Imaging faint
galaxies,
Or, Objects in Mirror are more distant than they
appear
Introduction
Everyone has to go to the optician every so often in order to
determine how well they can see. It is
important to know how far one can resolve certain objects and how to optimize
their limitations. In the world of
astronomy, it is also important to know the limits of one’s telescope or
instrument in order to know what objects can and cannot be seen and how to optimize
the viewing parameters in order to resolve distant, dim objects. By knowing how faint the telescope can see,
we can determine how distant into the universe we can observe. Of course, a telescope equipped with a CCD is
quite different from a human eye, and requires different methods to determine
this limit.
Objective
The purpose of my research project is to determine the ultimate
faintness that our telescope/CCD can detect before the signal-to-noise ratio
drowns out the signal. By knowing the
faintest magnitude the instrument can see, we can determine the furthest into
space we can see, and also how long to take certain exposures to determine the
best viewing methods of these faint objects.
Method of research
The method I used to approach this challenge is very
straightforward. I decided to image
galaxies, since they are the objects which will ultimately determine the limit
to our telescope—the fainter the galaxy, the more distant it is, and therefore,
the deeper into space we can see (of course, this relationship is not perfect,
but it is approximately true). I started
by researching and noting galaxies starting at about magnitude 8 and 9 and
up. I then determined which ones were in
my field-of-view (I am viewing from about the 45th latitude in St.
Paul/Minneapolis, MN). This segment of
my project was the most difficult and tedious, since most catalogues and
references do not organize objects by their magnitude. I used the messier catalog, new galactic
catalog and any others I happened to come by to determine which galaxies to
image. When I found a galaxy to image, I
started out using the visual filter, then red, blue, sometimes the infrared
filters to determine the best filter to use in imaging. The program I used that synced the telescope to
the sky and found the objects already had the (apparent) magnitude listed. I made a note of the magnitude and started
imaging. If I could not see the galaxy
after I was done imaging, I would image longer, until I could see it. The parameters and specifications of the
instruments used will be included with the references, listed below.
My other website, irrelevant to this
one