REPORT FROM ISAS
Monday, 8-June-92, L. Acton

Time sure does fly when you're having fun, or desparately trying to keep
up!  It has been 4 weeks since my last report--unacceptable, sorry.

It has been a fuitful month, about 30 refereed papers have submitted for
publication.  Here's the list:

Submitted to SCIENCE

1. L.Acton, S.Tsuneta, Y.Ogawara, R.Bentley, M.Bruner, R.Canfield, L.Culhane
      G.Doschek, E.Hiei, T.Hirayama, H.Hudson, T.Kosugi, J.Lang, J.Lemen
      J.Nishimura, K.Makishima, Y.Uchida
      The Yohkoh Mission for High Energy Solar Physics

Submitted to Publications of the Astronomical Society of Japan

2. G.Kawai, H.Kurokawa, S.Tsuneta, T.Shimizu, K.Shibata, L.Acton,
      K.Strong, N.Nitta
      Comparison between H-alpha and Yohkoh Soft X-ray Images of 
      Emerging Flux Regions

3. G.A.Doschek, J.T.Mariska, T.Watanabe, E.Hiei, J.Lang, J.L.Culhane,
      R.D.Bentley, C.M.Brown, U.Feldman, A.T.Phillips, K.J.H.Phillips, 
      A.C.Sterling
      Yohkoh Bragg Crystal Spectrometer Observations of the Dynamics and
      Temperature Behavior of a Soft X-ray Flare

4. J.Lang, R.D.Bentley, C.M.Brown, J.L.Culhane, G.A.Doschek,
      T.Watanabe, E.Hiei, R.D.Deslattes, A.Fludra, P.R.Guttridge,
      J.E.Magraw, J.Payne, C.D.Pike, M.W.Trow
      The Performance of the Yohkoh Bragg Crystal Spectrometer

5. J.L.Culhane, A.Fludra, R.D.Bentley, G.A.Doschek, T.Watanabe,
      E.Hiei, J.Lang, M.K.Carter, J.T.Mariska, A.T.Phillips,
      K.J.H.Phillips, C.D.Pike, A.C.Sterling
      Observations of Several Small Flares with the Bragg Crystal
      Spectrometer on Yohkoh

6. Tetsuya Watanabe, E.Hiei, J.Lang, J.L.Culhane, R.D.Bentley,
      G.A.Doschek, B.J.I.Bromage, C.M.Brown, U.Feldman, A.Fludra,
      T.Kato, J.Payne
      Helium-Like Sulphur Emission Lines in Solar Active Regions and 
      Their Sub-C Class Variability

7. H.Kurokawa, G.Kawai, T.Kitahara, R.Kitai, Y.Funakoshi, Y.Nakai,
      S.Tsuneta, T.Kosugi, S.Enome, L.Acton, Y.Ogawara
      Detailed Comparison between H-alpha and Yohkoh Soft X-ray Images
      of a Confined Two-Ribbon Flare

8. T.Shimizu, S.Tsuneta, L.W.Acton, J.R.Lemen, Y.Uchida, et al.*
      Transient Brightenings in Active Regions Observed by the
      Soft X-ray Telescope on Yohkoh
      (*: names should be explicitly given)

9. K.Ichimoto, T.Hirayama, A.Yamaguchi, K.Kumagai, S.Tsuneta, H.Hara,
      L.Acton, M.Bruner
      The Effective Geometrical Thickness and Electron Density of a
      Flare of Dec.2, 1991 Observed with the Soft X-ray Telescope
      of Yohkoh and Coronagraph

10. T.Sakurai, K.Shibata, K.Ichimoto, S.Tsuneta, L.W.Acton
      Flare-Related Relaxation of Magnetic Shear as Observed with
      the Soft X-ray Telescope of Yohkoh and with Vector Magnetographs

11. S.Tsuneta, T.Takahashi, L.Acton, M.Bruner, K.Harvey, Y.Ogawara
      Global Restructuring of the Coronal Magnetic Fields Observed with
      Yohkoh Soft X-ray Telescope

12. S.Tsuneta, H.Hara, T.Shimizu, L.Acton, K.Strong, H.Hudson
      Yohkoh X-ray Observation of a Large Loop Flare at the Limb

13. L.W.Acton, U.Feldman, M.E.Bruner, G.A.Doschek, T.Hirayama, 
      H.S.Hudson, J.R.Lemen, Y.Ogawara, K.T.Strong, S.Tsuneta
      The Morphology of 20 x 10^6 K Plasma in Large Solar Flares

14. K.Strong, K.Harvey, T.Hirayama, N.Nitta, T.Shimizu, S.Tsuneta
      Observations of the Variability of Coronal Bright Points by the
      Soft X-ray Telescope on Yohkoh

15. H.Hudson, L.Acton, T.Hirayama, Y.Uchida
      White-Light Flares Observed by Yohkoh

16. R.C.Canfield, H.S.Hudson, K.D.Leka, D.L.Mickey, T.R.Metcalf, 
      J.-P.Wuelser, L.W.Acton, K.T.Strong, T.Kosugi, T.Sakao, S.Tsuneta,
      J.L.Culhane, A.Phillips, A.Fludra
      The X Flare of 15 November, 1991: Coordinated Mees/Yohkoh
      Observations

17. J.A.Klimchuk, J.R.Lemen, U.Feldman, S.Tsuneta, Y.Uchida
      Thickness Variations along Coronal Loops Observed by the Soft
      X-ray Telescope on Yohkoh

18. P.C.H.Martens, D.O.Gomez
      Spatial Power-Spectra from Yohkoh Soft X-ray Images

19. T.Kosugi, T.Sakao, S.Masuda, K.Makishima, M.Inda, T.Murakami,
      Y.Ogawara, K.Yaji, K.Matsushita
      The Hard X-ray Telescope (HXT) on Board Yohkoh: Its Performance
      and Some Initial Results

20. M.Yoshimori, Y.Takai, K.Morimoto, K.Ohki
      Characteristics of Two Gamma-Ray Flares Observed with the 
      Wide Band Spectrometer aboard Yohkoh

21. M.Yoshimori, Y.Takai, K.Morimoto, K.Ohki, T.Watanabe, I.Kondo, 
      J.Nishimura
      The Yohkoh Wide Band Spectrometer: Performance and Initial Results

22. T.Sakao, T.Kosugi, S.Masuda, M.Inda, K.Makishima, R.C.Canfield, 
      H.S.Hudson, T.R.Metcalf, J.-P.Wuelser, L.W.Acton, Y.Ogawara
      Hard X-ray Imaging Observations by Yohkoh of the 15 November, 1991
      Solar Flare

23. K.Matsushita, S.Masuda, T.Kosugi, M.Inda, K.Yaji
      The Average Height of Hard X-ray Sources in Solar Flares

24. Takashi Watanabe, Y.Kozuka, M.Ohyama, M.Kojima, K.Yamaguchi,
      S.Watari, S.Tsuneta, J.A.Joselyn, K.L.Harvey, L.W.Acton,
      J.A.Klimchuk
      Coronal/Interplanetary Disturbances Associated with Disappearing
      Solar Filaments

25. K.Shibata, Y.Ishido, L.Acton, K.Strong, T.Hirayama, Y.Uchida, 
      A.McAllister, R.Matsumoto, S.Tsuneta, T.Shimizu, H.Hara,
      T.Sakurai, K.Ichimoto, Y.Nishino, Y.Ogawara
      Observations of X-ray Jets with the Yohkoh Soft X-ray Telescope

26. H.Hara, S.Tsuneta, J.R.Lemen, L.W.Acton, J.M.McTiernan
      High Temperature Plasmas in Active Regions Observed with the Soft
      X-ray Telescope aboard Yohkoh

27. N.Nitta, T.S.Bastian, M.J.Aschwanden, K.L.Harvey, K.T.Strong
      Simultaneous Observations of Coronal Bright Points in X-ray and
      Radio Wavelengths

28. Y.Uchida, A.McAllister, K.Strong, Y.Ogawara, T.Shimizu,
      R.Matsumoto, H.Hudson
      The Continual Expansion of Active Region Corona Observed by the
      Yohkoh Soft X-ray Telescope

29. A.McAllister, Y.Uchida, S.Tsuneta, K.Strong, L.Acton, E.Hiei,
      M.Bruner, Takashi Watanabe, K.Shibata
      Internal Structure of Coronal Soft X-ray Source Appearing in 
      Association with the Dark Filament Disappearance of September
      28, 1991 by Yohkoh Soft X-ray Telescope

30. Y.Ogawara, Y.Uchida, H.Hudson
      The Yohkoh Satellite:  Status and Initial Results

This submission of papers signals the completion of the initial phase of
data analysis and the opening up of opportunity for broader participation
in research and publication with Yohkoh data.  There will also be a good
representation of Yohkoh results at the AAS meeting in Columbus, OH, this
week.  

New scientific insights: I guess the most interesting recent developement
is the conviction, on my part at least, that there are fundamentally two
kinds of filament disappearance events.  In one kind, long discussed and
interpreted by the so-called Kopp & Pneuman model, the eruption breaks
through the overlying coronal fields and a large arcade of "McDonald's
arches" appear in x-rays.  In the other kind the erupting filament doesn't
manage to break out, the soft x-ray emission is intense over an extensive
area, and x-ray loops appear along as well as across the magnetic neutral
line.  The images that make this picture convincing were processed by Alan
McAllister over many all night sessions at the workstation in preparing
paper 29. 

Last week I celebrated submission of the SCIENCE paper (only 8 months late)
by visiting Norikura Coronagraph station.  This NAOJ facility is at an
elevation of about 3000 meters in the Japanese Alps.  My respect for the
likes of Hiei and Hirayama who climbed to this remote peak on skiis in the
days before sno-cats knows no bounds.  Now they have a very good
observatory with 25 cm and 10 cm coronagraphs.  The former is a Coude'
system with a high resolution spectrograph.spectroheliograph.  The latter
carries the new CCD filtergraph operating with H-alpha, Fe XIV, Fe X and
the continuum at 6300 A.  Paper 9 combines results from this instrument and
SXT observations.  I am looking forward to the analysis of a jointly
observed eruptive event on 20-Apr-92 which I've mentioned in an a previous
report. 

My 3 months here at ISAS is nearly complete, Evelyn and I leave Wednesday
for Thailand for a week's vacation and then back to California.  It has
been a scientifically exciting and productive time.  The SXT and, indeed,
all of the Yohkoh instruments continue to function beautifully. 
Reformatting and distribution of data tapes is almost caught up and the SXT
movie of full frame images is now being put onto the laser disk routinely. 
This is a tremendously useful research tool.  Sadly, we do not have an
equivalent capability at Lockheed but have to settle for a substantially
poorer qaulity product because our laser recorder isn't as good.  

Jim Lemen amd Piet Martens have arrived.  Hudson and Nitta are off at
meetings and Linford is home on R&R.  Mons returns to Palo Alto this
Wednesday.  The work that he has accomplished with the amazing reformatter
and data distribution software is a crucial link to our success.  Thanks,
Mons.  Also, thanks to Sam Freeland's Single Event Upset on-board
correction software the tremendous disruption of reacting to these
radiation belts hits is largely a thing of the past.  Thanks, Sam.

We are now successfully co-observing with the Lockheed team at LaPalma,
Canary Islands.  (I am continually amazed and delighted with the scientific
benefits that can accrue from good world-wide communications!) We have not
done any detailed comparisons yet but they report observing several small
flares, some at times of good seeing, that should have been also seen by
SXT.  With activity levels way down we spent some time today defining some
new experiments to run when the peak x-ray brightness and large-flare
probability is low.  Jim Lemen will be setting up some tables to do deep
exposures on faint things, and high time resolution observations of
sparkling active retions.

That's it for now.  Good bye