CTIO 5.75X5.75-inch Filters

A. Walker 18 Dec 2002

 

The Mosaic II imager, used at the Blanco 4-m prime focus, takes filters that are 146x146mm and 12mm (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
wavelegth		 fwhm focus offset
microns		 NOAO
code		 Status
      
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
aka VR
Supermacho		 6100 2000 0 c6027 transmission curve
      
C (Wash) 4000 1000 +260 c6006 OK
M (Wash) 5020 1020 +260 c6007 OK
D51 (DDO) 5130 154 -55 c6008 OK
      
[OII] 3727* 50 ? c3012 not tested yet
[OIII] 4990* 60 +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, fwhm approx
           
White 6500 5000 ? c6016 just a piece
of fused silica

 
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 ? -- broken...
Bj 4350 1650 ? -- broken...
I 8050 1500 +25 c6005 Filter damaged
Nov 2002-
The are civered 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 aprox. 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 aprox. 15A shift included.

 

Last updated: 2003 June 4 by C.Smith

Staff Contacts:
Alistair Walker: awalkerATnoao.edu
Chris Smith: csmithATnoao.edu