|WHY AMATEUR ASTRONOMERS WOULD MAKE EXCELLENT SATELLITE TRACKERS|
At one time, the amateur astronomer was
mainly known for gazing up at the night sky with at least the naked eye, or with
the help of some magnification, such as binoculars or telescopes. Today, many
amateur astronomers use more sophisticated technology, such as goto telescopes
and CCD cameras, to image the heavens. What some amateur astronomers may not
know is that the equipment they use to take beautiful images of the night sky
can also be used to take accurate photometric and/or astrometric measurements of
objects of interest in the heavens.
Many amateur astronomers are very
dedicated people who spend many hours watching the heavens and constantly
improving the designs of their observatories. They are extremely driven to push
their observing capabilities to extreme levels, as if they are trying to reach a
new high. This is a very commendable trait for any professional researcher. The
advantage of the amateur astronomer is that he/she improves his/her knowledge of
the subject right in the field. There might be people who believe that taking a
few courses for a few days will make you an expert in the subject in question.
My personal belief is that this is not true, especially when astronomy and
satellite tracking is concerned. Furthermore, my belief is that it takes many
years of practicing in the field, and not in the classroom or the office, to
truly learn the fine art of satellite tracking. Although I have been involved in
the subject for nearly ten years, I, in my opinion, do not consider myself a
satellite tracking expert.
OK, many would say the next sentence is
all I would need to say on this subject. The amateur astronomer is willing to
stay up all night, several nights in a row, to observe the night sky. For those
who are not convinced already, you try staying up for 24 hours straight (or
more) and enjoy it. The subject of satellite tracking demands this type of
dedication and endurance. When their own observatories are concerned, amateur
astronomers are on the verge of obsession, constantly tinkering and innovating
to improve their resolution, accuracy, limiting magnitude, or whatever he/she is
striving for at the time. How is this aspect different from what professional
researchers do? Satellite tracking demands this trait, as precision and accuracy
are essential components.
For the amateur astronomer living
within a very unstable weather zone (such as southern Ontario) patience is a
must. Most amateur astronomers know the feeling of missing an important
astronomical event (such as a total solar or lunar eclipse, occultation of a
planet, close fly-by of a comet, etc.) due to totally overcast skies (what
weather forecasters might call "partly cloudy"). For the amateur astronomer,
patience is learned through many years of observing. Eventually he/she will
either learn to accept that weather will not always agree, or he/she will move
to a more hospitable location.
Amateur astronomers are extremely enthusiastic about
the subject of amateur astronomy. To some, this might seem to be an obvious
statement, but consider the reason why the last sentence is true. The main
reason for this high enthusiasm is that amateur astronomers can freely observe
what they want, when they want. It is doubtful that amateur astronomy would have
as much appeal to most if paperwork and bureaucracy were involved. Amateur
astronomers can simply point their telescopes to their objects of choice when
the objects are accessible to them.
Before the CCD camera was commercially available,
amateur astronomers would not have had much of a chance to track most
Figure 2: This image depicts the predicted location of the two Telesat satellites Anik F1 and Anik F1-R at 05:58:56 U.T.C. October 2, 2005. The two satellite icons are seen amongst the virtual stellar background specifically for the amateur astronomer's convenience. The software used to accomplish this is Software Bisque's TheSky Version 5. This software is very inexpensive, more so today, because of the availability of TheSky Version 6. The field of view of the CASTOR facility (13.25 by 13.25 arc-minutes) is shown as a large red square on the image. The star catalogue used is the United States Naval Observatory (USNO) A2.0. A goto telescope can easily be controlled by this software. A simple "point and click" onto one of these satellites can send the telescope to the predicted location of it, provided the telescope is suitably aligned in the usual way.
If you are wondering this, good question! Right now,
amateur astronomers are discovering and tracking asteroids, comets, discovering
supernovae (both inter-galactic and extra-galactic), and discovering possible
new planets in our own solar system. The question should actually be stated,
"Why shouldn't amateur astronomers track satellites?". In my own view,
there is a far greater practical purpose to tracking satellites than all the
above combined. Our own satellite population directly serves us in the present.
If anything should go wrong with an active satellite orbiting the Earth, many
customers, and therefore millions of dollars, can be lost in very little time.
We depend on our satellite population for our communications every single second
of every single day. As far as near Earth asteroids are concerned, one MAY hit
us within the next few thousand years. In my view, tracking artificial
satellites to protect our valuable communications infrastructure is far more
important than tracking rocks in space that MIGHT hit us.
Figure 3: A CASTOR image of the Telesat
satellites Anik F1 and Anik F1-R, taken on 05:58:55.670 to 05:59:05.670 U.T.C.
October 2, 2005. The bright white dots in the image are the stars required as
benchmarks for precise astrometric analysis. Both satellites are known as
geostationary, in which both require a sidereal day to orbit the Earth once,
thereby rendering their ideal apparent positions with respect to the Earth's
surface stationary. The endpoints of the satellite streaks are the subjects of
astrometric analysis to determine where the satellite was (in R.A. and Dec.) at
the beginning and ending times of the exposure. This image was a simple ten
second exposure. North (Dec.) is at top, while East (increasing R.A.) is at
left. Both satellites seem to streak because the telescope is tracking the stars
(sidereal), not the satellites themselves. This allows much better astrometric
analysis because of the even distribution of individual stars on the CCD image.
If the sidereal tracking were turned off, the stars would streak and the
satellites would appear as star-like dots. Astrometry would not be as accurate
with this method, however.
Figure 4: Tracking data from the CASTOR
facility for the Telesat satellites Anik F1 and Anik F1-R. In this data, from
left to right, the observation ID, time of observation (year, day of year, hour,
minute, second, decimal second), and the determined coordinates (2000.0 R.A. and
Dec.) are shown. This tracking data can be used to perform a more up-to-date
determination of the satellite's orbit in order to predict where the
satellite will be in the future. Note how the declination of both satellites are
several degrees below the celestial equator. Although these satellites orbit
very nearly along the Earth's equatorial plane, CASTOR is located at a latitude
of nearly 45 degrees. The parallax experienced changes the apparent location as
seen by CASTOR to south of the celestial equator.
Figure 5: A CASTOR cropped image of the Russian Molniya 3-46 satellite taken on 06:21:35.670 to 06:22:15.670 U.T.C. October 2, 2005. Unlike the Anik satellites mentioned earlier, this satellite has a very uneven light curve. This suggests that the satellite is tumbling in space, and therefore inactive. The period of this tumbling can be determined using photometric analysis of the CCD image. The satellite is travelling left to right in this image (increasing R.A. and Dec.).
Figure 6: The results of the photometric analysis of the tumbling of satellite Molniya 3-46. Beneath the graph is the superimposed negative image of the tumbling satellite, scaled to match the time axis. Closer analysis of the data indicates that the satellite is tumbling with a period of about 8.7 seconds (or about 41.4 degrees per second in angular velocity). A vast database of satellite tumble periods for many satellites can be collected by amateur astronomers and can be analyzed for normal or sudden changes over time.
I am not saying that all amateur astronomers should
become satellite trackers. That would be an unfair statement on my part.
Besides, not all amateur astronomers would like the subject, just like some
amateur astronomers are not interested in observing planetary nebulae, for
instance. Satellite tracking is an extremely new subject, especially if you
consider that amateur astronomers have had access to it for only about 10 to 15
The amateur astronomer is extremely dedicated to the subject of amateur astronomy. The similarities between this subject and that of satellite tracking is enough such that the amateur astronomer has an advantage over those who have not experienced amateur astronomy in the field. Contrary to some beliefs, the amateur astronomer can begin tracking satellites with his/her own equipment right away. All he/she requires is a goto telescope, a CCD camera, a computer, and the enthusiasm and knowledge he/she has obtained from many hours of amateur astronomy. The worldwide amateur astronomy community can become a significant workforce dedicated to tracking our own satellite population. Amateur astronomers look at everything else in the heavens, why not artificial satellites too? Why would it be bad for amateur astronomers to track satellites for private satellite companies, and make a few bucks off it at the same time? These are some of the many questions that need to be answered within the realm of modern astronomy. When I first began tracking satellites, I fell in love with the subject. I would not be surprised if other amateur astronomers did as well. I myself love being a pioneer. I invite other amateur astronomers to do the same!
This page last modified: October 4, 2005