The Mosaic II imager, used at the Blanco 4-m prime focus, takes filters that are 146x146 mm and 12 mm (nominal) thick.
Focus offsets are referred to the R filter, since this is the filter we use for taking focus frames each night when the Mosaic is installed in order to monitor telescope performance.
We are (slowly) measuring these filters, let us know if there is any one you particular want to have us scan. Note that the Sloan set (griz) and the Johnson-Cousins BVR (but not I) sets should be near-identical to those at KPNO, see the KPNO Mosaic Filters.
A set of standardized filter names and IDs have been developed to ensure proper application of astrometric solutions and real-time display processing (as well as future archive uniformity). These official names are listed in the Mosaic filter list web page.
Filter center fwhm focus offset NOAO status
wavelength microns code
U 3570 650 -185 c6001 OK
B 4360 990 +10 c6002 OK
V 5370: 940: +30 c6026 from 21 Oct 2000
R 6440 1510 0 c6004 OK --- filter offset ref
I 8050 1500 +10 c6028 from 24 May 2003
VR Stubbs 6100 2000 0 c6027 transmission curve
aka VR Supermacho
C (Wash) 4000 1000 +260 c6006 OK
M (Wash) 5020 1020 +260 c6007 OK
D51 (DDO) 5130 154 -55 c6008 OK
[OII] 3727* 50 ? c6012 not tested yet
[OIII] 4990* 50 +130 c6014 OK
Halpha 6563* 80 +65 c6009 cwl,fwhm nominal
Halpha+8 6650* 80 -35 c6011 cwl,fwhm nominal
[SII] 6725* 80 +60 c6013 cwl,fwhm nominal
u (SDSS) 3600 400 +230 c6021 cwl, fwhm approx, Red Leak!
g (SDSS) 4813 1537 +30 c6017 "set #2" (in use 8/2000-)
r (SDSS) 6287 1468 +120 c6018 "set #2" (in use 8/2000-)
i (SDSS) 7732 1548 -20 c6019 "set #2" (in use 8/2000-)
z (SDSS) 9400 2000 -15 c6020 OK
Bj (Tyson) 4350 1650 ? c6024 #3, on loan from A. Tyson
I (Tyson) 8800 2000 ? c6025 cwl,fw approx
White 6500 5000 ? c6016 just a piece of fused silica
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Retired filters
g (SDSS) 4825 1380 ? c6015 "set #3", red cut-off a bit too red (in use < 8/2000)
V 5370 940 115 c6003 small chip in corner, in use < 10/2000
Bj 4350 1650 ? -- #1, broken...
Bj 4350 1650 ? -- #2, broken...
I 8050 1500 +25 c6005 Filter damaged Nov 2002 - the area covered by CCD-1 (SW corner) is unusable.
* = NOTE that the central wavelength of narrow band filters (actually all filters, but it is only significant for narrow band filters) is shifted ~15A to the BLUE in the f/2.87 beam of the Blanco 4m + PFADC corrector as compared to the transmission measured in parallel light. The central wavelengths quoted above are nominally for when the filters are used at PF, with the ~15A shift included.
Last updated: 2003 June 4 by C.Smith