In order to facilitate the TDC Hectospec reduction pipeline script
as well as to produce consistent, high quality data, we strongly
recommend that the following observing protocols be followed when
observing with Hectospec.
Observers' Responsibilities page to find out more, and read the
- Take 10 biases at the beginning of the evening
- Take darks every night, at least five at 15 minutes each.
These are usually taken at the end of the night.
- Take ten domeflats at the beginning of the evening. The
exposure time for domeflats is 2 seconds.
- 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
- Take sky flats every night when possible. These are
usually taken right after sunset but they can be taken
just before 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
- 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.
- 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.
- If you are observing stars, don't mix faint and bright
stars in the same field. Stars should vary by no more
than four magnitudes. You do not want to saturate the
bright stars to get the faint ones.
Make more than one configuration, if needed to separate stars of
- Check with quick look after each new target exposure to make sure you
have an adequate integration time and to check your positions: image and