Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-37334) (for the month of March, 1992) 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 >> On 29 Feb 1992 a small flare in the SE quadrant produced "filled" a large loop (2 arc min) with hot plasma. At the time of maximum brightness of this loop (09:23 UT) a twisted pair of very fine loops were seen to light up from the far end foot point of the flare loop to a point at high latitude nearly half a solar radius away in about 8 minutes - a propagation speed of over 500 km/s. The region that produced the M4 and X3 flares (21-Feb and 27-Feb) remained large and complex as it set over the west limb, but it did seem to have simplified considerably since its east limb passage and following the X flare. There was less height structure but still many interconnections between it and surrounding activity centers. The disk passage of this region will be a good subject to study for active region evolution and its relation to flares. There were still relatively few bright points for the week ending 7-Mar and those that were visible tended to be intense and long-lived often ending their existence in a small flare. Discussions were held about up-coming campaigns, in particular the CoMStOC campaign to use Yohkoh and the VLA to improve our measurements of coronal magnetic fields, and a campaign by Hida Observatory to look at emerging flux regions with SXT and their H-alpha telescope. The CoMStOC campaign will occur from the beginning of April and continue through May but will not be continuous, Page 2 only requiring observations on the VLA days. It is hoped that several rocket flights will happen in this time frame especially Marilyn Bruner's. The Hida campaign overlaps CoMStOC being from 20 April to 9 May. While this initially looked like a conflict in schedule after some discussion of goals it looks as though the two programs could complement one another by providing data at times when the other groups have none. The largest potential problem is the target selection during the common days, if the VLA is willing to let Hida choose the active region to observe then there would be no problem. If they can not follow the Hida region there should be plenty of full disk data to support both groups. It was suggested that the campaign coordinators (Joan Schmelz/Gordon Holman and Akioka-san, respectively) make contact through Nariaki Nitta and arrange a mutually beneficial programme. The large region that produced the big flares of the first two weeks of March showed an intriguing variety of large scale structures, including a double jet or "searchlight" event. There was also a helmet structure that was strikingly similar to that seen on the east limb two weeks before. Whether this was the same configuration (implying it is very stable) or a reactivation of the same structure will have to wait for a more detailed analysis. There were several long duration events seen by GOES that we expect come from this region. There was a C1 flare associated with a filament eruption between 0200 UT and 0900 UT on 12 March. Fortunately Yohkoh did not go into flare mode and made a patrol image at the right time so there are full frame and partial frame images simultaneously. Hence we have excellent time resolution on the flare site while being able to see the large-scale reconnection associated with it. A bright feature that can only be described as a 'y' shaped loop (maybe the origin of the bright ridges we have seen in previous similar events) formed slowly in front of the usual helmet structure. This does not seem to fit into any of the standard models. Late in the eruption two helmets form that are clearly joined at the cusps. Possibly even more interesting was the preflare configuration of the large-scale field and its evolution prior to the filament eruption. There are radical changes on 10 and 11 March which we can only partially follow because of the lack of reformatted DSN data. A typical polar region configuration seems to produce a high rope-like structure on 11 March that slowly unravels from both ends simultaneously forming what could be interpreted as a coil. Before the filament eruption the "coil" has become faint and seems to have dispersed. We have seen examples of such "coils" or spiral structures before but they have been dismissed as geometrical effects (as this one might be). With the Sun being so quiet in mid-March there were new opportunities that are not generally available. A small bright point near disk center produced a typical bright-point flare (sub C-level) involving a large-scale loop which fills with a velocity of over 500 km/s. As there was no other activity at that time the BCS is able too get S XV spectra and determine the temperature and timing of the event which should enable us to derive more accurate emission measures and velocities from the SXT data. Page 3 There has been considerable discussion over the last week about dark features. Several clear examples were visible in the data collected recently, where absorbing loops seem to form in and over existing bright structures. Several people have noted the lack of bright intersection points despite the forest of loops we see in active regions. Could this mean that the corona maybe more optically thick than we have believed to date? Between 22-Mar and 30-Mar, SXT tracked a single active region under the mode ARS2 (Active Region Selection, mode 2). In this mode the search for the brightest x-ray point is only done over a 2.7x2.7 arcmin box about the latest pointing address instead of over the entire active belt as is done in ARS1. This mode is necessary for effective coordinated with ground based observers and campaigns such as the Max '91 CoMSToC activity. The mode is working beautifully on NOA Active Region 7117 and some truly spectacular active region movies are being produced with a 1/2 minute time resolution. This big region has not been productive of flares but has been sufficiently bright that SXT stopped taking 15 second full disk exposures. Some work was done adjusting the standard SXT observing tables and on 27-Mar SXT performed the first routine run of a table with optical and CCD gain calibration. During the first week of April it is planned to run the routine dark frame table. It is planned to run each of these tables one set of invisible orbits each week. They have been written in such a way as to not unduly impact the normal full frame movie sequence. Interesting discoveries were made with regard to the structure of flare events. Alan McAlister and Uchida-san have found examples of filament eruptions that show that during the onset there is a bright ribbon running along the length of the arcade either inside the arcade or along the apex of the loops. There are also intriguing examples of a helmet structure seen in soft X-rays that is not open at the top but actually reconnects back to another similar structure raising doubts about the original simple models of these structures. Most of the science work at present is the gathering of data and quantifying results in preparation for the PASJ articles. << Instrument Operations and Health >> There was one SEU-related problem early in the week ending on 7-March when a warm reset error was discovered during a KSC contact as SXT was not taking images. A standard recovery was made and SXT performed flawlessly for the rest of the week. The Yohkoh orbit apogee moved to correspond to the SAA times so there was an increase in SEUs in mid-March. There was an SEU on Monday (9 Mar) at the first pass and the another on Friday (13 March, of course). There was some concern expressed at the one of the weekly ops meeting that SXT may not have been properly safed when the 13-Mar error was noted as the manuals Page 4 were not clear and too voluminous to follow. Shibata-san has offered to make a summary of the required procedures. No damage was done as SXT turned out to be in a standard safe configuration. We followed the usual recovery procedure in the subsequent orbits and little data was lost. A patch was made successfully on 15-Mar to the SXT-J software to help monitor such events. Between 25-Feb and 9-Mar there was a problem with the failure of the STT to track Canopus. The origins of the problem and possible ways to avoid it were discussed. During this period the roll angle may have been in error by as much as 3 degrees. On 10-Mar a small repoint of Yohkoh was attempted to test the X-ray response of the SXT CCD in the areas where damage has been seen in the diffuser images. The plan was to offset by 3 arcmin east and then return to sun center. Owing to a misunderstanding in the manuals the coordinates input to the commands were assumed to be relative not absolute. This was incorrect and so Yohkoh offpointed by about 3 arcmin east and about 5 arcmin south. Consequently the return was also in error as Yohkoh ended up pointed too far south and west. This was sorted out between passes and Yohkoh was correctly pointed by the end of the 5th pass. A quick check of the CCD response by Akita-san and Keith Strong shows no obvious sign of a degradation in the X-ray sensitivity in the "damaged" areas but a more rigorous analysis of these data needs to be made of these data. In later March there were two unexplained filter hard errors (filter not achieving the desired position after 3 tries). We do not believe that this represents a mechanical or bearing problem because no soft errors had been recorded (soft error is when the filter wheel does not position correctly the first time but does on the second or third try) and both hard errors took place during a day command activity. Samuel Freeland extended the SXTE-U Flight Software SEU detection routine to include an auto-recovery function. When a corruption of code is detected by the SEU routine, a copy of the corrupted code from ROM to RAM is initiated and the code is rechecked. If the corruption was repaired by the copy operation, the routine is exited and normal operations may continue. Ground and on-board command sequences were reviewed and updated to simplify recovery operations and to include the new SEU recovery code when a ground reset operation is required. The frequency of such recovery operations should decrease with the on-board SEU auto-recovery modification now in place. << Data Analysis Software >> The software to allow the registration of SXT images in order to make video movies was refined over the past month. A variety of technique are available and are being evaluated at this time. There are several spacecraft pointing instruments that can be used to establish the pointing (IRU, HXA, TFSS, SXT), but each one has idiosyncracies that make using one instrument by itself impossible. Page 5 << Data Flow >> A major milestone during the month was the distribution of the first Yohkoh data archive tape on March 10. As designed, the archive tapes include the reformatted data from all Yohkoh instruments and the software to access it. In addition, new users can install the data access and analysis software directly from the tape and set up a data analysis environment which has an nearly identical look and feel at other Yohkoh analysis institutions. This should allow scientists and investigators to move easily among various sites without the overhead associated with learning a new system and allow the free exchange of additional analysis information and routines. Difficulties in achieving system independent access of the data and software were overcome and several remote users have reported success in installing the software and accessing the data off of the first tape. Since then 5 more tapes have been distributed to all of the instrument teams (a single tape contains one week of data). Extensive tests were performed on the BCS VMS operating system and the tapes have proven to be compatible with all known operating systems used by the Yohkoh team. The program which generates the formal reformatted data and database has gone through extensive modifications and now does the following steps automatically. 1. Copy one week of data from the SIRIUS mainframe computer in 24 hour partitions 2. Reformat the 24 hour files 3. Break the 24 hour files into single orbit files (97 minutes) 4. Generate the observing log (OBS file) 5. Generate the pointing log file (PNT file) 6. Generate the command script to make the distribution tape and send a message to the operator that he/she can make the tape now 7. Generate a desaturated composite image file to be used in making standard movies (SFD and SFW files) In April, the program will be expanded to also perform the following steps: 8. Generate a dark current image log file (DCH file) 9. Generate a SXT instrument summary log file (SSL file) 10. Generate a complete engineering log file for SXT (SEL file) 11. Generate a file documenting the change in the aspect telescope transmission (OTH file) On 25-Mar Version 2.0 of the File Control Document was released to the Yohkoh users. The document contains a complete updated description of all of the reformatted data files and database files. << Problems >> No work was performed with regard to the aspect telescope transmission degradation. In allowing another month of data to accumulate it will allow for us to determine the rate of degradation better. Page 6 << Papers and Conferences >> There was a Yohkoh-wide workshop at ISAS on 30/1 March to discuss science plans, calibration and software issues. There were several splinter meetings, one of which was on instrument co-alignment An SXT team meeting was chaired by Shibata-san on Saturday 7 March from 11 am - 5 pm which covered many interesting and important topics. While it was mostly in Japanese two very able translators (Shimizu-san and Alan McAlister) made it possible for Keith Strong to participate fully in the meeting. The highlights of the meeting were: 1) A discussion of the upcoming Osaka ASJ meeting. A list of possible papers was discussed and potential authors form Japan and foreign institutes. The list comprised 28 entries ranging from quiet-sun evolution to Gamma-ray flares showing the power and flexibility of this mission. It is hoped that several members of the US and UK teams will be able to attend the meeting. It is to be held from 13-15 May 1992. 2) The PASJ papers were also discussed. Tsuneta-san volunteered to make up a final list and Keith Strong put it on the Team Bulletin Board after discussions with Uchida-san. It was decided to allow multiple entries and review in April the most mature for inclusion in the PASJ special issue for publication in October. We have not yet had a reply about additional space being available in PASJ so it is not known how many papers will be included. Some 30 YOHKOH papers have been submitted for the Astronomical Society of Japan meeting at Osaka in May and a similar number are planned for submission to the Publications of the Astronomical Society of Japan at the end of April. These opportunities constitute the official "first release" of YOHKOH scientific results. Thus, the author lists are long in order to recognize the many individual who have made this fantastic mission possible. Page 7 << Personnel Travel >> For the month of March, the following people were at ISAS Morrison 1-Mar to 26-Mar Acton 17-Mar to 31-Mar Strong 1-Mar to 20-Mar 31-Mar Linford 31-Mar Nitta 28-Mar to 31-Mar Hudson 14-Mar to 31-Mar Freeland 16-Mar to 30-Mar Friedlaender 17-Mar to 21-Mar Some of the non-Lockheed people at ISAS in March include John Mariska from NRL for a 3-week visit. Jaques Dubau visited for a few days. Len Culhane from MSSL also visited for two weeks. For the month of April, the following people are planning to be in Japan Morrison 14-Apr to 30-Apr Acton 1-Apr to 30-Apr Strong 1-Apr to 21-Apr Linford 1-Apr to 30-Apr (possible break in the middle) Nitta 1-Apr to 13-Apr 20-Apr to 30-Apr Hudson 1-Apr to 5-Apr 12-Apr to 30-Apr << Plans for April 1992 >> 1. Update the aspect telescope degradation predictions 2. Perform an experiment where the CCD TEC is turned off and signal level of visible light is monitored to see if there is contamination on the CCD which is outgassing when the CCD warms up. 3. Analyze the calibration data taken in March 4. Finalize the video which will be released as a publication 5. Continue to complete the document package. 6. Continue the Data Analysis and Reduction software development effort. 7. Continue mission operations and data analysis at ISAS. 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 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 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 | April 10, 1992 March 1992 |-------------------------------- | 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 Jan, 1992 |-------------------------------- |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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ No. Delivered From Subject Lines 2 Apr 5 1:32 POSTMAN [From: >> Friday, Apr 10, 1992 1:01 PM PDT