FMOS Spectrum Simulator
This calculator is still under development and results are subject to
change as the performance and characteristics of the instrument are
- (1) When you select one of the stellar
spectra as a template, this parameter is automatically set to
- (2) For "Milky Way", "LMC" & "SMC"
extinction curves, the analytic formulas by Pei (1992, ApJ, 395,
130) are used. If you select "Starburst", the analytic
formula by Calzetti et al. (2000, ApJ, 533, 682) is applied.
RV (= AV/E(B-V)) is assumed 3.1 for
the "Milky Way" and "LMC", 2.72 for
"SMC", and 4.05 for "Starburst".
- (3) This defines the total
magnitude of your target.
- (4) In "Additional lines", you can
add artificial emission/absorption lines on the selected
continuum spectrum. The line profile is assumed to be a Gaussian.
(No saturation effect is taken into account while it is likely to
be important for deep absorption lines. If the intensities are
calculated to be negative in a part of the line profile, they are
replaced with a very small positive value).
- (5)The differences between IRS1 and IRS2
on this simulator are only the readout noise of the detector and
conversion factor (e-/ADU). The throughputs are assumed to be the
- (6) The throughput data used inside this
simulator include the "best" estimate of the flux loss at the
fiber entrance for point sources. This mainly comes from the
spectra of relatively bright stars obtained in the engineering
observations. The data of faint galaxies tend to indicate more
loss, although they also show a large scatter due perhaps to the
intrinsic variety in their size & morphology as well as the
measurement error in the estimation). If you want to assume an
additional loss of flux from the fiber aperture, you can set a
non-zero value in percent (%) here. For example, input "50" if
you try to estimate feasibility when only half of the flux falls
onto the fiber (i.e. twice more is lost) compared with the "best"
- (7) The resolving power and dispersion
of Low Resolution Mode are ∼ 500 and 5 A /
pixel, respectively. For
High Resolution Mode, they are ∼ 2200 and 1 A /
- (8) The size of a re-imaged fibre core is
∼ 5 pixels in FWHM on the detector. Therefore 5 pixels
in dispersion direction approximately corresponds
to a spectral resolution element (∼ 25 A in Low Resolution
Mode and ∼ 5 A in High Resolution Mode). An 8 pixels aperture
is assumed in all calculations to extract a fiber spectrum from
an image on the detector.
- (9) The spectral coverage of FMOS is
0.9 -- 1.8 μm, and this is entirely covered by a single
exposure in LR. In HR, this is divided into 4 bands: J-short,
J-long, H-short, and H-long. If you choose Auto, the
entire region of each band is presented as a result of
simulation. Note that there will be no useful data at 1.35 - 1.40
microns because the fiber slit blocks the part of the primary
spectra formed on the mask mirror.
Questions and comments regarding this page should be directed to
Kentaro Aoki ( ).
Last updated: Jan 31, 2012
Copyrightę 2000-2012 Subaru Telescope, NAOJ. All rights reserved.