RE: Back to Work

["Gutzwiller, Michael" <mgutzwiller@lanvision.com>]

Actually I'd like to see some overlap of the TASS III and TASS IV data to
start with so we can compare photometry.  Adding in the Landolt standards
adds to the calibration sources.

I do agree with Arne that a longer exposure would be useful.  A crude back
of the envelope calculation says that a 300 second exposure would allow the
Mark IV to reach about 2 magnitudes deeper than the Mark III with about the
same background levels.


With this in mind I suggest either of the following:

* Two 300 second exposures of the same field then a rewind.
* Three 200 second exposures of the same field then a rewind.

Mike G.


-----Original Message-----
From: aah@nofs.navy.mil [mailto:aah@nofs.navy.mil]
Sent: Thursday, September 07, 2000 4:29 PM
To: tass@listserv.wwa.com
Subject: Re: Back to Work


Tom suggested 100second exposures on the equator,
backtracking every 12mins or so to pick up the next
field.  I agree you would get lots of Landolt standards,
but two things come to mind.  First, the deeper the exposure,
the better exposed the Landolt standards will be.  I'd
go longer and take fewer exposures/field.  Second,
since you are covering the Mark III fields, there is
little new information unless you go deeper than the
Mark III.  So again, I'd use longer exposures if you
can.
  Two other alternatives come to mind.  You don't have
to stay on the equator -- the photometry file from
Brian Skiff plus the Tycho-2 catalog are sufficient to
zero-point your data at any Declination strip.  Since
you have that ability, I'd suggest observing somewhere
that the Mark III could not.  Second, there are some
interesting single fields that you could just follow
for hours rather than trying to cover as much sky as
possible.  For example, there is an AAVSO group that
is trying to get light curves of Hipparcos and ROTSE
eclipsing binaries.  One such star is the 10th mag BP Vul:
  BP Vul = GSC 1644-2113
  RA 20h 25m 33.2s
  Decl +21o 02' 17"
It has a period of almost exactly six days, and the
eclipse phase will be visible from Sept15-30 or so.
Following that field for an hour or two can yield some
very useful information.  That can be done at the
beginning of the night, and then switch over to
survey mode when you go to bed.
Arne