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PROGRESS REPORT
THE SOLAR-A SOFT X-RAY TELESCOPE (SXT) PROGRAM
(CONTRACT NAS8-40801)
(for March 1997)
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, 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 Palo Alto Research 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
Preparations are underway for preparing the proposal for the Senior
Review. Last week Yohkoh/SXT images were shown on CNN in connection
with a CME event that was also detected by SOHO and was expected to
pass near by the Earth.
<< Solar Activity >>
Solar activity picked up considerably this month with a number of new
cycle regions crossing the disk. On the disk this month were AR's 8020
through 8027, more than we have seen for a while. The GOES background
was at the A level at the beginning of March but increased to near B
level as several moderately active AR's crossed the disk in the middle
of the month. Since the end of March the GOES background has been at
the B level. There have been several periods of flare activity in the
past month. The most dramatic was in the beginning of April when there
were numerous C class flares and even two M class flares.
<< Campaigns >>
An informal campaign involving SOHO CDS, SOHO EIT, and Sac Peak was
conducted 7-10 March under direction of Peter Young and Andrzej Fludra.
The objective was to observe an active region at the limb.
For Yohkoh operations, there is a text file accessible on the Web at
http://www.space.lockheed.com/SXT/html2/First_Light.html
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which also lists the current SXT Chief Observer, or the Unix command:
# finger campaign@isass0.solar.isas.ac.jp | more
The SOHO target planning is available from:
http://sohowww.nascom.nasa.gov/operations/targets/today
<< Science >>
David Alexander and Tom Metcalf submitted a fully revised version of the
paper using Pixons to study the Masuda event. The improved modulation
patterns and flux corrections led to some interesting amendments to the
conclusions. Alexander and Metcalf are still convinced that the
loop-top is non-thermal but we now believe that the emission from the
footpoints and loop-top are generated by two separate populations of
energetic particles.
Dick Canfield worked on a manuscript on flux tube twist and writhe and
active regions with Alex Pevtsov and submitted an SPD abstract on this
topic. Canfield also worked on understanding the role of flux
submergence in the interpretation of some Advanced Stokes Polarimeter
observations with Alex Pevtsov and Dana Longcope.
Nariaki Nitta attended the first SoHO-Yohkoh workshop on CMEs at GSFC
and made progress in two of the six events selected for coordinated data
analysis. In the 25/26 September 1996 event, the main CME (as observed
by LASCO) was both spatially and temporally separated from the eruptive
signatures observed by SXT in an active region. However, the two
phenomena seem to be physically related.
Greg Slater spent the first two weeks of March, visiting Beijing and
Mongolia en route to observing the total eclipse of the sun in Mongolia
on March 9. Unfortunately, the eclipse was clouded out, but otherwise
the trip was a wonderful cultural experience.
Mark Weber continued research on coronal differential rotation and did
analysis on SFD stackplots to look at the evolution of latitudinal
rotation rates; specifically, gradual accelerations vs abrupt
changes. This is a stickier problem than first hoped. The dimming of the
general corona and its features over the Yohkoh mission significantly
affects analysis. Also, it looks like it might be statistically
problematic to determine "a rotation rate" for a latitude at any given
time, perhaps due to the comparatively short evolution timescales of
some types of features.
<< Papers >>
Papers recently published
"Shrinkage of Coronal X-Ray Loops": J. Wang, K. Shibata, N. Nitta,
G. L. Slater, S. K. Savy and Y. Ogawara, ApJ Letters, 478, L41 (1997).
"The Solar Flare of 1992 August 17 23:58 UT": M. Takahashi, T. Watanabe,
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J.-I. Sakai, T. Sakao, T. Kosugi, T. Sakurai, S. Enome, H. S. Hudson,
S. Hashimoto, and N. Nitta, PASJ, 48, 857 (1996).
"A Filament Eruption and Accompanying Coronal Field Changes on
November 5, 1992": A. H. McAllister, H. Kurokawa, K. Shibata, and
N. Nitta, Solar Phys., 169, 123 (1996).
Papers recently accepted
"A Superhot Flare Observed by Yohkoh": N. Nitta and K. Yaji, ApJ., in press.
"X-Ray and Radio Studies of a Coronal Eruption: Shock Wave, Plasmoid and
Coronal Mass Ejection": N. Gopalswamy, M. R. Kundu, P. K. Manoharan,
A. Raoult, M. Pick, N. Nitta, and P. Zarka, ApJ., in press.
Papers recently submitted
"Hard X-ray Emission from Active Region Transient Brightenings" N. Nitta,
ApJ, submitted.
<< 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
Lockheed SXT WWW homepage (http://www.space.lockheed.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 March were
73973 accesses and 2586 Mbytes transferred, up about 25% from February.
<< Yohkoh Operations and Health >>
Yohkoh and the SXT continue to function very well. There has been no
further increase in stray light since 25 August 1996. The quiet patrol
image has been changed to Al/Mg (DPE=17) to try to improve the
performance of the active region selection algorithm for times when the
Sun is very quiet.
SXT experienced a normal level of Single Event Upset (SEU) events during the
month:
SXT bit map error 6-Mar-97 Pass 5: 970307-0721
recovered in Pass 1 on 7-Mar-97 (-0308)
SXT SEU error 7-Mar-97 Pass 5: 970307-0722
recovered in pass 3 on 8-Mar-97 (-0412)
SXT bit map error 10-Mar-97 Pass 1: 970310-0103
recovered in the same pass.
SXT bit map error 24-Mar-97 Pass 1: 970323-1239
recovered in the same pass.
SXT bit map error 26-Mar-97 Pass 3: 970326-1444
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recovered in the same pass.
SXT bit map error 27-Mar-97 Pass 5: 970327-0103
recovered in the same pass.
In addition, the spacecraft computer (the DP) had error flag set at
Pass4 (970326-1548) on the 26-Mar-97 (UT). The error code is `A3'. The
cause for the DP error seemed to be because that SXT was out of control
influence of the DP. This appears to be a symptom of the recovery of
SXT that was in progress at the time. The DP error flag was
successfully reset and there have been no other problems.
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<< Data Flow >>
------------------------------------------------------------------------------
Month Full Frame Images Observing Region Images
Received Lost Received Lost Loss %
QT FL Tot
Thru Dec-94 265943 115806 1146250 331358 1477608 575217 27.69
Jan-95 6870 2349 26103 1699 27802 10211 26.86
Feb-95 6556 2545 23635 3825 27460 10111 26.91
Mar-95 5915 2082 21485 3448 24933 8485 25.39
Apr-95 6244 2266 22946 4493 27439 9688 26.09
May-95 7084 2884 29617 2647 32264 15331 32.21
Jun-95 7210 3087 25251 307 25558 12045 32.03
Jul-95 6418 4145 21180 1639 22819 15109 39.84
Aug-95 7683 2597 26115 2181 28296 10537 27.13
Sep-95 6546 2853 22006 1753 23759 10433 30.51
Oct-95 6937 3502 22177 3853 26030 13044 33.38
Nov-95 5745 2944 21252 517 21769 12119 35.76
Dec-95 6163 2615 24059 901 24960 11652 31.83
Jan-96 6474 2530 27015 1708 28723 14151 33.01
Feb-96 6200 2581 21380 890 22270 10773 32.60
Mar-96 6908 2869 25437 1460 26897 12274 31.33
Apr-96 7172 2124 45445 671 46116 18848 29.01
May-96 6925 2426 30272 1089 31361 12367 28.28
Jun-96 7522 2716 31984 1536 33520 14489 30.18
Jul-96 5954 1995 29886 4769 34655 12427 26.39
Aug-96 7214 3010 21187 1607 22794 9887 30.25
Sep-96 6904 2618 29906 303 30209 12663 29.54
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 5165 868 19081 1209 20290 4333 17.60
Apr-97 0 0 0 0 0 0 0.00
Total 446504 185985 1822978 385516 2208494 882856 28.56
Number of Full Frame Images Received: 446504
Number of Observing Region Images Received: 2208494
Total: 2654998
Approximate Number of Shutter Moves/CCD Readouts: 4659066
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 (%)
Jan-95 48.55 676.7 89758 5457 20.0 N/A
Feb-95 48.70 682.1 92457 5781 25.2 / 3 20.5 N/A
Mar-95 48.35 668.9 85527 5271 19.4 N/A
Apr-95 48.72 682.8 93904 5627 19.1 N/A
May-95 48.73 683.4 94000 5820 18.8 N/A
Jun-95 49.08 696.3 100780 6281 19.6 N/A
Jul-95 49.34 706.2 106408 6628 18.1 N/A
Aug-95 49.72 720.4 114414 7101 19.5 N/A
Sep-95 49.79 723.1 115165 7222 19.6 N/A
Oct-95 50.29 741.9 126452 7911 20.2 N/A
Nov-95 50.11 735.1 122163 7814 25.2 / 2 20.3 N/A
Dec-95 50.19 737.9 123705 7927 22.6 N/A
Jan-96 50.81 761.3 136197 8888 21.5 N/A
Feb-96 50.67 755.8 133263 8705 22.5 / 2 21.5 N/A
Mar-96 50.85 762.9 136982 8973 20.3 N/A
Apr-96 51.14 773.6 142250 9500 19.9 N/A
May-96 51.16 774.4 140697 10018 19.1 N/A
Jun-96 51.56 789.2 147705 10634 20.7 N/A
Jul-96 57.45 1010.2 146293 12228 19.8 N/A
Aug-96 52.58 827.5 165676 12393 19.6 N/A
Sep-96 52.47 823.3 162784 12350 20.0 N/A
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 57.00 993.3 155248 12217 21.5 N/A
Apr-97 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.
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<< Personnel Travel >>
SXT Foreign Travel between 1-MAR-97 and 31-MAR-97
ACTON 13-MAR-97 22-MAR-97 10
28-MAR-97 31-MAR-97 * 4
(total of 14 days)
HUDSON 25-MAR-97 31-MAR-97 7
(total of 7 days)
LEMEN 1-MAR-97 * 14-MAR-97 14
(total of 14 days)
METCALF 1-MAR-97 * 7-MAR-97 7
(total of 7 days)
SAVY 1-MAR-97 * 31-MAR-97 * 31
(total of 31 days)
----------------------------------------------------------------
Grand Total of 73 days for 5 people
NOTE: The "*" signifies travel that actually ends after 31-MAR-97
SXT Foreign Travel between 1-APR-97 and 30-APR-97
ACTON 1-APR-97 * 12-APR-97 12
(total of 12 days)
ALEXANDER 2-APR-97 30-APR-97 * 29
(total of 29 days)
HUDSON 11-APR-97 30-APR-97 * 20
(total of 20 days)
SAVY 1-APR-97 * 18-APR-97 18
(total of 18 days)
----------------------------------------------------------------
Grand Total of 79 days for 4 people
NOTE: The "*" signifies travel that actually ends after 30-APR-97
Respectfully submitted,
James R. Lemen
Frank M. Friedlaender
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=================================================================
Montana State Univ Activity Report for February 1997-March 1997
=================================================================
(R. C. Canfield)
INTRODUCTION
The MSU group has carried out operations, data analysis, graduate and
undergraduate research, public outreach, worked with a SOHO visitor,
and organized and participated in meetings.
A highlight of the report period is that Sean Sandborg, a sophomore
Physics and Honors major who is using Yohkoh data tp study large-scale
structures that are possibly related to the solar dynamo, won a 1997
Barry M. Goldwater scholarship in Mathematics, Science, and
Engineering. He'll be traveling to Washington for the award ceremony
next week.
YOHKOH AND SXT OPERATIONS
During the latter half of March Acton traveled to ISAS and began
examining the health of the CCD on SXT. Although showing the effects
of age, it continues to return remarkably good x-ray images. He has
determined to try some UV flood experiments to see if some of the
accumulated ionizing radiation damage at the solar limb positions can
be restored. In February and March Canfield served as Yohkoh Duty
Scientist at Mees.
RESEARCH AND EDUCATION
Weber continued coronal differential rotation research with SXT data
and started on an offshoot project to see what SXT stackplots might
say about discrete and gradual changes in the differential rotation
profile.
Canfield worked on flux tube twist and writhe with Longcope and
Pevtsov. He worked with Foley to get the CD-R writing program working
properly. He gave a Relativity/Astrophysics Seminar on twist and
writhe in solar active regions. He worked on a manuscript on flux tube
twist and writhe and active regions with Alex Pevtsov. He submitted an
SPD abstract on this topic. Worked on understanding the role of flux
submergence in the interpretation of some ASP/SXT observations with
Alex Pevtsov and Dana Longcope.
Acton, Canfield, Weber, McKenzie, and Larson participated in
Solar Journal Club, reviewing various SXT papers.
Submitted for publication:
"Periodic Modulation of X-Ray Intensity from Coronal Loops: Heating by
Resonant Absorption," McKenzie, D.E. and Mullan, D.J. (submitted to
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Solar Physics). Abstract also sent to "CoolNews" Newsletter.
"Search for Periodicity in Image Sequences from Yohkoh Soft X-Ray
Telescope," Dissertation Summary, McKenzie, D.E., (submitted to PASP)
"Studies of Coronal Temperature", L. Acton & J. Lemen, in Observational
Plasma Astrophysics, Five Years of Yohkoh and Beyond, Eds: T. Watanabe,
T. Kosugi, and A. C. Sterling.
"On the Origin of Helicity in Active Region Magnetic Fields",
A. A. Pevtsov and R. C. Canfield, in Observational Plasma Astrophysics,
Five Years of Yohkoh and Beyond, Eds: T. Watanabe, T. Kosugi, and A.
C. Sterling.
OUTREACH and SERVICE:
McKenzie and Larson attended Pre-college Education Workshop hosted by
the Space Science Institute, in Boulder. Took requests (from workshop
attendees) for approx. 3000 SXT posters, to be sent to 5 different
institutions. Upon return, Larson & McKenzie gave a summary briefing
to the Solar Journal Club.
The MSU half of the YPOP team hosted the Lockheed half of the team at a
meeting held at MSU during March 19-20. Discussion regarding matters
of the overall design and structure of the YPOP web site, as well as
matters of scientific and educational content of the product
materials. McKenzie, Larson, Tim Slater, and Acton worked on YPOP
web pages, most notably a Beta version of the Solar Tour: "Surfing for
Sunbeams."
In February Acton became aware that the budget which gives NASA new
obligation authority for MODA funding under the Sun-Earth Connections
(SEC) theme looked very bleak in FY99 and beyond. During much of the
report period Acton worked on this MO&DA crisis, which may be resolved
in the coming year with a portion of the OSS "new start" wedge in the
President's budget that has recently gone to Congress.
Acton and Canfield attended the meeting of the combined Sun-Earth
Connections Roadmap Integration Team and the Sun-Earth Connections
Advisory Committee in San Antonio on 24-25 March. Solar-B was agreed
as the top-priority mission of the Sun-Earth Connections theme.
Canfield worked on a proposal for a Chapman conference on magnetic
helicity in solar and space plasmas. He finished the web page for SPD
meeting abstracts. He participated in Sun-Earth Connections Advisory
Subcommittee meeting.
VISITORS:
Craig DeForrest visited in March, presented a colloquium on SOHO
results, and worked with us on coordinated SXY/SOHO research.
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=======================================================================
Univ of Calif, Berkeley Activity Report for February 1997-March 1997
=======================================================================
(J. McTiernan)
All of the Yohkoh work in the past two months has benn concentrated on
the calculation of Differential Emission Measures (DEM) for soft X-ray
flares, using the SXT, BCS and GOES detectors. Results from this work
will be presented at the SPD meeting in Montana in June. We use
parametrized model fits to the DEM, along with multi-temperature models,
to estimate the dependence of the plasma cooling time as a function of
temperature. From preliminary results, we see that the flare plasma is
not isothermal, and it is often difficult to describe the DEM using any
smoothly decreasing function; functions of temperature with multiple
peaks are more useful in many cases; using any kind of model, we find
that higher temperature plasma peaks earlier and cools faster.
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=============================================================
Univ of Hawaii Activity Report for February 1997-March 1997
=============================================================
(B. LaBonte)
MAJOR ACTIVITIES FOR FEBRUARY AND MARCH
Our activities included support of Yohkoh operations and data analysis
at ISAS, coordinated ground-based data acquisition (including
designated Yohkoh campaigns) at Mees, collaborative analysis of
Yohkoh/Mees data, and preparation of manuscripts.
Operational support for SXT was provided by Nitta at
Mees and LaBonte in Manoa.
Our colleagues Jiao and Mickey at Manoa, Canfield at Montana State University,
Wuelser and Metcalf at Lockheed, and Hudson at Solar Physics Research
Corporation aided in advice and oversight of Mees operations.
Observations at Mees were limited by weather and illness of
the observer and technicians.
LaBonte continued work with Hudson on the isolated active region
AR 7978 / 7981. A manuscript for the proceedings of the Yoyogi
meeting was prepared.
Mickey and Wuelser at Lockheed continued work on the analysis
of the March 1996 polar plumes data. The principal question is
the determination of the orientation of the photospheric magnetic
fields with respect to the overlying coronal structures.
Graduate student Kristin Blais successfully defended her PhD
thesis "A Search for Optical Proxies for High Energy Emissions
from Solar Flares". While her work was principally concerned
with the spatially integrated properties of flares, using GOES
and GRO - BATSE data, the SXT full disk images were fruitful
in removing the confusion of multiple active regions on the Sun.
For a subset of her flares, the spatial dimensions of the coronal
loops inferred from the optical data was checked against the
SXT flare mode images. A more detailed analysis of those flares
in her sample which have SXT imaging will be done once
her thesis work is published.
PUBLICATIONS AND PRESENTATIONS DURING DECEMBER AND JANUARY
Papers submitted:
"NOAA 7978: The Last Best Old-cycle Region?", H.S. Hudson, B.J.LaBonte,
A. Sterling, and T. Watanabe, Yohkoh 5th anniversary meeting.
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============================================================
Stanford Univ Activity Report for February 1997-March 1997
============================================================
(M. Wheatland)
The reconstruction of force-free fields from boundary data is an
important problem in solar physics. Reliable reconstructions of fields
in active regions may allow detailed tests of existing theories of the
physics of solar flares and of coronal heating. A new method has been
devised by George Roumeliotis, based on the procedure of minimizing a
a function defined for the region of interest which describes the departure
of the field from a force-free and solenoidal state. This approach
treats the reconstruction process as a global optimization problem.
A computer code to reconstruct arbitrary 3-d fields from boundary data,
based on this approach, has been written and is being tested. The method
has been tried against known analytic force-free solutions, which highlight
the advantages and shortcomings of our approach. In the near future the code
will be applied to real boundary data, allowing a variety of physical
problems to be addressed.
Magnetic field typically plays a role (either active or passive) in theories
of coronal heating. It may be possible to evaluate these theories by
investigating the relationship between the coronal energy budget (the total
power requirement of the corona) and measurable properties of the
photospheric magnetic field. Clare Parnell and Peter Sturrock are
examining the relationship between the total X-ray flux (a useful proxy
for the total power needed to maintain the corona) as measured by the GOES
instruments, and the total magnetic flux, as estimated from the NSO
instrumentation at Kitt Peak. In particular, they intend to use this
relationship to test the recent proposal that coronal heating is due to sudden
magnetic relaxation. According to this concept, reconnection in the
chromosphere of the footpoint regions of two oppositely directed flux tubes
leads to a new flux tube, with widely separated footpoints, which erupts
rapidly and generates sound waves that heat the corona. A simple "kinetic
theory" model is adopted for the photospheric and chromospheric processes,
and is used to obtain an estimate of the magnetic flux reconnection rate in
terms of the mean field strength and of the parameters (diameter, flux and
random speed) that characterize the elementary flux elements. The sudden
magnetic relaxation model gives a simple relation between the
magnetic flux budget and the coronal energy budget, which may be
compared with the available observational data.
Peter Sturrock, Guenther Walther (of the statistics department at Stanford),
and Mike Wheatland concluded their investigation of the Homestake solar
neutrino data. A paper was prepared and submitted to the Astrophysical
Journal.
Papers submitted:
Sturrock, Walther and Wheatland, "Search for Periodicities in the
Homestake Solar Neutrino Data," submitted to the Astrophysical Journal
Page 13
===========================================================================
Solar Physics Research Corp. Activity Report for February 1997-March 1997
===========================================================================
(Karen L. Harvey and Hugh S. Hudson)
KAREN L. HARVEY:
(1) Continued development and refinement IDL program to draw the irregular
coronal hole boundaries on the NSO/KP He I 10830 spectroheliograms. The
program has been adapted for the NSO/KP Carrington rotation He I 10830 maps
and was applied the synoptic rotation maps Carrington rotations 1892 to
1984 to define the boundaries of coronal holes (latitudes and longitudes).
These data were sent to M. Neugebauer for a comparison with the predicted
locations of coronal holes based on 3-D modeling of the coronal magnetic
fields and observations of the solar wind made by Ulysses. A paper of the
results of this comparison is currently being written with M. Neugebauer,
co-authors: Z. Mikic, J.-M. Wang, A. Lazarus, R. Forsyth, Lepping, R. Wimmer,
A. Galvin, R. von Steiger, K. Harvey.
(2) Analysis of observations of XBPs obtained though a collaboration of
several ground-based observatories and the Yohkoh SXT instrument, and SOHO
in early April: Work is concentrating on the 12 April 1996 data and
comparisons of the He I 10830 line depth, magnetograms, and the series of
EIT images made in He II 304, Fe XII 195, Fe 171. Initial results, to
be included in a paper on EIT/SOHO first results by D. Moses, indicate
Examined an 8 x 8 arc-minute area centered at N9.7 E0.8 on 12 April 1996.
This area corresponds to that observed by the NSO/KP spectromagnetograph
in the He I 10830 line. Overlap in EIT time series with the NSO/KP data
is one hour from 1900--2000 UT. The Yohkoh SXT image is 7 x 2,6
arc-minutes. There observations cover the EIT period with the exception
of the 30-35 minutes each orbit when Yohkoh in night.
1. Where there are simultaneous data, all X-ray Bright Points seen in the
SOHO EIT Fe 171 and Fe 195 images is are also seen in the Yohkoh SXT data.
Within the Yohkoh field-of-view, 16 XBPs in the Fe 195 data: 14 were
bright during SXT observations, and correspond to SXT XBPs. 2
occurred during SXT night.
Within the Yohkoh field-of-view, 19 XBPs in the Fe 171 data: 14 were
bright during SXT observations, and correspond to SXT XBPs. 2 occurred
during SXT night; 1 was not observed in SXT data (this was a very small
XBP in Fe 171, and was not observed in Fe 195. 2 of the Fe 171 XBPs
(large, but fuzzy) also did not correspond to stronger areas in the SXT
data, nor to enhanced coronal emission in Fe 195.
2. The relative intensities and in some cases the spatial extent of the
XBPs in Fe 171 and Fe 195 sometimes differs with what is seen in the
Yohkoh SXT images (AlMg)
Page 14
3. All of the Fe 195 XBPs (67) correspond to He II 304 structures (and
based on one image) to He I 10830 dark points.
4. Most (61 and 64) of the Fe 171 XBPs correspond to He II 304 structures
and (based on one image) to He I 10830 dark points, respectively. The
3 exceptions are relatively large, fuzzy patches of coronal emission
that overlie smaller scale He I and He II structures. These patches do
not appear to have a counterpart in the Fe 195 images.
5. About 1/3 (64/184, 61/184) of the He II 304 bright points correspond
to Fe 171 and Fe 195 XBPs. Within the Yohkoh field-of-view, the
correspondence is slightly higher (48%) for the Fe 171 and (43%) for
the Fe 195. With the day-night cycle for the Yohkoh SXT data, the
percentage is 35%.
6. All of the coronal bright points overlie magnetic bipoles, most of
which are cancelling (I cannot be quantitative on this point, since I
only have a couple of magnetograms). Similarly, all of the He II 304
enhanced structures overlie magnetic bipoles.
7. There are several cases in which there appears to be propagation of
X-ray emission (in the 2 EIT and the Yohkoh/SXT data sets) along a
loop. There is nothing obvious in the He II 304 data, although we
have often seen something similar in He I 10830 observations, as well
as evidence of ejections (small filaments and surge like events).
(3) Preparation of NSO/KP full-disk magnetograms and He I 10830
spectromagnetograms for SXT investigators for studies of the magnetic
field and He I 10830 structures associated with X-ray structures.
(4) Assisted N. Nitta in updating the SXT list of publication.
Activities for April and May are to continue the refinement of the
coronal hole boundary routines and implementing these routines using the
NSO/KP data. The analysis of the data acquired during XBP campaigns will
continue with the writing of the first in a series of planned papers on
X-Ray Bright Points. The analysis of the history of the activity complex
7958/7978, the evolution of the fields and connections will continue, and
the production of drafts of the next two papers planned on this work.
Papers submitted:
Harvey, K. L., and Hudson, H. S., "The Formation and Evolution of the
Coronal Holes Associated with NOAA Region 7978" submitted to Proc.
Yoyogi conference.
Abstract submitted:
Harvey, K. L., Penn, M., Tarbell, T., Saba, J., Moses, D., Hassler,
D., and Fludra, A., "The Height and Temporal Structure of X-Ray Bright
Points", poster paper for the 1997 SPD meeting.
Page 15
HUGH S. HUDSON
ACTIVITIES IN FEBRUARY AND MARCH
The main activity for H. Hudson during this period consisted of preparing
for and participating in the first SOHO/Yohkoh Coordinated Data Analysis
Workshop, held at NASA/GSFC March 3-7. The subject was CMEs, mainly the
integration of the low-coronal data (SXT, Nobeyama, EIT) with the coronagraph
data (LASCO). The Sun has cooperated fully; the "solar minimum" year of
1996 was full of nice CME events, and we selected six for study. These
include the "Rosetta Stone" EIT/LASCO event of 23-Dec-96, a flare-associated
event of 30-Nov-96, and - perhaps most interesting even if it's almost a
null result - the halo CME of 6-Jan-97. The workshop went very well and
some of its results will be displayed on the Web.
In addition to this Hudson visited Rutherford Appleton Labs for a day,
working on CDS/SXT comparisons of active-region loops and on CMEs. The
second SOHO/Yohkoh CDAW has been fixed at MEDOC (Paris) this fall, on the
subject of active regions.
PLANS FOR APRIL AND MAY
In April Hudson intends to spend ten days visiting D. Melrose in Sydney,
and this will be an opportunity to think more deeply about the Masuda
event and the general status of the non-thermal electron problem in solar
flares. Work on CMEs will also continue in several directions. There is
a possibility of some work being done on "Uchida loop expansions", one of
the major Yohkoh discoveries, in conjunction with the remarkable LASCO
observations of quasi-continuous outflow in the streamers. Finally, although
this is a bit of a long shot, the recent discoveries of X-rays from comets
(Rosat) and of sungrazing comets (SOHO) suggest research directions for
Yohkoh and Nobeyama.
Papers published
Webb, D.A., Hudson, H., and Howard, R., ``X-ray Signatures of CMEs
Observed in White Light'', EOS, 77, F563, 1996.
Aschwanden, M. J., Wills, M. J., Hudson, H. S., Kosugi, T., and
Schwartz, R. A., ``Electron Time-of-flight Distances and Flare Loop
Geometries Compared from CGRO and Yohkoh Observations,''
Astrophys. J., 468, 398, 1996.
Silva, A. V. R., White, S. M., Lin, R. P., De Pater, I., Gary, D. E.,
McTiernan, J. M., Hudson, H. S., Doyle, J. G., Hagyard, M. J., and
Kundu, M. R., ``Comprehensive Multiwavelength Observations of the 1992
January 7 Solar Flare,'' Astrophys. J. (Suppl.), 106}, 621, 1996.
Papers submitted
Hudson, H., LaBonte, B., Sterling, A., and Watanabe, T., ``NOAA 7978:
the Last Best Old-Cycle Region'', submitted to Proc. Yoyogi conference.
Page 16
Harvey, K. L., and Hudson, H. S., ``The Formation and Evolution of the
Coronal Holes Associated with NOAA Region 7978'', submitted to Proc.
Yoyogi conference.
Page 17
-------------------------------------------------------------------------------
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 April 1997
March 1997 |-------------------------------
| 6. PERFORMING ORG
| CODE: O/H1-12
-----------------------------------------------|-------------------------------
7. AUTHOR(S) | 8. PERFORMING ORGANIZA-
J. R. Lemen | 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/H1-12 |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
| of March 1997
|-------------------------------
|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