Archive Presentation

[Tass Mailing List <tass@mail.alembic.net>]

Date: Sat, 22 Sep 2007 12:44:32 -0500
From: Thomas F. Droege <droege@fastmail.fm>
To: tass@tass-survey.org
Subject: Archive Presentation

I previously proposed a data archive where there was a file for each
camera for each day of operation.  The tom2 data in this format is
available on dan.

For my purposes, I collect all the information for each star seen by
each telescope.  The star data is then sorted into one degree bins.  In
the sort process I make a summary file.  The summary file shows each
star seen, the number of times observed, the mean V and I, and the sigma
for V and I.  This is useful for looking for interesting stars.  The
summary file looks like:

   1145732    85  12.82   0.16  12.07   0.15
   1145742    23  13.23   0.15  12.20   0.15
   1145743    11  15.11   1.30  13.43   0.34
   1145744    51  12.12   0.09  11.53   0.10
   1145746    10  13.66   0.16  12.44   0.10
   1145754    50  12.81   0.18  11.42   0.11
   1145759    22  13.91   0.28  12.68   0.15
   1145768     3  14.69   0.80  20.00  20.00
   1145769    17  12.58   0.14  11.05   0.14

The first column is a sequence number shared by the data file.  The data
file has 85 lines with the sequence number 1145732 with the position,
time and the V and I measurements in the usual format.

This produces (eventually) 2160 archive files.  The summary files total
(currently) about 10 million lines.  The data files are about 300
million lines.  My guess is about 35 GBytes for all the data, less than
a GByte for the summary file.

The 1 degree blocks for each telescope make reasonable size blocks for
study.  The 10 to < 11 degree slice for tom2 is 450,000 lines long and
the summary file is 60,000 lines long.

A quick sample of a couple of tom2 1 degree slices shows 100 stars per
square degree with 50 or more measurements.  I recall that this was the
range sought by Bohdan Paczynski.

I have poked around some of the data and the hunting looks good.

Comments, anyone?

Tom Droege
-- 
  Thomas F. Droege
  droege@fastmail.fm