Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for March 1998) OVERVIEW The YOHKOH Mission is a program of the Japanese Institute of Space and Astronautical Science (ISAS) with collaboration by the U. S. National Aeronautics and Space Administration and the U. K. Science and Engineering Research Council. The YOHKOH satellite was launched on 30 August 1991 from Kagoshima Space Center (KSC) in Japan. The purpose of this mission is to study high energy phenomena in solar flares and the Sun's corona. Under an international cooperative agreement, Lockheed, 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 Palo Alto Research 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 proposal for operations support at ISAS in 1998 that was submitted to MSFC has still not been definitized. It seems to be unusually slow this year. In view of the serious funding constraints for FY99 and beyond it makes it especially hard to plan for the immediate future. On another front, some progress is being made in creating interest to get additional funding for SXT through solar maximum. << Solar Activity >> Solar activity increased during the beginning of March, with numerous C-class flares, mainly from AR 8171 (29 of them by 6-Mar), but no M or X events. The most interesting feature was the sunspot group appearing at N48. "The occurrence of active regions at the exceptional latitude of 50 degrees is rare, but most common at the beginning of a solar cycle; however, for that region to be large is most unusual. A hallmark of the strongest known sunspot cycle, Cycle 19 with peak in 1957-58, was the appearance of large Class-E spot groups at high latitudes" [Pat McIntosh]. The extraordinary high-latitude region (46N plus solar tilt) gave us a novel perspective on AR loops away from the E or W limbs. In mid-March, solar activity remained at a high level, including some major flares. The high-latitude region in the N rotated off the limb, but there was another high latitude region in the S, interconnected to another same-hemisphere region. In late March, the GOES background level showed a slight decline due to big Page 2 complex AR 8179/8180 rotating behind the limb, but solar activity remained quite high. During 22-27 March, we had one > C5 flare a day, either from AR 8185 (CMP on 27 March) or AR 8179/8180 at the southwest limb. Two of them occurred during Yohkoh day. The other four were largely subject to spacecraft night, but the one on 24 March was a long duration event and its morphological change was well observed. << Campaigns >> There were no formal campaigns this month. << Science >> Alexander worked with Alan Gary on the effects of currents in active regions, including analyzing active region data to determine the radial dependence of the plasma beta. In agreement with studies by Gibson and Suess and others we find that beta=1 at a height of about 0.2 solar radii. This relatively low value surprised me but what do I know. He also did a comparison of SXT density and temperature with the SOHO CDS. The rather crude density estimates from the SXT data turned out to be pretty good when compared to the CDS line ratio densities. Metcalf continued SXT/HXT data analysis of the 1993 Feb 17 flare and have expanded the study to a number of other flares looking for signatures of coronal trapping in flares, much like what was observed in the 1992 Jan 13 flare. Preliminary results show trapping similar to the 1992 Jan 13 flare in several events. Nitta continued to compare hard and soft X-ray loop top sources in 36 flares, and to study in more detail the relationship between the displacement of the two sources and the apparent motion of the soft X-ray source. First, the soft X-ray source is quite extended in several flares, larger than 100 SXT FR pixels at the 50% level. Second, in other flares, the HXT L-band source predominantly comes from an area not bright in soft X-rays, suggesting a super-hot area physically distinct from the main flare loop. He overlaid hard X-ray images in higher energy channels from earlier times with the images showing the loop top sources. The loop top source was not necessarily located between what appeared to be footpoint sources, indicating a complicated relationship between the nonthermal processes and their thermal responses. But about a half of the flares show a relatively simple loop structure. For those flares, the displacement of the HXT L-band source from the soft X-ray source generally coincides with the direction the latter source moves. Wuelser started work on coordinated EIT and Yohkoh observations of solar flares", with Metcalf and Lemen. The research is motivated by some nice flares last fall which were well observed by Yohkoh and also resulted in some EIT images. One of the events shows an interesting EIT loop-top source. The results may serve as a little preview for things to come with TRACE. << Public Use of SXT Images >> We are continuing to make Yohkoh/SXT images available for a variety of uses. Page 3 Efforts continue to make selected images available on the Lockheed SXT WWW homepage (http://www.space.lockheed.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 March were 71317 accesses and 2413 Mbytes transferred. << Yohkoh Operations and Health >> The recovery from the filter rupture of Jan. 24 is almost complete. We continue to make terminator images to help compensate for the extra light; we now have terminators in four different filter configurations. Yohkoh and the SXT continue to function very well. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT Bitmap error 16-Mar-98 Pass 5: 980316-0102 recovered in the same pass. Page 4 << Data Flow >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Dec-95 345314 149675 1432076 358621 1790697 713982 28.37 Jan-96 6474 2530 27015 1708 28723 14151 33.01 Feb-96 6200 2581 21380 890 22270 10773 32.60 Mar-96 6908 2869 25437 1460 26897 12274 31.33 Apr-96 7172 2124 45445 671 46116 18848 29.01 May-96 6925 2426 30272 1089 31361 12367 28.28 Jun-96 7515 2723 31952 1536 33488 14521 30.25 Jul-96 5954 1995 29886 4769 34655 12427 26.39 Aug-96 7214 3010 21187 1607 22794 9887 30.25 Sep-96 6904 2618 29906 303 30209 12663 29.54 Oct-96 7405 2853 16463 1842 18305 8034 30.50 Nov-96 7001 2296 24292 5395 29687 9340 23.93 Dec-96 7144 2643 25331 2087 27418 10412 27.52 Jan-97 7186 2747 21126 1257 22383 9915 30.70 Feb-97 6016 2034 22097 1072 23169 8961 27.89 Mar-97 7152 1300 26991 1209 28200 6394 18.48 Apr-97 6018 1055 23639 3890 27529 5349 16.27 May-97 7703 1455 29574 3783 33357 7121 17.59 Jun-97 7671 1557 25649 1396 27045 8045 22.93 Jul-97 8614 1385 32503 431 32934 6559 16.61 Aug-97 7316 987 23136 3519 26655 4990 15.77 Sep-97 7051 1479 33646 9596 43242 8887 17.05 Oct-97 7023 1134 26813 1827 28640 6043 17.42 Nov-97 6691 1376 26297 15306 41603 7131 14.63 Dec-97 6806 1013 28472 2136 30608 5263 14.67 Jan-98 5715 1803 23479 3232 26711 9918 27.08 Feb-98 6606 1644 25257 3606 28863 8989 23.75 Mar-98 3923 1135 15155 5384 20539 6308 23.50 Apr-98 0 0 0 0 0 0 NaNQ Total 529621 202447 2144476 439622 2584098 969552 27.28 Number of Full Frame Images Received: 529621 Number of Observing Region Images Received: 2584098 Total: 3113719 Approximate Number of Shutter Moves/CCD Readouts: 5424507 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 (%) Jan-96 50.81 761.3 136197 8888 21.5 N/A Feb-96 50.67 755.8 133263 8705 22.5 / 2 21.5 N/A Mar-96 50.85 762.9 136982 8973 20.3 N/A Apr-96 51.14 773.6 142250 9500 19.9 N/A May-96 51.16 774.4 140697 10018 19.1 N/A Jun-96 51.56 789.2 147705 10634 20.7 N/A Jul-96 57.45 1010.2 146293 12228 19.8 N/A Aug-96 52.58 827.5 165676 12393 19.6 N/A Sep-96 52.47 823.3 162784 12350 20.0 N/A Oct-96 52.21 813.8 157689 12047 22.5 / 2 21.3 N/A Nov-96 52.45 822.9 161683 12534 21.9 N/A Dec-96 53.08 846.2 171224 13860 22.9 N/A Jan-97 52.35 818.9 164785 11354 23.8 / 7 23.3 N/A Feb-97 51.95 803.9 159426 10346 21.1 N/A Mar-97 55.99 955.6 158428 12190 21.2 N/A Apr-97 53.14 848.4 176207 13265 20.8 N/A May-97 52.96 841.7 172052 13094 20.7 N/A Jun-97 53.71 869.8 182715 14910 19.8 N/A Jul-97 54.44 897.3 184518 20173 22.5 / 2 21.1 N/A Aug-97 54.06 883.1 188485 15549 20.1 N/A Sep-97 54.77 909.7 196501 17757 21.0 N/A Oct-97 54.85 912.8 198157 17857 21.5 N/A Nov-97 55.17 924.8 202153 18993 22.5 / 2 23.1 N/A Dec-97 55.51 937.6 206194 20219 21.9 N/A Jan-98 56.06 958.0 212189 22121 23.9 N/A Feb-98 55.94 953.7 209254 22122 23.8 / 2 22.6 N/A Mar-98 56.28 966.4 213320 23305 21.8 N/A Apr-98 N/A N/A N/A N/A 0.0 N/A NOTES: * The dark current calculations are using full half resolution 2.668 sec images not taken in during the SAA. The dark current rate assumes a "fat zero" of 30.5 DN and a gain of 100 e/DN. * The entrance filter failure of 13-Nov-92 eliminated the capability of taking optical images, so the optical transmission is not available after Nov-92. It also caused an increase in the dark current signal, however some of the increase shown here is an increase in the readout noise and is not a function of exposure duration. Page 6 << Personnel Travel >> SXT Foreign Travel between 1-MAR-98 and 31-MAR-98 DAVEY 30-MAR-98 31-MAR-98 * 2 (total of 2 days) FREELAND 29-MAR-98 31-MAR-98 * 3 (total of 3 days) HUDSON 1-MAR-98 20-MAR-98 20 30-MAR-98 31-MAR-98 * 2 (total of 22 days) MCKENZIE 1-MAR-98 * 5-MAR-98 5 (total of 5 days) NITTA 26-MAR-98 31-MAR-98 * 6 (total of 6 days) ---------------------------------------------------------------- Grand Total of 38 days for 5 people NOTE: The "*" signifies travel that actually ends after 31-MAR-98 SXT Foreign Travel between 1-APR-98 and 30-APR-98 CANFIELD 18-APR-98 30-APR-98 13 (total of 13 days) DAVEY 1-APR-98 * 11-APR-98 11 (total of 11 days) FREELAND 1-APR-98 * 11-APR-98 11 (total of 11 days) HUDSON 1-APR-98 * 26-APR-98 26 (total of 26 days) MCKENZIE 27-APR-98 30-APR-98 * 4 (total of 4 days) NITTA 1-APR-98 * 24-APR-98 24 (total of 24 days) SHIRTS 25-APR-98 30-APR-98 * 6 (total of 6 days) SLATER 25-APR-98 30-APR-98 * 6 (total of 6 days) ---------------------------------------------------------------- Grand Total of 101 days for 8 people NOTE: The "*" signifies travel that actually ends after 30-APR-98 Respectfully submitted, Thomas R. Metcalf Frank Friedlaender Page 7 8 ================================================================= Montana State Univ Activity Report for February 1998-March 1998 ================================================================= (L. W. Acton) MSU ACTIVITY REPORT FOR FEBRUARY - MARCH 1998 The most critical surprise of this bimester was to learn that the POP guidelines to MSFC for Yohkoh/SXT were $1.5M/year for each of FY 1999- 2001. This is only half of the budget needed for the program and recommended by Senior Review 1997. This shortfall reflects an over all MODA problem for the Solar Maximum Campaign, although SXT has been hurt more than some of the other missions. The U.S. SXT Principal Investigator to NASA, L. Acton, is working actively with Congress in the anticipation of repairing the MODA deficit for the Solar Maximum Campaign in the NASA appropriations bill for FY 1999. David McKenzie spent a month at ISAS serving as SXT Chief Observer and working on data analysis with Hugh Hudson. Coordinated SXT observations with SOHO and ground-based campaigns keeps the Chief Observer busy. McKenzie and other members of the Yohkoh Team organized a very successful observation by SXT of the 26 February eclipse. The resulting movies may be seen online at http://www.space.lockheed.com/YPOP/Intermission/recent_eclipse.html. Alisdair Davey traveled to ISAS to assist Sam Freeland in preparing the computer systems for the April Coordinated Data Analysis Workshop (CDAW). He remained for the CDAW itself. Since joining the MSU group in January, Dr. Davey has been very busy upgrading and organizing our local area network. Working with Canfield he specified a new and much more powerful DEC server which will be ordered and supplied by Lockheed-Martin as a replacement for SXT4, which has become quite obsolete and unable to cope with the work of the group. With pending improvements in the bandpass of the internet link coming into MSU and local net speeds on campus and within our building we will be much better prepared for analysis of Yohkoh and TRACE data. Pevtsov is using SXT and Kitt-Peak data to study if the surface differential rotation may produce sheared coronal loops. Initial results are negative. McKenzie received notification that his SR&T proposal with Dermott Mullan to use SXT data to look for global mode resonance in coronal loops was approved. He will pursue his part of the work under SXT funding. Acton, Tim Slater and Jim Manning of the Museum of the Rockies received a $30K grant from the IDEAS program of the Space Telescope Science Institute to produce a planetarium show on the dynamic sun. On another note connected with the MSU Museum of the Rockies, Mckenzie gave a keynote talk as part of the Southwest Montana Astronomical Society's 'Astrofair'. The topic was "A Space-Age Portrait of the Active Sun" -- lots of images and movies for a general audience of about 80 folks. Page 8 Pevtsov and Canfield continued their organizational work on the Chapman Conference on Magnetic Helicity which will take place at HAO in Boulder on 28-31 July 1998. SXT images were prepared and sent to the publishers of two text books for use in new editions. Several papers were reviewed by members of the MSU Yohkoh Team. A 2 day meeting was held at MSU to define the closing work on the Yohkoh Public Outreach Project which will be completed at the end of FY98. We are all very pleased with how this collaboration has succeeded. If you haven't browsed the web site at http://www.space.lockheed.com/YPOP/ please do so. You'll be in for a treat. Dick Canfield, Tim Slater and others are working on what we hope will become a NASA Space Science Update based upon the discovery of the sigmoid-shaped arcade pattern associated with halo CMEs. McKenzie, Longcope, Canfield and Acton starred in a short segment produced for local TV about the solar physics program at MSU. This was arranged by Tim Slater in his role of SXT Press Agent. PAPERS and ABSTRACTS SUBMITTED "Chirality of Large-Scale Flux Systems in the Solar Corona", Sean C. Sandborgh, Richard C. Canfield, and Alexei A. Pevtsov, Second Undergraduate Research Poster Session on Capitol Hill, Council on Undergraduate Research, April 21, 1998 "Helicity and Reconnection in the Solar Corona: Observations", Richard C. Canfield, Chapman Conference of Magnetic Helicity in Laboratory and Space Plasmas, Boulder, July 1998. "Physical Structure of a Coronal Streamer in the Closed Field Region as Observed from UVCS/SOHO and SXT/Yohkoh", J. Li, J. C. Raymond, L. W. Acton, J. L. Kohl, M. Romoli, G. Noci and G. Naleto. Submitted to The Astrophysical Journal. "Chirality of Large-Scale Flux Systems in the Solar Corona", Sean C. Sandborgh, Richard C. Canfield, and Alexei A. Pevtsov, Spring AGU meeting (submitted). "Coronal heating in active regions as a function of global magnetic variables", Fisher, G.H., Longcope, D.W., Metcalf, T. R. and Pevtsov, A. A., submitted to Astrophysical Journal. "NOAA 7926, A kinked submerging Omega loop?", A. Pevtsov and D. Longcope. Submitted revised manuscript to the ApJ. PAPERS ACCEPTED "The Nature of the Heating Mechanism for the Diffuse Solar Corona" Page 9 by E. R. Priest, C. R. Foley, J. Heyvaerts, T. D. Arber, J. L. Culhane and L. W. Acton has been accepted for publication in Nature. ============================================================= Univ of Hawaii Activity Report for February 1998-March 1998 ============================================================= (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 in Manoa. Our colleagues Jiao 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 during this interval has been extraordinary. Only one day of observations were lost to weather. All instruments are working well. Mickey and Wuelser finished their manuscript on the vector magnetic fields at the base of polar plumes. They find no evidence in the photosphere for super-radial orientation of the fields, as is seen in the corona. ============================================================ Stanford Univ Activity Report for February 1998-March 1998 ============================================================ (M. Wheatland) Mike Wheatland is continuing his work on reconstructing magnetic fields in the corona from observed boundary values, under the assumption the fields are force-free. Reliable methods of reconstruction have many potential applications to understanding the physics of coronal heating and flares, and interpreting Yohkoh soft X-ray images. Recently Mike Wheatland has investigated the use of linear force-free field methods. It is well known that the problem of finding the linear field above a plane for a given value of the force-free constant and with the normal component of the field prescribed in the plane does not have a unique solution. A number of different solutions appear in the literature, defined by additional implicit boundary conditions. All of the methods ignore the additional information that is contained in the transverse component of the field in the plane. Mike Wheatland is currently investigating a method that takes advantage of this additional information, by looking for the linear field which has transverse field components closest to the observed boundary values. This method may be Page 10 of use in active regions that have weak currents and for regions of small extent, although non-linear methods would be of greater utility. Mike Wheatland continues to work on one such method, based on an optimization approach. Peter Sturrock and Mike Wheatland are developing a collaboration with Sasha Kosovichev and Rick Bogart of the Stanford University MDI team to pursue their investigation of the relationship between the coronal power budget and the mean photospheric magnetic field strength. Sturrock's investigation of data compiled by Loren Acton, comprising full-disk averages of Carrington rotations, yields a clear quadratic relationship between the two quantities. In order to put this relationship on a more secure footing, Sturrock and Wheatland propose to get a sequence of daily SXT flux measurements from a prescribed region of the solar disk, and Kosovichev and Bogart propose to obtain magnetic-field histograms for the the same region at the same time intervals. The details are now being discussed by the four investigators. Sturrock is also examining the consequences of a quadratic relationship between the coronal power budget and the mean photospheric magnetic field strength. He has reviewed a number of theories of coronal heating, so far in outline form, to determine the power-law index to be expected from each theory. The only two that clearly yield a power-law index of 2 are (a) flare-like heating as proposed by Parker, provided that the time scale that characterizes energy accumulation and release is independent of field strength; and (b) sudden magnetic relaxation (a mechanism that Sturrock presented at the Bath Yohkoh conference) provided that the migration of flux elements at the photosphere may be regarded as a random-walk process. =========================================================================== Solar Physics Research Corp. Activity Report for February 1998-March 1998 =========================================================================== (Karen L. Harvey and Hugh S. Hudson) KAREN L. HARVEY: Activities for February and March: (1) Continued study of the magnetic field and coronal hole evolution of the active region complex that occurred during several rotations in the summer 1996. The magnetograms and He I 10830 spectroheliograms were re-mapped into latitude and longitude coordinates maintaining the original spatial resolution of the data. A total of 69 images covering 5 months were then co-aligned on the original active regions in the complex (7958) and its polarity inversion. The corresponding re-mapped He I 10830 spectroheliograms were co-aligned with the set of co-aligned magnetograms. The evolution of the fields is being assessed by viewing the images first as a movie either during one or several rotations to understand the emergence patterns of the active regions in the complex and the motions of the fields over the its several rotation lifetime. We find, for example, that most of the major regions emerged at nearly the same Carrington Longitude, but that the diffusing magnetic fields in the older Page 11 regions rotate faster than the Carrington rate, consistent with the differential rotation rate for a latitude of the complex (around S10). In terms of the motions of the fields, readily apparent is differential rotation and supergranular motions, as well as systematic motions of patches of fields a few to several supergranules in extent. These motions are not typical in the direction of differential rotation or meridional flow. The next steps in this analysis are quantifying the motions of the fields on both the small and large scale and relating them to the formation of filaments and coronal holes, as observed in the HeI 10830 images and to the coronal connections as observed in the Yohkoh/SXT images. (2) Attended a small prominence workshop held at NSO/SP March 29-31, 1998. At this meeting, I presented results on the comparison of filaments and filament channels observed in He I 10830 images with the coronal cavities observed by the SXT during 1997 and on the preliminary results of the work discussed in (1) above. (3) Preparation of NSO/KP full-disk magnetograms and He I 10830 spectro- heliograms for SXT investigators for studies of the magnetic field and He I 10830 structures associated with X-ray structures. Planned Activities for April and May: The analysis of the magnetic field and coronal hole evolution of the 1996 activity complex will continue for presentation at the AGU/SPD meeting in late May 1998. This analysis will include investigating the connections of the coronal fields based on the SXT data with the photospheric magnetic field over several months as this complex evolved. An investigation of the magnetic field evolution around the filament channel observed as a coronal cavity in 1997 will also be started. HUGH S. HUDSON Activities in February and March Work continued on the 1997 filament cavity and on the Nov. 6, 1997 X-class flare. However, the main activity was preparation for the CDAW on magnetic connectivity (one of the twice-yearly SOHO/Yohkoh data workshops), which will take place Apr. 6-10 at ISAS. Please refer to http://www.solar.isas.ac.jp/CDAW3/ for details on the CDAW and its scientific orientation. SXT operations took a good fraction of the time during these two months, with Yohkoh tohban, SXT chief observer, and operations software tasks. Plans for April and May The CDAW will occupy the first week of April, after which I hope to submit the first paper on the filament cavity of 1997 with Acton, Harvey, and McKenzie. This has turned into one of the focal points of the CDAW because of the exciting prospect of learning something about the connectivity of the Page 12 newly-discovered hot core region, aided by the exceptional stability of this cavity. CDAW participants Kosovichev and Wheatland have both expressed interest. The GRL paper on sigmoid => arcade flare development was accepted and returned to the journal, but then they lost it. There will be a small delay in publication! In the meanwhile related work will also be a feature of the CDAW, so I hope to resume productive research in this area as soon as the meeting is finished. At the end of May, I will attend the AGU/SPD meeting in Boston. Papers published Sterling, A. C., and Hudson, H. S., Yohkoh SXT Observations of X-Ray `dimming' Associated with a Halo Coronal Mass Ejection, Ap J 491, L55, 1997 Aschwanden, M.J. Bynum, R.M., Kosugi, T., Hudson, H.S., and Schwartz, R.A., Ap. J. 487, 936, 1997. Page 13 ------------------------------------------------------------------------------- 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 April 1998 March 1998 |------------------------------- | 6. PERFORMING ORG | CODE: O/H1-12 -----------------------------------------------|------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- T. R. Metcalf | TION REPORT NO: F. M. Friedlaender | |------------------------------- -----------------------------------------------|10. WORK UNIT NO. 9. PERFORMING ORGANIZATION NAME AND ADDRESS | Lockheed Martin Missiles and Space |------------------------------- Advanced Technology Center, O/H1-12, B/252 |11. CONTRACT OR GRANT NO. 3251 Hanover Street, Palo Alto Ca. 94304 | NAS8 - 40801 -----------------------------------------------|------------------------------- 12. SPONSORING AGENCY NAME AND ADDRESS |13. TYPE OF REPORT AND Marshall Space Flight Center (Explorer Program)| PERIOD COVERED Huntsville Alabama 35812 | Progress report for the month Contact: John Owens | of March 1998 |------------------------------- |14. SPONSORING AGENCY | CODE MSFC / AP32 -----------------------------------------------|------------------------------- 15. SUPPLEMENTARY NOTES ------------------------------------------------------------------------------- 16. ABSTRACT The SOLAR-A Mission is a program of the Institute of Space and Astronautical Science (ISAS), the Japanese agency for scientific space activity. The SOLAR-A satellite was launched on August 30, 1991, to study high energy phenomena in solar flares. As an international cooperative agreement, Lockheed, under NASA contract, is providing a scientific investigation and has prepared the Soft X-ray Telescope (SXT), one of the two primary experiments of the mission. --------------------------------------|---------------------------------------- 17. KEY WORDS (SUGGESTED BY | 18. DISTRIBUTION STATEMENT AUTHOR(S)) Solar-A, X-ray, CCD, | Space Science, Solar Physics ------------------------|-------------|----------|-----------------|----------- 19. SECURITY CLASSIF. | 20. SECURITY CLASSIF. | 21. NO OF PAGES |22. PRICE (OF THIS REPORT) | (OF THIS PAGE) | | None | None | 13 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office