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Data table for comparison of JWST spectroscopic sensitivity to other observatories. v1.2, 1/2013

# Data table for comparison of JWST spectroscopic sensitivity to other observatories. 
# v1.2, 1/2013, by Jane Rigby. 
# If you have comments or questions, please write to Jane.R.Rigby@nasa.gov
# Columns are:  
#  (1) name of filter and/or band
#  (2) wavelength (micron)
#  (3) limiting line flux (W/m^2) that can be detected in a point source at 10 sigma in 10^4 s.
#  (4) Resolution R, where R= lambda / (delta lambda)
#  (5) Code for instrument/observatory.
#        0=nirspec, 1=NIRCAM, 2=MIRI, 4=HST, 5=WISE, 6=Spitzer, 9=Keck, 10=gemini, 11=VLT, 12=sofia, 13=TMT, 14=ELT
#  (6) Reference for the sensitivity.  For JWST, the requirement document is given.  For other observatories, 
#      the calculation method is given.
#
#instr  wave(um)  lineflux(W/m^2) R code reference
miri    6.4       0.79E-20    2400   2   Appendix C of JWST-RQMT-2063
miri    9.2       1.0E-20     2400   2   ISIM-153; also Appx 3 of JWST-RQMT-2063
miri    14.5      1.2E-20     1600   2   Appendix 3 of JWST-RQMT-2063
miri    22.5      5.6E-20     1200   2   ISIM-153
miri    22.5      6.0E-20     1200   2   Appendix C of JWST-RQMT-2063  [Disagrees w above]
#
nirspec 2.0       1.8E-21     2700   0  ISIM-153, scaled by sqrt(10^4s/10^5s)

# NIRCam grisms
#src    wave(um) lineflux(W/m^2)  R        flg  source   
F277W  2.77      8.8E-21    1000            1    Table 3 of Greene et al. 2007 SPIE, scaling S/N=5 to S/N=10
F332W  3.22      9.4E-21    1000            1    Table 3 of Greene et al. 2007 SPIE, scaling S/N=5 to S/N=10
F356W  3.56      6.2E-21    1000            1    Table 3 of Greene et al. 2007 SPIE, scaling S/N=5 to S/N=10
F410M  4.10      5.0E-21    1000            1    Table 3 of Greene et al. 2007 SPIE, scaling S/N=5 to S/N=10
F444W  4.44      9.0E-21    1000            1    Table 3 of Greene et al. 2007 SPIE, scaling S/N=5 to S/N=10

#
Keck   1.8       7E-20          1000  9    Scaled from Erb et al 2006
#
Gemini  1.25     1.9E-19        1000  10  NIRI Gemini website
Gemini  1.65     6.5E-20        1000  10  NIRI Gemini website
Gemini   2.2     7.3E-20        1000  10  NIRI Gemini website
#
ISAAC    1.25    2.2E-19       3000   11   ISAAC on VLT, ETC, SW MRes
ISAAC    1.65    2.9E-19       3000   11   ISAAC on VLT, ETC, SW MRes
ISAAC    2.0     1.8E-19       3000   11   ISAAC on VLT, ETC, SW MRes 
ISAAC    3.55    13E-19        2000   11   ISAAC on VLT, ETC, LW MRes
ISAAC    4.50    160E-19       2000   11   ISAAC on VLT, ETC, LW MRes
#
# Spitzer/IRS:
IRS-SH   10.5   7.7E-19       600  6  ETC
IRS-SH   12.5   5.8E-19       600  6  ETC
IRS-SH   15.0   5.4E-19       600  6  ETC
IRS-SH   17.    5.7E-19       600  6  ETC
IRS-SH   19.0   7.7E-19       600  6  ETC
IRS-LH   21.0   1.3E-18       600  6  ETC
IRS-LH   22.0   1.0E-18       600  6  ETC
IRS-LH   25.0   8.3E-19       600  6  ETC
IRS-LH   30.0   9.8E-19       600  6  ETC
#
sofia-flitecam  1.25  9.6E-19  1700 12  converted from ETC
sofia-flitecam  1.65  1.0E-18  1700 12  converted from ETC
sofia-flitecam  2.2   5.4E-19  1700 12  converted from ETC
sofia-flitecam  3.55  3.8E-18  1700 12  converted from ETC
sofia-flitecam  3.76  4.9E-18  1700 12  converted from ETC
sofia-flitecam  4.75  1.7E-17  1700 12  converted from ETC


TMT-IRMS  1.0  4.2E-22  3270  13   # Table 5.1 of TMT Detailed Science Case 2007.  Assumes AO, and bkg between-OH-lines.
TMT-IRMS  1.2  4.4E-22  3270  13
TMT-IRMS  1.6  2.8E-22  3270  13
TMT-IRMS  2.2  5.1E-22  3270  13

#
#
# Further description of where these numbers come from:
# The JWST spectroscopic requirements use a variety of different units (W/m^2; W/m^2/Hz), a variety
# of integration times, and compute either limiting lineflux or continuum sensitivity,
# depending on resoln. and science case.  For this plot, let's standardize to a 10 sigma detection of 
# LINE FLUX for a point source, in units of W/m^2, in an integration of 10^4s.
# This is how the MIRI sensitivity requirements are defined, so I've just plotted them.  I've added
# a point at 14.5um from the STScI sensitivity page, which is not in the MIRI requirements.
#
# NIRSpec: The ISIM sensitivity requirement (ISIM-153) has 2 requirements for NIRSpec (med and low res); 
# the lowres one applies to continuum fnu (W/m^2/Hz); so I put that on the lower-res plot.
# The medium resolution ISIM-153 NIRSpec requirement is in lineflux, and is for 10^5 s, so I scaled by 
# sqrt(10^4/10^5s).  The NIRSpec Functional Requirements Document (JWST-RQMT-002060) has no other 
# sensitivity requirements.  However, the STScI Sensitivity website 
# http://www.stsci.edu/jwst/instruments/nirspec/sensitivity/ gives anticipated 
# performance NIRSpec curves for point sources, 10^5s integration, SN=10 per spectral resoln element.  
# For narrow, unresolved lines, should be same as line sensitivity.   Again, scaled by sqrt(t) 
# from 10^5 to 10^4s.  Agrees w ISIM-153 requirement at 2.0um, as it should.
#
# Keck/Nirspec:  No ETC online, so must take sensitivity from published papers.  I tried several approaches.  
# First, I took flux uncertainties in Rigby et al. (2011) and Wuyts et al. 2011 (in prep), and scaled to 10^4s.  
# But these are very pessimistic, because the uncertainties dominated by errors in the continuum fit, 
# which scale with line flux, rather than raw sensitivity.  Second, I scaled the flux limits in Erb et al 2006, 
# who measured 1 sigma uncertainties of 3E-18 erg/s/cm^2 = 3E-21 W/m^2.  So 10 sigma = 3E-20 W/m^2.  
# Those were stacks of ~15-20 hr total integration (1-1.5 hr x 15 galaxies stacked), so I scaled to 10^4s.
#
# NIRI/Gemini performance estimates come from:
# http://www.gemini.edu/sciops/instruments/niri/itc-sensitivity-and-overheads?q=node/10088
#
#ISAAC on VLT:  Used their ETC, with secz=1.3, medium resolution (R=3000), 0.65" seeing, 1" slit.  
#
#
# FLITECAM on SOFIA:
# I used the ETC, http://flitecam.sofia.usra.edu/cgi-bin/flitecam/flitecam_calc2.cgi, 
# to compute limiting continuum fluxes (in units of W/m^2/micron).  I then converted to limiting line 
# fluxes (in W/m^2), by using this equation for an unresolved line:  
#       F_line (W/m2) = sqrt(2*pi) * lambda (micron) * F_lambda_0 (W/m2/micron) / (2.355*R)
# where R is the resolving power (~1700 for a 1" FLITECAM slit and 850 for a 2" slit).  This equation came 
# from Bill Vacca at SOFIA (priv com); it's also eqn. 2.7 in the Spitzer IRS Instrument Handbook (v5, 
  http://irsa.ipac.caltech.edu/data/SPITZER/docs/irs/irsinstrumenthandbook/).
# For these calculations, I assumed the 1" slit, a source flux at 2.2um of 1mJy, and a 100K blackbody spectrum.
# I chose different single frame exposure times to optimize sensitivity and avoid saturation:  
# 300s for JHK, 30s for 3.5 and 3.8um, and 3s for 4.75um.
#
# Historical NOTE: In the 2011 versions of these plots, I used Flitecam sensitivity numbers from graphs
# on the SOFIA website, which I now think were wildly optimistic, and which no longer appear on SOFIA's website.