Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for the month of June, 1993) OVERVIEW 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 from Kagoshima Space Center (KSC) in Japan, and renamed Yohkoh. The purpose of this mission is to study high energy phenomena in solar flares. 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 by Lockheed in cooperation with the National Astronomical Observatory of Japan, and the Institute for Astronomy of the University of Tokyo. MAJOR ACTIVITIES IN THE MONTH << Solar Activity and Observation Planning >> Generally the solar activity was not very high for the week of 30-May to 5-Jun and remained in the same level as the previous week. Yaji-san at KSC, however, reported a lot of jet phenomena and rapid expansion of active region (NOAA7519) and a few flares. There were some flares at the M level. Two experimental operations were carried out: high time resolution, and the first routine coronal offpoint. There were no special coordinated observations during this period. The solar activity increased some during the week of 6-Jun to 12-Jun. The X-ray sun was dominated by NOAA Active Region 7518, which produced four GOES M class flares (YOHKOH observed only one which was M5.4 at 14:25 7-Jun) and numerous C-class events. The GOES background remained at a high B level until the AR 7518 passed the West limb, at which time it dropped to around B1. A number of B and C class flares were observed on the West limb. The sun became very, very quiet for the week of 13-Jun to 19-Jun, with the background level remaining below B-1 for most of the week. The largest flares were around the GOES B5 level in soft X-rays. << Science >> LaBonte made substantial progress on analysis of SXT data from post-flare loop systems, using all of the bells and whistles of the Yohkoh analysis software plus some tricks of his own. Ichimoto presented half of the regular Yohkoh seminar on H-alpha and SXT observations of one such system. It is clear that these large loop systems have properties unexpected from the classical observations (and from the classical models). Hudson presented the other half of the Yohkoh seminar, reviewing progress on solar radius measurements. Morrison has been systematically calculating X-ray limb locations using Metcalf's software, and the results are quite Page 2 encouraging for future coalignment calibrations. Hara pointed out that a systematic change in the SXT white-light radius values coincided nicely with the major decrease of solar activity in early 1992. Bruner has worked on the co-alignment of rocket C IV images with SXT images. The initial comparisons show striking similarities and intriguing discrepancies in the image morphology. The comparisons were carried out with the aid of selection software completed by Morrison, and with the aid of a blink comparison program prepared earlier by Kashyap and Bruner. The data covered the active region that was the prime target of the campaign, and also a nearby emerging flux region (EFR). As with the full frame images, we find that most of the X-ray loops have bright C IV emission at their footpoints. The EFR was fairly active at the time of the rocket flight, and a considerable amount of evolution of the overlying X-ray structure was seen during the orbit covering the launch. In addition to the bright footpoints seen elsewhere in the C IV image, very thin loops could be seen that were more or less parallel to the X-ray arcade, but were not coincident with any of the X-ray loops. The most prominent C IV loop was at the East edge of the X-ray arcade. A second seemed to lie between two of the X-ray loops. The blink comparator analysis also revealed a loop in the active region that was common to both C IV and X-ray images over part of its length. The C IV image extended further in one direction, and the X-ray portion of the loop extended further in the other, suggesting the presence of an axial temperature gradient. Extended analysis of these structures should prove to be quite interesting. << Data Analysis Software >> Some progress has been made on stream-lining the image alignment software and it is hoped that a new set of procedures will be released within the next month. << Instrument Operations and Health >> There were 18 arcminute offpoints to the east and west on 3-Jun, 10-Jun, 17-Jun, 23-Jun, and 30-Jun. There were some microprocessor errors which were recovered at the following pass by resetting the microprocessor. SXT Bit Map Error 9-Jun SXT Bit Map Error 14-Jun SXT Bit Map Error 15-Jun SXT Bit Map Error 20-Jun SXT Bit Map Error 21-Jun SXT Bit Map Error 23-Jun SXT Bit Map Error 30-Jun Page 3 << Data Flow >> The magneto-optical (MO) disk archive for the whole Yohkoh mission is now available at ISAS. There are 67 MO disks which hold about 800 megabyes per disk. All of the instrument files plus the ADA file for the whole mission are available (the CBA files are not copied to the MO disks). The disks are located in the larger Yohkoh computer room on the 4th floor of D-toh. << Papers and Conferences >> A significant amount of effort is being expended by all Yohkoh members to prepare for the Solar Physics Division (SPD) of AAS conference which will be held at Stanford July 13-16. << Engineering Summary Table >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Sep-91 517 397 21174 3541 24715 5481 18.15 Oct-91 4106 2532 6393 12437 18830 3401 15.30 Nov-91 5291 2475 12149 14696 26845 10952 28.98 Dec-91 4858 3228 4983 16837 21820 6910 24.05 Jan-92 5544 3177 10084 5972 16056 6849 29.90 Feb-92 4868 2865 15449 9623 25072 13579 35.13 Mar-92 5910 2699 19236 2653 21889 10589 32.60 Apr-92 6751 3483 20157 5423 25580 12327 32.52 May-92 7032 3158 25464 4589 30053 13745 31.38 Jun-92 6417 3632 21648 12725 34373 14782 30.07 Jul-92 6345 3275 23941 10510 34451 14717 29.93 Aug-92 6572 2978 24207 11154 35361 13550 27.70 Sep-92 6087 2916 26832 20042 46874 15729 25.12 Oct-92 6743 2589 50985 14709 65694 23687 26.50 Nov-92 6658 2939 24416 14696 39112 12924 24.84 Dec-92 6775 2999 24253 6633 30886 12356 28.57 Jan-93 6888 3351 24067 4861 28928 13069 31.12 Feb-93 6833 3004 24479 18149 42628 12302 22.40 Mar-93 7177 3460 25874 19537 45411 14657 24.40 Apr-93 7754 3644 34128 8352 42480 17967 29.72 May-93 8571 3950 41832 7518 49350 21971 30.81 Jun-93 6303 2133 48352 10833 59185 18296 23.61 Total 134000 64884 530103 235490 765593 289840 27.46 Number of Full Frame Images Received: 134000 Number of Observing Region Images Received: 765593 Total: 899593 Approximate Number of Shutter Moves/CCD Readouts: 1595624 Page 4 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. Month Avg Dark Level # of Dark Spikes CCD Warmings Front Optical (DN) (e/sec) Over 48 Over 64 High / # Support Trans Temp /Days Temp (%) Oct-91 31.11 22.9 671 33073 10.5 77.8 Nov-91 31.17 25.2 1058 35129 11.9 64.4 Dec-91 31.19 25.8 1347 36013 14.0 52.5 Jan-92 31.21 26.7 1270 39486 0.5 / 2 14.9 38.4 Feb-92 31.58 40.6 2120 46059 14.3 31.8 Mar-92 31.48 36.5 1355 49557 14.8 25.1 Apr-92 31.56 39.7 1705 50107 23.8 / 4 14.6 22.8 May-92 31.72 45.7 1674 57201 14.4 20.1 Jun-92 32.11 60.5 2184 70669 -2.5 / 3 15.1 17.4 Jul-92 32.22 64.4 1852 79326 15.5 14.1 Aug-92 32.21 64.1 1922 77488 14.9 13.1 Sep-92 32.38 70.5 2062 84758 -1.2 / 3 15.9 12.2 Oct-92 33.04 95.3 3761 96756 16.8 11.5 Nov-92 35.99 205.9 6405 159878 18.0 11.0 Dec-92 43.10 472.4 20382 255875 17.9 N/A Jan-93 42.57 452.4 12808 261134 23.8 / 2 19.2 N/A Feb-93 N/A N/A N/A N/A 17.7 N/A Mar-93 43.27 478.7 14562 261579 17.7 N/A Apr-93 43.16 474.6 14433 261595 23.8 / 2 16.9 N/A May-93 43.44 485.2 16398 261621 17.3 N/A Jun-93 43.97 504.9 19557 261628 16.3 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. << Personnel Travel >> SXT travel for the month of June, 1993: BRUNER 1-JUN-93 * 30-JUN-93 * 30 (total of 30 days) HUDSON 1-JUN-93 * 20-JUN-93 20 28-JUN-93 30-JUN-93 * 3 (total of 23 days) MORRISON 1-JUN-93 * 24-JUN-93 24 (total of 24 days) LABONTE 1-JUN-93 * 30-JUN-93 30 (total of 30 days) METCALF 8-JUN-93 30-JUN-93 * 23 (total of 23 days) Page 5 Planned SXT travel for the month of July, 1993: BRUNER 1-JUL-93 * 1-JUL-93 1 (total of 1 days) HUDSON 1-JUL-93 * 6-JUL-93 6 20-JUL-93 31-JUL-93 * 12 (total of 18 days) MORRISON 6-JUL-93 14-JUL-93 9 (total of 9 days) NITTA 21-JUL-93 31-JUL-93 * 11 (total of 11 days) SLATER 19-JUL-93 31-JUL-93 * 13 (total of 13 days) METCALF 1-JUL-93 * 2-JUL-93 2 (total of 2 days) WUELSER 6-JUL-93 30-JUL-93 25 (total of 25 days) Respectfully submitted, Mons D. Morrison Frank Friedlaender Page 6 -------------------------------------------------------------------------------- UNIVERSITY OF HAWAII ACTIVITY REPORT (DR. R. CANFIELD) MAJOR ACTIVITIES FOR THE MONTHS OF MAY AND JUNE Our most important activities included support of Yohkoh operations and data analysis at ISAS, coordinated ground-based data acquisition at Mees, collaborative analysis of Yohkoh/Mees data, preparation of papers for publication, and presentation of papers at meetings. During this period operational support for SXT was provided by Hudson and LaBonte at ISAS, Judd, Nitta, and Douglass at Mees, and Canfield, Jiao, Leka, Metcalf, Mickey, and Wuelser in Manoa. At the end of April Koon resigned to take a position at the Mauna Loa Solar Observatory; his replacement, Jeffrey Douglass, started at Mees in mid-June. Solar activity was generally low, but highly variable. Mickey ran the IVM as part of the X-ray Bright Point campaign May 17-21. Mickey, Metcalf, and Canfield set up an IVM observing mode to look for flare-associated changes in magnetic structures, and it is now being run each day by the Mees observers. The hardware problems that plagued the IVM and MCCD during the previous report period were largely solved by Mickey and the Mees engineering staff, although the Exabyte tape drives continue to cause problems from time to time. Several IVM problems, mostly associated with the image stabilizer, were repaired, and the IVM was back in full operation by the last week of May. Mickey upgraded IVM control code to create SPAM entries, so there is one entry for each magnetogram. He also made several improvements to the IVM data reduction codes. Wuelser made good progress on an improved white light telescope designed to improve the accuracy of co-registration of Mees and Yohkoh images. Delivery was taken on the control computer, and the telescope fabrication was completed in the IfA shops. Wuelser and Canfield participated in the Flares-22 meeting in Ottawa; Wuelser presented his SXT/HXT/Mees study of transport process in large flares, and Canfield presented his SXT/Mees study of tether cutting prior to the 1992 Nov 15 flare. Wuelser submitted a manuscript on energy transport in the 1992 Nov 15 flare to Ap.J. Leka, LaBonte, and Metcalf were all at ISAS for collaborative data analysis. Leka is currently writing two papers on NOAA 7260, with van Driel-Gestelyi and other Yohkoh team members. She will be presenting a poster at the SPD meeting in Stanford, and will give an oral presentation at the Sac Peak Summer Workshop on Active Region Evolution in late August. LaBonte studied the temperature distribution in the loop system seen above the flare of 1992, 25 June. He has made a systematic comparison of the temperatures determined from the thick to thin aluminum ratio with that from the Be to thick aluminum ratio, finding a bi-modal distribtuion in the correlation plot. The structure of the loop system is clearly visible in the temperature maps, and there is a high temperature region above the loop tops (where the emission measure is low) that appears to be statistically significant. At intermediate altitudes, the temperature Page 7 appears to be highest on the axes of the loops and to drop with distance from the axes. Metcalf co-aligned the Yohkoh SXT and and HXT data with the IVM data for the October 27, 1992 flare. He also analyzed and co-aligned the Stokes magnetogram data for this flare. He wrote a program to generate quick-look HXT images. With this code it is possible to generate such HXT images for an entire flare in a matter of minutes. He worked with Fludra to generate several figures incorporating Mees Stokes data and SXT data for the 23 June 1992 flare. He worked with Mickey on the initial analysis of the IVM H-alpha flare data. Finally, he worked with Jiao to prepare a poster talk for the SPD meeting on the height dependence of the chromospheric magnetic field. Hudson worked on various aspects of flares, including a search for "black light flares" in collaboration with Lidia van Driel-Gesztelyi. This search has been unsuccessful thus far, although the SXT aspect-sensor data are in some ways well-suited for a search. Instead they have extended the list of white-light flares to a present total of 9, reaching down in GOES classification to about M7. He also prepared for the IAU Colloquium in Boulder on solar variability. The naive (engineering level) determinations of the optical radius of the Sun, based upon the archived SXT aspect-sensor data, turn out to be better than ground-based observations. The data also show clear effects of sunspot "dips" and have promise for related photometric studies. Jiao started a collaborative project with Leka, Metcalf, Klimchuk, and Canfield on the relationship between electrical current density (from Mees magnetograms) and loop cross-section variation (from SXT images). Canfield and Reardon discovered evidence, in H-alpha dyamics and SXT brightenings, for tether cutting and associated thermal energy release before the 1991 Nov 15 flare. Canfield worked with Sakurai on planning for the AR7260 Coordinated Data Analysis Workshop, which will take place in August. PLANS FOR JULY AND AUGUST Canfield, Leka, Hudson, Jiao, Metcalf, and Mickey will present SXT-related papers at the SPD meeting in Stanford. Wuelser and Hudson will support SXT operations at ISAS (Wuelser, in particular, made the sacrifice of doing so during the July SPD meeting!). Wuelser will work on transport processes in various large flares observed by Mees and Yohkoh, including that of 1992 July 16. In August, after he returns from ISAS, he will resume work on the white-light telescope. Jiao, Metcalf and Canfield will continue to work on the relationship between SXT loop cross-section variation and foot-point current density. Leka will analyze the electric current systems in AR7260, but will most likely also conduct observations with the IVM, to obtain a second dataset for her thesis. She will be involved in final tuning and calibration testing of the IVM in the process. Hudson plans to work on the high time resolution SXT data. SXT was operated in "PFI dominant mode", which gives two-color cadences of 4 sec. Some of these data were simultaneous with MCCD observations. The results include microflares, for which the higher time resolution turns out to have been justified, and also other as-yet-unexplained rapid Page 8 variability. Hudson will also assess the first of the routine Yohkoh offpoints with respect to image quality and science content. The offpoint data include the session on April 12 done in support of the SPARTAN coronagraph observations. Mickey plans to reduce the X-ray Bright Point observations, continue active-region evolution observations, including rapid-cadence observations if flare likelihood is significant, and continue to develop the data reduction software in the course of reducing current datasets. In August Mickey plans to investigate and eliminate, if possible, a ghost image in the IVM which has been giving us trouble. Metcalf will will submit the paper on AR6952 and the lack of any correlation between x-ray brightness and long-lived photospheric currents. He will write up the work with Jiao studying the height dependence of the magnetic field using a combination of Na-D and FeI magnetograph data. He will continue the analysis of the IVM H-alpha data. Finally, he plans to analyze the rapid cadence IVM magnetograms to look for flare related changes in the electric current. -------------------------------------------------------------------------------- UNIVERSITY OF CALIFORNIA AT BERKELEY (DR. S. KANE) J. McTiernan has written a paper on the temperature and density structure of a flare which occurred on 2-NOV-91. This has been submitted to the Astrophysical Journal Letters, and we are currently awaiting the referee's report before sending out preprints. A future paper on temperature analysis, which will include data from many flares, and a statistical study of the energy contained in the soft X-ray plasmas of flares is in preparation. Work on the comparison of spatially dependent hard X-ray spectra obtained with HXT with thick-target electron beam models is proceeding. We now have the ability to model data from loops which are not symmetric; i.e., loops which have different magnetic field mirror ratios at different footpoints. Fairly accurate values for the density of the solar atmosphere in a flare loop can be obtained from SXT data. A model such as this may account for the behavior of the 15-NOV-91 flare, which had two hard X-ray footpoints with different spectral indices. Preliminary results from this study, along with results from the comparison of Yohkoh HXS spectra with Ulysses and PVO spectra for the 15-NOV-91 flare, will be presented at the SPD meeting at Stanford on July 13-16, 1993. -------------------------------------------------------------------------------- STANFORD UNIVERSITY (DR. P. STURROCK) During the past two months, Jim Klimchuk has compared SXT data and microwave data from the Owens Valley Radio Observatory in collaboration with Dale Gary of Caltech. The data sets can be used independently to infer the temperature and emission measure of the corona. Differences in the inferred temperatures and emission measures are an important indication of nonuniformities along the line-of-sight (for example, the variation of temperature with height in the corona). The preliminary results of this study will be presented at the Solar Physics Division meeting on July 13. As part of this study, Klimchuk has carefully examined the estimates of uncertainties in the temperatures and emission measures that are determined from SXT data. He has found that the formula for Page 9 the emission measure uncertainty in the current version of the IDL procedure sxt_teem2.pro is incomplete and predicts uncertainties that are much too small. He has derived a complete formula. Lisa Porter has continued to search the SXT data for good examples of coronal loops that will form the basis for the loop study that she and Klimchuk are undertaking. The primary objective is to learn about spatial dependence of coronal heating. During the next two months, Klimchuk will continue his collaborations with Dale Gary and Lisa Porter. -------------------------------------------------------------------------------- SOLAR PHYSICS RESEARCH CORPORATION (KAREN L. HARVEY) Activity these last two months has continued in several areas: (1) continued update of bibliography of SXT/Yohkoh papers (2) continued work on the collaborative observing program between SXT/Yohkoh and the NSO/KP magnetograph of XBPs on 9 and 10 December 1993. The results from the analysis of the high temporal and spatial resolution PFI observations of 19 XBPs and the coordinated magnetic field observations were submitted in May 1993 as a contribution to the Proceedings of the Yohkoh Science meeting at ISAS in February 1993 (authors: K. L. Harvey, N. Nitta, K. Strong, S. Tsuneta) and will be part of the doctoral thesis of K. L. Harvey (submitted 25 May 1993). (3) a multi-observatory collaborative observing program was undertaken from 17 to 21 May 1993 to study X-ray bright points. Magnetic field observations were obtained by National Solar Observatory/Kitt Peak, Big Bear Solar Observatory (with Sara Martin and Hal Zirin), and Mees Solar Observatory (with Don Mickey and Dick Canfield). An initial survey of the SXT PFIs yielded a variety of bright point activity, though not as many bright points as seen in the 9 December 1992 collaboration. The difference may be that the 9 December observations were in a coronal hole where the overall coronal emission is extremely low, while the observations in May were located in several quiet Sun areas with variable coronal emission levels. (4) the results of the bright point collaborations is being prepared for presentation at the July 1993 Solar Physics Division meeting to be held at Stanford University. -------------------------------------------------------------------------------- MONTANA STATE UNIVERSITY (LOREN ACTON) It has been a busy and productive bimester. All planned work listed in the last report from MSU has been accomplished. Reading and responding to e-mail requires about 1-2 hours per day. Regular management and planning telecons with Lemen, Strong, and Friedlaender continue and have proven to be very useful. I found my visit to LPARL in June to be extremely worthwhile. Page 10 Dr. David Alexander of the University of Glasgow has accepted the post of Yohkoh post-doctoral research scientist. He is an extremely well-qualified scientist and I am delighted to have him join the SXT team. He will visit MSU at the end of July and will come to stay in October. During the period I gave five talks in which SXT results were included: 5/13 Conf. on Skylab, Spacelab and Space Station, Huntsville, AL 5/19 Seniors (2 classes), Big Sky High School, Missoula, MT 5/30 Commencement, Ennis High School, Ennis, MT 6/03 Kiwanis Club, Bozeman, MT 6/24 Aerospace Workshop, Eastern MT College, Billings, MT I also worked with Lockheed Public Affairs on plans for distribution of the educational video, "What's It Like to Fly in Space -- with Loren Acton". Work continued as needed on providing information and support to NASA in the on-going consideration of MODA funding for a Yohkoh extended mission and the GI program. This continues to be an activity exceeded in priority only by SXT operations and health. OPERATIONS AND CALIBRATION In addition to daily monitoring of GBO-mail reports and e-mail related to operations I worked the following calibration and operational issues: 1. Based on a querry from Andrej Fludra I studied the problem of x-ray signal discrepancies in the faint parts of flare PFI's and discovered the presence of x-ray scattering from the x-ray neutral density filter at the <1% level. This much signal scattered from the bright parts of the flare can easily make a factor of 2 difference in the faint parts of the image. A preliminary calibration note (#33) was released. We need to do an on-orbit calaibration of the ND filter to verify the pre-launch calibration -- available data are not appropriate. 2. Looked into the reasons for secular variations in stay light and reached no conclusion. 3. Researched and published a note on SXT x-ray pixel size. Recommended that we stick with the pre-launch calibration value of 2.453 arcsec. 4. Carried on an e-mail exchange with Roland Vanderspek of MIT on the question of degradation of SXT optics. 5. Worked on the effective area and x-ray optical axis questions from the White Sands calibration data. Rich Fuller and Jim Lemen have been working on these questions for some time with unsatisfactory results. At present there is a great scatter in the WSMR data which is not understood. SCIENTIFIC WORK I completed my review and comment on papers by Feldman and by Cheng. The Sky & Telescope article is finally finished and will be published in the Page 11 September issue with (probably) a cover picture from SXT. Thanks much to Lemen, Strong and Roethig for work on the cover picture and caption. Peter Sturrock and I discussed our plans for the Annual Reviews article on Coronal heating, which is due in October, while I was in Palo Alto. Carried on an e-mail discussion on the "openness" of the SXT image data base set up for public FTP access at Hiraiso. The agreement is that the data base will be fully open but with a README file urging users to collaborate with the Yohkoh team if the data are to be used in research for publication. PLANS FOR NEXT REPORTING PERIOD - Install laser disk player and monitors at MSU - Order remainder of hardware for MSU (X-terminals, color printer, VCR). - Continue work on Annual Reviews and IAU Colloquium 144 papers. - Host visit by David Alexander. - Keep current on SXT/Yohkoh operations -- interact as required. - Depart for ISAS on 1 August. Page 12 -------------------------------------------------------------------------------- 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 | July 10, 1993 June 1993 |-------------------------------- | 6. PERFORMING ORGANIZATION | CODE: O/91-30 -----------------------------------------------|-------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- M. D. Morrison | TION REPORT NO: F. M. Friedlaender | |-------------------------------- -----------------------------------------------|10. WORK UNIT NO. 9. PERFORMING ORGANIZATION NAME AND ADDRESS | Lockheed Palo Alto Research Labs B/252 |-------------------------------- Solar & Astrophysics Laboratory O/91-30 |11. CONTRACT OR GRANT NO. 3251 Hanover Street, Palo Alto Ca. 94304 | NAS8 - 37334 -----------------------------------------------|-------------------------------- 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 | of June, 1993 |-------------------------------- |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 | 12 | ------------------------|------------------------|-----------------|------------ For sale by: Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402-0001 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Command? SCAN! ALL No. Delivered From Subject Lines 2 Jul 10 22:37 POSTMAN [From: >> *** SAG *** Tuesday, Jul 13, 1993 10:16 AM CDT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~