EFOSC2 

ESO Faint Object Spectrograph and Camera
   
EFOSC2 Imaging Filters
Filters are located on the filter wheel which lies in the parallel beam (after the collimator). Up to 11 filters can be mounted on the wheel. Of these, one should be a Free position which is necessary for spectroscopy.

In principle, filters should not, and in fact most do not, change the focus of the instrument. Some of the Stromgren and interference filters may necessitate a refocus.

The filter wheel is located at a relatively large distance from the focal plane and so filter defects have a considerable effect on the image quality. Observers should keep this in mind while bringing their own filters.

The maximum dimension which can be accommodated on the filter wheel is a diameter of 60mm and thickness of 10mm. Please note that the filter and the grism wheels are located very close to each other and so there is very little possibility of squeezing in larger filters.

The basic EFOSC2 filter set is listed below. The entire filter set for La Silla may be obtained by invoking in Midas:

> create/gui filters

The La Silla filter database can also be queried at the following URL: 

http://filters.ls.eso.org/

which can be reached from the Observatory front page. Many (but not all) of these can be mounted on the EFOSC2 filter wheel. In particular you should look for filters with 60mm diameter.

Important  Users who either wish to use one of the filters not in the basic EFOSC2 list (either an ESO filter or one of their own) should contact the telescope support team well in advance of their run to make sure that their needs can be met.
 

The EFOSC2/3.6m Basic Set

 
Filter Name
ESO Numbers
Central 
Wavelength
(nm)
FWHM
(nm)
Peak 
Transmission
(%)
Red Leak
Transmission Curve1
Current
EFOSC2 @2.2m
EFOSC1 @3.6m
       
U Bessel 
#640
#631
#630
354.5
53.8
68
<0.005%  @1100nm
eso0640.gif
B Bessel 
#639
#583
#552
440.0
94.5
54
  0.012%  @1150nm
eso0639.gif
V Bessel 
#641
#584
#553
547.6
113.2
87
0.055%   @1150nm
eso0641.gif
R Bessel 
#642
#585
#554
643.1
165.4
86
0.076%   @1150nm
eso0642.gif
Gunn g 
#782
#616
#612
516.9
77.6
81
0.010%   @1100nm
eso0782.gif
Gunn r 
#786
#617
#613
681.4
83.8
83
0.010%   @1100nm
eso0786.gif
Gunn i 
#705
#618
#614
793.1
125.6
83
0.010%   @1100nm
eso0705.gif
Gunn z 
#623
#619
#615
> 840.0 
-
98
-
eso0623.gif
H Alpha 
#692
#694
#691
657.7
6.2
56
<0.010% 
eso0692.gif
H Alpha Red 
#709
#698
#756
664.5
7.1
88
-
eso0709.gif
H Beta 
#742
#746
#744
-
-
-
-
eso0742.gif
Hbe Cont 
#743
#747
#745
-
-
-
-
eso0743.gif
[OIII] 
#687
#689
#686
500.4
5.6
74
-
eso0687.gif
[SII] 
#700
#702
#699
673.0
6.2
56
<0.010% 
eso0700.gif
Tyson B 
#724
  - 
   - 
-
-
-
-
eso0724.gif
1 In some of the graphs they are labelled SUSI, but in fact the curves are instrument independent.
 

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