Selecting Filters
From the Main Menu of the TCS.
Select:
- 5 GAM Menu
- 1 Set Motor Position
- Motor: 3
- Position: 1 to 6, depending
on filter required as listed above
- Any Changes: N
After about 30 seconds or less, the filter wheel will have rotated into
position. The status of the filter wheel is given in the lower left box
on the TCS monitor. It will read M3=# and the number
should equal the one you selected. The exception is for filter 1,
which is selected as filter 1 but is reported as 0. Ask DFM about
that one.
Wide-Band Filters
We have the standard astronomical series of filters: U-B-V-R-I. When in
use, please keep the wide-band filters in the filter wheel position
listed below:
| Filter |
Filter Wheel Position |
Spectral Range |
Peak Transmission |
Range Width |
| Clear |
1 |
2900 - 8500 |
98% |
5600 |
| Ultraviolet |
2 |
3100 - 3900 |
65% |
800 |
| Blue |
3 |
3800 - 4800 |
70% |
1000 |
| Visible |
4 |
4800 - 5800 |
80% |
1000 |
| Red |
5 |
5300 - 7000 |
80% |
1700 |
| Infrared |
6 |
7200 - 10040 |
90% |
2800 |
Narrow-Band Filters
There are 20 narrowband filters and each has a full width of 10 nm.
These are the filter's central wavelength in nm
| OII |
H beta/OIII |
H alpha |
| 380 |
486 |
656 |
| 390 |
490 |
660 |
| 400 |
500 |
670 |
| 410 |
510 |
680 |
|
520 |
690 |
|
530 |
700 |
|
540 |
710 |
|
550 |
720 |
The filters are 50 mm circular interference filters. Peak transmission
in the bandwidth is about 70% and transmission outside the
bandwidth is 10-4.
Location of the Filters
The narrow-band filters and
wide-band filters
are located in two white boxes with orange labels on them in the
first cabinet from the door to the control room. There is a filter installation tool (to
put
in and take out the narrow-band filters
filters),
and the metal filter holders. The
filters themselves come in
plastic cases in small square boxes. There should also be a box of purple
nitrile powderless gloves in the same cabinet (if there is not, Please tell someone).
Preparing the Narrow-Band Filters for Use
- Put on a pair of purple nitrile gloves; it is very important to wear them whenever
handling the filters because hand oils will destroy the filter.
- Find the desired filter in the white box. There are labels on
the side of the filter box and also printed on the side of the filters;
the first 3 numbers after P/N: gives the wavelength in nanometers.
- ex. P/N: 656FS10-50 is the label for the H alpha 656 filter.
- Use a phillips head screwdriver to take the 3 screws in the filter
holders out.
- There are 6 metal filter holders for the narrow band
filters. The filter wheel holds square filters, however, the
narrow band filters are round. These
holders allow the narrow band filters to be placed securely in the
filter wheel. The metal holders have 4 holes, but only 3 screws
holding the two pieces together. The last hole is larger than the other
3 and used for the installation tool.
- Take the top piece off and put the filter into the bottom
piece. One side of the filter is reflective and the other
transparent; make sure the reflective side is face up in the holder.
- Put the top piece on, replace the 3 screws in the opening they came
out of.
- Screw the end of the tool in the hole. The tool is needed to
put the filters in the wheel because it is a tight fit.
Follow these instructions for inserting and removing filters from the filter wheel.