shafranov) method. Once one has an equilibrium state, it will be possible the examine the stability properties of that configuration by means of an energy theorem. Publications ------------ Wolfson, Roald, Sturrock and Weber, 1999, "Coronal X-ray Brightness and Photospheric Magnetic Field: A Study in Correlations," ApJ, submitted Wolfson, Roald, Sturrock, Lemen and Shirts, 1999, "Temperature Structure of the Quiet Corona: an SXT-SUMER Discrepancy", ApJ, submitted Roald, Sturrock and Wolfson are jointly presenting three papers to a poster session at the Chicago AAS Meeting in June. These are as follows: Page 12 Roald, Wolfson and Sturrock, 1999, "Coronal X-ray Brightness and Photospheric Magnetic Field: A Simple Model", AAS Mtg 194, #16.16 Sturrock, Roald and Wolfson, 1999, "Chromospheric Magnetic Reconnection and its Possible Relationship to Coronal Heating", AAS Mtg 194, #16.18 Wolfson, Roald and Sturrock, 1999, "Coronal X-ray Brightness and Photospheric Magnetic Field: Observational Correlations", AAS Mtg 194, #16.17 =========================================================================== Solar Physics Research Corp. Activity Report for April 1999-May 1999 =========================================================================== (Karen L. Harvey and Hugh S. Hudson) KAREN L. HARVEY: Activities for April and May: (1) Continuing with analysis of data taken in collaboration with NSO/KP, Yohkoh/SXT, SOHO, TRACE, BBSO during observing program May 4-6, 1998 and June 14-17, 1998 to study the behavior of magnetic flux in canceling bipoles observed in the quiet sun. We have been successful in reducing the simultaneous measurements at two levels of the solar atmosphere -- in the chromosphere and the photosphere -- of the magnetic and velocity fields, line depth and equivalent width using the Ca II 8542 and Fe 8538 lines. The data are being analyzed to determine if magnetic flux in canceling bipoles in the quiet sun is submerging below the photosphere or not. A detailed comparison will be made with intensity images from the SXT, TRACE and SOHO in the X-ray and EUV lines to deduce the height structure of the associated coronal bright points. A talk on the subject is planned for the August TRACE meeting. (2) Continuing the analysis of the complex of activity in the summer months of 1996 and the associated formation of coronal holes. A paper is now being written for publication. (3) Study of the effect of the disappearance of sunspots on the connections observed in the SXT FFIs. The NSO/KP daily full-disk magnetograms covering 1996 through 1998 have been decomposed into several major magnetic structures -- active regions, decaying regions, enhanced network and quiet network -- in order to study the contribution of these structures to spectral irradiance. As product of this decomposition, we found several regions in which sunspots disappeared near disk center. The objective of this study is to determine if the magnetic flux in the disappearing sunspots migrates into the plage fields or disappears from the surface as suggested by an earlier investigation by Wallenhorst and Howard (Solar Phys. 76, 203, 1982). An important element is this study is the evolution of the coronal fields, as inferred by the SXT data, as the sunspots disappear. (4) 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 Page 13 10830 structures associated with X-ray structures. Planned Activities for June and July: Continued analysis of (1) 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 the 14-17 June 1998; (2) the magnetic fields and coronal holes related to the 1996 activity complex and the large scale field patterns with the objective of publication of the results in a referred journal. This includes determining using the SXT data how the coronal connections develop relative to the photospheric magnetic field evolution over the several month lifetime of this complex and the new cycle regions; (3) of the evolution of the coronal loops in conjunction with the disappearance of sunspots; (4) the spatial relation of coronal holes inferred from He I 10830 spectroheliograms and those observed with the SXT. HUGH S. HUDSON Activities for April and May: 1. Assisted David McKenzie with reporting his measurements of the velocity field above a post-flare arcade, specifically Jan. 20 1999 (ApJ letter now accepted, soon to appear), but also others. We think that we're seeing reconnection byproducts, and they have unexpected properties. 2. Continued analysis of the May 6, 1998 wave. The paper, not yet submitted, has been converted to a full paper rather than a Letter. Its content was presented at the SPD meeting by Nariaki Nitta, since none of the authors could attend. 3. Assisted Franta Farnik et al. with analysis of transequatorial interconnecting loops (TILs), the subject of many science nuggets owing to their wonderful visibility in the SXT data. Proposed an "inchworm reconnection" model to explain their formation. Planned activities for June and July: 1. Continue (finish?) work on the May 6, 1998 wave, and look for more. 2. Assist J. Khan in analysis of TILs. 3. Write a comment for Science regarding the oscillating waves observed by TRACE, and on the subject of coronal heating in general. Try to take advantage of Piet Martens's visit to ISAS to learn some relevant MHD. PUBLICATIONS: Papers Accepted McKenzie, D. E., and Hudson, H. S.: "X-ray Observations of Motions and Page 14 Structure above a Solar Flare Arcade," ApJL (June 1999) http://isass1.solar.isas.ac.jp/~hudson/publications/mh_apjl99.pdf Papers Published Aschwanden, M. J., Fletcher, L., Sakao, T., Kosugi, T., and Hudson, H. S.: "Deconvolution of Directly Precipitating and Trap-precipitating Electrons in Solar Flare Hard X-Rays," ApJ 517, 977-989 (1999). =========================================================================== Naval Research Laboratory Activity Report for April 1999-May 1999 =========================================================================== (J. Lean) Magnetic Modulation of the Global Solar X-Ray Corona During the past two months we prepared talks and posters for the AAS/SPD mtg. Judith, Yi-Ming and John, with coauthor Loren, prepared a poster describing ten potential field model simulations of coronal x-ray variability, compared with the SXT flux variations during solar rotation and the solar cycle. The ten simulations covered the period from 1991 to 1997, and adopted a variety of scaling relations between the footprint field strengths and lengths of magnetic loops. Jim presented his work on coronal heating scaling laws. John, Jim and Judith attended the SPD meeting. We are now working on writing papers about the results presented at the SPD. =========================================================================== University of New Hampshire Activity Report for April 1999-May 1999 =========================================================================== (T. Forbes) Publications: Forbes, T.G. (1999) Solar and stellar flares, Phil. Trans. Roy. Soc. A, in press. Lin, J. and Forbes, T.G. (1999) The effects of reconnection on the CME process, J. Geophys. Res., submitted. ======================================================================= University Of California Activity Report for April 1999-May 1999 ======================================================================= (G. Fisher) Berkeley personnel involved with Yohkoh research over the past 2 months include George Fisher, D. Tod Woods, Neil W. Griffiths, Chris Johns-Krull, and Jim McTiernan. Page 15 Jim McTiernan is extending his study of the Neupert effect in solar flares by including many more flares (147) than the 80 used in his original study published earlier this year. A simple correlation technique is used to determine whether the soft X-ray time derivative is similar to the hard X-ray light curve for each flare of a large sample of flares. In order to compare the degree of consistence with the Neupert effect at different temperatures, data from the FeXXV band of the Yohkoh BCS, and the Al.1 filter of the Yohkoh SXT are used in comparison with data from the Yohkoh HXT. The results are then compared to those obtained by comparing the soft X-ray curves to random samples of the hard X-ray curves. Preliminary results for a sample of 137 flares show that high temperature radiation, as seen in the BCS-FeXXV channel is consistent with the Neupert effect for 47 of the flares. This is approximately twice the number of flares that would show consistence from a random sample. For low temperature radiation, as seen by the SXT-Al.1 filter, only 10 of the 137 flares are consistent with the Neupert effect, which is the same number as would be expected from a random sample. These results were presented at the recent AAS/SPD meeting in Chicago. Fisher, Griffiths and Woods have been working on the analysis of overlapping SXT and SUMER data for a small unnamed active active region along the central meridian, observed on 19-APR-1997. The combination of density diagnostics from the OIV 1399,1401 lines, and differential emission measures determined from strong O and N transition region lines observed by SUMER, in conjunction with the SXT data, allows us to to characterize the differential emission measure distribution, density distribution, and ``filling factor'' for the emitting material in this small active region. We find a power law relationship between the emitted power in transition region radiation and the electron density, with a power law index of roughly one. A similar study of the quiet Sun yields a power law index of roughly 1/2. We find that the SXT temperature and emission measure were consistent with the differential emission measure distribution determined from our SUMER observations. These results were presented at the recent AAS/SPD meeting in Chicago. We hope to submit a paper to the astrophysical journal describing these results shortly. 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 June 1999 May 1999 |------------------------------- | 6. PERFORMING ORG | CODE: O/L9-41 -----------------------------------------------|------------------------------- 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/L9-41, 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: Larry Hill | of May 1999 |------------------------------- |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