SUMER/CDS INTENSITY CROSS-CALIBRATION

Author(s): R.A. Harrison (CDS), K. Wilhelm (SUMER)

Progress:

Draft Scheme                            From CDS/SUMER      
                                        Blue/Red Books      
Discussion at SICWG                     June 13 1994        


Detailed PlanMinor Revisions            August 10 1994      
                                        November 4 1994     

CDS ID: ICCAL

Objective: To cross-calibrate CDS and SUMER

Scientific Case: This scheme should be part of our regular calibration programme - performed on a monthly basis at least. It makes use of common bands between CDS-NIS, CDS-GIS and SUMER. Exposure times are fixed to provide accuracies of better than 10% on the brighter lines. The wavelength overlaps between CDS and SUMER and between the CDS spectrometers are given below (the brighter lines in these ranges are listed):

• CDS-GIS/SUMER - 662-787Å: We require bright, well separated lines. In practice, this gives us one line - Ne VIII 770.40Å. However, the band 1524-1564Å gives supplementary information on N IV 765.14Å, Ne VIII 780.30Å.

• CDS-NIS/SUMER - 517-633Å: Again, we require bright, well separated lines. The He I 584.33Å, Mg X 609.79Å lines are the best for this use, though they cannot be in the same wavelength band. The bands 1150-1190Å and 1215-1255Å cover these two and will give supplementary information on Mg X 624.94Å.

• CDS-GIS/NIS - 310-346Å: Brighter lines - Fe XIII 312.16Å, Mg VIII 313.73Å, Mg VIII 317.01Å, Fe XIII 320.80Å, Fe XV 327.02Å, Fe XIV 334.17Å, Fe XVI 335.40Å, Si IX 341.95Å, Si IX 345.13Å.

Operating Details:

• CDS
  • Phase 1: NIS, Raster area 32x240 arcsec, Slit 4x240 arcsec, 8 locations. Exposure time = 30 seconds. Total duration = 240 sec. Line selection - He I 584.33Å, Mg X 609.79Å, 624.94Å, Fe XIII 312.16Å, Mg VIII 313.73Å, Mg VIII 317.01Å, Fe XIII 320.80Å, Fe XV 327.02Å, Fe XIV 334.17Å, Fe XVI 335.40Å, Si IX 341.95Å, Si IX 345.13Å - 12 lines, 21 pixels across each - 48 sec to telemeter. Total cadence = 288 sec.

  • Phase 2: GIS, Raster area 32x32 arcsec, Slit 4x4 arcsec, 64 locations. Exposure time = 20 seconds. Total duration = 1280 sec. Extract all data (emphasis of study is on lines listed above). Telemetry time = 13 sec. Total cadence = 1293 sec.

  • Operation: Phase 1, Phase 1, Phase 2, repeat three times - Total duration = 112 minutes (including 20% overhead for mode changes etc...)

• SUMER
  • Phase 1a: Raster area 30x300 arcsec, Slit 1x300 arcsec, 40 x 0.76 arcsec steps, accumulate

    7.5 s per step = 300 sec. Wavelength selection = 1150-1190Å.

  • Phase 1b: Raster area 30x300 arcsec, Slit 1x300 arcsec, 40 x 0.76 arcsec steps,

    accumulate 7.5 s per step = 300 sec. Wavelength selection = 1215-1255Å.

  • Phase 2: Raster area 30x300 arcsec, Slit 1x300 arcsec, 40 x 0.76 arcsec steps, accumulate

    over 32 seconds per step = 32 x 40 = 1280 sec. Wavelength selection 1524-1564Å.

    Operation: Phase 1a, Phase 1b, Phase 2, repeat three times - Total duration = 94 minutes.