The information on this page is for quick reference. Please consult the LMI Users Manual for more detailed information, including filter transmission curves and data.

LMI Filters:

Currently available filters for LMI are given in the table below. 

  • The value shown under FITS Header will appear in the FILTERS keyword of your image headers. 
  • The Pattern String is the LOUI display string you need to use if creating a Telescope Motion Pattern File.  
  • Focus Offset indicates how much additional focus offset is applied to the Active Optics System to account for filter refraction – it is most helpful for determining which filters are parfocal.
  • For taking dome flats (using the CLSD lamps at 12V), an approximate Exptime for 20k counts is provided.  For the bluest filters (both broad- and narrow-band), the usual "LMI Lamps" do not provide sufficient flux in the bandpass to easily collect dome flats.  For these, a second exposure time is listed using the Photo Floods (a.k.a. IGRINS lamps) on the lamp boom.  These are 600-W photographic flood lamps with very short lifetimes – please use sparingly.
  • For selected filters, the Central Wavelength and Filter Width (both in Å) are listed.

Sample dome flats for the various filters taken over time can be found on the LMI Filter Characterization page.


Filter

FITS Header

Value

Pattern

String

Focus 

Offset

(µm)

Exptime for

20k counts

(seconds)

Filter

Central

Wavelength (Å)

Filter

Width (Å)

Non-Filter Positions
OPENOPENOPEN0


DARKDARKDARKN/A


4 Hole Mask4HOLEMASK4Hole



Johnson-Cousins Filters
UUU+140178 / 4*

BBB+1059

VVV+1055

RRR+1403.5

III+1403.3

Sloan (SDSS) Filters
SDSS u'SDSS-USL-u

+180

313 / 4.5*

SDSS g'SDSS-GSL-g+1804.5

SDSS r'SDSS-RSL-r+1803.5

SDSS i'SDSS-ISL-i+1804.25

SDSS z'SDSS-ZSL-z+1803.25

Other Broad Band Filters
V+RVRVR+1856091.71763.9
YishYISHYISH+10526

General Narrow Band Filters

[OIII]

OIIIOIII+2051805001.725.5
Hα-OnHALPHAONHa-on+1551156564.930.1
Hα-OffHALPHAOFFHa-off+155376459.1114.6
Wolf-Rayet Filters
WCWR-WCWC+1651154660.449.5
WNWR-WNWN+160
4690.949.6
CTWR-CTCT+170
4756.154.6
Comet Filters  (Note: These filters are 4 inches round and suffer some vignetting on LMI)
Ultraviolet ContinuumUCUC+175500** / 80*344979
Blue ContinuumBCBC

+175

130 / 3.5*445361
Green ContinuumGCGC+175119525956
Red ContinuumRCRC+17570713358
C2C2C2+175465135119
C3C3C3+175406358
CNCNCN+175480 / 14*386956
CO+CO+CO++175160426664
H2O+H2O+H2O++175
7028164
OHOHOH+175480** / 400*309758
NHNHNH+175
336154
Assorted Other Filters (inquire if you want to use, as they may not be readily available)
W032W032W032+176
5300
502750275027+130
5027
K1593K1593K1593+194
5010

** OH & UC counts were at about the bias level for this exposure time using the CLSD lamps at 12V.

* Using the photo floods (a.k.a. IGRINS lamps) on the LMI lamp boom

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