CDS observing details

Various modes of CDS observations (2D movies, 2D raster, 1D sequences) are proposed. All CDS data will be obtained with the normal incidence spectrometer (NIS). The CDS procedure is optimized in order to get the full spectral profiles of different spectral lines, originated in different layers of the solar atmosphere in the larger 2D FOV around the fixed SUMER 1D slit position. The 100 duty cycle is planned for the measurements to optimize the telemetry.

The brightest spectral lines were selected for the diagnostics of the plasma dynamics ( "dynamics diagnostics lines") with an attempt to cover wider range of temperatures : He I 584.33 Å (2.0x10 K), O V 629.74 Å (2.5x10 K), Mg IX 386.04 Å (1.0x10 K), Si XII 520.67 Å (2.0x10 K).

Measurements planned for the diagnostics of the plasma density ( "density diagnostics lines") are also included in the JOP (temperatures around 10 K, densities in the interval 10-10 cm ). Namely 4 density-sensitive lines were selected for the plasma density estimation (after Mason, 1997) : Si IX 349.87 + 345.13 Å, Si X 356.03 + 347.40 Å.

The previous 4 "dynamics diagnostics lines" (He I 584.33, O V 629.74, Mg IX 386.04, Si XII 520.67 Å) and also 6 additional lines (He II 304 A, Fe XVI 335.40, Fe XV 360.76, Fe XII 354.47, O III 599.59, Mg X 624.94 Å) have been selected for the simultaneous measurements together with the density-sensitive lines. The reason is the check of the possible blends in some "dynamics diagnostics lines" which should appear at higher levels of activity (Brekke et al., 1997). The other reason is the co-alignment of the CDS and EIT data.

The He I 584 Å spectral line was selected for the fine SUMER CDS post-facto co-alignment. The CDS should work in the movie mode and also in 2D rastering around the central slit position. As the telemetry allows to transfer other data too, the O V 629.74 and Mg IX 386.04 lines were included to the SUMER CDS co-alignment sequence part.

CAUTION : The CDS dwell times are estimated ONLY on the base of different papers where such information was reported (e.g. Ruedi et al., 1997 and some JOPs). Therefore the introduced timing of CDS parts has to be calculated and the total number of exposures or scans must be optimized to fill the required duration of different parts of observations (SUMER CDS Alignment, "dynamics diagnostics", "density diagnostics") in order to keep the proposed schedule of measurements.

CDS sequence part 1 : CDS SUMER co-alignment

Large FOV movie of the disk center area :

Lines : He I 584.33, O V 629.74, Mg IX 386.04 Å

Slit : 90'' x 240''

Detector Area (HxV) : 61 x 120 pixels = 124'' x 244''

Steps : 0'', 0''

Number of exposures : 60

Exposure Time : 25 seconds (+ app. 6 seconds overhead) -> 31 seconds

Duration : 60 x 31 = 1860 sec = 31 min

Telemetry/Compression : truncate to 12bits

CDS sequence part 2 : CDS SUMER alignment

Small FOV movie of the disk center area :

Lines : He I 584.33, O V 629.74, Mg IX 386.04 Å

Slit : 90'' x 240''

Detector Area (HxV) : 13 x 70 pixels = 26'' x 142''

Steps : 0'', 0''

Number of exposures : 300

Exposure Time : 5 seconds (+ app. 2 seconds overhead) -> 7 seconds

Duration : 300 x 7 = 2100 sec = 35 min

Telemetry/Compression : truncate to 12bits

CDS sequence part 3 : CDS SUMER alignment

2D sequential raster of the disk center area :

Lines : He I 584.33, O V 629.74, Mg IX 386.04 Å

Slit : 2'' x 240''

Detector Area (V) : 70 pixels = 142''

(H) : 21, 21, 25 pixels, respectively

Steps : 2'', 0''

Number of positions per raster : 13

Number of rasters : 10

Number of exposures : 13 (per raster) x 10 (rasters) = 130

Exposure Time : 5 seconds (+ app. 7 seconds overhead) -> 7 seconds

Duration : 10 x (13 x 7) = 10 x 97 sec = 970 sec = 16 min

Telemetry/Compression : truncate to 12bits

CDS sequence part 4 : "dynamics diagnostics"

2D sequential raster of the disk center area :

Lines : He I 584.33, O V 629.74, Mg IX 386.04, Si XII 520.67 Å

Slit : 2'' x 240''

Detector Area (V) : 70 pixs = 142''

(H) : 21, 21, 25, 15 pixels, respectively

Steps : 2'', 0''

Number of positions per raster : 11

Number of rasters : 204

Number of exposures : 11 (per raster) x 120 (rasters) = 1320

Exposure Time : 5 seconds (+ app 3 seconds overhead) -> 8 seconds

Duration : 204 x (11 x 8) = 204 x 88 sec = 18000 sec = 300 min

Telemetry/Compression : truncate to 12bits

CDS sequence part 5 : "dynamics diagnostics"

1D position in the center of the previous 2D rasters of the disk center area :

Lines : He I 584.33, O V 629.74, Mg IX 386.04, Si XII 520.67 Å

Slit : 2'' x 240''

Detector Area (V) : 70 pixs = 142''

(H) : 21, 21, 25, 15 pixels, respectively

Steps : 0'', 0''

Number of exposures : 240

Exposure Time : 5 seconds (+ app. 3 seconds overhead) -> 8 seconds

Duration : 240 x 8 = 1920 sec = 32 min

Telemetry/Compression : truncate to 12bits

CDS sequence part 6 : "density diagnostics"

2D sequential raster of the disk center area :

Lines : A/ 4 density diagnostic lines : Si IX 349.87 + 345.13 Å, Si X 356.03 + 347.40 Å

B/ 4 dynamics diagnostic lines: He I 584.33, O V 629.74, Mg IX 386.04, Si XII 520.67 Å

C/ 6 additional lines : Fe XVI 335.40, Fe XV 360.76, Fe XII 354.47,

He II 304 A, O III 599.59, Mg X 624.94 Å

Slit : 2'' x 240''

Detector Area (V) : 70 pixs = 142''

(H) : A/ interval : 344.5 - 351.0 Å = 6.5 Å = 82 pixels

A/ interval : 354.5 - 357.5 Å = 3.0 Å = 38 pixels

B/ dynamics diagnostics lines : 4 x 33 pixels

C/ additional lines : 6 x 33 lines

Steps : 2'', 0''

Number of positions per raster : 11

Number of rasters : 5

Number of exposures : 11 (per raster) x 5 (rasters) = 55

Exposure Time : 55 seconds (+ app. 5 seconds overhead) -> 60 seconds

Duration : 5 x (11 x 60) = 5 x 660 sec = 3300 sec = 55 min

Compression/Telemetry : none, 16bits data transfered

Summary of the CDS observing run sequences :

The brief description of the proposed CDS procedure of the selected sequence parts, together with the timing, are given below in the following tables :

 
Table 5: The brief description of the CDS sequence parts.

 
Table 6: The timing and basic parameters of the CDS sequence parts.