Page 1
PROGRESS REPORT
THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM
(CONTRACT NAS8-40801)
(for December 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
The current SXT contract has been extended through March 31, 2000. More
energy is now going into getting the RFP finalized and issued so that
there will be a smooth and continuing transition for long term
operations and data analysis.
SOLAR ACTIVITY
In early December solar activity remained low. We are assuming that
this is a courteous Sun prolonging Yohkoh's orbit lifetime for overlap
with HESSI and SOLAR-B. Again the Sun is lopsided: at the end of
November all of the regions were delta spots but as December rolled in,
none were. No doubt this produced beautiful rotational modulation of
all of the global indices. The GOES time profile for the three-week
interval provided a beautiful example of the decoupling between the
background coronal luminosity and flare occurrence. The lopsidedness
really just refers to flare occurrence, since the background level only
changed by a factor of two or so. Ergo, there are two kinds of coronal
structures: hot transient ones, and cool steady ones.
In mid-December, the GOES X-ray background became higher (beyond the C1
level) due to two bright regions AR 8798 and AR 8806. However, the most
intense flares barely reached M1. AR 8806 was more flare productive.
M-class flares after 22 December exceeded the GOES M1 level, but no
large CMEs occurred.
At the end of the month, solar Activity held steady with a background
level around C1. There were three M-class flares, but then little else.
Page 2
1999 turned out to be a dud from the point of view of X-class flares;
only four all year so far as we're aware. Ed Cliver pointed out that
this may have something to do with the "Gnevyshev Gap," a known tendency
for geomagnetic activity to diminish temporarily at solar maximum. It is
also well-known anecdotally that proton flares and other major solar
activity also favor the rising and decaying phases of a solar
maximum. But, could we consider 1999 to be the year of maximum? It does
not sound quite right.
CAMPAIGNS
There were no formal joint observing campaigns, but we continued with
high-rate whole-sun images, hoping to catch wave events from events
below the flare trigger level (perhaps C6 at its present setting).
We may have been rewarded with a detection, but it is only feebly
significant and can't be believed until we confirm that EIT saw it too.
If so, this will mean that we can start to build up statistics on
how the soft X-ray and EUV views of the corona differ under global
wave conditions.
The upcoming Flare Genesis telescope observations will see a major joint
observing campaign effort. We have been asked to offer opinions about
target regions (two targets: flares and sigmoids) and have been
practicing this while waiting for stratospheric wind patterns to permit
the balloon launch. We sent daily messages to Antarctica in support of
target selection. The Flare Genesis telescope is still poised at its
launch site in the Antarctic at the time of writing.
SCIENCE
Sky and Telescope magazine has been running an online poll to select the
10 most inspiring astronomical images of the *century*. The results are
announced (and shown) in the January 2000 issue. The #10 winner is a
1991 Yohkoh image of the X-ray Sun.
The sudden dimming of parts of the corona, as observed by Yohkoh's SXT,
give us a clue as to the origin of mass ejected into the outer corona
and solar wind. In the ancient history of this subject, as far back as
1997, we recognized four types of dimming: Transient coronal holes
(discovered with Skylab observations), "Above-the-arcade" dimming,
"Enveloping" dimming, and Moving cloud dimming. These are just
morphological classifications, not physical, and it might be that all
refer to the same basic process.
Recently J.I. Khan has found three examples of dimming signature with
strikingly different characteristics: the dimming occurs in
trans-equatorial loops. Briefly, he found three examples of the
sequence flare => global wave => loop disruption => prompt loop
reformation. These events do not show much evidence of helical
structure, which we know to play a role in many eruptive flares and
CMEs. All of the earlier four classes of X-ray dimming events might be
different manifestations of flux-rope eruption, whereas these
Page 3
interconnecting loops seem to be quite different.
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 December were 87809 accesses and
4036 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 Error 16-Dec-99 Pass 1: 991216-1548
Recovered in pass 5
SXT Bitmap Error 19-Dec-99 Pass 1: 991219-1446
Recovered in the same pass
SXT Error 29-Dec-99 Pass 1: 991229-1033
Recovered in the same pass
Page 4
DATA FLOW
Month Full Frame Images Observing Region Images
Received Lost Received Lost Loss %
QT FL Tot
Thru Oct-97 499878 195478 2025814 409958 2435772 931945 27.42
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 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 5179 2035 13828 2659 16487 6838 29.32
Total 664882 243147 2651904 711939 3363843 1182684 26.01
Number of Full Frame Images Received: 664882
Number of Observing Region Images Received: 3363843
Total: 4028725
Approximate Number of Shutter Moves/CCD Readouts: 6884492
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 (%)
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 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 60.46 1122.9 233117 53003 22.5 / 2 25.7 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-DEC-99 and 31-DEC-99
HUDSON 1-DEC-99 * 12-DEC-99 12
28-DEC-99 31-DEC-99 * 4
(total of 16 days)
NITTA 16-DEC-99 28-DEC-99 13
(total of 13 days)
SLATER 1-DEC-99 * 27-DEC-99 27
(total of 27 days)
----------------------------------------------------------------
Grand Total of 56 days for 3 people
NOTE: The "*" signifies travel that actually ends after 31-DEC-99
SXT Foreign Travel between 1-JAN-00 and 31-JAN-00
HUDSON 1-JAN-00 * 17-JAN-00 17
28-JAN-00 31-JAN-00 * 4
(total of 21 days)
MCKENZIE 16-JAN-00 31-JAN-00 * 16
(total of 16 days)
SHIRTS 15-JAN-00 31-JAN-00 * 17
(total of 17 days)
----------------------------------------------------------------
Grand Total of 54 days for 3 people
NOTE: The "*" signifies travel that actually ends after 31-JAN-00
Respectfully submitted,
Thomas R. Metcalf
Frank 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 January 2000
December 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 December 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 | 7 |
------------------------|------------------------|-----------------|-----------
For sale by: Superintendent of Documents, U.S. Government Printing Office