Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for June 1997) 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, 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 Palo Alto Research 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 program continued in its normal operational mode. There was a very good YOHKOH representation at the SPD meeting in Bozeman, Montana. << Solar Activity >> The Sun is not so lopsided as it was in 1996, judging from the last rotation. There are currently only new-cycle regions on the disk. During the first half of June, there were only B-class flares, and not too many of them, but of course the movie looks as beautiful as ever. The largest sunspot area reported was 160 millionths. During the second half of June and early July, the largest sunspot area reported was only 40 millionths, and there were just five GOES events listed (including the C1.1 on 30 June in AR 8057). A quite remarkable streamer bottom was observed on June 21 (E limb) and July 5 (W limb): it had a bright X-ray sheath around the cold filament and an exceptionally well-defined cavity, bulging outwards in a manner reminiscent of the celebrated 21 Feb 1992 flare event. A re-visit to Acton's analysis of the total SXT signal level confirms his conclusion that SXT saw its lowest levels in about June 15, 1996, +- one month, but the current lull could conceivably create a second local minimum. << Campaigns >> There were no formal campaigns during the first half of June, not counting the end of the Pic du Midi campaign. SXT followed SOHO target pointing where Page 2 possible, especially the CDS field of view. Over the weekend of 14-15 June, we tried out Quarter-resolution only (FFI's) to see if the factor-of-four improvement in cadence will help with Moreton wave detection. The motivation for this is checking out the SXT coverage for the five Moreton waves thus far listed by EIT and finding that it's almost always bad with our present system. At the end of the reporting period we supported a campaign with the VLA and SoHO to observe the active area west of AR8058. There were also joint campaigns with SOHO (polar jets, JOP057) and with the VLA (jets and loops). << Science >> Much of the science in June related to the Solar Physics Division meeting held in Bozeman, Montana June 26 through July 1. Acton presented a poster paper entitled, "Conversion of YOHKOH X-ray Observations to Temperature & Spectral Radiance" with Dave Weston and Marilyn Bruner. The conclusions were that SXT thin-filter temperature is a good approximation (0.1 in Log T) of the emission-measure-weighted mean coronal temperature along the line of sight. Also, the computed spectral radiance within the SXT pass band is accurate to better than 40% in all cases, _IF_ the SXT filter-ratio temperature is used to convert DN/sec to radiance. Canfield worked with Sean Sandborg and Alex Pevtsov on large-scale structures of active regions. Canfield also worked with Alex Pevtsov on his paper of the emergence and submergence of a kinked omega-loop as an explanation of ASP vector magnetic field observations of an active region. Lemen work on the HXT Image Reconstruction Poster for the SPD meeting with Alexander, Metcalf, Freeland, and McTiernan. The automatic software was used to prepare HXI (HXT Image files) for 124 flares. Freeland is working on an HTML interface that will permit anyone to view the HXT flare data from the L and M1 channels as gif movies. The plan is to eventually do this for all the events in the flare directories. The next step that might prove useful is to add this to the archive reformatter, and following on from there, writing the movies with SXT flare images to video disk for convenient viewing. Metcalf ran a number of Pixon and MEM simulations for his SPD poster comparing the two algorithms. The results indicate that the Pixon algorithm is more accurate photometrically. The MEM algorithm is considerably faster, however. He also wrote a routine (hxt_autoimg.pro) to automatically produce HXT images for Lemen's poster. Nitta analyzed SXT/HXT/BCS data for more superhot flares, in preparation for the SPD meeting. He found that his analysis of superhot flares using three SXT filters is consistent with the DEM analysis by Jim McTiernan, who identified two peaks at ~6 MK and ~20 MK with a higher-temperature tail. He also made some progress in studying the effect of emerging flux on flares in emerging flux regions such as AR 7260. It was found that the bright loop was Page 3 the emerging dipole itself, not something that was created as result of reconnection. This still needs to be investigated, because the separator (which the 3-D reconnection people consider to be the site of energy release) could be close to an original dipole. << 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 Lockheed SXT WWW homepage (http://www.space.lockheed.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 June were 40322 accesses and 1114 Mbytes transferred. << Yohkoh Operations and Health >> Yohkoh and the SXT continue to function very well. There has been no further increase in stray light since 25 August 1996. The quiet patrol image has been changed to Al/Mg (DPE=17) to try to improve the performance of the active region selection algorithm for times when the Sun is very quiet. SXT experienced a normal level of Single Event Upset (SEU) events during the month: SXT bit map error 24-Jun-97 Pass 1: 970524-1030 recovered in the 3rd pass Page 4 << Data Flow >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Mar-95 285284 122782 1217473 340330 1557803 604024 27.59 Apr-95 6244 2266 22946 4493 27439 9688 26.09 May-95 7084 2884 29617 2647 32264 15331 32.21 Jun-95 7210 3087 25251 307 25558 12045 32.03 Jul-95 6418 4145 21180 1639 22819 15109 39.84 Aug-95 7683 2597 26115 2181 28296 10537 27.13 Sep-95 6546 2853 22006 1753 23759 10433 30.51 Oct-95 6937 3502 22177 3853 26030 13044 33.38 Nov-95 5745 2944 21252 517 21769 12119 35.76 Dec-95 6163 2615 24059 901 24960 11652 31.83 Jan-96 6474 2530 27015 1708 28723 14151 33.01 Feb-96 6200 2581 21380 890 22270 10773 32.60 Mar-96 6908 2869 25437 1460 26897 12274 31.33 Apr-96 7172 2124 45445 671 46116 18848 29.01 May-96 6925 2426 30272 1089 31361 12367 28.28 Jun-96 7515 2723 31952 1536 33488 14521 30.25 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 5921 1218 18825 1230 20055 4222 17.39 Jul-97 0 0 0 0 0 0 0.00 Total 468126 190152 1902894 394419 2297313 901641 28.19 Number of Full Frame Images Received: 468126 Number of Observing Region Images Received: 2297313 Total: 2765439 Approximate Number of Shutter Moves/CCD Readouts: 4847607 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 (%) Apr-95 48.72 682.8 93904 5627 19.1 N/A May-95 48.73 683.4 94000 5820 18.8 N/A Jun-95 49.08 696.3 100780 6281 19.6 N/A Jul-95 49.34 706.2 106408 6628 18.1 N/A Aug-95 49.72 720.4 114414 7101 19.5 N/A Sep-95 49.79 723.1 115165 7222 19.6 N/A Oct-95 50.29 741.9 126452 7911 20.2 N/A Nov-95 50.11 735.1 122163 7814 25.2 / 2 20.3 N/A Dec-95 50.19 737.9 123705 7927 22.6 N/A Jan-96 50.81 761.3 136197 8888 21.5 N/A Feb-96 50.67 755.8 133263 8705 22.5 / 2 21.5 N/A Mar-96 50.85 762.9 136982 8973 20.3 N/A Apr-96 51.14 773.6 142250 9500 19.9 N/A May-96 51.16 774.4 140697 10018 19.1 N/A Jun-96 51.56 789.2 147705 10634 20.7 N/A 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 53.31 854.9 177691 13795 20.0 N/A Jul-97 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-JUN-97 and 30-JUN-97 HUDSON 2-JUN-97 23-JUN-97 22 (total of 22 days) SAVY 1-JUN-97 * 25-JUN-97 25 (total of 25 days) SLATER 1-JUN-97 * 27-JUN-97 27 (total of 27 days) WEBER 1-JUN-97 * 24-JUN-97 24 (total of 24 days) ---------------------------------------------------------------- Grand Total of 98 days for 4 people NOTE: The "*" signifies travel that actually ends after 30-JUN-97 SXT Foreign Travel between 1-JUL-97 and 31-JUL-97 HUDSON 3-JUL-97 31-JUL-97 * 29 (total of 29 days) LEMEN 6-JUL-97 30-JUL-97 25 (total of 25 days) NITTA 30-JUL-97 31-JUL-97 * 2 (total of 2 days) SAVY 5-JUL-97 31-JUL-97 * 27 (total of 27 days) ---------------------------------------------------------------- Grand Total of 83 days for 4 people NOTE: The "*" signifies travel that actually ends after 31-JUL-97 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 July 1997 June 1997 |------------------------------- | 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 Palo Alto Research Labs B/252 |------------------------------- Solar & Astrophysics Laboratory O/H1-12 |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 | of JUne 1997 |------------------------------- |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