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Phase II Checklist

GSAOI Phase II Check list

  • General
    • It is strongly recommended to read the notes in the Observing Strategies page before you start to fill the phase II for your program. The page provides some guidelines to maximize observing efficiency and avoid some common errors.
    • Have you selected appropriate templates from the GSAOI OT library? Have you gone through the checklist in the Top-level Program Overview note and included relevant standardized notes? Add notes with information about the program that will make it easier for the observer. Try to use the standardized notes provided in the OT Library.
    • Have you read the details about the overhead calculations? Have you added a note explaining how many reacquisitions you have assumed for the calculation of the overheads? Taking the correct overheads into account, do your defined observations fit within the allocated observing time?
    • Have you checked the GSAOI Baseline Calibrations to see what is offered/required?
    • If the PI requires calibrating standards beyond what is offered in the standard baseline calibrations, these must be defined, including a specific target, and time will be charged against the program for the observation.

  • OT Setup
    • In the GSAOI component, check that the best read mode has been selected for your science observation. Note that the minimum exposure times are defined by the read mode (see Detector Characteristics section)
    • Are the integration times for your science observations reasonable? Are co-adds necessary? The recommended maximum exposure time for a single frame can be found here.
    • Have you checked if the GSAOI observation sequences take no longer than 2.5 hours (including overheads)? If the observations of a particular target require several hours of on-source integration, be sure to create the necessary sequences to re-acquire the target?
    • Have you checked if the sky background (which refers to optical sky background) in the Observing Conditions component has been set to "Any" (1 - 2.5 microns)?
    • Have you checked if the water vapor in the Observing Conditions component has been set to "Any" (1 - 2.5 microns)?
    • If there is a chance that any source will saturate the PI should include a note telling the observer what to do. Possible actions include: 1) nothing, 2) stop the observation and request feedback from the PI, 3) decrease the exposure time, 4) decrease the exposure time and increase the number of co-adds. Decreasing the exposure time may require changing the read mode, so the note should state whether these changes are allowed. Use the standardized notes provided in the OT Library.
    • If the target will not be obvious the PI should include a finder chart or use the User (1) in the target component to identified the object. Add a note stating that centering is not important.
    • If the observing sequence is non-standard the PI should include a note so that the observer is not caught off guard (and to prevent the observer from trying to "fix" the observation).
    • Offset iterators should typically be located below sequence iterators (which change the instrument configuration) since the telescope offsets much more quickly than the instrument can reconfigure (e.g. change filters).

  • Sky frames
    • GeMS/GSAOI observations require background subtraction. In the case of sparse fields, the same science images can be used to create a master sky frame to subtract the background as long as enough dither positions are obtained to mask the objects in the individual frames. In the case of crowded fields, fields embedded in a large nebulosity or fields containing an extended object, sky frames have to be acquired using a blank region near the science target.
    • Are sky frames included in the observing sequences? Do you have enough sky frames to properly subtract the sky? The sky may varied significantly in a short interval (2-5 minutes). This particularly true in H (1.65 microns) and K (2.2 microns) bands. Have you included enough sky frame observations to take into account for these variations in the sky?
    • If the blank field for sky observations is located < 5 arcmin from the science target, the sky sequence should be included inside the same observing science sequence using a separate offset iterator (see examples in the OT library). If the blank field for sky observations is located > 5 arcmin from the science target, a separate sequence for the sky should be created. Detailed information about the different strategies to observe the sky can be found here.

  • Guide stars
    • Are CWFS (Canopus Wave Front Sensor) and ODGW (On-Detector Guide Window) guide stars selected for GSAOI? To choose the guide stars, use either the Auto GS or Manual GS (recommended) buttons in the OT position editor (see GeMS/GSAOI Guide Star selection page for details).
    • Ensure that the CWFS and ODGW guide stars are not galaxies. Galaxies are not allowed as Guide Stars.
    • The CWFS NGSs must remain inside the patrol field area of Canopus in all steps defined in the GSAOI offset iterator. The star used for flexure correction (ODGW) must remain inside the area defined by the array where the star was selected. In the case that the ODGW star moves outside the allowed area, an error message will be appear in the OT.
    • The guide state in the offset iterator should be "guide" for all science dithers, and "freeze" for the sky dithers.