Difference between revisions of "Simulation Recipes"

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(Nearby edge-on spiral)
(Nearby edge-on spiral)
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now we need to decide if this model data will work at the desired pixel scale  
 
now we need to decide if this model data will work at the desired pixel scale  
* the GRS resolution of 40" at ~10kpc is 0.04" at 10Mpc, so we should be able to do a simulation of observing at ~0.1-0.2".  [[File:Beamsummary.png]] indicates that for ALMA at 100GHz, configuration 20 is appropriate.
+
* the GRS resolution of 40" at ~10kpc is 0.04" at 10Mpc, so we should be able to do a simulation of observing at ~0.1-0.2".  [[File:Beamsummary.png|100pix]] indicates that for ALMA at 100GHz, configuration 20 is appropriate.
 
* if we intend to set <tt>cell=0.04arcsec</tt> in <tt>simdata</tt>, then the cube needs to be multiplied by  
 
* if we intend to set <tt>cell=0.04arcsec</tt> in <tt>simdata</tt>, then the cube needs to be multiplied by  
 
<math>2x10^8 * (.04/206265)^2 = 7.9x10^{-6}</math> to obtain Jy/pixel.  The cube peaks at ~3K, so we can perform the simulation with <tt>inbright=2.3e-5</tt>
 
<math>2x10^8 * (.04/206265)^2 = 7.9x10^{-6}</math> to obtain Jy/pixel.  The cube peaks at ~3K, so we can perform the simulation with <tt>inbright=2.3e-5</tt>

Revision as of 14:27, 16 December 2009

Massively Under Construction

(i.e. don't believe what you see here yet, or ask me when it doesn't make sense :)


Nearby edge-on spiral

Roughly modeled after NGC891

  • model data: Milky Way 13CO from the Galactic Ring Survey on the 14m FCRAO
  • units: K - first convert to flux surface brightness

[math]\frac{Jy}{Sr} = \frac{4\times 10^{23} k T}{\pi D^2 \Omega}[/math], where [math]\Omega[/math] is the beam solid angle. At 110GHz the factor is [math]2x10^8[/math]

now we need to decide if this model data will work at the desired pixel scale

  • the GRS resolution of 40" at ~10kpc is 0.04" at 10Mpc, so we should be able to do a simulation of observing at ~0.1-0.2". 100pix indicates that for ALMA at 100GHz, configuration 20 is appropriate.
  • if we intend to set cell=0.04arcsec in simdata, then the cube needs to be multiplied by

[math]2x10^8 * (.04/206265)^2 = 7.9x10^{-6}[/math] to obtain Jy/pixel. The cube peaks at ~3K, so we can perform the simulation with inbright=2.3e-5

will we be dominated by the noise in the input model?

  • input noise ~150mK or S/N~20, so at our scaled intensity, a few mJy/bm. The exposure time calculator says that ALMA will achieve 1.3mJy/bm in an hour, so we should set this up as a half hour snapshot.