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HST observing from beginning to end.
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During "Phase 1" the observer has to:
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Choose a target and what to study about it.

Figure out which instrument(s) would be useful.
(camera, spectrograph?)

Make sure that this has not already been done.
(check the HST data archive)

Figure out about how much time is needed on the telescope.

Write up a scientific justification and submit by annual deadline.
(exception: the observer can apply directly to the
Institute Director at any time)

Next the Telescope Allocation Committee Meets
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This is actually several committees of scientists in different fields.

They review all the proposals in their field and identify the best ones.

If the observer is given time they move on to "Phase 2" where they:
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Get an award letter from the Institute.

Get target information from the journals or other scientists.
(need position and brightness)

Measure the target coordinates in HST guide star reference frame.

Figure out all the observations needed.

Group them into sets of observations that can be done together.
(we call these visits)

Figure out the details of each set of observations and put them
together in an order which uses the target visibility periods best.

Write up observations in special HST observation language.
(this is like a specialized programming language)

Use special software to check the program (available on the WWW):

Is the syntax correct? (like a spell checker on an essay)
Is what was requested actually possible? (does the essay make sense)
(filters, tape recorder usage, # of orbits, ...)
Is there a time of year that this could be done?

Submit program to Institute.

At the Institute we do program preparation:
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Check that program reflects what was approved by the committee.

Check that these observations have not already been done.

Make charts that show the target on guide star plates.
(to double check position)

Prepare the program for flight.
(like compiling into executable code)

Look for suitable guide stars throughout the year.

Check that the observation can schedule given all the constraints.
time of day: target occultation, south atlantic anomaly
time of year: sun, moon, target visibility, guide stars
observer imposed: orientation, timing or phase, visit ordering

Create a plan for the year using all the programs.

Have an instrument scientist review the program.
(Is it safe, will the target be acquired?)

The next step is to schedule the visits for execution
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Start work about 4 weeks ahead.

7 days of visits must be bundled together to execute automatically.
(unlike ground observation where you can change your mind)
(more like programming a VCR for when you are on vacation)

It can be tricky fitting all the visits together to make
efficient use of the the telescope.
(like making a stone fireplace, there will always be gaps,
but the big gaps can be plugged with survey programs -
which contain lots of little observations that can go any time)

During and after execution
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Telescope slews to target.

Data is taken and recorded to the on board tape recorder.

The observations start and stop with each time the Earth gets
in the way of the target (occultation).

Later the telescope makes contact with a Tracking Data Relay Satellite
(TDRS) and data is down linked.

The actual path of the data is from HST to TDRS to Whitesands NM to a
domestic communications satellite to Goddard Space Flight Center to
the Institute.

Data is automatically processed for routine calibrations.

Raw and calibrated data is written to the archive.

The data is retrieved from the archive by the scientist.

Scientist begins to reduce the data using various specialized software
packages. (some specific to HST data, others not)

Scientist draws conclusions or at least raises questions and presents
this as a scientific paper or a talk at a conference.