Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for September 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 The Yohkoh spacecraft recently completed eight very successful years of operations. The SXT continues to function extremely well and we expect an equally successful ninth year to come. We anticipate the RFP for the continuation of operations and data analysis for FY2000 and beyond in the next month. SOLAR ACTIVITY In early September the X-ray background level was monotonically decreasing as AR 8673/8674 rotated off the west limb. The solar disk was dominated by compact regions only slightly larger than pre-TRACE X-ray bright points. The background level decreased from C2 to B7. In mid-September, solar activity remained low, with the GOES X-ray background fluctuating between B2 and B4 with small active regions continuing to dominate. Observation of an M-class flare (8-Sep-99) was interrupted in the early phase due to a DSN downlink. As the month progressed, there was a second M-class flare (17-Sep-99), and the GOES background increased slightly (>B5). In late September, the biggest flare was a C9.4 (Sep. 21), as solar activity remained low. Apart from the lack of intense flares, the GOES background level dropped to B3-4 around 23 September, looking as if solar maximum were still in a distant future or were already over. All the regions but one (AR 8700) that were seen during this period were in either alpha or beta configuration. Page 2 CAMPAIGNS There were no formal campaigns during September. However, SXT participated in informal specialized observations aimed at the ceaselessly interesting interconnecting loops. SCIENCE Canfield caught up with the SXT Chief Observers and finished cleaning up the Nuggets site so no html files use absolute links that are not needed. The master Nuggets site is http://solar.physics.montana.edu/nuggets/. Mirror jobs have been set up by Metcalf at Lockheed and ISAS and by Bentley at Mullard. An announcement will be made in SolarNews as soon as appropriate. McKenzie Worked on the "Supra-arcade downflows", characterized by downward plasma flows above (and into) LDE arcades. The flows were detected using SXT, but are not visible in EUV (EIT and TRACE) or in H-alpha (MLSO). A similar kind of motion has been seen in LASCO C2 (Wang et al. 1999, GRL, v.26, no.9, pp.1203-1206). Nitta Analyzed more SXT/TRACE data to study the relation between hot and cool loops, and more specifically which SXT loops are associated with TRACE moss (weekly nugget of 990917). It turns out to be difficult to isolate clear loops in SXT images, unless they are in the thermal or decay phase of nano or micro flares. Hudson pointed out that we see ejecta of many kinds - things fleeing centrifugally from the flare core - but very little evidence for inward motions. The motions that we see in the corona represent mass trapped on coronal field lines, and almost invariably the motions - if perpendicular to the field - are outwards. Mulling this curious asymmetry in what is by now a very large set of observations, it was irresistibly tempting to try to sharpen the well-known statement of the Aly conjecture (simply put, this states that it takes energy to "open" the solar magnetic field ... it doesn't just happen, like falling off a log). In this context it's puzzling because the observed magnetic explosions obviously result from an instability, and yet the field is going to a higher-energy state. The conjecture announced by Hudson, and now accepted for publication in Solar Physics, is that this implies the inward motion of some large number of field lines - a "magnetic implosion" that would be necessary to drive the "magnetic explosion". Sterling points out that the universe is full of invisible implosions leading to spectacular explosions, for example supernovae; in our case however the corona is optically thin and we have every expectation of being able to see the actual implosion and to learn about flare theory from it. Note that this conjecture applies to every theory that uses coronal magnetic fields as a source of energy - that is, to virtually every theory of flares or CMEs. Page 3 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 83682 accesses and 4196 Mbytes transferred. YOHKOH OPERATIONS AND HEALTH Yohkoh and the SXT continue to function very well. A combination of uplink problems (transmitter) and a major typhoon at the Kagoshima Space Center (KSC) caused the loss of two days of data (23-24 September), but operations have resumed normally since then. SXT experienced no Single Event Upset (SEU) events during the month. Page 4 DATA FLOW Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Jul-97 478488 191878 1942219 395016 2337235 912025 27.87 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 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-99 892 119 2668 594 3262 793 19.56 Total 641425 233488 2574792 677181 3251973 1142291 26.00 Number of Full Frame Images Received: 641425 Number of Observing Region Images Received: 3251973 Total: 3893398 Approximate Number of Shutter Moves/CCD Readouts: 6655633 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 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-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 58.68 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 N/A N/A N/A N/A 21.2 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-99 and 30-SEP-99 HUDSON 1-SEP-99 * 30-SEP-99 * 30 (total of 30 days) NITTA 1-SEP-99 * 24-SEP-99 24 (total of 24 days) SHIRTS 28-SEP-99 30-SEP-99 * 3 (total of 3 days) ---------------------------------------------------------------- Grand Total of 57 days for 3 people NOTE: The "*" signifies travel that actually ends after 30-SEP-99 SXT Foreign Travel between 1-OCT-99 and 31-OCT-99 CANFIELD 30-OCT-99 31-OCT-99 * 2 (total of 2 days) FLETCHER 12-OCT-99 31-OCT-99 20 (total of 20 days) HUDSON 1-OCT-99 * 15-OCT-99 15 22-OCT-99 31-OCT-99 * 10 (total of 25 days) MCKENZIE 5-OCT-99 31-OCT-99 * 27 (total of 27 days) SHIRTS 1-OCT-99 * 24-OCT-99 24 (total of 24 days) SLATER 20-OCT-99 31-OCT-99 * 12 (total of 12 days) ---------------------------------------------------------------- Grand Total of 110 days for 6 people NOTE: The "*" signifies travel that actually ends after 31-OCT-99 Respectfully submitted, Thomas R. Metcalf James R. Lemen Page 7 ======================================================================= Montana State University Activity Report for August 1999-September 1999 ======================================================================= (P. Martens) INTRODUCTION The MSU group carried out SXT operations, data analysis, graduate and undergraduate research, participated in meetings, and performed outreach activities. Highlights of this period were the first TRACE workshop in Monterey (with much joint TRACE/SXT analysis), and the debut of the repackaged SXT Nuggets, targeted at a wider, unspecialized but scientifically literate audience, see: http://solar.physics.montana.edu/nuggets/index.html with mirrors at LMSAL, ISAS, and at Mullard. Kudos to Hugh Hudson for writing so many of these excellent nuggets. Third highlight was the completion of the on-line searchable SXT data and campaign catalogs (cross-linked). The pages will be opened up to the public after clearance with Ogawara-sensei. They can be previewed at: http://solar.physics.montana.edu/ard/dmck/sxt_obsrpt.html These on-line catalogs greatly improve SXT data accessibility for the whole of the solar community. YOHKOH AND SXT OPERATIONS Dick Canfield served as Yohkoh Duty Scientist at Mees on August 10-16, and September 21-28. Brian Handy left on September 24 for ISAS to serve as SXT Chief Observer. Canfield, in collaboration with Hudson, Gibson (SOHO/CDS), and Kankelborg (TRACE), also led Max Millennium Observing Campaign 002, "Flares Associated with Sigmoids During Whole Sun Month 3", August 18-27. During this campaign observations of a single sigmoidal active region, AR 8668, were obtained over most of its disk transit. A CME was reported by UVCS & LASCO on the 26th, which was associated with a nice limb arcade and cusp in the Yohkoh SXT images. MEETINGS Much of the MSU Solar Physics group participated in the Monterey TRACE workshop "Physics of the Solar Corona and Transition Region", 24-27 August. The group presented six talks and posters as first authors, and chaired sessions. The meeting, organized by LMSAL, was unanimously considered one of the better solar physics workshops ever. Page 8 David McKenzie visited NOAA/SEC for a day, to spread the gospel of Sigmoids to a very receptive and enthusiastic group from SEC and HAO. RESEARCH Mark Weber is investigating the apparently bimodal behavior of the south polar coronal hole extension during the descending phase of the last activity cycle. Using SXT and Kitt Peak magnetograms together with moments of the flux transport equation, this behavior can be demonstrated to be a consequence of "active longitudes". He started to write the paper, which will be a good chunk of his thesis. Loren Acton has completed the programs sxl2radiance.pro and sxt_deleak.pro. The first one was used to prepare the spectral radiances for the Jupiter paper (see below) and will be used to prepare spectral irradiance from the new SXT movie for deposit in the NOAA data archive. The sxt_deleak program is designed to do a second-order leak correction by forcing the average signal outside of 1.7 R_sun in the new composite movie (SSCs) to be zero. It is used for correcting HR and QR FFIs. David McKenzie worked on the "Supra-arcade Downflows" paper, in which he describes twelve events characterized by downward plasma flows above (and into) the LDE arcades. The flows were detected using SXT, but are not visible in EUV (EIT and TRACE) nor in H-alpha (MLSO). A similar kind of motion has been seen in LASCO C2 (Wang et al. 1999, GRL, v.26, no.9, pp.1203-1206). Piet Martens and Charles Kankelborg, in collaboration with Nariaki Nitta, continued studying joint SXT & TRACE observations of moss. SERVICE AND OUTREACH After an idea of Piet Martens, Thomas Bethell, an undergraduate summer student from Cambridge University, under the direction of Dick Canfield, spent two months reformatting the SXT chief observer weekly reports through June 1999 into nuggets more suitable for outreach purposes on the web. Davey developed a search capability for the new page, which makes the nuggets useful for all of us for research, as well as outreach. Canfield worked on the July and August nuggets after Tom's summer appointment ended. The nuggets have been opened to the public now, and, judging from the large number of hits on the MSU server alone, the site is a great success already. Piet Martens and Prof. Sachiko Tsuruta are busy editing the procedures of IAU Symposium 195, "Highly Energetic Physical Processes and Mechanisms for Emission from Astrophysical Plasmas", held at MSU, 6-10 July 1999. David McKenzie and Alisdair Davey made the SXT observing log web-accessible via an HTML interface to SXT_OBSRPT.PRO. The observing log is paralleled and cross-linked with the SXT on-line campaign catalog produced by Piet Martens in July. These sites will be advertised to the solar community after receiving clearance from Ogawara sensei. Page 9 Piet Martens is leading the MSU graduate seminar on "Solar & Stellar Winds". Given the large amount of travel (operations, meetings) that MSU students and faculty do, the course was made as virtual as possible, see: http://solar.physics.montana.edu/martens/winds/index.html PUBLICATIONS: The MSU Solar Physics Group started an on-line preprint and reprint service, with papers from 1999 and 2000, at: http://solar.physics.montana.edu/sol_phys/archive.html Papers Published: ----------------- "Scientific Highlights from the Solar & Heliospheric Observatory", P.C.H. Martens and K. Muglach 1999, in: "Proceedings of the 2nd Solar Polarization Workshop: Solar Polarization", 325-335. K.N. Nagendra and J.O. Stenflo (eds.), Kluwer. Papers Accepted: ---------------- "A Method for Characterizing Rotation Rates in the Soft X-Ray Corona", M A Weber, L W Acton, D Alexander, S Kubo, & H Hara, Solar Physics, 2000, in press. "Transition Region and Chromospheric Coupling Effects on Resonant Absorption of Alfven waves in Coronal Loops", A.J.C. Belien, P.C.H. Martens, and R. Keppens 2000, in: "Ninth European Meeting on Solar Physics: Magnetic Fields and Solar Processes", ESA SP-448. A. Wilson (ed.), in press. "Multi-Imager Study of Transients and Propagating Disturbances in Active Region Loops (SOHO JOP80 Campaign)", D. Berghmans, F. Clette, E. Robbrecht, and D. McKenzie 2000; Ninth European Meeting on Solar Physics: Magnetic Fields and Solar Processes, ESA SP-448. A. Wilson (ed.), in press. "Transequatorial Loops in the Solar Corona", A.A. Pevtsov 2000, Astrophys. J., in press. Papers Submitted: ----------------- "Forward Modeling of the Coronal Response to Reconnection in an X-Ray Bright Point", Kankelborg, Charles C. and Longcope, Dana W. 2000, Solar Physics, submitted. Page 10 Talks Given: ------------ Mark Weber, "Bimodal Rotation Rates in the Soft X-ray Corona" on August 5, 1999, at Johns Hopkins Applied Physics Lab. David McKenzie, "Sigmoid Morphology as a Tool for Prediction of Solar Eruptivity", SEC, Boulder, 23 August, 1999 Six first author presentations by the MSU group in Monterey. Most of these have already been submitted for the proceedings (Solar Phys.). ============================================================= Univ of Hawaii Activity Report for August 1999-September 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 was good during this interval, with observations obtained on 90% of all possible days. Mees supported the Max Millenium Observing Campaign #2 (Sigmoids) during the last 2 weeks of August as part of Whole Sun Month, including seven day per week coverage. The observatory was closed for the first 2 weeks of September and that interval was used for various engineering tasks. J. Khan (MSSL) visited Hawaii in September to work with LaBonte on comparison of SXT flare events with Mees data. Events in AR 8210 (1998 May 01), AR 8214 (1998 May 06), and AR 8253 (1998 June 24) were identified as having the best overall observations. Small scale spot motions and emerging flux are present, but the flares produced have a wide range of energy release and compact/eruptive structure. Work on these events continues. Li finished her manuscript on the global corona, and has submitted it for publication. She has now turned to the analysis of the 1999 June Yohkoh/SOHO/TRACE streamer observations. PAPERS SUBMITTED: Page 11 "Background Solar Corona Revealed by Time Series Observations" Li, J., Kuhn, J., LaBonte, B., Raymond, J. C., and Acton, L. W. Astrophys. J. ============================================================ Stanford Univ Activity Report for August 1999-September 1999 ============================================================ (P. A. Sturrock) Colin Roald and Peter Sturrock are continuing their investigation of the coronal heating theory mentioned in previous reports, 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. One paper on this topic, by Sturrock, has now been published in the Astrophysical Journal. Another paper, by Sturrock, Roald and Wolfson, has been published in Ap J Letters. Following Richard Wolfson's sabbatical at Stanford, Roald, Sturrock and Wolfson have continued to investigate a more complete version of this model, which includes diffusion and takes account of collisions in the cell and in the network. For the energy flux-magnetic field relationship, this model is found to reproduce values of the power law index close to 2, appropriate for quiet regions. However, it does not lead to values closer to unity for strong-field situations, as is required by observational data. This is a puzzle to be pursued. Roald, Sturrock and Wolfson have submitted an article on this work to the Astrophysical Journal. Following his visit to Stanford in July, Michael Wheatland has continued to collaborate with Sturrock on the optimization-function approach to constructing force-free magnetic fields. This method has been applied to a known 3D force-free-field model due to Low and Lou, with very satisfactory results. An article by Wheatland, Sturrock and Roumeliotis has now been prepared for submission to the Astrophysical Journal. Wolfson has continued his collaboration with Roald and Sturrock, leading to two papers that have been submitted to the Astrophysical Journal. One paper on "Temperature structure of the quiet corona: an SXT-SUMER discrepancy", has now been accepted for publication. The other paper on "Coronal X-ray Brightness and Photospheric Magnetic Field: A Study in Correlations," is still in the review process. Sturrock continues to study periodicities of the type found by Rieger in 1984 (about 156 days). This periodicity was originally discovered in SMM data for hard X-ray flares, but is now known to occur episodically in many solar indices. It is also now known that there are related periodicities at 78 days and 52 days. These are all multiples of 26 days. This has led Sturrock to suspect that they are manifestations of r-mode oscillations in the convection zone. Sturrock, Scargle, Walther and Wheatland show, in a paper just published in Ap J Letters, that the 52 day periodicity can be identified in the GALLEX neutrino data. This strengthens the case that processes deep in the Page 12 convection zone are influencing activity on the surface. Sturrock plans to continue his analysis of the SXT-flux time series, kindly provided by Mark Weber of MSU, to search for evidence of r-mode oscillations in that data-set. Sturrock visited ISAS in September to discuss CMEs and other topics. He gave seminars on coronal heating and on mean-field electrodynamics. He also visited and spoke at the University of Tokyo and Kyoto University. Publications Roald, C.B., Sturrock, P.A., & Wolfson, R. 1999, The dependence of coronal heating on magnetic flux density in the photosphere, Ap J, submitted. Sturrock, P.A. 1999, Chromospheric Magnetic Reconnection and its Possible Relationship to Coronal Heating, Ap. J. 521, 451. Sturrock, P.A., Roald, C.B., & Wolfson, R. 1999, Chromospheric magnetic reconnection and its implications for coronal heating, Ap. J. (Letters), 524, in press. Sturrock, P.A., Scargle, J.D., Walther, G., & Wheatland, M.S. 1999, Rotational signature and apparent r-mode signature in the GALLEX solar neutrino data, Ap J (Letters), 523, L177. Sturrock, Roald, and Wolfson, 1999, "Chromospheric magnetic reconnection and its implication for coronal heating", ApJ, submitted Wheatland, M.S., Sturrock, P.A., & Roumeliotis, G. 1999, An Optimization Approach to Reconstructing Force-Free Fields, ApJ, to be submitted Wolfson, Roald, Sturrock and Weber, 1999, "Coronal X-ray Brightness and Photospheric Magnetic Field: A Study in Correlations," ApJ, pending Wolfson, Roald, Sturrock, Lemen and Shirts, 1999, "Temperature structure of the quiet corona: an SXT-SUMER discrepancy", ApJ, accepted =========================================================================== Solar Physics Research Corp. Activity Report for August 1999-September 1999 =========================================================================== (K. Harvey and H. Hudson) KAREN L. HARVEY: Activities for August and September: (1) Continued analysis of data taken in collaboration with NSO/KP, Yohkoh/SXT, SOHO, TRACE, BBSO during three observing campaigns: 18-23 September 1997, 4-6 May 1998, and 14-16 June 1998 to investigate the behavior of magnetic flux at sites between adjacent opposite polarity magnetic network elements in which the flux is observed to decrease or `cancel'. The reduction of the simultaneous measurements of the magnetic and velocity fields, line depth and equivalent width at two levels of the solar atmosphere: in the chromosphere Page 13 (Ca II 8542) and photosphere (Fe I 8538). The data are being analyzed to determine if magnetic flux at cancellation sites in the quiet sun is submerging below the photosphere. Intensity images from the SXT, TRACE and SOHO in several X-ray and EUV lines are being compared to deduce the height structure of the associated coronal bright points. The advantage of the NSO/KP magnetic flux measurements is the precise co-alignment of magnetic, velocity and intensity structures at two levels of the atmosphere separated by about 1200 km. These data were compared with chromospheric and coronal Intensity images to establish the timing of the emission structures associated with these magnetic structures as a function of height. We found that most of the cancellation sites show either that the bipole is observed longer in the photosphere than in the chromosphere and corona (44\%) or that the timing difference of the disappearance of the bipole between these levels of the atmosphere is unresolved. The magnetic axis of the structure associated with the cancellation sites are on average slightly smaller in the chromosphere than the photosphere. These observations suggest that magnetic flux is retracting below the surface for most, if not all, of the cancellation sites studied. (2) 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. (3) Updating the publication list of Yohkoh papers published, accepted, and submitted to refereed journals. Planned Activities for October and November: Continued analysis of (1) of the XBP data collected during several observing campaigns, concentrating on the more recent runs, in particular, looking at the behavior of the velocity field in the photosphere and chromosphere at magnetic cancellation sites in relation to the inferred evolution of the magnetic field. (2) the magnetic fields and coronal holes related to the 1996 activity complex and the associated large-scale field patterns. This includes determining from 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, and the association of coronal holes observed in He I 10830 spectroheliograms and the SXT full-frame images. HUGH S. HUDSON Activities for August and September: Helped Joe Khan work in his very interesting work on the behavior of trans-equatorial interconnecting loops during the flares of May, 1998. Unfortunately the paper on SXT global wave detection is still not submitted, but this will be presented as a poster at the HESSI meeting, and I hope that this will be incentive enough to get the ApJ paper out the door. The main thrills were associated with the TRACE workshop in Monterey. Ever Page 14 since Kopp and Pneuman I have had a queasy feeling about "opening and closing" flare models, which of course are also CME models. The best theoretical justification for this queasiness had always been the Aly Conjecture, which suggests the possibility of increasing the magnetic energy during the event, something I've always found to be quite counter-intuitive. But it is not that complicated. If one just thinks only about stored magnetic energy, there is a much sharper conjecture that I've now stated in my Monterey paper. It makes a clear prediction about the TRACE observations on large or small spatial scales, but it is not yet clear which! The TRACE flare data are extraordinarily important. A new project started after the TRACE meeting has to do with the interesting behavior of the high-energy end of the flare energy distribution function. Working with Alexander and Parnell, I have found that a cutoff may exist (as it must) in the observable range on an annual basis, and that it varies not in direct correlation with the solar cycle. I suspect that Aschwanden's presentation at Monterey pretty much signaled the end of any hope for nanoflares, always a kind of quixotic pursuit in any case. Planned activities for October and November: 1. Attend the HESSI meeting, thus making progress on slow LDEs and on SXT global waves. 2. Work further on bright-end flare distributions. 3. Continue with CME and flare relationships. PUBLICATIONS: Papers Accepted H. S. Hudson, "The Global Dynamics of the High-Temperature Corona", Solar Physics, in press, 1999. PAPER SUBMITTED J. I. Khan and H. S. Hudson, "Homologous Sudden Disappearances of Transequatorial Interconnecting X-ray Loops on the Sun," GRL, 1999. =========================================================================== University of New Hampshire Activity Report for August 1999-September 1999 =========================================================================== (T. Forbes) The paper "The Effect of Reconnection on the CME Process" by J. Lin and T.G. Forbes was submitted to the J. Geophys. Res. in August and is currently being revised, and the paper "Solar and Stellar Flares" by T.G. Forbes is now in press in Proc. Royal Astron. Soc. A. Both papers acknowledge support from Page 15 LMSAL's NASA grant. ======================================================================= University Of California Activity Report for August 1999-September 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. Fisher, Metcalf (LMSAL) and Klimchuk (NRL) have investigated the power spectrum of the current (computed from vector magnetograms taken with the HSP instrument at Mees Observatory) and its relationship to the soft X-ray luminosity of active regions. They used the 333 active region observations previously described in Fisher et al. (apj 508, 885). The idea was to see if shallower (harder) power spectra in the current might correlate with greater levels of coronal heating. This data showed no meaningful correlation between the power spectral index and either the X-ray luminosity or the X-ray flux from active regions. Fisher, Griffiths, Woods, Acton and Siegmund have submitted the paper "Simultaneous SOHO and Yohkoh Observations of a Small Solar Active Region" to ApJ. 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 1999 September 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 September 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