Flare Genesis/SoHO JOP 117      DRAFT    DRAFT    DRAFT

Received: 28 October 1999 / 22 November 1999

Title: The build-up and triggering Solar Flares

Authors: David Rust      (david.rust@jhuapl.edu)
         Brigitte Schmieder (Brigitte.Schmieder@obspm.fr)
         

We propose a JOP to study the genesis and development of solar flares,
using high cadence, high resolution, multi-thermal imaging from
Yohkoh/SXT, EIT and TRACE, and spectral measurements from SoHO/SUMER,
SoHO/CDS. The priority in this JOP is image cadence, and as such,
field-of-view will be sacrificed where necessary (Flare Genesis has a
100 x 100 arcsec FOV).

Scheduling considerations: 

The JOP is to be run during the flight of the Flare Genesis Experiment
(see http://sd-www.jhuapl.edu/FlareGenesis) in Antarctica.  It is
expected that this flight will start in mid-December 1999.  The launch
window opens about December 10 and closes about January 10.  In an
ideal observing run, this program should be run continuously for the
expected duration of the flight: 10 - 14 days.  The primary objective
is to understand the magnetic and chromospheric conditions that lead
up to a flare. A secondary objective is high-cadence observations of
the pre-flare changes and impulsive phase.  for the entire observing
period.

Target Selection: 

Target selection will be made by the SXT Chief Observer if SXT agrees
to provide this service. The target will be the brightest active
region on the sun, since this is the standard and safest mode of
operation for SXT.  However, we request that only active regions
within half a solar radius of disk center be selected, because Flare
Genesis is a vector magnetograph.  Our instrument will only
exceptionally be pointed at another region, (e.g., one which is
flaring repeatedly). In both cases we hope to stick with the target
for a few days, rather than 'flare chase' although the situation will
be reassessed by the SXT_CO and the Flare Genesis chief observer on a
daily basis.

If a flare occurs in a region other than the target region, i.e.,
other than the brightest region on the sun, SXT will by default go to
this region for flare observations. This is just bad luck.

Observations:   

   Science goal here is the study of the pre-flare build-up of the
   magnetically unstable conditions.  We are also interested in field
   extrapolation into the corona using other magnetograms, and in
   pre-heating as shown in UV, soft X-rays and hard X-ray information
   if available.  Also, we are interested in magnetic developments
   during flares and afterward. E.g., is there some kind of relaxation
   of the field?

   FGE - 4 vector magnetograms and 4 H-alpha images per hour continuously
                    
   HXT - LOW channel if available - no special observation mode
   (included for information)

   SXT - Filters     - Al.1/AlMg
         Pointing    - fixed pointing on target selected by SXT CO and FGE
         Duration    - Continuously for 4 days
         Exposures   - fixed maximum exposure to avoid problems of not
                       sitting on brightest active region (when applicable)
         F-O-V       - to cover active region - 2X2 PFI (?)
         Cadence     - not an issue

         Fixed pointing is suggested to make sure that pre-flare data
         for flare occurring in TRACE f-o-v is obtained. SXT will catch
         all 'daytime' flares as usual of course.

   TRACE - Filters   - (195 or 171)* and 1600A
           F-O-V     - restricted TRACE f-o-v  (384"x384")
           Cadence   - maximum possible with above filter complement

           Note (*) the EUV filters will be alternated, starting with 195. 
           In other words when the JOP starts, TRACE will run this part of 
           the program with rapid interleaved 195/1600 images until a
           flare is detected. At the next available opportunity (in
           practise this will be the next day) the filter will be changed
           in preparation for the next flare, so that rapid interleaved
           171/1600 images will be taken in Part 1.
           
           Further, the filter for the impulsive phase study and the
           filter for the preflare study will be the same, except if the
           284 filter is being used for the impulsive phase. In that case,
           the preflare images will be 195 images

Other Observations:
===================

SoHO-EIT: Helium 304 Angstrom observations at 15 minute cadence or faster


SoHO-CDS: Spectroheliograms of target active region in FeXVI, MgX, OV
and He1, with a field of view of 240"x240". As high a cadence as the
above restrictions allow. Contingencies exist for switching to a line
combination involving higher-temperature iron lines, e.g., Fe XIX, if
a flare is observed during real-time contact; this would be very
desirable for observing flare and post-flare line-shifts.

SoHO-SUMER: (if limb target) follow observing sequences outlined in
JOP 104 WILL BE CLOSE

SoHO-MDI: High cadence magnetograms if in hi-res FOV, otherwise
whatever MDI is doing at the time.

We will request coordinated observations from the following:
 
 Baikal Solar Vacuum Telescope 

 Big Bear Solar Observatory 
 

 Helio Research

 Hida Domeless Solar Telescope
                                                            
 Huairou Solar Station
                                                        
 Kitt Peak Tower Telescope (He 10830 doppler images)
                                                         
 Marshall Space Flight Center 
                                    
 Mees Solar Observatory 
 
 Meudon Observatory
                              
 National Astronomical Observatory of Japan, Mitaka 

 Sacramento Peak Tower Telescope (Advanced Stokes Polarimeter)

ARGENTINA 

BIALKOV 

Chinese and russian observatories.