ThrUMMS - The Three-mm Ultimate Milky Way Survey

ThrUMMS Technical Details

 

Planned ThrUMMS Coverage

 

Fig 1: The background image is taken from the Columbia-CfA Survey and the red box outlines the original planned coverage for ThrUMMS.

 

l Coverage
b Coverage
Mapped Area

No. of

Channels
Channel Width
Velocity Bandwidth
Angular Resolution
Spectral Lines Observed
rms
300° to 360°
-1° to 1°
120 deg2
4096 x 2 polarisations
85 m s-1 native*
360 km s-1
72"
12CO
13CO, C18O, CN
2.5 K/ch*
1.5 K/ch*

* This is for the native channel width in the digital filterbank. For public Data Releases, a 4-channel bin is used to improve the S/N (with half the listed rms values) and reduce the datacube sizes for downloads.

 

 

3mm Observations

Mopra details

  • Telescope: 22m diameter dish, beam FWHM 36" at 85-100 GHz (Ladd et al 2005)
  • Receiver: 3mm MMIC covering 75-116 GHz, Tsys < 200 K below 100 GHz in good weather
  • On-the-fly (OTF) mapping with ~beam sampling


We are using a combination of Fast Mapping (FM) and pseudo Fast Mapping (psFM; Barnes & Dame 2009) for very large OTF map areas. Typically a 0.5° × 0.5° map takes 1.5 – 2 hours of clock time.

 

MOPS digital filterbank

  • Bandwidth: 8 GHz instantaneous, comprised of four 2 GHz blocks, with up to 128k spectral channels
  • Zoom mode: 4 blocks with 2 polarisations, each with 4096 channels

ThrUMMS spectroscopy

Complete coverage of the entire fourth quadrant will be mapped for the following spectral lines, with an available zoom coverage up to ~360 km s-1:
  • C18O (J=1 to 0) at 109.78 GHz
  • 13CO (J=1 to 0) at 110.20 GHz
  • CN (J=1 to 0, 5 hyperfine components) at 113.50 GHz
  • 12CO (J=1 to 0) at 115.27 GHz

 

Current ThrUMMS Coverage

 

  • Phase II mapping (all 480 half degree maps) completed.
  • See the Data Release Bank for the current coverage available for download.