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SOFIA Instrument Time Estimator (SITE)
Please Check 'Notes and Known Issues' Before Proceeding
Spectroscopic Time Estimators and Tools
Imaging Time Estimators
The following four sections of this form are for imaging configurations: select the instrument, astronomical source, telescope, observing condition constraints and calculation method. Click on the
input parameter details
GREAT Band Frequencies
(THz, use 7 decimals)
Line Width (for averaging sky transmission):
Type of Observation:
SinglePoint or BeamSwitch
TP OTF/Raster Map
TP OTF Map Size (X × Y in arcsec):
Observer Velocity (VLSR, km/s):
UT Date (YYYY/MM/DD):
Select the calculation method
S/N ratio resulting from a Total Integration Time of
Total Integration Time to achieve a S/N ratio of
Astronomical Source Definition
Spatial profile and continuum brightness:
Choose point or extended source.
Spatially integrated brightness for the short wavelength (SWC) filter
in addition to the above continuum. The output SNR or observing time will be for the sum of continuum plus line.
Single emission line at wavelength
microns with line flux
Brightness Temperature, T
Source Velocity (km/s):
Observing Condition Constraints
Note: You can read the
for more information on the water vapor overburden.
Altitude in 1000's of feet:
Zenith Water Vapor Overburden (microns):
Notes and Known Issues
Windows machines should use the Firefox browser, as Microsoft Internet Explorer has known issues.
2) HAWC+ imaging and polarization sensitivity values were updated in July 2018 to reflect the in-flight (measured) instrument performance. The sensitivity values used in SITE for cycles before Cycle 6 were estimates based on the theoretical performance of the instrument. The current values are different from the June 2017 estimates by about a factor of two to four, so time and signal-to-noise calculations should be updated accordingly for Cycle 7 before proposal submission.
3) For HAWC+, the Cycle 7 version of SITE was incorrectly including overheads in the calculations. This was corrected as of 23 Aug 2018. Proposers are encouraged to recheck their signal-to-noise and time estimations with the revised version of SITE.
4) When the filter selections are changed, the entries in the flux boxes change to their default values (these are the fluxes for which an S/N of 4 is obtained in 900 seconds in single channel mode). The entries are set to the default values REGARDLESS of the values of time or S/N entered in the "Calculation Method" boxes. Furthermore, the entries follow the units set alongside the short wavelength box. [SPR509]
5) Note that SITE does NOT do any unit conversions for user-entered values.
6) To prevent any confusion regarding values and units, the user should perform these steps in the following order: (i) choose the desired filter or filter combination, (ii) choose the calculation method, (iii) choose the units desired, (iv) explicitly enter the fluxes (in the desired units) in both long and short wavelength boxes, and (v) click on the "Calculate" button.
7) For FORCAST, the *actual* filter configuration is determined after the TAC has awarded observing time, so that SITE may not reflect the current configuration. If filters are subsequently moved between short and long wavelength optical paths, the sensitivies will change from what is estimated here.
8) For HAWC_PLUS, in the polarization configuration, the returned/entered S/N is that for the polarized flux (p x F), not the fractional polarization ( p ) alone. If the S/N on total flux F is high, the S/N on the fractional polarization will be approximately the same as that on the polarized flux.
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