Phase I Checklist

Please read the guidelines for proposing here. The Phase I Tool (PIT) tutorial video is available here. Here, we provide details to help proposers fill out the observations section of PIT. 

• Instrument configuration

  • Is the chosen resolution mode sufficient for your science? 
  • Sky subtraction
    • In standard resolution mode, is the sky IFU (provided in IFU1) sufficient for your sky subtraction needs? If you need additional sky subtraction using IFU2, please only propose for single target observations
  • Dual target observations
    • Please only include the faint target in your proposal; and ensure the other target is within the field of view.
    • Your targets must be separated by more than 102 arcsec, and less than 7.34 arcmins. This must include the correction for proper motions to an approximate time of observation.
    • The observations should not binned by more than 8 in the spatial direction to avoid potential cross-talk
  • Guiding
    • Guiding is only possible with the peripheral wavefront sensor 2 (P2WFS).
    • In principle, there must be a P2WFS guide star within 6.75' for two IFUs, (and for a single target within 9.85'), and be reachable without vignetting. The guide star possiblities will be indicated in the Phase I proposal. 
    • Additional fine guiding on target is provided by dedicated microlenses surrounding the science IFUs, for bright targets.

• Time request

  • Please confirm the S/N achievable in your desired conditions, and the exposure time required using the GHOST ITC to calculate the correct observation time required for your science goals. 
  • ITC configuration parameters: observing times, read modes, and binnings
    • GHOST is usually mounted on the up-looking port at Gemini South.
    • Sky microlenses in standard resolution refers to either sky fibers in IFU1 (3), science IFU of IFU2 (7), or both combined (10). 
    • It is not recommended to bin spectrally in high resolution mode (undersampled). 
    • In general binning for dual targets spatially greater than a factor of 8 is not recommended due to potential crosstalk between fibers. 
    • Recommnded read modes for all observations are SLOW for the blue detector, and MEDIUM for the red detector given the similar overhead times, and readout characteristics
    • Exposure times are recommended to be under 20 mins. 
      If the conditions deteriorate after 1 hour for observations longer than 1 hour, time charged to the program will not be returned. 
  • Calibrations
  • Are the baseline calibrations sufficient for your science? If not, additional observing time must be requested for calibrations.
  • All observations requesting absolute flux calibrated spectra would require conditions better than CC50 (photometric skies) for standard resolution observations. These must also include time for a spectrophotometric standard.
  • If you require removal of telluric lines for your science, please include a telluric standard in your time request.
  • If your observations require a radial velocity standard, please include this in your time request.

• Target

  • Please include your target coordinates, V-band magnitudes, and proper motions (latter two if known). 
  • GHOST is not currently able to observe non-sidereal targets. 
  • GHOST currently cannot acquire using a non-standard acquisition mode during queue observations (for e.g., faint objects requiring blind-offsets, or companion guiding).

• Observing conditions 

  • Please consider whether the chosen IQ bin is appropriate for your science, given the wavelength range of interest, and the likely airmass of your observations. Remember the airmass and wavelength roughly degrade from the zenith seeing (measured in the V-band) by an exponent of 0.6, and −0.2 approximately. Given the finite width of the input aperture, the throughput degrades strongly as a function of seeing

  • The night sky significantly increases in brightness shortward of the R-band during bright moon phases. If your science needs observations at short wavelengths, please consider strong SB constraints to ensure enough S/N in the blue.
  • The level of cloud cover needed for your science depends on the combination of the brightness of your target, wavelength range needed for your science, and the S/N desired. Most spectroscopic observations of medium-bright targets at all wavelength ranges are sufficient when taken in thin cirrus or worse conditions. If you required accurate spectrophotometric calibration, please indicate so by choosing clear conditions.
  • Please ensure the observing conditions requested match your science goals.