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GMOS-S Filters

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The GMOS filters u', g', r', i' and z' are similar to the filters used by the Sloan Digital Sky Survey (SDSS). A description of the SDSS photometric system is presented in Fukugita et al. (1996, AJ, 111, 1748). See the description of optical photometric standard stars for details on the photometric standard calibration.

The filter CaT is a 150nm broad-band filter approximately centered on the Ca Triplet.

The filters Ha, HaC, OIII, OIIIC, SII, HeII, and HeIIC are narrow-band filters for H-alpha, H-alpha continuum, ionized oxygen, ionized oxygen continuum, ionized sulphur, ionized helium, and ionized helium continuum, respectively.

The filters GG455, OG515, RG610 and RG780 are 5mm thick Schott glass filters. These are long-pass filters which can be used to block 2nd-order contamination of the spectra or limit the wavelength range to allow multiple slit-banks in the multi-aperture mode.

Transmission curves based on lab measurements are available for the filters.

The table list the properties of the filters based on laboratory measurements. The wavelength interval given in the tables is the interval within which the transmission is larger than 50 per cent. For the long-pass filters and the filter z_G0328 the wavelength at the 50 per cent transmission at short wavelength edge is given.

Some of the filters can be combined; the allowed combinations are listed last in the table.

Imaging with GMOS requires use of a color filter (ugriz, CaT) or a narrow band filter. The long-pass filters GG455, OG515, RG610 and RG780 are not suitable for imaging. Also imaging without a filter is not available.

Users may supply their own filters for queue observations; see filter policy and specifications for details.


GMOS-S Filters
Broad Band Imaging Filters
G0332 u_G0332 350 336-385 data GMOS-S
G0325 g_G0325 475 398-552 data GMOS-S
G0326 r_G0326 630 562-698 data GMOS-S
G0327 i_G0327 780 706-850 data GMOS-S
G0333 CaT_G0333 860 780-933 data GMOS-S
G0328 z_G0328 >=925 >=848 data GMOS-S
Narrow Band Imaging Filters
G0340 HeII_G0340 468 464-472 data GMOS-S
G0341 HeIIC_G0341 478 474-482 data GMOS-S
G0338 OIII_G0338 499 496.5-501.5 data GMOS-S
G0339 OIIIC_G0339 514 509.0-519.0 data GMOS-S
G0336 Ha_G0336 656 653.9-660.0 data GMOS-S
G0337 HaC_G0337 662 658.1-664.9 data GMOS-S
G0335 SII_G0335 672 669.4-673.7 data GMOS-S
Spectroscopy Blocking Filters
G0329 GG455_G0329 >=555 >=460 data GMOS-S
G0330 OG515_G0330 >=615 >=520 data GMOS-S
G0331 RG610_G0331 >=710 >=615 data GMOS-S
G0334 RG780_G0334 >=880 >=780 data GMOS-S
Allowed Filter Combinations
  g_G0325 + GG455_G0329 506 460-552   GMOS-S
  g_G0325 + OG515_G0330 536 520-552   GMOS-S
  r_G0326 + RG610_G0331 657 615-698   GMOS-S
  i_G0327 + CaT_G0333 815 780-850   GMOS-S
  z_G0328 + CaT_G0333 890 848-933   GMOS-S

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