Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for February 1999) 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 contract with MSFC has now been fully definitized and signed by all parties. The Co-I's now have full work authority and are being funded. We are all looking for another productive year of operations as we are moving toward increased solar activity. << Solar Activity >> Solar activity was low at the beginning of the month, although there was abundant evidence of high activity on the invisible hemisphere as a C5 LDE was observed on Feb. 4, at which time the major spot group, 8446, was about two days beyond the West limb. Once again, the NS interconnecting loops showed some interesting behavior. Solar activity gradually increased through mid-February. The background level changed from B up to C1-level and there was one M-class flare (M1.5) during Yohkoh-night on 12-Feb, as well as some C-class flares. Activity continued at a reasonably high level in late February. The background level was around C1-level and there were six M-class flares during this period. There were two sunspot groups with areas larger than 600 millionths. One of these (NOAA 8458) produced a lovely LDE/CME event (Feb. 16) that resulted in a bright trans-equatorial cusp structure, as described in the science nugget for Feb. 19 (http://www.lmsal.com/YPOP/ProjectionRoom/Weekly/index.html). In general these interconnecting loop structures display remarkable behavior, and SXT images of the rising phase of this solar maximum show us such structures far better than those of the decline of the past maximum. Unfortunately Yohkoh did not directly observe the Feb. 16 event because of the timing of orbit night. Page 2 At the end of February, solar activity decreased as AR8462, which produced an M-class flare on Feb 21st, went behind the west limb. << Campaigns >> A flare-oriented observing campaign, led by Gianna Cauzzi and Roberto Falciani, ran from Feb. 1 through Feb. 12. It was something of a wipe-out via a pernicious conjunction of bad weather and low activity. The Sac Peak flare observing campaign clearly has re-established the truth of Murphy's Law. As soon as they stopped looking, flaring resumed in full force. At the end of February, there was an attempt to look at the same target as the VLA, a task made difficult by the fact that neither the VLA nor our standard coordination Web page has chosen to report VLA targets. SXT also worked with TRACE in an attempt to find clean loops for a Klimchuk analysis of loop geometry on Feb. 24. This campaign was perhaps not so successful, as it is quite difficult to find non-overlapping loops. << Science >> Aschwanden analyzed the 3-dimensional (3D) geometry of solar flares that show so-called "interacting flare loops" in soft X-ray, hard X-ray, and radio emission, as previously identified by Hanaoka and Nishio. The two flare loops that appear brightest after the flare are assumed to represent the outcome of a quadrupolar magnetic reconnection process, during which the connectivity of magnetic polarities is exchanged between the four loop footpoints. Aschwanden parametrized the 3D geometry of the 4 involved magnetic field lines with circular segments, additionally constrained by the geometric condition that the two pre-reconnection field lines have to intersect each other at the onset of the reconnection process, leading to a 10-parameter model. This 10-parameter model was fitted to Yohkoh SXT and HXT data of 10 solar flares. The findings and conclusions are: (1) The pre-reconnection field lines always show a strong asymmetry in size, consistent with the scenario of new-emerging small-scale loops that reconnect with pre-existing large-scale loops. (2) The relative angle between reconnecting field lines is near-colinear in half of the cases, and near-perpendicular in the other half, contrary to the anti-parallel configuration suggested in the model of Heyvaerts Priest and Rust (1977) (3) The shear angle between interacting field lines reduces by 10-50 deg after quadrupolar reconnection. (4) The small-scale flare loop experiences a shrinkage by a factor of 1.31+/-0.44, which is consistent with the scaling law found from previous electron time-of-flight measurements, suggesting that electron acceleration occurs near the cusp of quadrupolar configurations. (5) The quadrupolar reconnection geometry provides also a solution of "Canfield's dilemma" of the offset between the maximum of vertical Page 3 currents and the HXR flare loop footpoints. (6) The quadrupolar geometry provides not only a framework for interacting double-loop flares, but can also be considered as a generalized version of (cusp-shaped) single-loop flares, or as building block of more complex geometries, such as in arcade-like double-ribbon flares. McKenzie analyzed data on the 20-jan-99 flare arcade. With Hudson, he began writing an ApJ Letter about the motions and structures in this arcade. They see coronal dimming, loop shrinkage, a fan of rays above the arcade, and infall of dark blobs and are now working on scattered-light corrections to make useful temperature maps. << 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 February were 72583 accesses and 3656 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 DAT RG error 03-February-99 Pass 4: 990203-0825 recovered in the pass 1 on the next day. SXT Bitmap error 09-February-99 Pass 1: 990206-0309 recovered in the pass 2. SXT Bitmap error 17-February-99 Pass 1: 990217-1547 recovered in the same pass. SXT and its calibration software have recovered from the entrance-filter rupture at the end of January, and everything is now nearly normal. Page 4 << Data Flow >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Nov-96 420984 177702 1735309 379891 2115200 849269 28.58 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 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 3907 1106 24354 8987 33341 8406 20.14 Mar-99 0 0 0 0 0 0 NaNQ Total 600095 221765 2414699 584992 2999691 1076062 26.40 Number of Full Frame Images Received: 600095 Number of Observing Region Images Received: 2999691 Total: 3599786 Approximate Number of Shutter Moves/CCD Readouts: 6201895 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 (%) 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 57.05 995.1 215628 27690 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 58.30 1041.8 223335 35119 23.5 N/A Mar-99 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-FEB-99 and 28-FEB-99 ACTON 2-FEB-99 28-FEB-99 * 27 (total of 27 days) HUDSON 1-FEB-99 * 28-FEB-99 * 28 (total of 28 days) MCKENZIE 1-FEB-99 * 11-FEB-99 11 (total of 11 days) SLATER 1-FEB-99 * 18-FEB-99 18 (total of 18 days) ---------------------------------------------------------------- Grand Total of 84 days for 4 people NOTE: The "*" signifies travel that actually ends after 28-FEB-99 SXT Foreign Travel between 1-MAR-99 and 31-MAR-99 ACTON 1-MAR-99 * 2-MAR-99 2 (total of 2 days) HUDSON 1-MAR-99 * 31-MAR-99 * 31 (total of 31 days) NITTA 21-MAR-99 31-MAR-99 * 11 (total of 11 days) SHIRTS 15-MAR-99 31-MAR-99 * 17 (total of 17 days) ---------------------------------------------------------------- Grand Total of 61 days for 4 people NOTE: The "*" signifies travel that actually ends after 31-MAR-99 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 March 1999 February 1999 |------------------------------- | 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: Larry Hill | of February 1999 |------------------------------- |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