Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for October 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 We expect an RFP very soon for operations and data analysis for next year. << Solar Activity >> In early October, solar activity was moderate to high. Yohkoh observed two M-class flares on Oct 7 and many C-class flares from AR 8355. The GOES background level remained around the mid-B level. In mid-October, solar activity was moderate, with a number of C flares. NOAA 8361 produced a C7.1 flare on 19 October and NOAA 8358 produced a C7.4 class flare on 20 October; this flare was the brightest flare in this period. In late October, solar activity was low. Yohkoh observed 4 C-class flares. There were 8 NOAA regions (NOAA8366, NOAA8369-NOAA8375) on the solar surface. << Campaigns >> There were no formal campaigns this month, but TRACE and SXT cooperated to observe active region AR 8350 for a few days. This should be a rich data source. Also, SXT stared at a target region in the northeast, to support TRACE's hopes of seeing an emerging flux region. << Science >> The loop-top region in a solar flare has interesting properties revealed by Yohkoh soft X-ray imaging: there is often an apparently over-pressure blob there; and a celebrated "Masuda source" with an improbably high temperature located distinctly above the SXT soft X-ray source may also occur. What do we Page 2 see at lower temperatures? The EIT instrument on Soho, while not optimized for flare observations (usually with very poor cadence), can't help seeing some of them because of its whole-Sun field of view. Wuelser has analyzed a combination of SXT and EIT data for a flare which occurred on 1997 Sep 17. The images were taken during the impulsive phase of an M-class flare at the NW limb of the sun. The SXT instrument with its higher temperature response shows only weak and diffuse emission at the loop-top location. The EIT data show that This flare had a very localized loop-top source consisting of relatively cool (1-2 MK) plasma. Most interesting are the compactness of this source, its appearance during the early impulsive phase, and its low temperature compared to the "superhot" (~100 MK) loop-top sources reported by Masuda. Hudson recently analyzed data from the 1998 Oct 7 flare looking for evidence of the "Neupert Effect", named after GSFC solar physicist Werner Neupert. The Neupert effect simply notes that the hard X-rays occur during the rise phase of the soft X-rays. This general pattern is what one would expect if the hard X-ray flux somehow accompanied the energy release phase in the flare, when the hot plasma is building up in the coronal loops that we observe with Yohkoh SXT. The match in timing is not exact. Partly this is due to the integrating effects in the soft X-ray data; partly it must be due to local physics. The general trend - correlation between the soft X-ray flux and the integral of the hard X-ray flux - holds approximately from flare-to-flare, as well as for a given flare. Thus LDE events have weak but long-lived hard X-ray emission. We know of distinct deviations from exact Neupert-like behavior, but there are few theoretical tools to take advantage of these observations. Almost any flare model essentially predicts this kind of behavior, so its occurrence does not make any statement regarding mechanisms such as magnetic reconnection, shock waves, mysterious kinds of turbulent motions, or the like. However, there is a distinct need for more theoretical work. In spite of the simplicity and reasonableness of the picture presented by the Neupert Effect, there are many interesting and important physical questions that are not resolved yet. These are at the core of the flare process, because the "impulsive phase" of a flare marks the time of strongest energy release. << 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 October were 58472 accesses and 2863 Mbytes transferred. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. Page 3 SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT Bitmap error 05-October-98 Pass 2: 981005-1136 recovered in the same pass. This month Wuelser put a significant amount of work into writing software for the Yohkoh pointing solution. The new software will use the HXA scan (or intensity) data instead of the HXA limb address data. This approach is expected to be much less sensitive to the degradation of the HXA detector. The new software requires a new HXA SCAN database which Slater and Shirts are in the process of establishing. We will perform extensive testing before we use the new software for the ATT pointing solution. Page 4 << Data Flow >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Jul-96 392460 166925 1643461 370744 2014205 809345 28.58 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 6594 1852 25791 7357 33148 9712 22.66 Aug-98 5824 1960 22978 14126 37104 3764018 99.02 Sep-98 6776 1432 21814 11626 33440 7753 18.82 Oct-98 2236 428 7829 1851 9680 2145 18.14 Nov-98 0 0 0 0 0 0 NaNQ Total 573738 213621 2306698 512320 2819018 4783071 62.92 Number of Full Frame Images Received: 573738 Number of Observing Region Images Received: 2819018 Total: 3392756 Approximate Number of Shutter Moves/CCD Readouts: 7346805 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 (%) 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 57.05 995.1 215628 27690 21.4 N/A Aug-98 57.36 1006.7 217355 29544 18.2 N/A Sep-98 57.43 1009.5 218520 29683 20.9 N/A Oct-98 57.58 1015.0 220048 30298 21.2 N/A Nov-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-OCT-98 and 31-OCT-98 CANFIELD 31-OCT-98 31-OCT-98 * 1 (total of 1 days) FREELAND 20-OCT-98 30-OCT-98 11 (total of 11 days) HUDSON 1-OCT-98 * 4-OCT-98 4 10-OCT-98 26-OCT-98 17 31-OCT-98 31-OCT-98 * 1 (total of 22 days) MCKENZIE 1-OCT-98 31-OCT-98 * 31 (total of 31 days) SHIRTS 26-OCT-98 31-OCT-98 * 6 (total of 6 days) SLATER 1-OCT-98 * 3-OCT-98 3 (total of 3 days) WUELSER 1-OCT-98 * 2-OCT-98 2 (total of 2 days) ---------------------------------------------------------------- Grand Total of 76 days for 7 people NOTE: The "*" signifies travel that actually ends after 31-OCT-98 SXT Foreign Travel between 1-NOV-98 and 30-NOV-98 CANFIELD 1-NOV-98 * 13-NOV-98 13 (total of 13 days) HUDSON 1-NOV-98 * 7-NOV-98 7 16-NOV-98 30-NOV-98 * 15 (total of 22 days) LEMEN 5-NOV-98 16-NOV-98 12 (total of 12 days) MCKENZIE 1-NOV-98 * 30-NOV-98 30 (total of 30 days) NITTA 15-NOV-98 30-NOV-98 * 16 (total of 16 days) SHIRTS 1-NOV-98 * 20-NOV-98 20 (total of 20 days) WEBER 20-NOV-98 30-NOV-98 * 11 (total of 11 days) ---------------------------------------------------------------- Grand Total of 124 days for 7 people NOTE: The "*" signifies travel that actually ends after 30-NOV-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 November 1998 October 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 October 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