MOIRCS Filters
Available Filters
The following table lists the broad-band filters currently installed in MOIRCS, together with their estimated sensitivities. The transmission curves of each filter are from the data sheets supplied by the company. Estimated sensitivities listed are for a 5 sigma detection in 1 hour of integration, assuming good (0.5'') seeing and a moderately dark sky (Please see the Exposures page) . Point sources are measured in a 1.0'' diameter aperture. Extended source sensitivities are per pixel.Broad-Band Filters
| Filter | Wavelength [um] | Sensitivity (Vega magnitude) | mag for 1 e-/s |
||||
|---|---|---|---|---|---|---|---|
| Name | Plot | List | Centre | Width | [mag] | [mag/pixel] | |
| Y(Note2) |  |
 |
1.02 | 0.10 | --- | --- | --- |
| J |  |
|
1.26 | 0.17 | 23.6 | 25.9 | 26.0 |
| H |  |
|
1.64 | 0.28 | 22.5 | 24.8 | 26.2 |
| Ks(Note3) |  |
|
2.14 | 0.31 | 22.6 | 24.8 | 25.5 |
| K (Note4) |  |
|
2.20 | 0.40 | --- | --- | --- |
Note 1: The Imaging Exposure Time Calculator is available. Please note that the Imaging ETC does not calculate the entire overhead time accurately. You can instead calculate the accurate overhead time using the overhead calculator (Excel format). It is available in the "Guide to Imaging Exposure Times" page.
Note 2: The Y broadband filter is newly installed in July 2007. However the detail of the performance is still not well determined yet due to very limited engneering time. Therefore, the use of the filter may still be under the shared-risk policy during S08B.Note 3: The new Ks-band filter is available since S08A. This new Ks-filter uses the wedged filter substrate to supress the fringe pattern caused by the parallel-plane interference of OH lines in the filter. However, the overall performance is also not well tested yet, due to the same reason as Y filter. The use of the filter may also be under the shared-risk operation during S08B.
Note 4: Though the main purpose of the standard (Johnson) K filter is the order sorting of R1300 grism, it is also available for imaging. The filter, however, cannot take the dome-flat data, because the thermal emission from dome itself is already too bright.
Narrow-Band Filters
Three narrow-band filters (H2v=1-0, [FeII], NB119, and K-continuum) are available for imaging observation. The central wavelength(CW) and the bandwidth (BW: defined by FWHM) of H2, [FeII], and NB119 filters are each 2.116/0.021 um, 1.6444/0.026 um, and 1.1885/0.0141 um, respectively. For K-continuum filter the CW and the BW are slightly different among channel 1 and 2. For channel 1 the CW and the BW are 2.238 and 0.064 respectively, and for channel 2 they are each 2.257 and 0.061, respectively. The peak transmittance of these NB filters are all roughly 80 to 90%.
The actual value of the CW for these filters will slightly shift across the field of view, because the transmission curve moves as a function of the angle of incidence. The CWs described above are all the value at the center of the optics; i.e. around the center of each channel. If you need more information about the detail, please contact to the Support Astronomer.
Note that the background level of NB119 filter is very dark. Minimum exposure of ~30 minutes is sometimes required to reach the background-limited case. Sky subtraction is generally difficult due to the change of the background.
User Filters
We are accepting the user filters since S07A. The detail and the user filter policy can be found in information page. Currently the number of vacant turret slot is very limited.Please note that all data on these pages are subject to change as the evaluation of the performance of MOIRCS progresses.
Created by Yuka Katsuno Uchimoto (Feb 2006)
Revised by Ichi Tanaka (2008-02-06)