Page 1 PROGRESS REPORT THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM (CONTRACT NAS8-40801) (for November 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 In November, we received an RFP for one year of operations beginning in January 1999 and for additional data analysis. A proposal was prepared and submitted on December 7, 1998. The proposed effort will maintain the level of effort for operations and data analysis at about the same level as it is currently. This month we were visited by Charles Holmes from NASA HQ. We reviewed the current status of Yohkoh and discussed future plans including the fact that there will be another Senior Review of Sun Earth Connections programs next year. << Solar Activity >> Early November saw high solar activity with many flares coming from the large sheared region AR 8375. 44 C-class flares and 5 M-class flares occurred in the first week of November. Yohkoh obtained flare mode data for 17 of these events. To mid-November, Solar activity remained high. SXT observed several compact-type flares, and some apparent eruption events. 41 C-class flares and 4 M-class flares occurred in the second week of November. The largest flare was an M-class 1.8 flare on 10-Nov which began at 15:40. During the third week of November, solar activity started out low until an X3 flare occurred in AR 8384. We had two X-class flares on 22-Nov-98 from AR 8384. In both cases, Yohkoh came up from night only halfway to the GOES peak (06:30 and 16:20 UT), meaning most of the impulsive phase was not observed. Data for the first flare have to await transmission from DSN, but those for the second one have already been reformatted. It appears we caught the last hard X-ray peak, where the count rate of the HXT H-band was still 30 cts/s/sc Page 2 above background. The SXT quarter resolution images show motions in thin channels outside (SW of) the main loop structures, typical of the post-impulsive phase of an eruptive flare. There was an M1 flare about 2.5 hours later (18:40 UT) during Yohkoh daylight. Alas, SAA was waiting for us at ~20 % of the peak, so no flare mode data are available. In late November, solar activity remained high. Following the X3.7 flare reported previously, AR 8384 produced three more X-class flares on the southwest limb. Then another region, AR 8395, produced an X3.3 flare (LDE) in the northeast quadrant. << Campaigns >> In early November, we made some observations in support of Spartan, and observed bright points in the northern polar region at the same time that Spartan was looking just above the north pole. In mid-November, SXT made some fixed-pointing images of active regions in the southwest, to support TRACE observations. In late November, SXT attempted a coordinated observation with CDS to observe an active region in high cadence, but this attempt was not successful due to poor communication. << Science >> Thirteen X-class flares have already occurred in this solar cycle. Note please that only 23 X-class flares occurred during the Yohkoh coverage of the past maximum, so we are well on the way to the peak. The question of eruptivity is a key one for our understanding of flare physics. The classical large-scale reconnection model of course requires some form of eruption, and subsequent to the discovery of the Masuda flare, with its suggestion of a cusp (eruptive signature?) in a relatively compact flare, a search by Shibata et al. of a complete sample of limb events showed that all of them appeared to have evidence for ejective motions. Is this evidence for the formation and/or eruption of plasmoids? The X-class flares observed by SXT this cycle give us a good opportunity to ask this question where the answer is likely to be "YES". In fact, Yohkoh obtained good coverage for 9 of the 13 X flares, where "good" is defined as coverage of the impulsive phase. The Yohkoh new-cycle data on major flares thus confirm the Shibata et al. conclusions, namely that ejection is omnipresent. The new-cycle flare data are better than the old data for this purpose, because SXT now runs an "ejection special" program that provides good cadence with large fields of view (10 arc min and 5 arc min), so that we can make a more evenhanded survey for ejectivity. Page 3 Of course, simply because a flare ejects matter does not mean that large-scale reconnection has anything to do with energy release! Most of these ejecta are faint, many go at odd angles relative to the local vertical, and in no case do we see obvious inflow as a source of reconnection energy - see the critique of model predictions by Hudson and Khan for more discussion. << 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 November were 47037 accesses and 2555 Mbytes transferred. << Yohkoh Operations and Health >> 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 13-November-98 Pass 1: 981113-1341 recovered in the same pass. SXT Filter Soft error 25-November-98 Pass 1: 981125-103 recovered in the second pass. Page 4 << Data Flow >> Month Full Frame Images Observing Region Images Received Lost Received Lost Loss % QT FL Tot Thru Sep-96 406578 172553 1694554 372654 2067208 831895 28.62 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 5107 1450 18237 4720 22957 6980 23.32 Nov-98 0 0 0 0 0 0 NaNQ Dec-98 0 0 0 0 0 0 NaNQ Jan-99 0 0 0 0 0 0 NaNQ Total 576609 214643 2317106 515189 2832295 4787906 62.83 Number of Full Frame Images Received: 576609 Number of Observing Region Images Received: 2832295 Total: 3408904 Approximate Number of Shutter Moves/CCD Readouts: 7378729 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 (%) 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 57.55 1014.0 220241 30032 21.3 N/A Nov-98 N/A N/A N/A N/A 0.0 N/A Dec-98 N/A N/A N/A N/A 0.0 N/A Jan-99 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-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) 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 112 days for 6 people NOTE: The "*" signifies travel that actually ends after 30-NOV-98 SXT Foreign Travel between 1-DEC-98 and 31-DEC-98 FREELAND 9-DEC-98 18-DEC-98 10 (total of 10 days) HUDSON 1-DEC-98 * 4-DEC-98 4 12-DEC-98 19-DEC-98 8 (total of 12 days) NITTA 1-DEC-98 * 4-DEC-98 4 (total of 4 days) WEBER 1-DEC-98 * 20-DEC-98 20 (total of 20 days) ---------------------------------------------------------------- Grand Total of 46 days for 4 people NOTE: The "*" signifies travel that actually ends after 31-DEC-98 Respectfully submitted, Thomas R. Metcalf James R. Lemen Page 7 ================================================================= Montana State Univ Activity Report for October 1998-November 1998 ================================================================= (R. Canfield) INTRODUCTION The MSU group carried out SXT operations, data analysis, graduate and undergraduate research, and meeting organization. YOHKOH AND SXT OPERATIONS McKenzie spent October and November at ISAS, serving as SXT Chief Observer, SSOC Tohban, and carrying out a study of on-orbit statistical measurements of the electronic gain of SXT. Canfield spent two weeks at ISAS, serving one week as SSOC tohban. From Bozeman, he served two weeks as Yohkoh Duty Scientist at Mees Solar Observatory. Weber traveled to ISAS and served a week as SXT tohban. RESEARCH Acton worked on stray light Al.1 grill corrections, analyzing several hundred composite images. He found that the grill correction changes with each entrance filter failure -- as one would expect, but not as we have been correcting. He revised and re-submitted the paper Solar X-Ray Irradiance from Yohkoh, by Acton, Weston, and Bruner. The paper shows that SXT has a surprisingly good ability to derive mean temperatures and compute the X-ray irradiance. As well, Acton worked on limb observations obtained in coordination with the SOHO UVCS, to tie SXT and UVCS observations into a coherent picture. Canfield worked with Kankelborg and McKenzie to interpret observations of a small flare observed by SXT, TRACE, and EIT (JOP 80) in terms of active region topology. He also worked with McKenzie and Hudson on the relationship of sigmoidal structure to coronal using the SXT data for 1993 and 1997, and wrote a manuscript on the subject. Submission is on hold until the possible role of this paper in an upcoming Space Science Update is clear. He wrote a chapter on observations of helicity and reconnection in the corona for the magnetic helicity book Brown, Pevtsov and Canfield are editing. He collaborated with Pevtsov on another paper on photospheric observations of helicity for the same book. Finally, he worked with undergraduate physics major Angela Colman to make CDRs for Wuelser's list of eruptive flares which are well observed by both the Mees MCCD and Yohkoh. McKenzie analyzed images and light curves from the SXT data from the SXT/SOHO/TRACE JOP 80 flare. He did a period search, and also studied propagation of brightness along the "flow flare loop" seen in TRACE data. He devised a method to remove hot pixels from images; it is simple yet quite effective with less impact on photometry and resolution than de_spiker. The resulting images are very clean, and suitable for a study of small-scale transient brightenings. He worked with Canfield and Hudson on sigmoidal Page 8 active regions and eruptions. This involved looking at the SXT movie and characterizing the shape & eruption activity of two years' worth of active regions, and then working on some simple statistics. Weber and Davey worked to to determine and update the status of databases available in MSU group's CD-ROM archives-- specifically the SFD files of composite full-disk images. Passing this bottleneck has helped research on differential rotation seen by SXT. In November Weber made a presentation on differential rotation for the MSU Astrophysics seminar. Also, a review presentation of basic solar dynamo physics was shared amongst the MSU graduate students. A modified form of the differential rotation data was prepared for visiting SXT Co-I Peter Sturrock, who is interested in 155-day periodicities. Finally, Weber worked on a paper describing his SXT differential rotation results. SERVICE Acton and Canfield worked on various aspects of planning for the IAU Symposium 195, Highly Energetic Physical Processes and Mechanisms for Emission from Astrophysical Plasmas, MSU/Bozeman, 6-10 July 1999. Canfield worked with Alexei Pevtsov on the book tentatively titled "Magnetic Helicity in Space and Laboratory Plasmas", based on the AGU Chapman conference of the same name. Davey finished integrating a new DEC compute server alpha into our computer system at MSU, and added new user data and software space. As well, he took delivery of a Sun workstation, which has been on loan to Lockheed for several years, which will be used by Piet Martens starting next month. Papers submitted: "Helicity and Reconnection in the Solar Corona", Richard C. Canfield and Alexei A. Pevtsov, in "Magnetic Helicity in Space and Laboratory Plasmas", eds. M.R. Brown, R.C. Canfield, & A. A. Pevtsov, Geophys. Monogr. Ser., AGU, Wahington, D.C., submitted. "Helicity of the Photospheric Magnetic Field", Alexei A. Pevtsov and Richard C. Canfield, in "Magnetic Helicity in Space and Laboratory Plasmas", eds. M.R. Brown, R.C. Canfield, & A. A. Pevtsov, Geophys. Monogr. Ser., AGU, Wahington, D.C., submitted. Papers Accepted: "Magnetic Helicity in Space and Laboratory Plasmas", Richard C. Canfield and Alexei A. Pevtsov, EOS, in press. Papers Published: "The Eruptive Flare of 15 November 1991: Preflare Phenomena", Richard C. Canfield and Kevin P. Reardon, Solar Physics 182, 145-157, 1998. Talks Given: Page 9 "Active Region Topology as a Probe of the Solar Convection Zone", Richard C. Canfield, National Astronomical Observatory, Mitaka, Japan, Nov 10, 1998. ============================================================ Stanford Univ Activity Report for October 1998-November 1998 ============================================================ (P. Sturrock) Colin Roald and Peter Sturrock are continuing their investigation of the coronal heating theory mentioned in the previous report, in which the key process is magnetic reconnection at the chromospheric level. Our model involves the emergence of magnetic bipoles within supergranulation cells, the migration of magnetic elements into the network, and "collisions" of elements of opposite polarity (leading to "cancellation") in the network. An analytical treatment shows that the coronal energy flux will vary approximately as a power law function of photospheric magnetic flux, the power law index decreasing from 2 for weak fields to 1 for strong fields. Roald is developing a numerical model of this process. At this stage, the model assumes a circularly symmetric supergranule, where magnetic elements are brought to the surface at some rate in the interior, then advected into the network by a combination of steady outflow and random diffusion. Roald will compute collision rates, and hence infer the energy flux, for a range of reasonable values of production rate, velocity components, and collision cross-section. Preliminary results suggest a power-law relationship between the energy flux and the mean field strength with an index of around 1.9. Further calculations will show how this result depends on the assumptions of the model. We are continuing our collaborative investigation with Sasha Kosovichev and Jesper Shou of the Stanford University SOHO/MDI team concerning the relationship between the soft X-ray luminosity of the solar corona and the photospheric magnetic flux. Mark Weber of MSU has generously provided us with a sequence of measurements of mean SXT flux over a region at disk center. Kosovichev and Shou will produce daily averages of the absolute value of the magnetic field for the same region for the same time interval, for comparison with the magnetic flux measurements. In 1996 and 1997, Wheatland, Sturrock and Acton analyzed SXT data for a diffuse region on the limb, and found that the temperature and emission measure are consistent with a model in which the magnetic field is open, and the corona is heated by a downward heat flux. Since the region shows some loop-like structure, one is faced with the question of whether a suitable ensemble of loops could lead to the observed temperature and emission-measure profiles. Wolfson is therefore developing a loop model appropriate to spherical geometry, and will proceed to determine the expected count rates for different SXT filters, for different lines of sight. Wolfson will then determine whether it is possible to adjust the energy input into different loops to as to simulate the SXT data for the diffuse region. Page 10 We are also considering the possibility that the abundance distribution is a function of height. In recent work using SUMER data, Feldman and his colleagues have found that emission in iron lines drops more rapidly with altitude than does emission from lighter species -- presumably because of gravitational stratification. If this result is correct, then Yohkoh analyses that do not take account of gravitational stratification may give incorrect coronal temperature, since a lower flux through the Al filter is attributed (incorrectly) to a lower temperature rather than to lower iron abundance. Wolfson is applying our earlier analysis procedure (the one we applied to the diffuse corona) to the region analyzed by Feldman and his colleagues. We will then be able to compare the resulting temperature estimates with those obtained by Feldman and his colleagues. =========================================================================== Solar Physics Research Corp. Activity Report for October 1998-November 1998 =========================================================================== (Karen L. Harvey and Hugh S. Hudson) KAREN L. HARVEY: Activities for October and November: (1) Updated the compilation of Yohkoh papers published in refereed journals and conference proceedings. (2) Writing up results of study with Hugh Hudson on the evolution of the magnetic field and coronal holes associated with the active region complex which occurred during several rotations in the summer 1996 for publication in the proceedings of the COSPAR meeting in Nagoya in July. This paper was submitted 13 October 1998. (3) Preparation of NSO/KP full-disk magnetograms and He I 10830 spectro- heliograms for SXT investigators for studies of the magnetic field and He I 10830 structures associated with X-ray structures. (4) Continued with analysis of data taken in collaboration with NSO/KP, Yohkoh/SXT, SOHO, TRACE, BBSO during observing program May 4-6, 1998 studying the behavior of magnetic flux in quiet sun canceling bipoles. The initial analysis is of a 12 hour time sequence of MDI magnetograms and TRACE images taken on early 4 May 1998. Planned Activities for December: Continued analysis of (1) the magnetic fields and coronal holes related to the 1996 activity complex and the large scale field patterns with the objective of publication of the results in a referred journal. This includes determining the how the coronal connections using the SXT data develop relative to the photospheric magnetic field evolution over several months related to this complex and the new cycle regions; (2) of the XBP data collected during Page 11 several observing campaigns, concentrating on the more recent runs with the computer intensive reduction of the zonal scans (line profiles) in the Ca II 8542 and Fe I 8538 lines made during the 4-6 May and very successful 14-17 June 1998 runs and their relation to the XBP observed by SXT, (3) of filament channels related to coronal cavities, concentrating on the 1997 June-September observations and in 1993 February. PUBLICATIONS Papers Submitted: Harvey, K. L. and Hudson, H. S., "Solar Activity and the Formation of Coronal Holes", Adv. Space Rev., submitted (1998). HUGH S. HUDSON Activities for October and November: The fourth SOHO/Yohkoh CDAW took place in November, incorporating TRACE for the first time in this series. The organizers were Alexander, Schrijver, and Hudson, with Alexander doing most of the local work while simultaneously experiencing fatherhood. In this workshop we tried several avenues towards understanding the 3D structure of a particular active region, NOAA 8227, which all three spacecraft observed in an unprecedented coordination. Please see the summary Web pages at http://diapason.lmsal.com/~cdaw/. The three avenues towards this geometrical understanding were (i) modeling based on photospheric field extrapolation; (ii) stereoscopy, using Aschwanden's newly devised method, and (iii) bonehead trigonometry (e.g. Loughhead et al., 1983). Innumerable physical problems await knowledge of the 3D field, and this was the first effort we have made to use the new wonderful coronal image data for this purpose. The same AR will be studied, more from a physical point of view, at a Medoc workshop planned for March and organized by Louise Harra-Murnion. In addition to this CDAW, Hudson attended a good conference at Kiyosato (near the Nobeyama Radio Observatory) and gave a review of CME theories. During November both Brigitte Schmieder and Lidia Van Driel-Gesztelyi visited from Meudon. Hudson is collaborating with Van Driel and Nariaki Nitta on a full survey of the SXT white-light flares (1991-1992), which we're now being sadly reminded of by all of the X-class flares that are happening without SXT white-light capability. Plans for December: At the AGU meeting in December, Hudson is helping Nitta with superhot flares, and also Webb and Klimchuk on CMEs with complex magnetic structures. For the latter we've identified two great events, one of which suggests that a CME "front" structure might be neither a loop nor a bubble, but something else extremely interesting instead. Other planned work includes the necessary followup on the 3D CDAW. At the Page 12 meeting, software for "dynamic stereoscopy" and trigonometry was demonstrated, but prior to the Medoc workshop it would be nice to grind through a large amount of data in order to study the time variability of the large-scale magnetic structure. Since these techniques are being applied for the first time to multiple data sets, it would also be nice to see papers written describing how well they work and what quality of information they provide. It is my belief that image geometry, using one or more of the techniques discussed at the CDAW, will provide precise information that will be extremely complementary to the classical extrapolation techniques. PUBLICATIONS Papers Submitted: Harvey, K. L. and Hudson, H. S., "Solar Activity and the Formation of Coronal Holes", Adv. Space Rev., submitted (1998). Papers Published: Svestka, Z., Farnik, F., Hudson, H. S., and P. Hick, "Large-Scale Active Coronal Phenomena in Yohkoh SXT images. IV. Solar Wind Streams from Flaring Active Regions", Solar. Phys. 182, 179-193 (1998). Hudson, H. S., Lemen, J. R., St. Cyr, O. C., Sterling, A. C., and Webb, D. F.: "X-ray Coronal Changes during Halo CMEs," Geophys. Res. Lett. 25, 2481-2485 (1998). Gopalswamy, N., Hanaoka, Y., Kosugi, T., Lepping, R. P., Steinberg, J. T., Plunkett, S., Howard, R. S., Thompson, B. J., Gurman, J., Ho, G., Nitta, N., and Hudson, H. S. Geophys. Res. Lett. 25, 2485-2488 (1998). Wuelser, J.-P., Hudson, H.S., Nishio, M., Kosugi, T., Masuda, S., and Morrison, M., "Precise Determination of the Coordinate Systems for the Yohkoh Telescopes and the Application of a Transit of Mercury", Solar Phys. 180, 131-145 (1998). =========================================================================== Naval Research Laboratory Activity Report for October 1998-November 1998 =========================================================================== (J. Mariska) Magnetic Modulation of the Global Solar X-Ray Corona Work over the past two months has centered on beginning to develop an understanding of the solar sources of the soft X-ray variability. In an effort to understand the meaning of the daily average fluxes obtained from SXT soft X-ray images by Acton, we have been developing software to take daily time series of Yohkoh BCS data and GOES data and obtain statistical measures of the average soft X-ray flux, the variations about that average, and what we call the background soft X-ray flux as seen in these specific time series. Page 13 This background soft X-ray flux is a measure of the non-flaring soft X-ray Sun. It differs from the nonflaring averages computed using Acton's data in that we have established uniform criteria for selecting the portions of the daily data stream that constitute the background. These criteria are based on analysis of the histogram of the intensity distribution of the data for the day. This approach is possible with both the Yohkoh BCS and GOES data because there are generally many more observed flux values available in each day of observation. (For much of the time, the BCS takes spectra every 3 s.) We are currently in the process of deriving this background flux for all BCS S XV observations from 1991 Oct 1 to 1998 Sep 30 (approximately 15.7 million spectra). Once the data are in hand, we expect to conduct comparisons with measures of the nonflaring activity on the Sun to progress further toward our long term goal of understanding the magnetic origin and modulation of the total solar soft X-ray flux. =========================================================================== University of New Hampshire Activity Report for October 1998-November 1998 =========================================================================== (T. Forbes) Forbes is currently working on an a computer model animation which shows the upward motion of CME/flare loops along with the simultaneous downward motion of magnetic field lines within the loop system caused by field line shrinkage. The purpose of the movie is to show how the reconnection model of CME/flare loops can explain both the upward motion of the loop system and the downward motion of cool plasma condensations attached to individual field lines as reported by Hiei and Hundhausen (1996). The movie should be a great aid in helping people to understand the concept of field line shrinkage due to reconnection. Reference Hiei, E. & Hundhausen, A.J. (1996). Development of X-ray helmet structure, in Magnetodynamic Phenomena in the Solar Atmosphere, IAU Colloq. 153, eds. Y. Uc =========================================================================== University of California Activity Report for October 1998-November 1998 =========================================================================== (G. Fisher) Berkeley personnel involved with Yohkoh research over the past 2 months include Jim McTiernan and George Fisher. McTiernan has had two papers involving Yohkoh data analysis accepted by Apj, both will appear in March, 1999. In ``The Solar Flare Soft X-ray Differential Emission Measure and the Neupert Effect at Different Temperatures'', McTiernan, Fisher and Li obtain the DEM using SXT and BCS data. These results Page 14 are compared with model results, and the Soft X-ray Hard X-ray relationship is explored at high and low Temperatures, for a sample of 80 flares. A postscript copy of the paper can be found on the web at http://sprg.ssl.berkeley.edu/~jimm/dem98_pprx.ps. In ``Hard and Soft X-Ray Observations of Occulted and Nonocculted Solar Limb Flares'', John Mariska and McTiernan compare SXT, BCS and HXT results for a sample of 28 partially occulted limb flares and 17 non-occulted limb flares. Fisher is continuing his work on comparing relationships between the magnetic field in active regions, as measured with the Haleakala Stokes Polarimeter, with coronal heating determined from X-ray radiances, measured with SXT. Fisher and Metcalf (of Lockheed ATC) have succeeded in modifying the existing data analysis software to interactively correct poor vector magnetogram positions which are recorded in the magnetogram database. These corrections will allow a much greater fraction of the combined data to be used in the study (previously, magnetograms with incorrect positions on the disk were rejected from the study). In addition, Metcalf and Fisher have now extracted about half of the SXT data from the jukebox system at Lockheed onto disk to facilitate a more rapid analysis of the combined SXT and vector magnetogram data. Fisher and Chris Johns-Krull (also at SSL/UCB) traveled to Big Bear Solar Observatory (BBSO) in late October to test a new experimental setup to measure linear polarization in Halpha during solar flares. It has been proposed that strong center-to-limb linear polarization may be produced by proton beams during solar flares; the experiment is an attempt to look for such a signature. They succeeded in calibrating and testing the system, but no flares were observed during the week. They will return for further tests and observations during February, and will coordinate with Mees Solar Observatory in Hawaii and with Yohkoh HXT during that time. Page 15 ------------------------------------------------------------------------------- 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 December 1998 November 1998 |------------------------------- | 6. PERFORMING ORG | CODE: O/H1-12 -----------------------------------------------|------------------------------- 7. AUTHOR(S) | 8. PERFORMING ORGANIZA- T. R. Metcalf | TION REPORT NO: J. R. Lemen | |------------------------------- -----------------------------------------------|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 November 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 | 15 | ------------------------|------------------------|-----------------|----------- For sale by: Superintendent of Documents, U.S. Government Printing Office