Subject: The importance of being Early

From: Russet McMillan

Submitted: Thu, 3 Oct 2002 19:39:08 -0600 (MDT)

Message number: 618 (previous: 617, next: 619 up: Index)


It appears the time has come once again to remind our observers they
should be logging in at least an hour before the start of their
scheduled observing time.  This applies in particular to first-half
observers, especially DIS users.  The order in which we like to do
things on a promising evening is as follows: telescope and instrument
checkout, then DIS cals or SPIcam biases, as needed.  Then we can open
the dome, which is ideally done a good half hour before sunset to
allow time for cooling.  Twilight flats with GRIM or SPIcam can start
as early as five minutes after sunset, depending on the filter.  It is
dark enough to start focusing somewhere around 15-20 minutes after
sunset, and dark enough to observe a standard star after that.  That
brings us approximately to the end of 12-degree twilight and the
official start time for the program.  On a good night, more than an
hour of important work gets done before the time listed on the

Observers who don't log in until their scheduled start time, or just a
few minutes before their start time, will be losing dark sky to tasks
that could have been done in twilight (focusing, standards, in-dome
cals).  In addition, if the dome is kept closed through sunset to
allow darkness for cals (DIS cals in particular), this costs valuable
cooling time and degrades image quality when the observer is finally
ready to get on the sky.

We also appreciate having observers log in a little early if they are
scheduled for second half.  Remember that the instrument change time
shown on the schedule is a worst-case scenario; you may well be able
to start earlier than it says on the schedule.  The first half
observers may also give up early due to borderline conditions, or
perhaps because they can't make use of an exposure shorter than half
an hour.  Lastly, it's nice to know that the second half observer is
awake and ready to go, so that we don't have to wonder if we should
start looking for a replacement for a no-show.

Remote obseerving at APO is easier than travel to a national
observatory, but we would like it to be treated with the same
seriousness and advance preparation.  Thanks for you cooperation in
this matter.

				Russet McMillan

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