Page 1
PROGRESS REPORT
THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM
(CONTRACT NAS8-40801)
(for April 1999)
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
Effort continued to develop the contractual aspects of operations and data
analysis beyond 1999. This included a visit to MSFC by Frank Friedlaender to
discuss the best way to facilitate this with Larry Hill, the COTR, and Elaine
Hamner,from the contracts organization.
<< Solar Activity >>
At the beginning of April, solar activity was low, but the GOES level showed
an upturn as new regions arrived at the east limb. SXT observed several
M-class flares and an eruption, associated with a filament, on the NW limb (2
April).
In mid-April we observed one M-class flare. Bright regions included AR 8506
and AR 8508, which were also observed by TRACE. Among the interesting
phenomena were transequatorial loops between AR 8507 and an unnumbered area in
the southern hemisphere and reverse jets north of AR 8510. After this, Solar
activity dropped again, with a C-class flare or two. One interesting item was
the dark "notch" between highly inclined large-scale loops in AR 8508.
The Sun may be saving its strength, or we may have had an exceptionally fast
and brief solar maximum. We've had a month now (both sides of the Sun) in
which solar activity has been quite low.
Solar activity remained low at the end of April. The GOES background
increased to the middle-B range, and a number of flares were detected: several
"C", and one "M". A halo CME was observed by LASCO in connection with the
M-flare, which came from the S-shaped region AR 8524. Although this was
reported by LASCO as a halo CME, the flare in fact did not appear ejective in
the SXT data, did not form an arcade (nor a cusp), and was not an LDE. This
Page 2
must have been "the exception that (dis)proves the rule"!
<< Campaigns >>
In early April, we dedicated 1-2 passes a day for four days to observe the
TRACE target regions for Jim Klimchuk's study of loop width.
We cooperated with VLA observations aimed at characterizing the
differential emission measure distribution of active-region loops, and at
TRACE and EIT observations of loop structure.
SXT provided ARS2 support of the BBSO/Mees/SOHO/TRACE observations of AR 8518.
This was a long "stare" observation, ARS2, on region 8518. It was a dull
region during a dull time, but no doubt the systematic coverage by TRACE,
SOHO, and Yohkoh will provide an excellent data set for studies of
active-region evolution and of microflaring. Towards the end of the
observations we were rewarded by a sudden appearance of "moss" in the TRACE
data, as noted by Jake Wolfson; this coincided with the formation of a weak
arcade to the South of the active region. So, one byproduct of this campaign
could wind up being a first study of moss in the context of physical
parameters determined from simultaneous SXT observations.
<< Science >>
Acton spent the first week of April at LMSAL working with Lemen, Metcalf, and
Freeland on the new SXT Science movie. This database comprises all of the
composite or unsaturated medium and long exposure images for the entire
mission. These images will include all of the corrections in which we have
confidence and will be kept in floating point so that no information is lost
by data compression or exclusion of negative noise.
"X-Ray Observations of Motions and Structure Above a Solar Flare Arcade" by
McKenzie and Hudson was submitted to ApJ Letters at mid-month. In this Letter
they discuss the fan of bright rays seen above the 20-jan-99 flare arcade, and
the dark "X-ray voids" which are observed to move downward through the arcade
fan. There is a fascinating amount of motion and structural change, more than
one normally expects during the decay phase of a slow LDE. They interpret the
dark voids as evacuated flux tubes linking through the current sheet, and
shrinking downward into the arcade.
Nitta analyzed SXT images of 17 limb flares for eruptive signatures,
and compared them with LASCO C2/C3 data that were taken between three
hours before and five hours after the flare. He chose only those
flares that were observed by SXT from the beginning, because X-ray
ejection tends to be seen before or during the impulsive phase. A good
correlation exists between the presence of an X-ray ejection and a CME, if
we include in the latter a diffuse and thin ejection. However, it is
hard to believe that the X-ray ejecta directly result in a CME. Since
the CME can involve a larger angle subtended at disk center, its most
pronounced area can be away from the flare, and the estimated time of
take-off (assuming no deceleration) can come well before the flare.
On the other hand, the correlation between flare eruptivity and CME's
suggests the existence of a particular large-scale magnetic field
Page 3
configuration that is favorable for the both phenomena. Incidentally,
only one or two of the dozen CME-associated flares showed a clear cusp
structure in SXT images.
<< 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 69547 accesses and 4261 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 30-April-99 Pass 5: 990430-1240
recovered in same pass.
Page 4
<< Data Flow >>
Month Full Frame Images Observing Region Images
Received Lost Received Lost Loss %
QT FL Tot
Thru Feb-97 441330 185126 1803863 384307 2188170 878557 28.58
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 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 1939 378 6686 2612 9298 2291 19.77
May-99 0 0 0 0 0 0 -NaN
Jun-99 0 0 0 0 0 0 -NaN
Total 610663 224406 2452554 600769 3053323 1090641 26.32
Number of Full Frame Images Received: 610663
Number of Observing Region Images Received: 3053323
Total: 3663986
Approximate Number of Shutter Moves/CCD Readouts: 6304599
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
Month Avg Dark Level # of Dark Spikes CCD Warmings Front Optical
(DN) (e/sec) Over 48 Over 64 High / # Support Trans
Temp /Days Temp (%)
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 57.01 993.7 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 59.00 1068.3 226914 40146 21.9 N/A
May-99 N/A N/A N/A N/A 0.0 N/A
Jun-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-APR-99 and 30-APR-99
CANFIELD 24-APR-99 30-APR-99 * 7
(total of 7 days)
HUDSON 1-APR-99 * 24-APR-99 24
(total of 24 days)
MCKENZIE 21-APR-99 30-APR-99 * 10
(total of 10 days)
NITTA 1-APR-99 * 16-APR-99 16
(total of 16 days)
SHIRTS 1-APR-99 * 10-APR-99 10
(total of 10 days)
LABONTE 6-APR-99 22-APR-99 17
(total of 17 days)
----------------------------------------------------------------
Grand Total of 84 days for 6 people
NOTE: The "*" signifies travel that actually ends after 30-APR-99
SXT Foreign Travel between 1-MAY-99 and 31-MAY-99
CANFIELD 1-MAY-99 * 7-MAY-99 7
(total of 7 days)
HUDSON 2-MAY-99 27-MAY-99 26
(total of 26 days)
MCKENZIE 1-MAY-99 * 28-MAY-99 28
(total of 28 days)
SLATER 15-MAY-99 31-MAY-99 * 17
(total of 17 days)
----------------------------------------------------------------
Grand Total of 78 days for 4 people
NOTE: The "*" signifies travel that actually ends after 31-MAY-99
Respectfully submitted,
Thomas R. Metcalf
Frank M. Friedlaender
Page 7
-------------------------------------------------------------------------------
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 1999
April 1999 |-------------------------------
| 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 1999
|-------------------------------
|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 | 17 |
------------------------|------------------------|-----------------|-----------
For sale by: Superintendent of Documents, U.S. Government Printing Office