Coronal hole boundary observing sequence (BOUND)

Contributors - J. Insley & V. Moore (Imperial College), R. A. Harrison (RAL)

Scientific justification:

To understand the evolution of coronal holes one must identify processes at work in the boundaries, especially as the holes grow and decay. This study looks for small scale activity in the coronal hole boundaries as well as allowing an identification of the relationship between the boundary and supergranular structure. The study has three parts - Phase 1: looks for the structure of the boundary, with temperature and density diagnostics, using observations of a range of Fe and Si ions; Phase 2: sits at same location and, with a faster cadence, looks for small scale activity; Phase 3: is identical to Phase 1.

Study details:

Phase 1:

Spectrometer: 		Normal incidence
Slit:			2 x 240 arcsec
Raster area:		60 x 240 arcsec
Step (DX, DY):		2 arcsec, 0 arcsec
Raster locations:	30 x 1 = 30

Exposure time:		15 seconds
Duration of raster:	480 seconds
Number of rasters:	3
Total duration:		1440 seconds

Line selection:		Coronal hole line selection 2 

			Fe VIII 370.43Å - log Te 5.6
			Fe X 365.57Å - log Te 6.1
			Fe XII 364.47 - log Te 6.2
			Fe XII 338.26Å - log Te 6.2
			Fe XIV 334.17Å - log Te 6.3
			Fe XVI 335.40Å - log Te 6.4
			Si IX 349.87Å - log Te 6.0
			Si IX 341.95 - log Te 6.0
			Mg IX 368.06Å - log Te 6.0
			
Bins across line:	11

Phase 2:

Spectrometer: 		Normal incidence
Slit:			2 x 240 arcsec
Raster area:		60 x 60 arcsec
Step (DX, DY):		2 arcseconds, 0 arcseconds
Raster locations:	30 x 1 = 30

Exposure:		2.5 seconds
Duration of raster:	100 seconds
Number of rasters:	50
Total duration:		5000 seconds

Line selection:		Coronal hole line selection 3

			He I 584.33Å - log Te 4.3
			Mg IX 368.06 - log Te 6.0
			O III 599.59 - log Te 4.9
			Ne VI 562.83Å - log Te 6.2
			Fe XVI 335.40Å - log Te 6.4

Bins across line:	11

Phase 3:

See Phase 1

Total duration of sequence: 132 minutes

Pointing:		across coronal hole boundary

Frequency:		to be run on a number of occasions during mission

Product:		Three 60 x 240 arcsec maps at the beginning and end of
			the study period of the coronal hole boundary in a range
			of lines giving temperature and density diagnostics, 
			plus a series of 50 smaller maps of cadence 100 seconds 
			for a smaller group of lines, to identify flows, 
			brightenings, etc.

This page last updated 15th November 1995