Bill's Astronomy Page

I began my interest in astronomy around the time of Halley's comet.  After making a few dozen long exposure images of dim objects with home sensitized film and my darkroom processing, I went into asteroid lightcurve work.

Asteroid science for amateurs falls into two main categories, orbit discovery and and refinement; and rotation rate solution.  Collaboration with professionals occurs with both of these and with a third topic, pole orientation.  My work has been mostly in  light curve solution for rotation solution with some of the work done in collaboration but most done independently and most published in the Minor Planet Bulletin.  Some of my work has been with near-earth asteroids, some with main belt objects.

My first observatory was a manually operated rooftop  rotating dome housing an  0.25 meter newtonian scope with photometricly filtered SBIG ST6 detector, autoguided by a SBIG ST4.   A grant from the Planetary Society to upgrade some of the equipment and software for better professional collaboration eventually led to the second observatory.

My current observatory is a remote controled 15' "Prodome" housing a remote controled 0.4 meter scope with remote controlled  filters and SBIG three stage cooled ST8E detector.   Modifications include flocking in the optical tube, two small fans in the optical tube to disrupt any convection currents, and remote controlled interior-dome lights.  Seeing is only average, about 4 arcseconds.  The combination of equipment, seeing, and average light pollution gives me a limiting magnitude  of about 20 or 20.5 on very long unfiltered but dark subtracted flat fielded images.  For asteroid work , maximum integration times and sometimes filters for calibration reduce working magnitudes further.For 1 minute images and unfiltered light, my signal to noise ratio is 10 at magnitude 16.8, 25 at magnitude15.8, 65 at 14.8 and 150 at 13.8.  My system has a spectral response very close to photometric V on most objects.(+- 0.1 mag unfiltered, +- 0.03 magnitudes through a V filter corrected to a Landolt standard star.   Suitable light curve targets are in the magnitude range of 12 to 14.5; occasionally to magnitude 16.5 if the object has a large curve amplitude.  Rarely I can get rotation data on 18.5 magnitude objects if many factors are favorable.  For reference, Pluto is about magnitude 13.8

For dome control I operate from a control room using Digital DomeWorks.  I use "The Sky" for scope pointing, dome rotation linking, focusing,and for object tracking.  I use a version of Maxim DL CCD for camera and filter control and autoguiding.  I use either Canopus or a combination of Mira and a homemade excel template for data reduction and light curve solution.  For accurate time values in the time-magnitude or time-position data pairs, the computer is set automatically each observing session to the correct time from a WWV clock plugged into the back of the computer.  An independent remote electronic viewfinder aids in checking cloud cover during the night and refining scope pointing early in the observing session.

An example of a rotation solution is here. this is a 12kb PDF file

My equipment is best suited for quantitative work on dim point sources such as asteroids, gamma ray bursters, searching for extra-solar planets and working with dim varaible stars.

Some asteroid links are here:
http://cfa-www.harvard.edu/cfa/ps/mpc.html
http://www.minorplanetobserver.com/astlc/default.htm

  I have not been very active in this hobby this year due to other interests, mainly courses at a nearby college.