Welcome to the M33 CFHT variability survey web page
We have surveyed the Local Group galaxy M33 for variable stars, using
the wide-field camera MegaCam on the Canada-France-Hawaii telescope.
This page contains information about the survey and over time, it will
develop into an interface for accessing our data.
The survey, in a nutshell:
1 square degree,
3 filters (Sloan-like g'r'i')
3 seasons
33 epochs
We use image subtraction to detect variability. We have found 36000
variable objects, and we have over 80000 light curves.
We use
DAOPHOT to extract fluxes. There are roughly 2.5 million sources
detected in each passband. We have point source photometry for 4.7
million different sources; about 1 million sources detected in all 3
filters.
Data access:
A paper describing the search for variables is published (Hartman
et al. 2006, MNRAS 371, 1405), also available on astro-ph.
Over time, we will add more information as the work progresses
(catalogs for each types of variables -- Cepheids, Miras, etc. --
periods, calibrated photometry), but for now you can download several
tables (published in Hartman et al. 2006) that contain information
about the variables found.
WARNING:
The photometry is not
yet calibrated. We provide "semi-instrumental" magnitudes. We used a
constant zero point (provided by the observatory) for all images.
From one chip to another, there can be differences of a few tenths of
a magnitude.
The files are publicly available and you can do whatever you want with
the data. It is nice to let us know what you do though (dfb AT'
astro 'DOT' livjm 'DOT' ac 'DOT' uk).
There are two different groups of variables. One is for stars that
have a counterpart in the deep reference image (most "regular"
variables like Cepheids, Miras, LBVs, red giants, etc.). Download the
summary file and the light curves (gzipped, 30 Mb).
The other group is for stars that do not have a counterpart
(one-off things, possible novae, fast microlensing events, etc.).
Download the summary file and
the light curves (gzipped, 23
Mb).
Papers
Here is a list of links to papers based
on these data. Some of the papers have been written by other groups
making use of the data.
If you want your paper to be listed here, let me know (dfb AT'
astro 'DOT' livjm 'DOT' ac 'DOT' uk).
You can also check out some cool movies, made by Joel Hartman .
This is the whole galaxy, with the movie region highlighted [Credit:
T.A.Rector (NRAO/AUI/NSF and NOAO/AURA/NSF) and M.Hanna
(NOAO/AURA/NSF)]:
Here is the
movie
for this region.
Zooming in on a sub-region .
Last update on Oct 23 2006
