Caution!! Although I am happy to share my research notes below with all visitors to my webpages, these pages are mainly designed for my own use and subject to change without warning. I do not guarantee the correctness of all contents as well.

ARO HHT telescope (see more details at ARO HHT telescope's homepage)

Table of contents:

1. basic information
2. mainbeam temperature (T_mb)
3. mainbeam size and efficiencies (BWHM, eta_m)
4. convertion of T_mb to flux density [Jy]
5. mainbeam size and efficiencies used in literature
6. Data file formats (astro/horizon, Xremote)

Basic information of the HHT telescope

Name: Heinrich Hertz Submillimeter Telescope
Location: Kitt Peak
          East Longitude: -109d 53m 28.5s
          North Altitude: +32d  42m 05.8s
          Elevation: 3186 meters
Diameter = 10m.
Surface accuracy: <12um rms
Wavelength range: 0.3-1.3 mm
Pointing error: ?? arcsec
Mount: elevation over azimuth
Elevation range: -2 deg - 91 deg
Azimuth range: -90 deg - 450 deg

The temperature given in HHT observation data file is T*_A, the observed source antenna temperature corrected for atmospheric attenuation, radiative loss and rearward scattering and spillover. The main beam temperature can be calculated as

T_mb = T*_A / eta_fss / eta*_m = T*_A / eta_m

Here eta*_m is corrected main beam efficiency, 
     eta_fss is forward scattering and spillover efficiency, 
     eta_m is a special main beam efficiency defined for T*_A. (See values of eta_m below)

Beam sizes and telescope efficiencies                           [back to top]

I got the measurements of beam size and efficienies of HHT from Dr. Bill Peters, the ARO stuff member. The measurements are roughly valid for observations using 1.3mm receiver during 2004-2005, but should be also valid for other years not far from this time range. 

For observations with the Martin-Puplett installed (the image side band reducer used for single side band observations), the special main beam efficiency is 

    eta_m = 0.65 (+-0.1) for polarization channel A
    eta_m = 0.55 (+-0.1) for polarization channel B

(Note: The measured values of eta_m do not show significant variation with frequency or elevation within the measurement errors.)

For observations without the Martin-Puplett installed (e.g., the observations with the ALMA band 6 mixer), the efficency is somewhat higher, say, eta_m = 75-80%.

--------------------

FWHM main beam size can be calculated for different frequencies by the empirical formula:

    BWHM = 1.2 * Lambda / D  (for using the 1.3 mm receiver)
    BWHM = 1.25 * Lambda / D (for using the 345 GHz receiver)

where 1.2 and 1.25 are measured coefficients, Lambda is the observed wavelength in unit of meter and D is the physical diameter of HHT collector -- 10 m. The difference in the coefficients 1.2 and 1.25 is due to the slight difference in the illumination patterns for the two receivers. Examples of the main beam size:

    BWHM = 34 arcsec at 220 GHz (1.3mm receiver)
    BWHM = 32 arcsec at 230 GHz (1.3mm receiver)
    BWHM = 29 arcsec at 260 GHz (1.3mm receiver)
    BWHM = 24 arcsec at 320 GHz (345GHz receiver)
    BWHM = 22 arcsec at 345 GHz (345GHz receiver)
    BWHM = 21 arcsec at 360 GHz (345GHz receiver)

Flux density can be derived from the main beam temperature as             [back to top]

S_nu = BWHM(")² / lambda(cm)² * T_mb * 5.097 X 10^-4    [Jy]

Here BWHM is angular full beam width at half maximum of the Gaussian main beam in arcsec, lambda is observed wavelength in cm. 

HHT BWHM and special main beam efficiency used by literature:            [back to top]

The text version of the data in the plots are available: (click here). The fitted relations are: empirical fromula of BWHM mentioned above and eta_m = 1.123-0.0014*freq[GHz] in the shown frequency range. (conflict: Dr. Peters said, no significant variation of eta_m with frequency was observed, but a dependence with frequency is clearly shown in right figure! due to different instrument configurations?)

Data File Formats            [back to top]

# List of some Extended Green Objects:
G10.29-0.13 EQ 2000.0 18:08:49.3 -20:05:57 LS +13.4  # EGO
G10.34-0.14 EQ 2000.0 18:09:00.0 -20:03:35 LS +13.3  # EGO
G11.11-0.11 EQ 2000.0 18:10:28.3 -19:22:31 LS +27.8  # EGO
G12.42+0.50 EQ 2000.0 18:10:51.1 -17:55:50 LS +16.7  # EGO
G12.20-0.03 EQ 2000.0 18:12:23.6 -18:22:54 LS +51.1  # EGO