Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for the month of March 1994) 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, 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 Plans are being developed to maintain an effective ongoing Yohkoh program under the new ground rules. Requests from various public institu- tions and users for various items and explanations continue to make this program interesting as well as rewarding in that it continues to extract such a broad level of interest. << Solar Activity >> Solar activity was at moderate to low level throughout the month of March. There were about GOES 30 C-class flares. NOAA AR 7682 frequently produced such small flares at the beginning of the month. This size flare is optimum from Yohkoh's point of view as they are large enough to give good statistics in Yohkoh's sensitive soft X-ray instruments and to trigger flare mode reliably while not saturating the BCS or SXT. Even the modest-sized sunspot groups present last month have shown a general level of slow decay. There have been times during the past weeks when the GOES plot was absolutely flat and featureless at about an A8 level--yet the SXT images revealed a wealth of structure, variety of detail and active evolution. Page 2 X-ray bright points abound and SXT has made extensive observations that will help define their spatial, temporal, and size distributions. Filaments and prominences have been common and several eruptive events have been observed. The extensive southern polar coronal hole is tilted towards the Earth at the moment so is being particularly well observed. When the largest southern extension of that hole is at central meridian, as was the case near the end of the month, spacecraft in geosynchronous orbit have experienced episodes of deep charging. This can lead to the destruction of sensitive electronics. Yohkoh has been following the evolution of this hole since launch and has been correlating its observations with those of Ulysses and interplanetary scintillation. << Observation Planning >> We have continued our programme of southern polar offpoints this month in preparation for the Ulysses southern polar passage and have tried to resolve some of the interesting issues that are coming from the SPARTAN- Yohkoh comparison. We are planning another CCD bakeout early next month. << Campaigns >> SXT observing comprised a special X-ray Bright Point (XBP) campaign with Karen Harvey at KPNO during the second week of the month. This campaign involved an 8 arcmin offpoint from the southern pole. We also tested an observing mode designed to look at filament channels, which should be very useful in the years to come. The next coordinated observing campaign is to be for Bruner san's rocket experiment around 21 April. << Science Progress>> During the week of 8-15 March 1994 the SXT team carried out a coordinated X-ray Bright Point (XBP) campaign with Karen Harvey at Kitt Peak with the cooperation of Big Bear and Mees solar observatories. These campaigns are extremely taxing for the SXT Chief Observer, but we did manage to get some very interesting observations of tiny repetitive, paired, "picoflares" on 10-Mar-94. It remains to be seen if this can be called a "discovery". There were two excellent Yohkoh seminars at ISAS during the reporting period. Masuda san reported on his thesis research on the location, evolution, and physical conditions of impulsive hard x-ray sources. His most intriguing result is the observation of a hard x-ray source above the brightest part of the soft x-ray loop as well as the previously reported footpoint sources. At this location the soft x-rays, although faint, yield the highest temperatures in the image. An active discussion ensued on whether to interpret the hard x-rays on the basis of a thermal or non-thermal model--as you might have expected! Page 3 Dr. L. Golub and Dr. E. DeLuca visited the Lockheed Solar & Astrophysics Laboratory on 7-8 March. The primary purpose of their visit was to work on the comparison of the Yohkoh and NIXT sounding rocket data. NIXT flew on 12 April 1993 and obtained high-resolution multilayer images at 63 A (Fe XVI) simultaneously with SXT's broadband imaging. These data are complementary and can be used to derive extremely accurate temperatures and densities along the length of coronal loops. This type of data has not been obtained before and should aid the calibration of both SXT and NIXT. On 10-Mar-94 M. Yamada of the Princeton Plasma Physics Laboratory gave a talk on experiments on magnetic reconnection in the Spheromak machine at the University of Tokyo. In these experiments the magnetic Reynolds number is several hundred, far from the 10^7 in a flare but much more realistic than the magnetic Reynolds number of 1 or less in most lab experiments. The analogy to solar processes was, to me, quite compelling and exciting! I especially liked the comment that magnetic reconnection is going on everywhere anything moves--all the time. Keith Strong attended a workshop about the joint analysis of SPARTAN, Ulysses, and Yohkoh observations of the Sun. The meeting was located at GSFC and held on 16-18 March. The SPARTAN mission provided 40 hours of white-light images and UV line profiles of the outer corona. SPARTAN observed the northern and southern coronal holes, a streamer on the southeast limb, and an active region on the west limb, which produced a CME. Yohkoh provided the temporal evolution of the regions of interest before, during and after the SPARTAN flight, and showed the detailed temperature, density and magnetic structure of the region while Ulysses monitored the solar wind at a latitude of about 45S. Several exciting projects were defined and task teams were assigned to work on them. SPARTAN will fly again during the southern polar passage of Ulysses in September 1994 and again during the northern polar passage of Ulysses about a year later. Initial joint observing plans for these future missions were discussed on the last day of the workshop. It is evident from the current studies that Yohkoh SXT support will be an important element of these campaigns. Page 4 Acton is approaching the end of analyzing some 34,000 SXT images taken over the past 30 months with the collaboration of H. Hara. The integrated x-ray flux (smoothed) has decreased by about a factor of 10 although the total emission of the faint corona has remained surprisingly stable. All of the decrease has been in the bright stuff. I suppose that no one will be excited by the fact that I have discovered a very strong 27 day periodicity? Of more interest, I've summed all of the clean (non-SAA) data for the first year of Yohkoh operation for those cases where pictures were acquired through the thin Al and Dagwood filters within 5 min of one another (1755 cases). The temperature of the corona measured in this way is 3.0 MK and the emission measure is 2e49 cm^-3. This temperature is biased high, and the emission measure biased low, by the presence of higher temperature material. For the same period I derive a temperature of 5.6 MK and an emission measure of 1e48 for the bright cores of active regions. Barry LaBonte continues to study temperatures in some well-observed post-flare loops at the limb while Hugh Hudson is looking at the temperature distribution in flares with a super-hot component. Both of them seem to be finding that the hotter the temperature, the more diffuse the source. -- Papers Submitted [1]-- "Particle Acceleration and the Decay of Soft X-ray Non-thermal Line Broadening" D. Alexander and S. Matthews to Solar Physics -- Papers Published [1] -- "Impulsive Behaviour in Solar X-Radiation" H. Hudson, K. Strong, B. Dennis, D. Zarro, M. Inda, T. Kosugi, and T. Sakao, Ap. J. 422, L25-L27, 1994 - Presentations Given [1]-- "Solar Physics Research at MSU" by D. Alexander -- Abstracts Submitted [2]-- "The Low Energy Cut-off of Nonthermal Electrons in Solar Flares Inferred from Yohkoh SXT, BCS and HXT Observations", by J. M. McTiernan, S. R. Kane, J. R. Lemen, D. M. Zarro, and T. Kosugi. Spring AGU/SPD Meeting "Stereoscopic Determination of Coronal Loop Geometries" G. Slater for the May, 1994 AGU/SPD meeting. Page 5 << Public Use of SXT Images >> G. Linford and K. Strong produced another in a continuing series articles on solar activity for Sky & Telescope. This is the fourth such article to be published featuring SXT images. We continue to receive many requests for the SXT posters, public relations prints, and video tapes for educational purposes. The SXT poster is so popular at the Maryland Teacher's Resource center that they have taken down the sample copy otherwise they run out of it too quickly. We are designing a new poster showing the extended corona to be ready by the spring meeting of the AGU. K. Strong has been invited to write an article for Zenit, a Dutch popular-science magazine, on the CME-flare relationship. It will prominently feature Yohkoh data. Keith Strong contacted Larry D'Onofrio, the managing director of business development at WGBH, about using Yohkoh images in an edition of Nova. Mr. D'Onofrio expressed interest in the package of data that he had received and had passed it on to Bill Grant, who is in charge of the Nova series. During a side trip to WGBH in Boston on Friday 25 March, Strong visited WGBH and discussed with Bill Grant, the Executive Editor of Nova, the possibility of having an episode of Nova devoted to the active Sun and featuring Yohkoh observations. He was very enthusiastic and will assign a production editor to put together a story line with us. This will go forward in competition with something like 15 other titles to be adopted by producers as they become available. If successful the programme will take about a year to produce and will be aired in late 1995 or in 1996. << Spacecraft and SXT Operations and Health >> During recent operations both the BCS and SXT have experienced a nominal level of single event upsets (SEUs). The SXT SEUs were found: Found at: Recovery at: Error: 940228-0206 next pass Mailbox range error 940307-1901 next pass Bitmap error 940309-1341 same pass Bitmap error 940314-1444 same pass Bitmap error 940330-0813 same pass Bitmap error The DSN communications seemed to continue without significant problems. Page 6 << Data Flow >> ------------------------------------------------------------------------------ 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 4896 3190 5001 16837 21838 6892 23.99 Jan-92 5544 3177 10084 5972 16056 6849 29.90 Feb-92 5305 2803 16932 11382 28314 12019 29.80 Mar-92 6248 2361 20367 2653 23020 9458 29.12 Apr-92 6734 3500 20094 5423 25517 12390 32.69 May-92 7032 3158 25464 4589 30053 13745 31.38 Jun-92 7230 2819 24375 13361 37736 11419 23.23 Jul-92 6362 3258 24005 10510 34515 14653 29.80 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 6747 3027 24147 6600 30747 12495 28.90 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 7340 2589 64545 12539 77084 26299 25.44 Jul-93 8259 3650 47561 5352 52913 24213 31.39 Aug-93 7628 3638 30705 3563 34268 17436 33.72 Sep-93 6875 2899 22697 5600 28297 11252 28.45 Oct-93 7474 3657 33782 7548 41330 20104 32.72 Nov-93 8353 4015 42180 5849 48029 24669 33.93 Dec-93 5898 3047 21128 13297 34425 13001 27.41 Jan-94 6934 2804 28567 10960 39527 13746 25.80 Feb-94 6948 2892 22815 5819 28634 11463 28.59 Mar-94 4757 1431 40568 3391 43959 17493 28.47 Total 199761 92150 841553 300937 1142490 445286 28.04 Number of Full Frame Images Received: 199761 Number of Observing Region Images Received: 1142490 Total: 1342251 Approximate Number of Shutter Moves/CCD Readouts: 2353729 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 (%) Oct-91 31.07 21.3 509 261 10.5 77.8 Nov-91 31.06 20.9 648 277 11.9 64.4 Dec-91 31.04 20.2 804 353 14.0 52.5 Jan-92 31.13 23.6 985 450 0.5 / 2 14.9 38.4 Feb-92 31.32 30.8 1176 544 14.3 31.7 Mar-92 31.47 36.5 1355 626 14.8 25.1 Apr-92 31.44 35.2 1323 610 23.8 / 4 14.6 22.8 May-92 31.65 43.1 1417 653 14.4 20.1 Jun-92 32.12 60.9 2215 880 -2.5 / 3 15.1 17.4 Jul-92 32.19 63.2 1829 822 15.5 14.1 Aug-92 32.21 64.1 1922 886 14.9 13.1 Sep-92 32.38 70.5 2062 954 -1.2 / 3 15.9 12.2 Oct-92 32.64 80.3 2317 1055 16.8 11.5 Nov-92 36.24 215.1 6112 1391 18.0 11.0 Dec-92 42.58 452.8 17390 2024 17.9 N/A Jan-93 42.59 453.1 13006 2034 23.8 / 2 19.2 N/A Feb-93 42.28 441.5 13895 2090 17.7 N/A Mar-93 43.14 473.8 14047 2151 17.7 N/A Apr-93 43.13 473.4 14304 2146 23.8 / 2 16.9 N/A May-93 43.45 485.3 16405 2357 17.3 N/A Jun-93 44.03 507.2 20037 2531 16.3 N/A Jul-93 44.52 525.6 23977 2700 22.5 / 2 17.7 N/A Aug-93 44.24 515.0 21879 2643 25.2 / 3 17.2 N/A Sep-93 45.07 546.2 27469 2745 17.5 N/A Oct-93 45.40 558.6 31684 2982 17.7 N/A Nov-93 45.31 554.9 31892 3224 23.8 / 3 19.7 N/A Dec-93 45.92 578.1 38515 3101 19.2 N/A Jan-94 46.18 587.9 42560 3464 22.5 / 2 20.3 N/A Feb-94 46.03 582.1 40449 3246 19.3 N/A Mar-94 46.02 581.8 41142 3426 18.1 N/A NOTES: * The dark current calculations are using full half resolution 2.668 sec images not taken 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-MAR-94 and 31-MAR-94 ACTON 1-MAR-94 * 31-MAR-94 * 31 (total of 31 days) HUDSON 1-MAR-94 * 31-MAR-94 * 31 (total of 31 days) LINFORD 1-MAR-94 * 9-MAR-94 9 (total of 9 days) SLATER 21-MAR-94 31-MAR-94 * 11 (total of 11 days) LABONTE 1-MAR-94 * 31-MAR-94 * 31 (total of 31 days) HARVEY 21-MAR-94 31-MAR-94 * 11 (total of 11 days) ---------------------------------------------------------------- Grand Total of 124 days for 6 people NOTE: The "*" signifies travel that actually ends after 31-MAR-94 -- Planned SXT travel for the month of March 1994: -- SXT Foreign Travel between 1-APR-94 and 30-APR-94 ACTON 1-APR-94 * 30-APR-94 * 30 (total of 30 days) ALEXANDER 2-APR-94 30-APR-94 * 29 (total of 29 days) HUDSON 1-APR-94 * 30-APR-94 * 30 (total of 30 days) SLATER 1-APR-94 * 21-APR-94 21 (total of 21 days) LABONTE 1-APR-94 * 30-APR-94 * 30 (total of 30 days) HARVEY 1-APR-94 * 11-APR-94 11 (total of 11 days) KLIMCHUK 21-APR-94 30-APR-94 * 10 (total of 10 days) ---------------------------------------------------------------- Grand Total of 161 days for 7 people NOTE: The "*" signifies travel that actually ends after 30-APR-94 Respectfully submitted, Keith Strong Frank Friedlaender ------------------------------------------------------------------------------- Page 9 ------------------------------------------------------------------------------- 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 1994 February 1994 |------------------------------- | 6. PERFORMING ORG | CODE: O/91-30 -----------------------------------------------|------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- K. T. Strong | 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 March 1994 |------------------------------- |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 | 9 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402-0001