The DEIMOS slitmask cassette has room for 11 masks, but since one slot is typically reserved for the focusing mask, only 10 are typically available for observer use. In addition to custom-designed user masks, the observatory maintains a set of standard masks for longslit observations and instrument focusing, as described below.

Mask Name Description DesID Barcode Status
Longslit Masks
LVMslitC Multiple slitlets (0.7, 0.8, 1.0, 1.2, 1.5 arcsec widths; all 20 arcsec long) on reflective mask. From left to right as seen on the guider are slits of width 1.5, 1.2, 1.0, 0.8, and 0.7. Identical to mask LVMslitB except that slits are shift by 10 arcsec toward the mask center in spatial direction to avoid bad columns. See notes on manufacturing this mask. 11725 10260 damaged, retired March 2017
9400 no shoulders, retired 2017-08-10
10810 damaged, retired 2017-08-17
10830 damaged, retired 2020-11-09
10840 active
LongMirr 0.7 arcsec wide × 205 arcsec long single slit on reflective mask 1684 11352 active
11353 spare
1218 damaged,retired
Long0.7 0.7 arcsec wide longslit, consisting of 12 separate slitlets, each 82 arcsec long, with a small gap or "bridge" in between in order to prevent the slit from buckling. 523 4948 damaged, retired
7357 damaged, retired
9120 damaged, retired
9645 active
9800 spare
Long0.8 0.8 arcsec longslit, consisting of 12 separate slitlets, each 82 arcsec long, with a small gap or "bridge" in between in order to prevent the slit from buckling. 524 7441 active
7371 spare
Long1.0B 1.0 arcsec longslit, consisting of 12 separate slitlets, each 82 arcsec long, with a small gap or "bridge" in between in order to prevent the slit from buckling. 525 7358 retired
9090 retired
10150 retired
10141 active
10140 spare
10139 spare
Long1.2 1.2 arcsec longslit, consisting of 12 separate slitlets, each 82 arcsec long, with a small gap or "bridge" in between in order to prevent the slit from buckling. 526 4311 retired
1090 retired
7359 active
Long1.5 1.5 arcsec longslit, consisting of 12 separate slitlets, each 82 arcsec long, with a small gap or "bridge" in between in order to prevent the slit from buckling. 527 7069 retired
11351 active
NONE spare
LVMslitB Multiple slitlets (0.7, 0.8, 1.0, 1.2, 1.5 arcsec widths; all 20 arcsec long) on reflective mask. From left to right as seen on the guider are slits of width 1.5, 1.2, 1.0, 0.8, and 0.7.   7542 retired, superseded by LVMslitC
LongSlit 1.0 arcsec longslit   1982 retired
LongA 1.0 arcsec longslit   1891 scratched up, retired
Long1.0 1.0 arcsec longslit   488 retired?
LngVrMir Multiple slitlets (0.7, 0.9, 1.1, 1.5 arcsec widths; all 20 arcsec long) on reflective mask
From left to right as seen on the guider are slits of width 1.5, 1.1, 0.9, and 0.7.		   1556 retired
Focusing Masks
GOH_X (GOH_foo) Grid of pinholes through mask, imaging focus mask.
This is the mask typically used for focusing DEIMOS in the afternoon.		 448 487 retired
2124 retired
2125 retired
10160 active
10180 active
spare
GOSpH Grid of spectral holes; spectroscopy focus mask.
This mask is used only for engineering purposes.		 6741 6205 retired
6206 active
6207 spare
GOH_TV Grid of holes not quite drilled through the mask, intended for helping determine TV focus   1926 obsolete; retired
GOSpH3 Grid of spectral holes; spectroscopy focus mask   1966 obsolete, retired
GOH_X Grid of pinholes through mask, imaging focus mask   1927 damaged, retired
GOH_foo Grid of pinholes through mask, imaging focus mask   486 damaged, retired
GOSpH Grid of spectral holes; spectroscopy focus mask   1930 retired
GOSpH2 Grid of spectral holes; spectroscopy focus mask   1977 retired

See Also