Filter Notes

As of September 2009, the standard for moving filters in NIRSPEC is to use the "filt" or "filter" commands from the command line. Previous observing scripts used the "fil1pos" or "fil2pos" keywords. These keywords still exist and should work when NIRSPEC is on RNAS (non-AO); however, the "filt"/"filter" combination is recommended.

The shell script "filter" uses the index positions as defined in the table below to move the two filter wheels. For instance, to use the KL filter, one types "filter 5 11" to move filter 1 to position 5 (KL) and filter 2 to position 11 (OPEN). To use the NIRSPEC-7 with the thin blocker (standard), one types "filter 1 6".

The shell script "filt" is a higher level script that interprets filter names then calls the "filter" script. To use the KL filter, one types "filt kl". The script knows to send filter 2 to the OPEN position when NIRSPEC is non-AO and knows to send filter 2 to the AO STOP when NIRSPEC is behind AO. To use NIRSPEC-7 with the thin blocker, one types "filt n7" or "filt n7 thin".

Position Motor Steps Filter 1 Filter 2
0 0 OPEN NIRSPEC-1¹
1 9000 THIN NIRSPEC-2
2 18000 AO-STOP NIRSPEC-3
3 27000 L-PRIME NIRSPEC-4
4 36000 M-PRIME NIRSPEC-5
5 45000 KL² NIRSPEC-6
6 54000 HeI NIRSPEC-7²
7 63000 Pa-Beta AO-STOP³
8 72000 FeII CO
9 81000 H2 K
10 90000 M-wide K-PRIME
11 99000 BLANK¹ OPEN

Footnotes

  1. Primary initialization position
  2. Secondary initialization position
  3. AO-STOP replaced Br-Gamma in September 2009

Other Notes