Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for the month of November, 1993) OVERVIEW 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 from Kagoshima Space Center (KSC) in Japan, and renamed Yohkoh. The purpose of this mission is to study high energy phenomena in solar flares. 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 by Lockheed in cooperation with the National Astronomical Observatory of Japan, and the Institute for Astronomy of the University of Tokyo. MAJOR ACTIVITIES IN THE MONTH << Solar Activity and Observation Planning >> Solar activity during the week of 31-Oct was generally low, especially in the latter half. Two C-class flares occurred, and C3.2/SF on NOAA 7613 was the largest one. Goes background fell into A-level again. Between 7-Nov and 14-Nov the solar activity was generally low, though it became higher due to new active region coming from east limb. An M2-class flare occurred on 12 Nov. near 2 UT in NOAA 7618. All but the late decay phase, however, occurred during night and/or SAA. An interesting B-class flare occurred on 9 Nov. 10:34-10:51 in NOAA 7631, which was associated with an X-ray filament eruption. This might be the smallest flare associated with X-ray filament eruption until now. Solar activity during the week of 14-Nov faded away, although over the weekend a new active region appeared on the NE limb, with some rather spectacular loops. The biggest flare was about C2. The week of 21-Nov had low solar activity. Most of the activity was from AR 7620, which grew rapidly on Nov.25. A BearAlert was issued for this region. The largest flare in the week was C5.7. << Special Observations - Mercury Transit >> The planet Mercury crosses in front of the disk of the Sun only rarely, about once in eight years. In the episode just completed, 6 November 1993, the Yohkoh solar research satellite succeeded in capturing this Page 2 rare event for the first time in X-radiation, the natural emission of the million-degree hot solar corona. The soft X-ray telescope (SXT) observations were made in two broad wavelength bands at about 1 keV. The transit was visible for approximately six hours. During this time approximately 500 images were recorded at a minimum time resolution of about 16 seconds--corresponding to about 2.5 arc seconds motion of Mercury. The size of the disk of Mercury at this transit was 10 seconds of arc--about 3 times the angular resolution of the SXT. A full disk image of the x-ray sun was obtained by the SXT at 11:16 UT, about 7 hours after the midpoint of the Mercury transit across the sun's south pole. The full-sun image has many interesting features, in particular a large number of x-ray bright points. In addition, one can see nice overlapping loops in the southeast active region complex (lower left hand side), and a huge coronal hole in the north. Solar activity was extremely low at the time of the transit. SXT obtained images showing the motion of Mercury across the corona. The first-contact data shows Mercury traversing a dark coronal hole channel. An x-ray bright point flared up about 30 arc seconds north of Mercury. The primary use of these data will be for in-orbit calibration of the optical performance of the SXT. Mercury's disk is a perfect absorber of X-rays so we will use the dark disk of Mercury as a dark "standard candle" to allow us to evaluate scattered light within the telescope. In addition to this, the motion of Mercury across the Sun can be used to infer more detailed information about solar features. The existence of coronal fine structure is known from the observation of interplanetary scintillation (as used in quasar research), but its identification in terms of known solar physics has remained a puzzle. << Special Observations - Partial Solar Eclipse >> SXT obtained an image of a partial solar eclipse that occurred on 13 Nov. 1993. SXT recorded a whole series of images of the Moon occulting parts of the solar disk and the corona. These unique observations are quite important scientifically, because they allow for direct determinations of the X-ray intensity independent of scattering from SXT's grazing-incidence optics. The axis of the Moon's shadow passed above the Earth's south pole, so that partial eclipses could be seen from the Antarctic and from other southern landmasses, << Campaigns >> During 29 Nov - 3 Dec there was a bright point campaign which was organized by Karen Harvey. It involved ground-based observations from Kitt Peak, BBSO, and Mees. Page 3 << Data Analysis Software >> During the preparation of the next release of the Yohkoh User and Reference Guides it came to light that the HXT and WBS teams did not have any "official" software which had been reviewed by the key team members. The release of the guides has been postponed for a few weeks in order to allow the teams to sort through their existing software to create programs which can be used by all of the Yohkoh members. Instructions on how to use these routines and what they do will be included into the guides. Sam Freeland completed and released a system of UNIX C-Shell scripts which allow remote sites to automatically upgrade the Yohkoh SW using anonymous ftp. With this system in place, a single command issued at remote sites is sufficient to perform a network upgrade, current to within 24 hours of the ISAS master copy. This command can be included in a 'cron job' at the remote site to allow full automation of the upgrade process. In between new releases, this system makes use of a compressed, incremental tar file to minimize network traffic. The use of ftp reduces concerns about remote system security (when compared to the unix 'rdist' utility). Changes to the installation procedure (scripts) can occur transparently since the newest set of scripts is copied to the remote sites as the first step in the procedure. The same set of scripts will also perform initial Yohkoh SW installation and setup for new sites (also with a single line command). << Spacecraft Operations and Health >> After the KSC holiday (Nov 23), a problem was found in the transmitter at KSC. No command uploads were possible on Nov 24 and 25. The transmitter was repaired on Nov 25, and the usual connection between KSC and Yohkoh resumed on pass 1 of Nov 26. SXT started observations on pass 4 of 26 Nov. Yohkoh performed a 16'south offset pointing OG in the 4-Nov OP for the Mercury transit observation, in order to escape the stray light. This was successfully done and we got nice images of Mercury over corona with special SXT table. The standard 8 arcminute offpoints were performed on 3-Nov, 11-Nov, 17-Nov, and 28-Nov. Special 16 arcminute offset pointings were performed on 4-Nov, 6-Nov and 13-Nov for the Mercury and moon transits. A tentative schedule for Yohkoh year-end operations has been proposed: last KSC operation ~12:00 JST 28-Dec-93; first KSC operation ~09:00 4-Jan-94. Page 4 << Instrument Operations and Health >> There were SXT Bit Map Errors on the following days (with a full recovery during the same pass or the next pass): 9-Nov-93 Pass1 SXT Bit Map ERR 18-Nov-93 Pass1 SXT Bit Map ERR The CCD was baked out to clear off contaminants (this operation is executed every 2-3 months). TEC OFF and heater ON were performed on Nov. 8, and heater OFF and TEC ON were performed on Nov. 10. A special table to try to observe the far scattering wings with a fixed exposure in flare mode was uploaded during Week 46. This is a complex table that was originally developed by Acton with some help from Lemen last April. The table takes some images in flare mode with a 1x8 OR with fixed exposure. This table really only works well if there is one active region on the Sun. Unfortunately, we did not see a flare trigger during the time it was loaded. It should be noted that the spacecraft off-pointing turns out to be a very effective means for reducing the visible stray light contamination caused by the entrance filter failure. This spacecraft offset allows SXT to observe very faint features. SXT plans to use this procedure to enhance the signal-to-noise of the observations of the south pole if SXT is able to observe during the time of the Ulysses closest approach. << Data Flow >> The near real-time data from KSC was interrupted twice in late November because the telemetry stream was mis-labeled as ASCA data when the data was transferred from KSC to ISAS. The data was later recovered, but it was not available to the ISAS observers for real time planning purposes. The official reformatting of week 47 (14-Nov to 21-Nov) has still not been performed. There is one pass of data that is missing from a DSN downlink, and there have been repeated problems in having the data re-sent to ISAS. The cause of the problem in the delay is not understood. Page 5 << Engineering Summary Table >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Sep-91 517 397 21174 3541 24715 5481 18.15 Oct-91 4106 2532 6393 12437 18830 3401 15.30 Nov-91 5291 2475 12149 14696 26845 10952 28.98 Dec-91 4858 3228 4983 16837 21820 6910 24.05 Jan-92 5544 3177 10084 5972 16056 6849 29.90 Feb-92 5305 2803 16932 11382 28314 12019 29.80 Mar-92 6248 2361 20367 2653 23020 9458 29.12 Apr-92 6734 3500 20094 5423 25517 12390 32.69 May-92 7032 3158 25464 4589 30053 13745 31.38 Jun-92 6937 3112 23307 13221 36528 12627 25.69 Jul-92 6345 3275 23941 10510 34451 14717 29.93 Aug-92 6572 2978 24207 11154 35361 13550 27.70 Sep-92 6087 2916 26832 20042 46874 15729 25.12 Oct-92 6743 2589 50985 14709 65694 23687 26.50 Nov-92 6658 2939 24416 14696 39112 12924 24.84 Dec-92 6775 2999 24253 6633 30886 12356 28.57 Jan-93 6888 3351 24067 4861 28928 13069 31.12 Feb-93 6833 3004 24479 18149 42628 12302 22.40 Mar-93 7177 3460 25874 19537 45411 14657 24.40 Apr-93 7754 3644 34128 8352 42480 17967 29.72 May-93 8571 3950 41832 7518 49350 21971 30.81 Jun-93 7340 2589 64545 12539 77084 26299 25.44 Jul-93 8259 3650 47561 5352 52913 24213 31.39 Aug-93 7628 3638 30705 3563 34268 17436 33.72 Sep-93 6875 2899 22697 5600 28297 11252 28.45 Oct-93 7474 3657 33782 7548 41330 20104 32.72 Nov-93 4152 1791 13000 4114 17114 6746 28.27 Total 170703 80072 698251 265628 963879 372811 27.89 Number of Full Frame Images Received: 170703 Number of Observing Region Images Received: 963879 Total: 1134582 Approximate Number of Shutter Moves/CCD Readouts: 2013070 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 Month Avg Dark Level # of Dark Spikes CCD Warmings Front Optical (DN) (e/sec) Over 48 Over 64 High / # Support Trans Temp /Days Temp (%) Oct-91 31.07 21.3 509 261 10.5 77.8 Nov-91 31.06 20.9 648 277 11.9 64.4 Dec-91 31.04 20.2 804 353 14.0 52.5 Jan-92 31.13 23.6 985 450 0.5 / 2 14.9 38.4 Feb-92 31.32 30.8 1176 544 14.3 31.7 Mar-92 31.47 36.5 1355 626 14.8 25.1 Apr-92 31.44 35.2 1323 610 23.8 / 4 14.6 22.8 May-92 31.65 43.1 1417 653 14.4 20.1 Jun-92 32.12 60.9 2215 880 -2.5 / 3 15.1 17.4 Jul-92 32.22 64.4 1852 832 15.5 14.1 Aug-92 32.21 64.1 1922 886 14.9 13.1 Sep-92 32.38 70.5 2062 954 -1.2 / 3 15.9 12.2 Oct-92 32.64 80.3 2317 1055 16.8 11.5 Nov-92 36.24 215.1 6112 1391 18.0 11.0 Dec-92 42.58 452.8 17390 2024 17.9 N/A Jan-93 42.59 453.1 13006 2034 23.8 / 2 19.2 N/A Feb-93 42.28 441.5 13895 2090 17.7 N/A Mar-93 43.14 473.8 14047 2151 17.7 N/A Apr-93 43.13 473.4 14304 2146 23.8 / 2 16.9 N/A May-93 43.45 485.3 16405 2357 17.3 N/A Jun-93 44.03 507.2 20037 2531 16.3 N/A Jul-93 44.52 525.6 23977 2700 22.5 / 2 17.7 N/A Aug-93 44.24 515.0 21879 2643 25.2 / 3 17.2 N/A Sep-93 45.07 546.2 27469 2745 17.5 N/A Oct-93 45.40 558.6 31684 2982 17.7 N/A Nov-93 45.10 547.2 30141 3384 23.8 / 3 18.5 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. << Papers and Conferences >> Keith Strong gave a review talk on the discoveries from the SXT at the Solar Perspectives Investigations (SPINS) workshop at S.E.L. in Boulder, Colorado. Page 7 << General Public Using SXT Images >> Images of the Mercury transit and the moon transit are included in recent issues of SCIENCE magazine and SKY AND TELESCOPE. Gary Linford and Keith Strong have prepared the first in a series of monthly solar activity reports for Sky and Telescope. They comprise an SXT picture and a short description of the highlights of what Yohkoh has seen over the last month. Sky and Telescope may expand this concept to include ground based data (H-alpha, 10830, and magnetograms) which we will likely provide. << Personnel Travel >> SXT travel for the month of November, 1993: FREELAND 1-NOV-93 * 23-NOV-93 23 (total of 23 days) HUDSON 1-NOV-93 * 27-NOV-93 27 (total of 27 days) LEMEN 1-NOV-93 * 5-NOV-93 5 15-NOV-93 30-NOV-93 * 16 (total of 21 days) NITTA 1-NOV-93 * 21-NOV-93 21 (total of 21 days) LEKA 1-NOV-93 * 12-NOV-93 12 (total of 12 days) Grand Total of 104 days for 5 people Planned SXT travel for the month of December, 1993: FREELAND 1-DEC-93 22-DEC-93 22 (total of 22 days) HUDSON 5-DEC-93 21-DEC-93 17 28-DEC-93 31-DEC-93 * 4 (total of 21 days) LEMEN 1-DEC-93 * 17-DEC-93 17 (total of 17 days) NITTA 5-DEC-93 31-DEC-93 * 27 (total of 27 days) Grand Total of 87 days for 4 people Respectfully submitted, Mons D. Morrison Frank Friedlaender Page 8 -------------------------------------------------------------------------------- UNIVERSITY OF HAWAII ACTIVITY REPORT (DR. R. CANFIELD) No input required for this month -------------------------------------------------------------------------------- UNIVERSITY OF CALIFORNIA AT BERKELEY (DR. S. KANE) No input required for this month -------------------------------------------------------------------------------- STANFORD UNIVERSITY (DR. P. STURROCK) No input required for this month -------------------------------------------------------------------------------- SOLAR PHYSICS RESEARCH CORPORATION (KAREN L. HARVEY) No input required for this month -------------------------------------------------------------------------------- MONTANA STATE UNIVERSITY (LOREN ACTON) No input required for this month Page 9 -------------------------------------------------------------------------------- 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 | December 10, 1993 November 1993 |-------------------------------- | 6. PERFORMING ORGANIZATION | CODE: O/91-30 -----------------------------------------------|-------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- M. D. Morrison | 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/91-30 |11. CONTRACT OR GRANT NO. 3251 Hanover Street, Palo Alto Ca. 94304 | NAS8 - 37334 -----------------------------------------------|-------------------------------- 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 November, 1993 |-------------------------------- |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 | 9 | ------------------------|------------------------|-----------------|------------ For sale by: Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402-0001