SOHO Joint Observing Plan 018: Sunspot Velocity Field and Line
Profiles
JOINT CDS/SUMER PROGRAMME
Sunspot Velocity Field and Line Profiles
Per Maltby, ITA, University of Oslo
Scientific Justification
The velocity field in and around sunspots is known to be
rather complicated.
Whereas the velocity field is mainly restricted to the
sunspot at photospheric heights, the flow has a larger
horizontal extent in the chromosphere and appears to follow
superpenumbral filaments.
In the transition region both upflows and downflows may
occur within the same sunspot area.
Detailed studies of the line profiles strongly suggest a fine
structure in the flow field, since more than
one distinct line-of-sight velocity may occur within the
same spatial resolution element.
In order to investigate the nature of the fine structure
in the flow field, observations of the whole line profile
are required.
Since complicated line profiles also have been observed
outside active regions, additional observations of quiet Sun
regions may be of interest.
------
Observing sequences:
SUMER: POP 18 and sequences below
CDS: Sequences below
------
CDS
---
INITIAL POINTING Pre-planned sunspot location
SPECTROMETER Normal Incidence
RASTER AREA 60 x 120 arcsec
SLIT 2 x 240 arcsec
RASTER LOCATIONS 30
DWELL TIME 15 seconds
NUMBER OF RASTERS open
REPOINTING none
DURATION OF RASTER 450 seconds
LINE SELECTION O IV 554, Ne VI 562, He I 522, O III 599,
O V 629, Mg VIII 315, Fe XIV 334,
Fe XVI 360, Mg IX 368
BINS ACROSS LINE 21
EST. COMPR. FACTOR 16 to 12 bit
CO-OPERATION SUMER
SUMER (1)
-----
INITIAL POINTING To pre-planned location
Sunspot
SLIT 1" x 120"
SCAN AREA 60" x 120"
STEP SIZE 0.76"
SCAN LOCATIONS 79
DWELL TIME 2 s
DURATION OF SCAN 158 s
NUMBER OF SCANS 2
MIRROR SETTINGS 1 ??
REPOINTING None
TOTAL DURATION 36 min (data transmission from memory)
LINE SELECTION N V (1238.821), N V (1242.804),
O V (629.729)
BINNING Spatial: 1 px
Spectral: 1 px
REFERENCE PIXEL 800, N V (1238.82)
IMAGE FORMAT 50 x 120
COMPRESSION SCHEME Bytescale 16 -> 8 bit
CO-OPERATION CDS
Solar rotation compensation on
SUMER (2)
-----
INITIAL POINTING To pre-planned location
Sunspot
SLIT 1" x 120"
SCAN AREA 60" x 120"
STEP SIZE 0.76"
SCAN LOCATIONS 79
DWELL TIME 2 s
DURATION OF SCAN 5.5 min
NUMBER OF SCANS 2
MIRROR SETTINGS 1 ??
REPOINTING None
TOTAL DURATION 44 min (data transmission from memory)
LINE SELECTION Band 1: Ly beta (1025.722),
O VI (1031.912), O VI (1037.613)
Band 2: C II (1036.337)
BINNING Spatial: 1 px
Spectral: 1 px
REFERENCE PIXEL 850 Band 1; Ly beta (1025.72),
512 Band 2; C II (1036.337)
IMAGE FORMAT 50 x 120
COMPRESSION SCHEME Bytescale 16 -> 8 bit
CO-OPERATION CDS
Solar rotation compensation on
SUMER (3)
-----
INITIAL POINTING To pre-planned location
Sunspot
SLIT 1" x 120"
SCAN AREA 60" x 120"
STEP SIZE 0.76"
SCAN LOCATIONS 79
DWELL TIME 8 s
DURATION OF SCAN 23 min
NUMBER OF SCANS 2
MIRROR SETTINGS 1 ??
REPOINTING None
TOTAL DURATION 37 min (data transmission from memory)
LINE SELECTION Band 1: C IV (1548.202), C IV (1550.774),
Si I (1554.700)
Band 2: Ne VIII (770.409),
Ne VIII (780.324), N II (775.965)
BINNING Spatial: 1 px
Spectral: 1 px
REFERENCE PIXEL 550 Band 1; C IV (1548.202)
850 Band 2; Ne VIII (770.409)
IMAGE FORMAT 50 x 120
COMPRESSION SCHEME Bytescale 16 -> 8 bit
CO-OPERATION CDS
Solar rotation compensation on
SUMER (4)
-----
INITIAL POINTING To pre-planned location
Sunspot
SLIT 1" x 120"
SCAN AREA 60" x 120"
STEP SIZE 0.76"
SCAN LOCATIONS 79
DWELL TIME 5 s
DURATION OF SCAN 14 min
NUMBER OF SCANS 2
MIRROR SETTINGS 1 ??
REPOINTING None
TOTAL DURATION 54 min (data transmission from memory)
LINE SELECTION Band 1: Na IX (694.27), Si IV (1393.755),
Si IV (1402.770), O IV (1407.386)
Band 2: O IV (1401.156), O III (702.899)
BINNING Spatial: 1 px
Spectral: 1 px
REFERENCE PIXEL 800 Band 1; Na IX (694.270)
500 Set 2; Si I (1551.86)
IMAGE FORMAT 50 x 120
COMPRESSION SCHEME Bytescale 16 -> 8 bit
CO-OPERATION CDS
Solar rotation compensation on