NEWFIRM Filters

Currently Installed Filters

GUI Button Name

FW1 (upper)
Position
FW2 (lower)
Position
FW1
Serial #
FW2
Serial #
JX 8 1 ---- 2104
HX 8 2 ---- 3104
KXs 8 3 ---- 4103
1187 5 1 2302 2104
2096 6 3 4304 4103
[Fe II] 2 6 3301 3302
2124 3 4 4301 4303
Br γ 4 4 4302 4303
J1 1 5 2201 2202
1066 8 7 ---- 1404
Dark 7 8 ---- ----

 

Filter Availability and Change Policy

There exist more NEWFIRM-specific filters than can be accommodated in the Dewar at one time.  NEWFIRM has two filter wheels, each with 7 slots for filters.  Some of the filters must be used with a blocking filter (i.e., two slots must be used). It takes a minimum of five weeks to change filters (instrument warm-up, change filters, cool-down).  The availability of filters in any given semester will depend on decisions that only can be made after the TAC meets and has provided it raked list of programs.

Changing filters is a time-consuming procedure that removes NEWFIRM from service and does result in some risk to the filters and instrument. Hence, decisions on the filter complement involve balancing scientific rankings of individual proposals, the overall scientific output achievable in any semester, other scheduling concerns, and the health of the instrument.

Filter Identification and Properties List

  • This list compiles identifications and basic bandpass properties for all filters produced for NEWFIRM and in our possession.  Prior to recommissioning NEWFIRM on the CTIO 4-m Blanco telescope, some filters required permission of the filters' owners for use by general observers.  As of recommissioning, all NEWFIRM filters can be used by NEWFIRM observers without permission from their owners.  The owners request that general observers using these filters cite their work (details below).
  • The term "filter" here means a single piece of glass.  NEWFIRM science bandpasses often require two pieces of stacked glass in series, one in each filter wheel.  One piece defines the bandpass and the second provides longwave out-of-band blocking for the InSb arrays.  Definition of these combinations, and the complement of filters used in NEWFIRM at various times can be found in separate documents.
  • Serial numbers: each piece of glass is assigned a unique four digit number according to the following scheme:
    • Filter number XYab
      • X designates the band from 1 to 4
      1. 1 micron band window, shortward of the J window
      2. J window, 1.2-1.4 microns
      3. H window, 1.5-1.8 microns
      4. K window, 2.0-2.4 microns
      • Y designates the spectral resolution R = (λ0 / Δλ)
      1. broadband, 4 < R < 10
      2. intermediate band, 10 < R < 50
      3. narrow band, 50 < R < 100
      4. ultranarrow band, R > 100
      • ab together are a running number from 01 to 99, generally assigned according to the order of delivery of the filters from vendors. 
  • The resolution and order-of-receipt criteria are not strictly applied, in order to group together bandpass-defining filters and out-of-band blockers that form natural sets.
  • Filter names: these are logical and convenient identifiers used in the filter wheel GUI.  Alternative names used previously at various times are given for completeness, but future use of these alternatives is discouraged.

 

Serial

Number

Name Alternative Names

Bandpass properties

λ0, bandwidth (nm)

(65 K, 0 deg incidence)

 

Use with
14011 1056 nm  1056  1056.37, FWHM 0.74 1403
14021 1063 nm  1063  1063.09, FWHM 0.81 1403
1403

1060
blocker

 1 μm blocker, 1056 +
 1063 blocker

 1063.5, OD 1 @ 994, 1133
 (room temperature)
1401, 1402
14041

1066

 

 1066, FWHM 0.35  
2101 J 241*    1246, FWHM 158 2103
2102 J 253    1252, FWHM 158 @ 5 deg
 incidence
2103
2103

 J
blocker

   1322, FWHM 533 2101, 2102
2104 JX      
22012 J1  Yale J1  1048.4, FWHM 160.6 2202
2202

J1
blocker

 Yale J1 blocker 1097, FWHM 321 2201
22032 J2  Yale J2  1190.3, FWHM 152.8 2205
22042 J3  Yale J3  1283.7, FWHM 151.6 2205
2205

J2+J3
blocker

 Yale J1 + J2 blocker  1272, FWHM 442 2203, 2204
2301

1187
test*

 (returned to vendor

 05 Feb 2008)

 1190.2, FWHM 11.6 2104
23023 1187 nm  1187, 1.19 μm continuum  1186.4, FWHM 11.1 2104
3101 H 127    1627, FWHM 286 3103 or 3203
3102 H 133*    1634, FWHM 286 3103 or 3203
3103

H + K
blocker

   2030, FWHM 1320 3101, 3102
3104 HX    1631, FWHM 308  
32012 H1  Yale H1  1555.7, FWHM 174.7 3203
32022 H2  Yale H2  1705.9, FWHM 168.3 3203
3203

H1 + H2
blocker

Yale H1 + H2 blocker  1622, FWHM 472

3101, 3102,

3201, 3202

3301 1644 nm  1644, 1.64 μm [Fe II]  1649.1, FWHM 17.2 3302
3302

1644
blocker

 [Fe II] blocker  1593, FWHM 451 3301
4101 Ks 313*    2128, FWHM 315 3103
4102 Ks 318    2129, FWHM 312 3103
4103 KXs    2150, FWHM 320  
4301 2124 nm  2124, 2.12 μm H2  2131.9, FWHM 24.0 4303
4302 2168 nm  2168, 2.16 μm Brγ  2177.0, FWHM 24.4 4303
4303

2124 + 2168
blocker

 2 μm blocker  2165, FWHM 257 4301, 4302
43043 2096    2096, FWHM 20.4  

* These filters have never been used in NEWFIRM.
1 There are no restrictions for community use of these filters. If used, please (a) send a brief email to the owners, James Rhoads (james.e.rhoadsATnasa.gov) and Sangeeta Malhotra (Sangeeta.MalhotraATasu.edu) describing the project and (b) cite Coughlin et al. 2018, ApJ, 858, 96 in your publications.
2 There are no restrictions for community use of these filters. If used, please cite van Dokkum, P.G, et al. 2009, PASP, 121, 2
in your publications
3 There are no restrictions for community use of these filters.

 

Updated on September 5, 2023, 12:52 pm