Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for April 2000) 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 proposal for the extended mission is being evaluated by NASA. The current contract has been extended to go through May of this year. Contract negotiations should be accomplished during the latter part of May. SOLAR ACTIVITY In the first half of April, there were 9 M flares. There were many active regions, 15 on April 4, but no huge regions and no X-class flares. GOES X-ray background level was gradually decreasing and dropped to C1 level. In the second half of April, there were no M flares. As in the first half of the month, there were many active regions, including one (8970) which exceeded 1,000 millionths in sunspot area. But, no major flares. The southern large spot group, 8970, matched the longitude of another large spot group in the north, 8971. Their mutual CMP was about April 27. The proximity of these two led to the trans-equatorial loops we enjoyed in week 18. CAMPAIGNS Yohkoh ran special tables supporting VLA observations on April 2 and April 8. The rapid-run SFDs were successful. Yohkoh supported SOHO JOP083. This normally meant ARS2, initially with an obscure region but finally with AR8948 (CMP April 10), which then became quite active. It produced two of the M flares, for which we hope Page 2 that comprehensive (eg TRACE) data now exist. The JOP targeted microflares, but we all know that the more of them there are, the more of the big ones there are too. Yohkoh supported an attempt at a new JOP119 oriented towards trans-equatorial loops. SCIENCE Acton studied changes in the SXT sensitivity at the time of the zeroth entrance filter failure in October 1992 (not presently accounted for in our database). He was surprised to find that the signal level through Al.1 increased by up to 30% in the quiet (cool) corona at the time of this event. Our entrance filter model will have to be improved. Aschwanden and Acton analyzed long-exposure and off-pointing Yohkoh/SXT data of the solar corona observed on 1992 Aug 26. They developed a new tomographic method which is based on a forward-fitting method of a 4-parameter model to the observed soft X-ray fluxes of two SXT wavelength filters as function of height h. A direct consequence of the multi-scale height atmosphere is that the filter ratio temperature is predicted to increase with height, even if all magnetic field lines are isothermal. Their model-fitting reveals that coronal holes and Quiet Sun regions are in perfect hydrostatic equilibrium, but that coronal streamers have a scale height that exceeds the hydrostatic scale height by a factor of up to ~ 2.3, which underscores the dynamic nature of coronal streamers. Their density measurements in coronal holes are slightly lower than most of the white-light polarized brightness inversions, and seem to come closer to the requirements of solar wind models. With Nitta, Alexander, LaBonte, Zarro, and others, Canfield studied the co-aligned SXT, TRACE, SoHO, BSO, and SOON movies and Mees vector magnetograms for certain flares that were observed in the sigmiodal active region AR 8668 during Whole Sun Month 3. Canfield and Alexander are trying to sort out how the filament data relate to the topological model of Titov and Demoulin (A&A 1999). Canfield worked with various students on the analysis of SXT and MCCD data. Trish Van Lew studied SXT jet / MCCD surge events using the Blehm/Pevtsov list of jets and surges inferred from SXT SFD files throughout the mission to date. Angela Colman wound up her task of identifying moving blueshift events similar to those observed by Canfield et al before the Nov 15 1991 event. Yuriko Yamazaki (ACE Language Institute) and Eric Erickson and Tyler Bangs (Headwaters Academy) studied the relationship between sigmoids and signatures of eruptions in the SXT SFD movies on videodisk. Metcalf worked with George Fisher and Neil Griffiths on some code to extend their coronal heating work to check whether the length of highly sheared neutral line correlates with X-ray luminosity, as suggested by the MSFC folks. It turns out that the length of sheared neutral line Page 3 does not correlate once the dependence on total magnetic flux is removed. Nitta reanalyzed the 36 Fe XXVI flares studied by Jakimiec et al. He found only a few cases where the low energy hard X-ray loop-top source coincides with or even overlaps with the SXT high-temperature region. This suggests that the loop-top source as seen in HXT L and M1 bands following the impulsive phase represents bremsstrahlung of non-thermal electrons with a very soft spectrum and low-energy cutoff at > 10 keV. The paper in preparation on this topic also discusses the quality of SXT temperature maps. PUBLICATIONS Submitted: "Tomography of the Soft X-Ray Corona: I. Measurements of Electron Densities, Temperatures, and Differential Emission Measure Distributions above the Limb by Markus J. Aschwanden and Loren W. Acton, ApJ Accepted: "The Effect of Hydrostatic Weighting on the Vertical Temperature Structure of the Solar Corona", Aschwanden,M.J. and Nitta,N. 2000, ApJ Lett Canfield, R. C. and Pevtsov, A. A. "Vector Magnetic Fields, Sub-surface Stresses, and Evolution of Magnetic Helicity", Invited Paper for IAU Colloquium 179, Pevtsov, A. A. and Canfield, R. C., "Coronal Structures as Tracers of Sub-Surface Processes", Invited Paper for IAU Colloquium 179 "Cyclical Evolution of Solar Magnetic fields: Advances in Theory and Observations", December 13-16 1999, Kodaikanal, India, J. Astrophys. Astr. in press, 2000. Published: 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 April were 176289 accesses and 7999 Mbytes transferred. Page 4 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: Bit Map Error 03-Apr-00 Pass 1: 000403-1239 Recovered in the same pass Bit Map Error 07-Apr-00 Pass 1: 000407-1134 Recovered in the same pass Bit Map Error 12-Apr-00 Pass 1: 000412-0929 Recovered in the same pass Shutter Error 12-Apr-00 Pass 3: 000413-1136 Recovered in pass 4 Page 5 DATA FLOW Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Jan-98 519090 199670 2104062 430632 2534694 954257 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 5768 2011 21890 3434 25324 10846 29.99 Oct-99 5768 2308 22994 10487 33481 11517 25.59 Nov-99 7552 3425 20754 18772 39526 11974 23.25 Dec-99 7488 2791 22047 5354 27401 10663 28.01 Jan-00 5426 1736 19802 4040 23842 8958 27.31 Feb-00 6533 2052 21801 7017 28818 8982 23.76 Mar-00 2202 817 8072 5606 13678 4261 23.75 Total 681270 248509 2709484 731297 3440781 1208699 26.00 Number of Full Frame Images Received: 681270 Number of Observing Region Images Received: 3440781 Total: 4122051 Approximate Number of Shutter Moves/CCD Readouts: 7042652 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 6 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 (%) 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 60.04 1107.3 231585 49084 21.8 N/A Oct-99 59.66 1092.9 229735 45263 22.8 N/A Nov-99 59.90 1102.0 231288 47102 23.0 N/A Dec-99 60.55 1126.3 233523 53920 22.5 / 2 25.3 N/A Jan-00 60.27 1115.9 233820 50214 23.4 N/A Feb-00 60.93 1140.6 235079 56836 23.8 N/A Mar-00 60.22 1114.0 232439 49840 23.0 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 7 PERSONNEL TRAVEL SXT Foreign Travel between 1-APR-00 and 30-APR-00 ACTON 1-APR-00 * 12-APR-00 12 (total of 12 days) HANDY 17-APR-00 30-APR-00 * 14 (total of 14 days) HUDSON 1-APR-00 * 23-APR-00 23 29-APR-00 30-APR-00 * 2 (total of 25 days) ---------------------------------------------------------------- Grand Total of 51 days for 3 people NOTE: The "*" signifies travel that actually ends after 30-APR-00 SXT Foreign Travel between 1-MAY-00 and 31-MAY-00 HANDY 1-MAY-00 * 27-MAY-00 27 (total of 27 days) HUDSON 1-MAY-00 * 16-MAY-00 16 (total of 16 days) NITTA 14-MAY-00 31-MAY-00 * 18 (total of 18 days) ---------------------------------------------------------------- Grand Total of 61 days for 3 people NOTE: The "*" signifies travel that actually ends after 31-MAY-00 Respectfully submitted, Thomas R. Metcalf Frank Friedlaender Page 8 ------------------------------------------------------------------------------- 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 May 2000 April 2000 |------------------------------- | 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 April 2000 |------------------------------- |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 | 8 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office