CTIO 5.75 x 5.75 -inch FILTERS



The Mosaic II imager, used at the Blanco 4-m prime focus, takes filters that are 146x146 mm and 12 mm (nominal) thick. A set of standardized filter names and IDs for both Mosaic I on the KPNO Mayall and Mosaic II on the CTIO Blanco 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.

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.

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.

Note: The central wavelength of narrow band filters (actually all filters, but it is very 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 quoated below are nominally for when the filters used at PF, with the ~15A shift included.  Furthermore,
the filter transmission curves presented below show the simulated filter tranmission curve for the Blanco 4m + PFADC f/2.87 beam.

Note: The Blanco prime focus corrector has poor response in the UV: 90% (4000A), 85% (3800A), 74% (3650A), 54% (3500A), 31% (3400A), 11% (3350A), 0% (3300A). These are calculations from the glass types and AR coating specifications, and the figures for 3300-3400A are rather uncertain. YOU STRONGLY ENCOURAGED TO USE THE u(SDSS) filter rather than the U filter. Neither of these filters, in combination with the CCDs and optical corrector, match the standard passbands perfectly. The U filter uses a (troublesome!) copper sulphate solution as red blocker, whereas the SDSS u filter is an interference filter.


Filter Central
Wavelength (Å)
FWHM
(Å)
Focus Offset
(μm)
NOAO
Code
Status
Transmission
Curve
Transmission
Table
U 3570 650 -185 c6001 OK
c6001.ps
c6001.jpg
c6001.txt
B
4360
990
+10
c6002
OK
c6002.ps
c6002.jpg
c6002.txt
V
5370
940:
+30
c6026
from 21 Oct 2000
c6026.ps
c6026.jpg
c6026.txt
R
6440
1510
0
c6004
OK; filter offset ref
c6004.ps
c6004.jpg
c6004.txt
I
8050
1500
+10
c6028
from 24 May 2003
c6028.ps
c6028.jpg
c6028.txt
VR Stubbs
(aka VR Supermacho)
6100
2000
0
c6027
OK
c6027.ps
c6027.jpg
c6027.jpg (OLD)
c6027.txt








C (Wash)
3850
1075
+160
c6029
from 05 Jan 2011
c6029.pdf
c6029.jpg


M (Wash)
5115
1375
+210
c6007
OK
c6007.ps
c6007.jpg
c6007.txt

D51 (DDO)
5130
154
-55
c6008
OK
c6008.ps
c6008.jpg
c6008.txt









[OII]
3727
50
?
c6012

c6012.ps
c6012.jpg
c6012.txt
[OIII]
4990
50
+130
c6014
OK
c6014.ps
c6014.jpg
c6014.txt

6563
80
+65
c6009
cwl, FWHM nominal
c6009.ps
c6009.jpg
c6009.txt
Hα+80
6650
80
-35
c6011
cwl, FWHM nominal
c6011.ps
c6011.jpg
c6011.txt
[SII]
6725
80
+60
c6013
cwl, FWHM nominal
c6013.ps
c6013.jpg
c6013.txt








u (SDSS)
3600
400
+230
c6022
cwl, FWHM approx,
replacement for c6021, NO RED LEAK
c6022.ps
c6022.jpg
c6022.txt
g (SDSS)
4813
1537
+30
c6017
"set #2" (in use 8/2000-)
c6017.ps
c6017.jpg
c6017.txt
r (SDSS)
6287
1468
+120
c6018
"set #2" (in use 8/2000-)
c6018.ps
c6018.jpg
c6018.txt
i (SDSS)
7732
1548
-20
c6019
"set #2" (in use 8/2000-)
c6019.ps
c6019.jpg
c6019.txt
z (SDSS)
9400
2000
-15
c6020
OK
c6020.ps
c6020.jpg
c6020.txt








Bj (Tyson)
4350
1650
?
c6024
#3, on loan from A. Tyson
c6024.ps
c6024.jpg
c6024.txt
I (Tyson)
8800
2000
?
c6025
cwl, FWHM approx
c6025.ps
c6025.jpg
c6025.txt








White
6500
5000
?
c6016
Fused Silica




RETIRED Filters

Filter
Central
Wavelength (Å)
FWHM
(Å)
Focus Offset
(μm)
NOAO
Code
Status
Transmission
Curve
Transmission
Table
g (SDSS)
4825
1380
?
c6015
"Set #3",red cut-off
a bit too red (in use < 8/2000)


C (Wash)
3850
1075
+260
c6006
some fine scratches on the anti reflection coating
c6006.ps
c6006.jpg
c6006.txt

V
5370
940
115
c6003
small chip in corner (in use < 10/2000)
c6003.ps
c6003.jpg
c6003.txt
Bj
4350
1650
?
--
#1 broken...


Bj
4350
1650
?
--
#2 broken...


Old I
8050
1500
+25
c6005
Filter damaged Nov 2002
Area covered by CCD-1 (SW corner)
is unusable.
c6005.ps
c6005.jpg
c6005.txt



Kitt Peak Filters Frequently Used with Mosaic 2

Filter
Central
Wavelength (Å)
FWHM
(Å)
Focus Offset
(μm)
NOAO
Code
Status
Transmission
Curve
Transmission
Table
wrc3 WR CIII
4666.15
51.71
+75
k1021
OK
k1021

wr475 WR 475
4764
51.27
+60
k1022
OK
k1022

wrhe2 WR HeII
4702.6
50.31
+80
k1023
OK
k1023


Last updated: 2011 Nov, AMK

Staff Contacts:
Sean Points: spoints@ctio.noao.edu
Andrea Kunder: akunder@ctio.noao.edu
Alistair Walker: awalker@ctio.noao.edu