Duties for Hectospec Observers -

Responsibilities and Observing Protocols

Feb 18, 2005
Revised Nov 14, 2005

I. Responsibilities

We believe that the queue observing mode for Hectospec and Hectochelle has been a scientific and operational success.   These queues are run somewhat differently than those elsewhere; here are the main concepts:
(1) each project is allocated queue time equal to the number of assigned nights,  where a "night" is equal to the average length of all the Hecto nights.
(2) As much as possible,  during the first 3-4 nights, some data will be obtained for each of the projects.
(3) After that period, we will try to maintain an equal fraction of completion (time_spent/time_allocated) for all projects.  In this manner, bad weather is evened out among the projects.  Some variation from equality will naturally occur during the brighter moon phases and marginal conditions, times which we tend to observe targets that can withstand such battering.
(4) Each configuration is charged 20 minutes overhead; each exposure is charged 1.5 minutes.  Time spent on a target where it is determined the configuration was faulty (e.g., bad guide stars) is charged to the project.   Time spent during marginal conditions on ultimately worthless spectra is not charged (so one needs to look at the data soon after it is taken).
(5) Flats, comparison exposures etc are taken during the afternoons.  Flux & velocity standards are not routine, and will be charged to the project.

Up until 2005, the Hecto team and FLWO staff have supported the operation of the queue in four ways: (1) SAO scientists and engineers have maintained andserviced the instruments as necessary, (2) Nelson Caldwell has scheduled the queue observations, (3) Perry Berlind and Mike Calkins have operated the robots, and (4) a Hecto team member has typically been present to provide nightly scientific supervision.  For now, we intend to keep the first three elements in place, but hope to turn thenightly scientific supervision over to trained observers from the pool of those with assigned Hectospec and Hectochelle time.  We have requested that observers come to the telescope during their assigned time in the past, but would now like to clarify what is expected of observers and have them come to the telescope in blocks of time that make better sense for queue operation.

We would plan to divide each Hecto run into blocks of ~3 nights which would be managed by one or two observers. The nights will not necessarily correspond to the assigned nights on the telescope schedule.  We have the freedom to shift the times around for the convenience of observers and the queue. During the assigned nights, the astronomer would attend to the following items, which center around insuring that good quality data are obtained.

Observer Responsibilities

- Run the spectrograph/CCD acquisition control software

- Annotate the data logs (now under automation), with comments
  on conditions, data quality, problems encountered, etc.
- Check the operation of the spectrograph/CCD at the beginning of the
  night, and monitor readout noise, spectrograph focus, thermal
  flexure, etc.  Normally, the actual focussing would be done by the robot
  operators, Perry and Mike, who  would also fill the CCD dewar.

- Be knowledgeable about the fiber assignment code "xfitfibs", in
  particular with regard to the retrictions on rotator position and
  guide star selection, to the extent of being able to run the program
  at the telescope should the need arise.
- Be knowledgeable about the normal sequence of operating the
  positioner and acquiring fields, so that when problems with
  acquiring a field occur, the robot operators can be advised as to
  how to proceed (e.g., moving on to another field because of poor
  guide stars).  This would not include actually operating the
  positioner; that task would remain in the capable hands of trained

- Do quick look reductions of data as it appears, checking for overall
  quality, and in particular insuring that the spectra fullfill
  program goals. E.g., are objects detected at all (coords ok?), are
  objects underexposed or overexposed, etc.

- Help make decisions regarding the queue during times of marginal
  weather or seeing, choosing targets from a the nightly list.

To aid the on-site astronomers, each group with Hectospec time will
be expected to supply a brief summary of their data and calibration

In order to facilitate scheduling of observing blocks, we will ask people
with allocations  for their availability to go to the telescope.  Any team
member is eligible.

II. Observing Protocols

       In order to facilitate the TDC Hectospec reduction pipeline script
        as well as to produce consistent, high quality data, we require
        the following observing protocols be followed when
        observing with Hectospec.

        1.  Take ten biases at the beginning of the evening.
        2.  Take darks every night, at least five at 15 minutes each.
            These are usually taken at the end of the night.

        3.  Take ten domeflats at the beginning of the evening.  The
            exposure time for domeflats is 2 seconds.
        4.  Take comps (henears) right after domeflats if possible. 
            There should be five 300 second exposures, or, if that is
            not possible, a minimum of three 300 second exposures.
            The comp exposures must be contiguous as they will be
            combined to make one file. It is important to take comps
            and domeflats close in time because the domeflat extraction
            profile, without any shift, is used for the comp extraction
            and there can be a small drift in the fiber positions over
            the night.
        5.  Take sky flats every night when possible. These can be started
            right after sunset and/or up to sunrise.
            We recommend a series of up to ten
            sky flats in increasing exposure times after sunset or
            in decreasing exposure times before sunrise.  So, for
            example, you might have a series of sky flats with
            exposure times of:  2, 5, 5, 8, 12, 20, 25, 30.  The
            increase or decrease in exposure time is made because
            of the rapidly darkening or brightening sky.  Sky flats
            are used for the fiber throughput correction in the
            reduction pipeline.

        6.  At least three contiguous observations should be made of
            your science fields.  We need a minimum of three to do a
            good job of removing cosmic rays in the combine program.       

        7.  A minimum of thirty fibers must be used for skys, more
            if you can do so without losing a significant amount of
            data/observing time.  Set the parameter for the number
            of skys in the fitfibs program to 30 or higher when
            you are preparing your observing fields.  Skys are
            subtracted separately for each chip so a total of
            thirty or more skys increases the liklihood of having
            an adequate number on each chip.
        8.  If you are observing stars, don't mix faint and bright
            stars in the same field .  The range of magnitudes should
            not be greater than four magnitudes.  You do not want to
            saturate the bright stars to get the faint ones. Make more
            than one configuration if needed.

nc, st & dgf