Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for February 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, 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 proposal for operations support at ISAS in 1998 was submitted to MSFC. Subsequently a notification was sent to us that the allocated resources for FY 1999 and beyond have been cut in half. This will have very serious consequences for SXT and will preclude both operations of the SXT instrument and support of Co-I's and data analysis. We are hopeful that this situation can be resolved in the near future. << Solar Activity >> Solar activity was low, with the GOES 1-8 A flux never reaching the C level during the first half of February, in spite of some smaller events. The soft X-ray flux was especially low on the morning of 6-Feb-98, after regions AR 8143, 8145 and 8146 rotated behind the west limb. We saw the emergence of at least two compact regions, AR 8150 and 8152. There were several B-class flares, and their frequency increased towards the weekend, presumably due to the growth of AR 8152. AR 8156 had reached an area of 500 millionths as of Feb. 14, and was quite visible on images, complete with leader spot, followers, etc. In mid-February, Solar activity was slightly higher. The GOES background level remained in the mid-B range, but the Sun did produce a number of C flares, mostly from region AR 8156. Solar activity decreased at the end of the month: the GOES background level was again under B, with a few small flares. The main event at the end of the month was the solar eclipse on 26-feb. SXT observations of the eclipse went Page 2 very well; the results can be seen at http://www.space.lockheed.com/YPOP/Intermission/eclipse.html << Campaigns >> There were no official campaigns in early February, but SXT observed AR 8151 to support SOHO/CDS and observed expanding loops in this S-shaped region. On 26-Feb, SXT observed the solar eclipse. Quarter-resolution FFIs were made at 32-second cadence during the three eclipse events. Full-resolution PFIs were made at 10-seconds cadence, to see a small active region partially eclipsed. The data look very good. << Science >> Alexander completed a number of projects relating to the Whole Sun Month campaign and is currently involved in writing these up for publication in JGR. In particular, his analysis incorporated the recent updates to the calibration routines for the SXT. These included an orbital correction for the selection of dark frames and a better leak image selection. The improvement for the analysis of the quiet Sun is quite amazing. Lemen worked with Bentley on their project to extend the Ca abundance analysis of Yohkoh BCS events that were reported previously in a short Cospar paper. He also did some work on the analysis of the Ca XIX ionization fraction. By fitting old BCS data they are able to determine the N(Ca XIX)/N(Ca) fractional dependence with temperature. McKenzie studied an X-ray source in the core of a stable filament cavity. The analysis involved mapping out the morphology of the structure, and comparing to the appearance of the filament channel when on the disk. Nitta worked on a comparison between HXT L-band and SXT Be images for the same 36 flares that Jakimiec et al. analyzed, now that their paper is in press. In order to understand the displacement of the HXT loop top source from the SXT counterpart, we need to recall that the flare loop does not necessarily stand vertically, and that usual assumption between the height and the angular distance from disk center (via projection) can be quite misleading. The fact that the soft X-ray loop top source often appears to move in the direction of the hard X-ray source, whether or not it matches the apparently increasing height, implies that we really need to think of the loop in 3-d, even close to the limb. Nitta also worked on understanding how the recent modifications of basic database and analysis software improve the SXT quantitative analysis. In short, for thin Al images, the closest terminator image can often be found at a ~2" separation using the definition that also incorporates the solar radius. Surprisingly, a pair of terminator images (in thin Al) taken at a < 1" separation (including solar radius) are quite different (up to 10 DN/s/HR pix). Page 3 Pevtsov used Yohkoh and Kitt-Peak data to study if the surface differential rotation may produce sheared coronal loops. He has found three good examples of the loops oriented in a way to be sheared by the differential rotation. So far, none shows an indication that the surface motions play a dominant role in shearing the coronal loops. Wuelser noted that the alignment between SXT and the Aspect Sensor on HXT has slowly changed over the last couple of years. The difference had grown to about 4 arcseconds recently. This affected data analysis with SXT, since the HXT Aspect Sensor is used for the pointing solution. He updated the pointing solution on January 24 to remove the discrepancy. Wuelser re-reduced Mees Imaging Vector Magnetogram observations of the South Pole of March 6/7, 1996. The new analysis confirms earlier results on the vector magnetic field at plume footpoints. The measured total field strength is about 300 G. The observations are consistent with a magnetic field normal to the photosphere, a magnetic fill factor of about 0.18, and a true magnetic field strength near or above 1500 G. << 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 February were 67070 accesses and 2059 Mbytes transferred. Page 4 << Yohkoh Operations and Health >> The recovery from the filter rupture of Jan. 24 is almost complete. We continue to make terminator images to help compensate for the extra light; we now have terminators in four different filter configurations. 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 05-Feb-98 Pass 1: 980205-0723 recovered in the same pass. SXT Bitmap error 10-Feb-98 Pass 4: 980210-0930 recovered in the same pass. SXT Filter Hard error 17-Feb-98 Pass 3: 980217-0620 recovered in the 4th pass. SXT Bitmap error 19-Feb-98 Pass 1: 980219-0411 recovered in the same pass. Page 5 << Data Flow >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Nov-95 339151 147060 1408017 357720 1765737 702330 28.30 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 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 3399 784 13238 1279 14517 4261 22.69 Mar-98 0 0 0 0 0 0 NaNQ Total 522491 200452 2117302 431911 2549213 958516 27.33 Number of Full Frame Images Received: 522491 Number of Observing Region Images Received: 2549213 Total: 3071704 Approximate Number of Shutter Moves/CCD Readouts: 5353172 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 (%) 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 53.71 869.8 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 56.09 959.1 210383 22813 22.5 N/A Mar-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 7 << Personnel Travel >> SXT Foreign Travel between 1-FEB-98 and 28-FEB-98 HUDSON 1-FEB-98 * 1-FEB-98 1 8-FEB-98 18-FEB-98 11 (total of 12 days) MCKENZIE 6-FEB-98 28-FEB-98 * 23 (total of 23 days) NITTA 1-FEB-98 11-FEB-98 11 (total of 11 days) SLATER 20-FEB-98 28-FEB-98 * 9 (total of 9 days) ---------------------------------------------------------------- Grand Total of 55 days for 4 people NOTE: The "*" signifies travel that actually ends after 28-FEB-98 SXT Foreign Travel between 1-MAR-98 and 31-MAR-98 HUDSON 1-MAR-98 31-MAR-98 * 31 (total of 31 days) MCKENZIE 1-MAR-98 * 5-MAR-98 5 (total of 5 days) NITTA 25-MAR-98 31-MAR-98 * 7 (total of 7 days) SLATER 1-MAR-98 * 25-MAR-98 25 (total of 25 days) ---------------------------------------------------------------- Grand Total of 68 days for 4 people NOTE: The "*" signifies travel that actually ends after 31-MAR-98 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 March 1998 February 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 February 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 | 8 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office