Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for May 2000) 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 Although the new contract is only ten days old, we are continuing the distribution of the Monthly Progress Report on the tenth of the month so as to provide all participants a seamless transition into the next phase of this project. SOLAR ACTIVITY In early May, the background GOES level dropped to B2. But, a huge flare marked the disappearance of the AR 8971-8977 complex. Although only M1.5, and with a puny peak microwave flux of 67 SFU at 2695 MHz, the regions were 10-25 degrees beyond the limb - if the latter, which on-disk flares suggest, the occultation height was some 70,000 km. So this was really one of our missing X-class flares. An impressive CME was observed mainly off the southwest limb. Also, Trace EIT difference images clearly showed a Morton wave traveling through the lower corona which was evidently produced by the same flare. As Yohkoh finished supporting JOP122 (network flares), activity began to rise from its amazingly low level to something more substantial. There were major flares from several regions. Truly the Sun can be lopsided. There were nine M flares and the soft X-ray background rose from B3 to C2. The growth of the sunspot regions on the disk was quite spectacular: 8996 grew a factor of three in area in one day. In mid-May, baseline solar activity, according to GOES, was nearly constant after the big increase earlier in the month. The Sun produced several M-class flares, the biggest of which happened outside of visible contacts and its onset was unfortunately during spacecraft night. Three warnings of CMEs arrived from Mauna Loa and one of them probably Page 2 corresponded to a small but dandy event on May 17, as recorded nicely by SXT. In late May, the GOES background flux decreased roughly from C1 to B6, with a period of enhanced flare activity superimposed (24/25 May). Solar X-ray brightness decreased substantially, as regions with big spots either decayed or rotated off the west limb. None of these flares reached the M2 level. The X-ray Sun was dominated by AR 9002/4 complex and then by AR 9017. There were 11 M-class flares, all occurring by 24 May. Repeated formation of TILs was seen to originate in a faint area west of AR 8996. CAMPAIGNS In early May, Yohkoh supported JOP122 (network flares), a campaign ideally planned from the solar point of view (zero activity) but badly timed from the Yohkoh point of view (weekend operations on invisible orbits). The exposure times to see network flares were too long, even though the Sun providentially went through its deepest mini-minimum in a while, so we probably won't schedule quiet-Sun observations in the near future again. During the latter half of May, we did not officially participate in any coordinated campaigns, but occasionally observed AR 9002, which was the La Palma/TRACE target region. The TRACE-La Palma campaign was to observe sunspots. SCIENCE With Zarro, Myers and LaBonte, Canfield worked on the co-aligned SXT, TRACE, SoHO, BSO, and SOON movies and Mees vector magnetograms for flares observed in the sigmiodal active region AR 8668 during Whole Sun Month 3. BBSO high-resolution H-alpha images of filaments proved to be particularly interesting in trying to understand the role of a flux rope in these events. Canfield continued to work with various MSU graduate and undergraduate students on the analysis of SXT and MCCD data. Trish Van Lew studied SXT jet / MCCD surge events using the Blehm/Pevtsov list of jets and surges inferred from SXT sfd images. Daniel Bambeck began the development of software for objective recognition of sigmoids in SXT sfd images. Rebecca McMullen started a study of active region twist vs tilt using both Mt Wilson and Mees data. Andy Burnettte is winding up a comparison of force-free field parameters derived from SXT images to those derived from Mees vector magnetograms. Eric Erickson and Tyler Bangs (Headwaters Academy) studied the relationship between sigmoids and signatures of eruptions in the SXT sfd movies on videodisk. With Pevtsov, Canfield helped write up a study of geomagnetic storms temporally associated with the eruption of 18 individual coronal X-ray sigmoids observed with SXT. This was an attempt to understand why the relationship between the geomagnetic index Ap and the sunspot number S Page 3 for cycles 17-22 shows no compelling evidence that either the large-scale dipolar field or active regions uniquely modulate Ap/S on solar-cycle time scales during that period. We conclude that the magnetic structure of individual active regions plays a significant role in geomagnetic events, and no simple cycle-dependent generalization is useful in predicting the geomagnetic effects associated with an individual solar eruption. Canfield was awarded MSU's Wiley Prize for meritorious research. The award cited his work with Hudson and McKenzie on sigmoids as a tool for the identification of solar regions likely to produce Coronal Mass Ejections and his contributions to the success of the Yohkoh mission and the solar group at MSU. Nitta continued the study of the relationship between SXT and HXT L/M1 channel sources in flares. He found that the high-temperature regions in SXT filter-ratio temperature maps are located higher than the HXT source. If the temperature maps are real and the HXT L/M1 channels capture a thermal source, this means that there is a temperature gradient cool-very hot-hot as we go up. He doubts the reality of the SXT high-temperature pixels, largely because of the uncertainty in the wavelength dependence of the SXT PSF. He also found that the SXT high- temperature region provides one to two orders of magnitude less emission measure to account for the BCS Fe XXV spectra, even though the temperatures of the SXT and BCS at face value are a close match. This is summarized in the 000526 nugget. PUBLICATIONS Submitted: Innes, D. E., Curdt, W., McKenzie, D. E., Schwenn, R., Solanki, S., and Stenborg, G., ``Flare and CME onset: explosive reconnection in the solar corona" was submitted to Nature. McKenzie, D. E., and Hudson, H. S., ``Downflows and Structure above LDE arcades: Possible Signatures of Reconnection?", submitted to Earth, Planets and Space, special issue: Proceedings of the meeting "Magnetic Reconnection in Space and Laboratory Plasmas", Tokyo, Japan, Feb 29-Mar 4, 2000. Pevtsov, A. A. and Canfield, R. C. ``Solar Magnetic Fields and Geomagnetic Events", JGR, submitted, 2000. Sturrock, P.A., Wheatland, M.S., & Wolfson, R. 2000, Metastable magnetic configurations and their significance for coronal mass ejections. Ap J, submitted. Wheatland, M.S., Sturrock, P.A., & Roumeliotis, G. 1999, An optimization approach to reconstructing force-free fields, ApJ, submitted. Aschwanden,M.J. and Acton,L.W. 2000, Submitted (May 4), "Tomography of Page 4 the Soft X-Ray Corona: Measurements of Electron Densities, Temperatures, and Differential Emission Measure Distributions above the Limb", URL="ftp://sag.lmsal.com/pub/aschwand/2000_acton.ps.gz" "Non-coronagraphic Observations of CMEs": Hudson, H. S. and Cliver, E. W. J. Geophys. Res., 2000. Accepted: Canfield, R. C. and Pevtsov, A. A. ``Vector Magnetic Fields, Sub-surface Stresses, and Evolution of Magnetic Helicity'', Invited Paper for IAU Colloquium 179, ``Cyclical Evolution of Solar Magnetic fields: Advances in Theory and Observations'', December 13-16 1999, Kodaikanal, India, J. Astrophys. Astr. in press, 2000. Pevtsov, A. A. and Canfield, R. C., ``Coronal Structures as Tracers of Sub-Surface Processes'', Invited Paper for IAU Colloquium 179, ``Cyclical Evolution of Solar Magnetic fields: Advances in Theory and Observations'', December 13-16 1999, Kodaikanal, India, J. Astrophys. Astr. in press, 2000. Roald, C.B., Sturrock, P.A., & Wolfson, R. 1999, The dependence of coronal heating on magnetic flux density in the photosphere, Ap J, in press. Wolfson, R., Roald, C.P., Sturrock, P.A., and Weber, M. 1999, Coronal X-ray brightness and photospheric magnetic field: A study in correlations, ApJ, in press. Aschwanden,M.J., Nightingale,R.W., and Alexander,D. 2000, ApJ 542, (2000 Oct 10 issue), in press, (accepted May 17) "Evidence for Nonuniform Heating of Coronal Loops Inferred from Multi-Thread Modeling of TRACE Data" URL="ftp://sag.lmsal.com/pub/aschwand/2000_serio.ps.gz" Published: Aschwanden,M.J. and Nitta,N. 2000, ApJ Lett. 535, L59-L62, (2000 May 20 issue.) "The Effect of Hydrostatic Weighting on the Vertical Temperature Structure of the Solar Corona" URL="ftp://sag.lmsal.com/pub/aschwand/2000_vertical.ps.gz" http://www.journals.uchicago.edu/ApJ/journal/contents/ApJL/v535n1.html Aschwanden,M.J. 2000, in "High Energy Solar Physics: Anticipating HESSI", ASP Conference Series Vol.206, R.Ramaty and N.Mandzhavidze (eds.), p.197-203. "Hard X-Ray Timing Experiments with HESSI" URL="ftp://sag.lmsal.com/pub/aschwand/1999_hessi.ps" Metcalf, T. R. and Alexander, D. 2000, "Coronal Trapping of Energetic Flare Particles: Yohkoh/HXT Observations", in "High Energy Solar Physics: Anticipating HESSI", ASP Conference Series Vol.206, R.Ramaty and N.Mandzhavidze (eds.), p.233-238. Page 5 Trimble,V. and Aschwanden,M.J. 2000, Publ.Astr.Soc.Pacific, Vol.112, Issue 770, p.434-503. "Astrophysics 1999" (Invited Review) URL="ftp://sag.lmsal.com/pub/aschwand/1999_trimble.ps" (excerpt of chapter 2: "Solar Physics") "Does Magnetic Flux Submerge at Flux Cancellation Sites?": Harvey, K. L., Jones, H. P., Schrijver, C. J., and Penn, M. J., Solar Physics, 190, 45--55 (1999). "Homologous Sudden Disappearances of Transequatorial Interconnecting Loops": Khan, J. I. and Hudson, H. S. , Geophys. Res. Let. 27, 1083, 2000. 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 140772 accesses and 7157 Mbytes transferred for the SXT website and 177648 accesses and 3924 Mbytes transferred for the YPOP website. 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: Bit Map Error 01-May-00 Pass 1: 000501-0514 Recovered in the same pass Page 6 DATA FLOW Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Mar-98 531739 203370 2152348 444637 2596985 974185 27.01 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 6459 1807 35467 12092 47559 13757 22.44 Jun-99 6217 1915 23542 13051 36593 10086 21.61 Jul-99 5591 1745 20409 25747 46156 9670 17.32 Aug-99 6827 2503 21725 23361 45086 11844 20.80 Sep-99 5768 2011 21890 3434 25324 10846 29.99 Oct-99 5768 2308 22994 10487 33481 11517 25.59 Nov-99 7552 3425 20754 18772 39526 11974 23.25 Dec-99 7488 2791 22047 5354 27401 10663 28.01 Jan-00 5426 1736 19802 4040 23842 8958 27.31 Feb-00 6533 2052 21801 7017 28818 8982 23.76 Mar-00 6447 2007 22692 21914 44606 11192 20.06 Apr-00 6412 2100 31195 7214 38409 13438 25.92 May-00 6180 1270 25348 14159 39507 7410 15.79 Total 698107 253069 2780647 768978 3549625 1236478 25.83 Number of Full Frame Images Received: 698107 Number of Observing Region Images Received: 3549625 Total: 4247732 Approximate Number of Shutter Moves/CCD Readouts: 7228612 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 7 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-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 58.68 1056.4 225385 37726 21.6 N/A Jun-99 59.40 1083.0 230091 42440 22.0 N/A Jul-99 59.78 1097.5 231236 46337 23.8 / 1 20.6 N/A Aug-99 59.39 1083.0 229319 43067 21.7 N/A Sep-99 60.04 1107.3 231585 49084 21.8 N/A Oct-99 59.66 1092.9 229735 45263 22.8 N/A Nov-99 59.90 1102.0 231288 47102 23.0 N/A Dec-99 60.55 1126.3 233523 53920 22.5 / 2 25.3 N/A Jan-00 60.27 1115.9 233820 50214 23.4 N/A Feb-00 60.93 1140.6 235079 56836 23.8 N/A Mar-00 60.72 1132.8 234174 54661 22.9 N/A Apr-00 61.10 1147.0 235252 58348 22.2 N/A May-00 60.73 1133.0 233774 54742 21.1 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 8 PERSONNEL TRAVEL SXT Foreign Travel between 1-MAY-00 and 31-MAY-00 HANDY 1-MAY-00 * 4-MAY-00 4 12-MAY-00 20-MAY-00 9 (total of 13 days) HUDSON 1-MAY-00 * 15-MAY-00 15 (total of 15 days) NITTA 14-MAY-00 31-MAY-00 * 18 (total of 18 days) SLATER 9-MAY-00 17-MAY-00 9 (total of 9 days) ---------------------------------------------------------------- Grand Total of 55 days for 4 people NOTE: The "*" signifies travel that actually ends after 31-MAY-00 SXT Foreign Travel between 1-JUN-00 and 30-JUN-00 HANDY 15-JUN-00 30-JUN-00 * 16 (total of 16 days) HUDSON 1-JUN-00 16-JUN-00 16 26-JUN-00 30-JUN-00 * 5 (total of 21 days) NITTA 1-JUN-00 * 09-JUN-00 9 (total of 9 days) ---------------------------------------------------------------- Grand Total of 46 days for 3 people NOTE: The "*" signifies travel that actually ends after 30-JUN-00 Respectfully submitted, Thomas R. Metcalf Frank Friedlaender Page 9 8 ================================================================ Montana State University Activity Report for April 2000-May 2000 ================================================================ (D. McKenzie) Montana State University solar physics group, bimonthly report of SXT-related activity: April-May 2000 * SPECIAL NEWS: We have some new faces at MSU this spring: - Prof. Arnab Choudhuri, from the Indian Institute of Science, Bangalore, India, is our distinguished visitor for May and June. We are quite pleased to host Professor Choudhuri, and to benefit from his lectures on the physics of fluids and plasmas. - Dr. Tetsuya Magara, formerly of Hida Observatory of the University of Kyoto, Japan, joins our group as a new postdoc. He will be working closely with Dana Longcope, in MHD theory and numerical modeling. - A search was conducted for a new experimental space physicist faculty position, to be hired soon. - Piet and Kathleen Martens welcomed a new child to their family: Welcome to Gabriel Ene Martens! Canfield was awarded MSU's Wiley Prize for meritorious research. The award cited his work with Hudson and McKenzie on sigmoids as a tool for the identification of solar regions likely to produce Coronal Mass Ejections and his contributions to the success of the Yohkoh mission and the solar group at MSU. Mark Weber departed MSU, fresh PhD in hand, to start a postdoc at Stanford with Peter Sturrock. Best of luck, Mark! * OPERATIONS: Handy was resident at ISAS April 17--May 4 and May 12-May 20 for SXT operations. He doggedly worked with G. Slater to get the systems back up after power systems tests at ISAS. Canfield served as Yohkoh Duty Scientist at Mees Solar Observatory the first week of April. * SCIENCE: Acton helped Jing Li to access SSC files at MSU, and sent irradiance data to Pradip for correlation with SOHO/CELIAS/SEM data. Acton continued analysis of the change in SXT sensitivity at time of zeroeth entrance filter failure in October 1992 (not presently accounted for in the SXT database). With Zarro, Myers, LaBonte, and several others, Canfield worked on the co-aligned SXT, TRACE, SoHO, BSO, and SOON movies and Mees vector magnetograms for flares observed in the sigmiodal active Page 10 region AR 8668 during Whole Sun Month 3. With Pevtsov, Canfield helped write up a study of geomagnetic storms temporally associated with the eruption of 18 individual coronal X-ray sigmoids observed with SXT. Pevtsov & Acton worked on soft X-ray luminosity in quiet Sun, and submitted an SPD abstract on this subject. McKenzie corresponded with SOHO colleagues on some eruptive flares from May 1999, and continued working on supra-arcade structures and motions: submitted an SPD abstract about the motions, and discussed with Martens & Longcope how to analyze the structures more closely. Handy worked with Metcalf and Shirts on sub-pixel resolution enhancement. Kankelborg worked on a nonlinear force-free field loop modeling code, with some success. Canfield continued to work with a thundering herd of MSU graduate and undergraduate students on the analysis of SXT and MCCD data: Trish Van Lew studied SXT jet / MCCD surge events using the Blehm/Pevtsov list of jets and surges inferred from SXT sfd images. Daniel Bambeck began the development of software for objective recognition of sigmoids in SXT sfd images. Rebecca McMullen started a study of active region twist vs tilt using both Mt Wilson and Mees data. Andy Burnettte is winding up a comparison of force-free field parameters derived from SXT images to those derived from Mees vector magnetograms. Angela Colman wound up her task of identifying moving blueshift events similar to those observed by Canfield et al before the Nov 15 1991 event. Yuriko Yamazaki (ACE Language Institute), and Eric Erickson and Tyler Bangs (Headwaters Academy) studied the relationship between sigmoids and signatures of eruptions in the SXT sfd movies on videodisk. * PUBLICATIONS Canfield, R. C. and Pevtsov, A. A. ``Vector Magnetic Fields, Sub-surface Stresses, and Evolution of Magnetic Helicity'', Invited Paper for IAU Colloquium 179, ``Cyclical Evolution of Solar Magnetic fields: Advances in Theory and Observations'', December 13-16 1999, Kodaikanal, India, J. Astrophys. Astr. in press, 2000. Innes, D. E., Curdt, W., McKenzie, D. E., Schwenn, R., Solanki, S., and Stenborg, G., ``Flare and CME onset: explosive reconnection in the solar corona" was submitted to Nature. McKenzie, D. E., and Hudson, H. S., ``Downflows and Structure above LDE arcades: Possible Signatures of Reconnection?", submitted to Earth, Planets and Space, special issue: Proceedings of the meeting "Magnetic Reconnection in Space and Laboratory Plasmas", Tokyo, Japan, Feb 29-Mar 4, 2000. Pevtsov, A. A. and Canfield, R. C. ``Solar Magnetic Fields and Geomagnetic Events", JGR, submitted, 2000. Pevtsov, A. A. and Canfield, R. C., ``Coronal Structures as Tracers of Sub-Surface Processes'', Invited Paper for IAU Colloquium 179, ``Cyclical Evolution of Solar Magnetic fields: Advances in Theory and Observations'', December 13-16 1999, Kodaikanal, India, J. Astrophys. Page 11 Astr. in press, 2000. Thanks to Martens, Tsuruta, and Weber, the Proceedings of IAU 195, "Highly Energetic Physical Processes and Mechanisms for Emissions from Astrophysical Plasmas", were completed. The book is now in press (ASP). * WORKS IN PROGRESS: Acton worked with Markus Aschwanden on forward coronal temperature and DEM modeling paper. This work is based on the one-minute exposures with offpointing obtained in August 1992. Handy continued working on an EIT/MDI opus that sprang from his thesis work. Other papers in the works: ``Hard X-rays from Slow Flares", by Hugh Hudson and David McKenzie, to be submitted to Earth, Planets and Space, special issue: Proceedings of the meeting "Magnetic Reconnection in Space and Laboratory Plasmas", Tokyo, Japan, Feb 29-Mar 4, 2000. "The Relationship Between Flux Tube Cross-Section and Curvature" by Charles Kankelborg and Piet Martens, and "Chromospheric Damping of Alfven Waves", by B. De Pontieu, P.C.H. Martens, and H.S. Hudson. * SERVICE: Canfield, Kankelborg, Martens, McKenzie, and Pevtsov refereed six papers, for ApJ, A&A, Solar Physics, and JAA (Journal of Astrophys & Astron). Acton traveled to Tucson for the AURA Solar Observatory Council at end of May. * OUTREACH: Canfield reformatted the SXT Chief Observer's weekly reports at http://solar.physics.montana.edu/nuggets/ and mirror sites at Lockheed, ISAS, and MSSL. Handy wrote two SXT nuggets during the April-May ISAS trip concerning the rate of degradation of Yohkoh orbit as a function of solar activity. Canfield gave a public talk entitled "The Sun Earth Connection in the Space Age" at the National Academy of Sciences, and also worked on the solar planetarium show for the Museum of the Rockies. He gave a physics department colloquium, "The Sun Earth Connection in the Space Age". Martens gave a seminar entitled "On the Nature of Moss" for the SoHO Science Club at NASA-GSFC. McKenzie presented the MSU Relativity/Astrophysics/Solar seminar on "Observational Signatures of Magnetic Reconnection in Eruptive Solar Flares", and also judged a local middle school science fair. Acton traveled to Moscow, ID, and Spokane, WA, on student-event astro-gigs. Page 12 * MISCELLANEOUS: Kankelborg & Martens attended the Living With a Star meeting at GSFC, May 10-12. ====================================================== Univ of Hawaii Activity Report for April 2000-May 2000 ====================================================== (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 was generally good, with some observations obtained on 82% of all scheduled days. Mees observations supported the SOHO/TRACE/YOHKOH JOP 120 campaign on the formation and evolution of sigmoidal active regions. During the campaign we succeeded in observing full disk vector magnetic field mosaics of a sigmoidal structure that erupted. This structure was formed in weaker fields, outside active regions, and therefore is of particular interest. Processing of the data has begun. LaBonte is continuing work on the mapping of electric currents in several active regions, including the Whole Sun Month region of August 1999 and the flare productive region AR8210 of May-June 1998. Li is working with G. Slater (LMSAL) to extend her mapping of coronal streamers to the full Yohkoh/SXT dataset, covering nearly an entire solar cycle. The SXT data processed thus far show streamer and global coronal structure much more clearly than the SOHO/EIT data, because of the absence of transition region emission. ===================================================== Stanford Univ Activity Report for April 2000-May 2000 ===================================================== (P. A. Sturrock) The big news is that Mark Weber arrived at Stanford a few weeks ago and is reviewing a long list of topics of interest to both him and Peter. Page 13 Mark's main current activity is to pursue a topic related to CMEs outlined in the last bimonthly report. We are exploring the possibility that, if a field configuration contains a component that is detached from the photosphere, it may have more energy than the corresponding open configuration. We are examining a configuration in which a closed magnetic toroid, located at the equator, is held in place by an overlying arcade-type magnetic field. Field lines of the overlying field are rooted in the photosphere, but field lines in the toroid are not. It seems possible that the Aly-Sturrock theorem [according to which no closed magnetic configuration can have more energy than the corresponding open configuration] may not hold in this situation, since not all field lines are rooted in the photosphere. Mark is planning to solve the relevant partial differential equations by a relaxation procedure. Peter also continues to collaborate with Jim McTiernan in Berkeley concerning the optimization-function approach to the reconstruction of force-free magnetic field configurations from photospheric vector magnetograph data. The optimization-function method rests on the minimization of the integral of a sum of terms, each term being the square of the error in each relevant equation. One difficulty has been that it is necessary to specify (or guess) the magnetic field on the outer surfaces (away from the photosphere). We have found that we can generalize the optimization procedure by multiplying each term by a weighting function, and arranging that each such weighting function drops to zero at the outer surface of the domain. The boundary condition on that surface then becomes irrelevant, so that it is not necessary to specify the field on the outer surfaces. It is possible also to add another term to the optimization function to seek the solution that matches the photospheric boundary conditions and falls off as rapidly as possible with distance from the source. Jim has run some cases and finds that the procedure does indeed work. In its present form, when applied to a known test case, it tends to pack too much flux into the source region. This is not an important defect, but we will examine variants of the scheme to try to avoid the defect. With co-authors Mark Weber, Mike Wheatland and Rich Wolfson, Peter has submitted to Ap J an article on the energetic requirement for a twisted flux tube to erupt through an overlying magnetic arcade. The initial configuration comprises a twisted flux tube of finite length, held down by the arcade. The final state comprises an untwisted flux tube that has ruptured the arcade and expanded into interplanetary space. Comparison of the total energy of the initial and final configurations leads to an estimate of the twist required for an eruption to be energetically possible. It turns out that this condition is significantly less restrictive than the condition that the flux tube be unstable according to linear MHD theory. The implication is that such configurations can be metastable - i.e stable against small perturbations but unstable against sufficiently large perturbations. We believe that this finding is relevant to the CME phenomenon. If the pre-CME state is a filamentary flux tube held down by a magnetic arcade, and if additional twist is injected into the flux tube from below the photosphere, the system will Page 14 become metastable. A small perturbation could then lead to the sudden eruption of the filament, breaking through the overlying arcade, and expanding out into interplanetary space. A more detailed examination of such systems will require the development of a technique for computing the configuration and evolution of magnetic configurations involving one or more current sheets. Ordinary MHD codes are not well suited to such problems, since they always involve numerical resistivity, which leads to the rapid reconnection of the current sheets. We are examining the possibility of analyzing such systems by means of the displacement-vector formalism [see, for instance, Plasma Physics (CUP, 1994) Chapter 16]. We could set up an initial configuration that has the correct topology but is not in equilibrium. We could then examine the energy as the configuration is displaced, and seek a state with minimum energy. We hope to test this concept on a simple system to see if it works as simply as it has been described. Publications Roald, C.B., Sturrock, P.A., & Wolfson, R. 1999, The dependence of coronal heating on magnetic flux density in the photosphere, Ap J, in press. Sturrock, P.A., Wheatland, M.S., & Wolfson, R. 2000, Metastable magnetic configurations and their significance for coronal mass ejections. Ap J, submitted. Wolfson, R., Roald, C.P., Sturrock, P.A., and Weber, M. 1999, Coronal X-ray brightness and photospheric magnetic field: A study in correlations, ApJ, in press. Wheatland, M.S., Sturrock, P.A., & Roumeliotis, G. 1999, An optimization approach to reconstructing force-free fields, ApJ, submitted. ==================================================================== Solar Physics Research Corp. Activity Report for April 2000-May 2000 ==================================================================== (K. Harvey and H. Hudson) KAREN L. HARVEY: Activities for April and May: (1) Continued with a comparison of the coronal holes identified in NSO/KP He I 10830 rotation maps and with corresponding Yohkoh/SXT rotation maps to ascertain if the structures identified as coronal holes Page 15 in He I 10830 correspond to low coronal emission or are in fact some other coronal feature. We are also investigating the formation process of coronal holes, that is, what new connections are established with the evolution of the magnetic fields of emerging and dispersing active regions that lead to the formation of isolated, sub-polar holes. (2) Terry Forbes visited in early May to discuss a project concerning He I 10830 2-ribbon flares associated coronal hole changes and long-duration X-ray arcades. We focused on how to proceed with measurements of the magnetic flux associated with the ribbons and associated transient coronal holes. A few well observed events will be selected for this study on the basis that (1) there is good temporal coverage by the SXT full-frame images, (2) the position of the event is on the solar disk at a location to minimize the geometrical effects in the line-of-sight magnetic flux measurements, and (3) the boundaries of the flare ribbons and transient coronal holes can be well established using the SXT images and He I 10830 spectroheliograms. The objective of this study is to determine the reconnection rate of the flare. Two measurements will be made with time using a singe NSO/KP full-disk magnetogram (this assumes that the photospheric field does not change over the observed life of the flare): first the magnetic flux within the flare ribbons, and second the magnetic flux with the transient holes. (3) Prepared two figures using Yohkoh/SXT data of X-ray bright points for inclusion in a book, the first Japanese photograph book dedicated only to the Sun, by Masamitsu Ohyama and Kazunari Shibata. This book will be published this year by Shokabo Company. (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 10830 structures associated with X-ray structures. (5) Updating of the Yohkoh/SXT publication list. PUBLICATIONS: Papers Published "Does Magnetic Flux Submerge at Flux Cancellation Sites?": Harvey, K. L., Jones, H. P., Schrijver, C. J., and Penn, M. J., Solar Physics, 190, 45--55 (1999). HUGH S. HUDSON Activities for April and May: I attended a small workshop at ISSI (Bern), organized by Einaudi, on the subject of sub-telescopic structure. Otherwise the main activity was to complete the JGR paper "Non-coronagraphic observations of CMEs", as presented at the Catholic U. meeting in March. En route a seminar talk was given at MSSL - "Coronal implosions and explosions". This subject Page 16 continues to intrigue me, of course - the rest of the world yawns, I am sure, but I find it fascinating to see how easy it is to get totally confused within the confines of MHD theory, even at an amateur level. I gave pretty much the same talk at U. Glasgow in an informal seminar and then put the material, as is now my practice, on the Web at http://isass1.solar.isas.ac.jp/~hudson/talks. The ISSI workshop brought me to the realization - really the same fact as the implosions conjecture - that rather than heating the corona, events such as flares, microflares, and nanoflares probably actually cool it! Whereas the gas may be heated, the net energy loss to the coronal field must reduce the overall coronal pressure. Sound too radical? Some work was done on checking the SXT jitter motions, via analysis of the full set of IRU readouts. There is still of course a residual worry about temperature maps that do not reflect the very best pointing information, since Siarkowski et al. showed that sub-pixel errors could seriously bias the temperature patterns. Another project begun was some internal consistency checks of HXT response. PUBLICATIONS: Papers Published "Homologous Sudden Disappearances of Transequatorial Interconnecting Loops": Khan, J. I. and Hudson, H. S. , Geophys. Res. Let. 27, 1083, 2000. Papers Submitted "Non-coronagraphic Observations of CMEs": Hudson, H. S. and Cliver, E. W. J. Geophys. Res., 2000. Page 17 ------------------------------------------------------------------------------- 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 2000 May 2000 |------------------------------- | 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 2000 |------------------------------- |14. SPONSORING AGENCY | CODE MSFC / AP32 -----------------------------------------------|------------------------------- 15. SUPPLEMENTARY NOTES ------------------------------------------------------------------------------- 16. ABSTRACT The SOLAR-A Mission is a program of the Institute of Space and Astronautical Science (ISAS), the Japanese agency for scientific space activity. The SOLAR-A satellite was launched on August 30, 1991, to study high energy phenomena in solar flares. As an international cooperative agreement, Lockheed, under NASA contract, is providing a scientific investigation and has prepared the Soft X-ray Telescope (SXT), one of the two primary experiments of the mission. --------------------------------------|---------------------------------------- 17. KEY WORDS (SUGGESTED BY | 18. DISTRIBUTION STATEMENT AUTHOR(S)) Solar-A, X-ray, CCD, | Space Science, Solar Physics ------------------------|-------------|----------|-----------------|----------- 19. SECURITY CLASSIF. | 20. SECURITY CLASSIF. | 21. NO OF PAGES |22. PRICE (OF THIS REPORT) | (OF THIS PAGE) | | None | None | 17 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office