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Proposal preparation

, Updated

Observing Strategies


MAROON-X has only one fixed instrument setting and currently one readout mode (100kHz, 1x1 binning). Observing strategies depend on the science case, i.e. whether general purpose echelle spectroscopy or high-resolution radial velocity observations are desired. The latter will require more careful planning of calibrations, both instrument stability tracking via the simultaneous calibration fiber as well as bracketing etalon exposures during the night.

Since MAROON-X was designed for high-precision radial velocity measurements, some design compromises are limiting the ability of the instrument to obtain spectra of very faint objects.

Exposure time limit: The 100um thick high-rho CCD in the red arm collects more and longer cosmic ray signals than a classical thin epitaxial CCD. The CCD has also a few cosmetic artefacts that have a stronger impact on pixel neighbors based on exposure time. We thus advise to limit individual exposure times to 30 min or less.

Signal limit:  The spectrum is distributed over three fibers, sampled by 10 spatial pixels each (hence 30 pixels per 1D spectral bin). Hence the signal level in each stripe is lower than in the combined spectrum. For long exposure times (and hence high level of cosmic ray hits) this might compromise the ability for outlier rejection if the signal level per pixel is so low that optimal extraction techniques are no longer feasible.

Detailed information about the Gemini Phase I Tool (PIT) can be found here.

Checklist for MAROON-X Phase I proposals:

  • Instrument configuration:
    • ​N/A (there is only one mode)
  • Telescope peripheral wavefront sensors:
    • PWFS2 is used for MAROON-X. 
  • Calibrations:
    • Has sufficient observing time been requested for additional calibrations?
    • Are precision radial velocity measurements needed? If so, have RV standard stars and bracketing etalon exposures been included?
    • ​Is accurate removal of telluric lines needed? If so, have telluric standard stars been included?
    • Are the baseline calibrations sufficient? If not, what additional calibration data are required for your program?
  • Observing time:
    • ​Did you confirm the exposure time and S/N using the MAROON-X ITC pages?
    • Did you adjust the observing conditions specified to match your requested conditions?
    • Are overheads included in the time requested in your proposal?
    • Have overheads been included for additional calibrations?
  • Observing conditions:
    • MAROON-X observations are scheduled in classical mode and restricting observing conditions is not advisable. Rather note the minimum SNR or count level in the notes.  
  • Scheduling constratins:
    • In the Scheduling section of the PIT, in addition to the timing constraints, please also specify the minimum number of nights requested for the program.