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PROGRESS REPORT
THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM
(CONTRACT NAS8-40801)
(for April 2000)
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
The proposal for the extended mission is being evaluated by NASA. The
current contract has been extended to go through May of this year.
Contract negotiations should be accomplished during the latter part of
May.
SOLAR ACTIVITY
In the first half of April, there were 9 M flares. There were many
active regions, 15 on April 4, but no huge regions and no X-class
flares. GOES X-ray background level was gradually decreasing and dropped
to C1 level.
In the second half of April, there were no M flares. As in the first
half of the month, there were many active regions, including one (8970)
which exceeded 1,000 millionths in sunspot area. But, no major flares.
The southern large spot group, 8970, matched the longitude of another
large spot group in the north, 8971. Their mutual CMP was about April
27. The proximity of these two led to the trans-equatorial loops we
enjoyed in week 18.
CAMPAIGNS
Yohkoh ran special tables supporting VLA observations on April 2 and
April 8. The rapid-run SFDs were successful.
Yohkoh supported SOHO JOP083. This normally meant ARS2, initially with
an obscure region but finally with AR8948 (CMP April 10), which then
became quite active. It produced two of the M flares, for which we hope
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that comprehensive (eg TRACE) data now exist. The JOP targeted
microflares, but we all know that the more of them there are, the more of
the big ones there are too.
Yohkoh supported an attempt at a new JOP119 oriented towards
trans-equatorial loops.
SCIENCE
Acton studied changes in the SXT sensitivity at the time of the zeroth
entrance filter failure in October 1992 (not presently accounted for in
our database). He was surprised to find that the signal level through Al.1
increased by up to 30% in the quiet (cool) corona at the time of this
event. Our entrance filter model will have to be improved.
Aschwanden and Acton analyzed long-exposure and off-pointing Yohkoh/SXT
data of the solar corona observed on 1992 Aug 26. They developed a new
tomographic method which is based on a forward-fitting method of a
4-parameter model to the observed soft X-ray fluxes of two SXT
wavelength filters as function of height h. A direct consequence of the
multi-scale height atmosphere is that the filter ratio temperature is
predicted to increase with height, even if all magnetic field lines are
isothermal. Their model-fitting reveals that coronal holes and Quiet
Sun regions are in perfect hydrostatic equilibrium, but that coronal
streamers have a scale height that exceeds the hydrostatic scale height
by a factor of up to ~ 2.3, which underscores the dynamic nature of
coronal streamers. Their density measurements in coronal holes are
slightly lower than most of the white-light polarized brightness
inversions, and seem to come closer to the requirements of solar wind
models.
With Nitta, Alexander, LaBonte, Zarro, and others, Canfield studied the
co-aligned SXT, TRACE, SoHO, BSO, and SOON movies and Mees vector
magnetograms for certain flares that were observed in the sigmiodal
active region AR 8668 during Whole Sun Month 3. Canfield and Alexander
are trying to sort out how the filament data relate to the topological
model of Titov and Demoulin (A&A 1999).
Canfield worked with various students on the analysis of SXT and MCCD
data. Trish Van Lew studied SXT jet / MCCD surge events using the
Blehm/Pevtsov list of jets and surges inferred from SXT SFD files
throughout the mission to date. Angela Colman wound up her task of
identifying moving blueshift events similar to those observed by
Canfield et al before the Nov 15 1991 event. Yuriko Yamazaki (ACE
Language Institute) and Eric Erickson and Tyler Bangs (Headwaters
Academy) studied the relationship between sigmoids and signatures of
eruptions in the SXT SFD movies on videodisk.
Metcalf worked with George Fisher and Neil Griffiths on some code to
extend their coronal heating work to check whether the length of highly
sheared neutral line correlates with X-ray luminosity, as suggested by
the MSFC folks. It turns out that the length of sheared neutral line
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does not correlate once the dependence on total magnetic flux is
removed.
Nitta reanalyzed the 36 Fe XXVI flares studied by Jakimiec et al. He
found only a few cases where the low energy hard X-ray loop-top source
coincides with or even overlaps with the SXT high-temperature region.
This suggests that the loop-top source as seen in HXT L and M1 bands
following the impulsive phase represents bremsstrahlung of non-thermal
electrons with a very soft spectrum and low-energy cutoff at > 10 keV.
The paper in preparation on this topic also discusses the quality of SXT
temperature maps.
PUBLICATIONS
Submitted:
"Tomography of the Soft X-Ray Corona: I. Measurements of Electron
Densities, Temperatures, and Differential Emission Measure Distributions
above the Limb by Markus J. Aschwanden and Loren W. Acton, ApJ
Accepted:
"The Effect of Hydrostatic Weighting on the Vertical Temperature
Structure of the Solar Corona", Aschwanden,M.J. and Nitta,N. 2000, ApJ
Lett
Canfield, R. C. and Pevtsov, A. A. "Vector Magnetic Fields,
Sub-surface Stresses, and Evolution of Magnetic Helicity", Invited
Paper for IAU Colloquium 179,
Pevtsov, A. A. and Canfield, R. C., "Coronal Structures as Tracers of
Sub-Surface Processes", Invited Paper for IAU Colloquium 179
"Cyclical Evolution of Solar Magnetic fields: Advances in Theory and
Observations", December 13-16 1999, Kodaikanal, India, J. Astrophys.
Astr. in press, 2000.
Published:
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 April were 176289 accesses and 7999
Mbytes transferred.
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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:
Bit Map Error 03-Apr-00 Pass 1: 000403-1239
Recovered in the same pass
Bit Map Error 07-Apr-00 Pass 1: 000407-1134
Recovered in the same pass
Bit Map Error 12-Apr-00 Pass 1: 000412-0929
Recovered in the same pass
Shutter Error 12-Apr-00 Pass 3: 000413-1136
Recovered in pass 4
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DATA FLOW
Month Full Frame Images Observing Region Images
Received Lost Received Lost Loss %
QT FL Tot
Thru Jan-98 519090 199670 2104062 430632 2534694 954257 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 6810 1892 27046 7357 34403 9970 22.47
Aug-98 5823 1960 22978 14126 37104 11167 23.13
Sep-98 6776 1432 21814 11626 33440 7753 18.82
Oct-98 6573 1901 23520 5198 28718 9220 24.30
Nov-98 6442 1695 25124 26948 52072 9920 16.00
Dec-98 5962 2005 21490 15770 37260 10561 22.08
Jan-99 5494 1825 20087 17620 37707 9622 20.33
Feb-99 5729 1525 30802 9798 40600 10630 20.75
Mar-99 6807 1844 24721 12354 37075 10064 21.35
Apr-99 6715 1371 25113 4179 29292 7791 21.01
May-99 6459 1807 35467 12092 47559 13757 22.44
Jun-99 6217 1915 23542 13051 36593 10086 21.61
Jul-99 5591 1745 20409 25747 46156 9670 17.32
Aug-99 6827 2503 21725 23361 45086 11844 20.80
Sep-99 5768 2011 21890 3434 25324 10846 29.99
Oct-99 5768 2308 22994 10487 33481 11517 25.59
Nov-99 7552 3425 20754 18772 39526 11974 23.25
Dec-99 7488 2791 22047 5354 27401 10663 28.01
Jan-00 5426 1736 19802 4040 23842 8958 27.31
Feb-00 6533 2052 21801 7017 28818 8982 23.76
Mar-00 2202 817 8072 5606 13678 4261 23.75
Total 681270 248509 2709484 731297 3440781 1208699 26.00
Number of Full Frame Images Received: 681270
Number of Observing Region Images Received: 3440781
Total: 4122051
Approximate Number of Shutter Moves/CCD Readouts: 7042652
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.
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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 (%)
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 57.01 993.7 215499 27493 21.4 N/A
Aug-98 57.36 1006.7 217355 29544 20.9 N/A
Sep-98 57.43 1009.5 218520 29683 20.9 N/A
Oct-98 57.59 1015.3 220504 30221 21.3 N/A
Nov-98 58.17 1037.0 223755 34614 22.5 / 2 23.4 N/A
Dec-98 57.86 1025.5 221918 32420 23.8 N/A
Jan-99 58.74 1058.6 227503 38238 23.1 N/A
Feb-99 58.44 1047.4 224002 36198 23.2 N/A
Mar-99 59.26 1078.1 227900 43051 21.7 N/A
Apr-99 58.82 1061.4 225973 38963 23.8 / 1 21.4 N/A
May-99 58.68 1056.4 225385 37726 21.6 N/A
Jun-99 59.40 1083.0 230091 42440 22.0 N/A
Jul-99 59.78 1097.5 231236 46337 23.8 / 1 20.6 N/A
Aug-99 59.39 1083.0 229319 43067 21.7 N/A
Sep-99 60.04 1107.3 231585 49084 21.8 N/A
Oct-99 59.66 1092.9 229735 45263 22.8 N/A
Nov-99 59.90 1102.0 231288 47102 23.0 N/A
Dec-99 60.55 1126.3 233523 53920 22.5 / 2 25.3 N/A
Jan-00 60.27 1115.9 233820 50214 23.4 N/A
Feb-00 60.93 1140.6 235079 56836 23.8 N/A
Mar-00 60.22 1114.0 232439 49840 23.0 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.
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PERSONNEL TRAVEL
SXT Foreign Travel between 1-APR-00 and 30-APR-00
ACTON 1-APR-00 * 12-APR-00 12
(total of 12 days)
HANDY 17-APR-00 30-APR-00 * 14
(total of 14 days)
HUDSON 1-APR-00 * 23-APR-00 23
29-APR-00 30-APR-00 * 2
(total of 25 days)
----------------------------------------------------------------
Grand Total of 51 days for 3 people
NOTE: The "*" signifies travel that actually ends after 30-APR-00
SXT Foreign Travel between 1-MAY-00 and 31-MAY-00
HANDY 1-MAY-00 * 27-MAY-00 27
(total of 27 days)
HUDSON 1-MAY-00 * 16-MAY-00 16
(total of 16 days)
NITTA 14-MAY-00 31-MAY-00 * 18
(total of 18 days)
----------------------------------------------------------------
Grand Total of 61 days for 3 people
NOTE: The "*" signifies travel that actually ends after 31-MAY-00
Respectfully submitted,
Thomas R. Metcalf
Frank Friedlaender
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-------------------------------------------------------------------------------
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 May 2000
April 2000 |-------------------------------
| 6. PERFORMING ORG
| CODE: O/L9-41
-----------------------------------------------|-------------------------------
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/L9-41, 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: Larry Hill | of April 2000
|-------------------------------
|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