Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for August 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 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 Plans are being initiated for FY'99 operations. All indications are that minimal funding will be available to sustain operations for next year. Under the present contractual arrangements a proposal will have to be prepared by LM against an RFQ provided by the government for this activity. << Solar Activity >> In early August, the level of solar activity continued to be low, despite the presence of several active regions. The target of the Hida campaign was AR 8294/95 in the first half of the week. Although it was not a bright region, it showed several signatures of minor flux emergence, according to the reports from Hida. The second target, AR 8293, was more active and brighter. SXT images showed recurrence of small loop brightenings and jets, which was probably attributable to emerging flux. In mid August, the level of solar activity again continued to be low, despite the presence of several active regions. The target of the Whole Sun Fortnight (WSF) campaign was AR 8299/8297 and a large filament in the southern hemisphere. The active region observations showed some interesting inter-region loop activity as well as some nice loop brightenings. SXT could not see anything in the region of the filament channel. Four M-class flares and more than 30 C-class flares took place. After mid-month, the level of solar activity picked up with the appearance of AR8307 which produced several M- and X-class flares. Many of these occurred during Yohkoh day and one was detected during a real-time contact. The Whole Sun Fortnight campaign continued with various targets including: AR8303 + southern extension of north polar coronal hole, AR8304 in the south with some Page 2 interesting sigmoid shaped loops, and AR8307 with many flares. There was a solar eclipse on 21/22-Aug-98, visible on Earth in the South Pacific, and a special table was prepared and executed. Yohkoh saw 4 episodes of this eclipse with good coverage of at least 3 of these. The latter two episodes appear in a recent science nugget. For Yohkoh observations see http://isasxa.solar.isas.ac.jp/~hudson/aug98_eclipse.html (predictions) and ftp://isass0.solar.isas.ac.jp/pub/sxt_co/980829.html (results). Unfortunately, this operation, as has happened before, resulted in a temporary spacecraft mis-pointing. Recovery from this condition was slow (but successful!). At the end of the month, the level of solar activity was high with AR8307 producing several M- and X-class flares. One of them became a major solar-terrestrial event but alas Yohkoh was at night during the rise phase, and SXT was in HALT mode because of the safehold due to the eclipse. On Aug. 30 the GOES level was almost continuously above C. There were at least 5 X flares and 9 M flares; Yohkoh unfortunately missed the interesting part of the event of August 24, an event with great geoeffective potential. Large spot groups have been present continuously, with AR 8307 reaching almost 600 millionths of the solar disk. << Campaigns >> In early August, we coordinated with TRACE and Hida Observatory to observe signatures of emerging flux. The weather at Hida was not cooperative. This coordination continued through 8-Aug-98. In the latter half of August, we took part in the active region and magnetic field study of the Whole Sun Fortnight coordinating with many ground-based observatories and TRACE. This coordination continued through 25-Aug-98. The conclusion of the Whole Sun Fortnight was a bit inglorious because of the safehold interruptions caused by the eclipse operation. This effort produced data quite strikingly different from those obtained in the original Whole Sun Month, which took place during solar minimum conditions of mid-1996. << Science >> Acton prepared an overlay of the 5-Oct-96 CME from the LASCO C2 coronagraph and an SXT deep-exposure difference image prepared by Hugh Hudson. The SXT difference image shows a coronal depletion at the equator and enhanced emission north and south of that. The extent of the enhancement corresponds roughly to the north and south boundaries of the CME "bubble." This is a very large-volume phenomena and deserves further study and interpretation and more events. The new thing reported here is an SXT analysis that we have not done very often: the summation of "super-long" exposures, typically 30 s each in the AlMg filter, and then a difference before and after to search for CME counterparts in the low corona. Not only does the dimming appear right above Page 3 the active region, as we already knew, but - the whole W limb lights up. This is the first time such widespread effects have been seen with SXT, we believe, and probably the lack of scattered light from bright active regions contributed to this detection. In any case we have no idea just now how to explain this, unless both the northern and southern polar-crown streamers are re-forming simultaneously. But they presumably did not blow out, since the CME originated near the equatorial plane even though it had a huge angular extent. Aschwanden analyzed the footpoint separation and HXR flux asymmetry of 54 HXT double footpoint flares commonly analyzed with BATSE/CGRO, finding that the footpoint separation of double footpoint sources is energy-independent and confirming the scaling law of loop size with the electron time-of-flight distance. The altitude of HXT footpoint sources decreases with energy, from 5900 km in Lo-channel to 3500 km in M2-channel in one flare. Using an asymmetric trap model, the fractions of direct- and trap-precipitating electrons are calculated separately at both magnetically conjugate footpoints. The timing of Sakao's conjugate HXT data is consistent with double-sided trap precipitation. << 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 August were 60580 accesses and 2857 Mbytes transferred. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT Bitmap error 10-August-98 Pass 1: 980810-1237 recovered in the same pass. SXT Bitmap error 12-August-98 Pass 1: 980812-1238 recovered in the same pass. SXT Bitmap error 29-August-98 Pass 1: 980829-0721 recovered in the same pass. Filter Soft error 31-August-98 Pass 1: 980831-0618 recovered in the next pass. The eclipse operation, as has happened before, resulted in a temporary spacecraft mis-pointing. Recovery from this condition was slow because it occurred during a period of relatively poor visibility for the star Canopus, the fundamental roll calibration reference for Yohkoh. Page 4 << Data Flow >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Jun-96 386506 164930 1613575 365975 1979550 796918 28.62 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 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 2314 901 8531 2007 10538 4342 29.18 Aug-98 0 0 0 0 0 0 NaNQ Sep-98 0 0 0 0 0 0 NaNQ Oct-98 0 0 0 0 0 0 NaNQ Total 554622 208850 2236817 479367 2716184 1003785 26.98 Number of Full Frame Images Received: 554622 Number of Observing Region Images Received: 2716184 Total: 3270806 Approximate Number of Shutter Moves/CCD Readouts: 5687645 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 (%) 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 56.29 966.6 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 56.77 984.5 214236 26016 23.1 N/A Aug-98 N/A N/A N/A N/A 0.0 N/A Sep-98 N/A N/A N/A N/A 0.0 N/A Oct-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-AUG-98 and 31-AUG-98 ALEXANDER 3-AUG-98 28-AUG-98 26 (total of 26 days) HUDSON 1-AUG-98 5-AUG-98 5 20-AUG-98 31-AUG-98 * 12 (total of 17 days) NITTA 1-AUG-98 * 8-AUG-98 8 30-AUG-98 31-AUG-98 * 2 (total of 10 days) SHIRTS 1-AUG-98 * 14-AUG-98 14 (total of 14 days) SLATER 1-AUG-98 * 14-AUG-98 14 (total of 14 days) ---------------------------------------------------------------- Grand Total of 81 days for 5 people NOTE: The "*" signifies travel that actually ends after 31-AUG-98 SXT Foreign Travel between 1-SEP-98 and 30-SEP-98 HUDSON 1-SEP-98 * 18-SEP-98 18 25-SEP-98 30-SEP-98 * 6 (total of 24 days) NITTA 1-SEP-98 * 20-SEP-98 20 (total of 20 days) SLATER 9-SEP-98 30-SEP-98 * 22 (total of 22 days) WUELSER 7-SEP-98 30-SEP-98 * 24 (total of 24 days) ---------------------------------------------------------------- Grand Total of 90 days for 4 people NOTE: The "*" signifies travel that actually ends after 30-SEP-98 Respectfully submitted, Thomas R. Metcalf Frank M. Friedlaender Page 7 ------------------------------------------------------------------------------- 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 September 1998 August 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 August 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 | 7 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office