|TRACKING TELESAT'S PAST FROM RIDEAU FERRY|
On the night of October 29-30, 2005, I attended Rob Dickís Open House at Rideau Ferry. Normally at such an event, I would show the curious attendees some planets (like Mars, Uranus and Neptune), galaxies (like M31), nebulae (like M27), etc. I had done just that for the first few hours, but after midnight, when most of the attendees had thinned out, I decided to conduct an experiment. Since I had my 11-inch Celestron and SBIG ST-9XE CCD camera with me, I decided to determine if I could detect, and therefore track, all of Telesatís satellites, past and present, from that location.
Telesat Canada is best known for its ground-breaking efforts
in satellite communications in Canada. With 16 satellites under its belt,
beginning with Anik A1 in 1972, it remains a pioneer for Canadaís satellite
OBSERVING CANADA'S FIRST "LITTLE BROTHERS" - THE ANIK A SERIES
In the past, I had already tracked several of Telesatís satellites, including the Anik F series, and the Nimiq series, both actively servicing customers. These are extremely easy to detect because they are very large and very reflective. I could not detect the Anik A series from my backyard in Orleans, however. I theorized that this was because of a combination of the Anik Aís smaller size, lower reflectivity, and the light pollution in the Ottawa area.
At about 00:30 E.D.T., I began with Telesatís first
satellite: Anik A1. Anik A1 was the worldís first
commercial geostationary communications satellite
(source: www.telesat.ca). An image of the Anik A1 satellite before its launch is
shown in Figure 1. It has been retired since July 15, 1982 (source:
www.telesat.ca) after nearly 10 years of faithful service. It now sits in a
geosynchronous orbit with an inclination of 14.5 degrees to the Earthís
equatorial plane. From my vantage point at Rideau Ferry, the satellite sat at
139 degrees in azimuth and 45 degrees in altitude at the time. The phase was a
very favorable 85%.
1: The Anik A series
satellite. At 560kg, it is the lightest of all the Anik satellite series. Its
small size and low reflectivity makes for a difficult object to optically
detect, especially since it was about 37,000km from Rideau Ferry on that day.
Image courtesy Telesat Canada.
My first attempt at detecting Anik A1 that night was done with the telescopeís sidereal drive turned on. Using this, the stars would show up as dots and the geostationary satellites would appear as horizontal streaks in the camera orientation that I use (North at top, increasing R.A. to the left). Since Anik A1 was no longer an active satellite, the streak should be seen as slightly inclined (to the North or to the South, depending on if the satellite is ascending or descending, respectively) from the horizontal. The satellite streak was just above the background noise on the 10-second exposure image, but it was definitely there! This was from a site that was extremely dark! How dark? With my naked eye, I could easily see that portion of the Milky Way that lies in Orion! Thatís pretty dark!
In order to obtain a brighter image of the satellite, I
decided to switch my sidereal drive off so that the telescope would more closely
track the satellite using the Earthís rotation as the tracking instrument. In
this way, the satelliteís reflected light would be seen to travel across the CCD
pixels much more slowly than when using the sidereal drive. The result was that
the satellite did show up much brighter than the image background, and is shown
in Figure 2.
An image of the Anik A1 satellite
taken at the Astronomy Open House at Rideau Ferry. A satellite in a
geostationary orbit would appear as a dot in the same circumstances. The long
horizontal streaks are stars trailing across the CCD chip during the exposure,
as the telescopeís sidereal drive was switched off. The satellite was traveling
northward, which indicates it was ascending in its 14.5 degree inclined orbit at
that time. This image was a 60-second exposure.
I also tried for Anik A2 and Anik A3, and was able to detect both. Like Anik A1, both were quite faint, due to their very similar designs to Anik A1, and their similar distances from my observing location.
(the only Anik B series satellite), was located 45 degrees below the local
horizon that night, and therefore could not be detected.
TUMBLING! - THE ANIK C
3: An artistís conception
of the Anik C series satellite. Image courtesy Telesat Canada.
Anik C1 was not accessible from Rideau Ferry, being 46 degrees below the local horizon that night. However, on July 28 of the same year, I was able to detect this satellite in Orleans when it was above my local horizon. It was found to be tumbling with a period of about 2 seconds.
Anik C2 was accessible from Rideau Ferry, being at 31 degrees above the local horizon. After obtaining an image of the satellite, it was obvious that its light curve was completely different from that of the Anik A series. It looked more like a string of pearls than a solid streak, which suggested that the satellite had no functioning attitude control, and therefore tumbling in space. After a preliminary determination of the tumble rate, it was determined that the Anik C2 satellite is currently tumbling at a very fast period of 2 seconds. More data is needed to obtain a better statistical analysis of the tumble period. The image of Anik C2 is shown in Figure 4.
It must be stressed that just because a satellite streakís
brightness looks uniform does not mean that the satellite is not tumbling. Since
the Anik A series has long since been retired, it is a good bet that all three
of them are tumbling. One possible explanation is that the satellites are
tumbling very slowly, thereby looking uniform in brightness for a long period of
time. Another explanation is that the reflectivity of all three Anik satellites
is nearly uniform throughout their surface area, thus not changing the apparent
brightness appreciably over time as the satellite tumbles. Of course, both of
the above can be true too!
4: An image of the Anik
C2 satellite. From this 20-second exposure image, it is apparent that the tumble
period is approximately 2 seconds, which means an angular velocity of 180
degrees per second. This satellite was launched by the Space Shuttle Challenger
Anik C3 was 25 degrees below the local horizon, and therefore was inaccessible that night.
5: An artistís
conception of the Anik D series satellite. Image courtesy Telesat
Anik D1 was 26.5 degrees
in altitude that night, and so that was the next target to shoot for. It was
easily seen as another tumbler, but with a larger tumble period of about 3
seconds. The image of the Anik D1 satellite is shown in Figure 6.
6: An image of the Anik
D1 satellite within a very rich star field. From this 10-second exposure
image, it is apparent that the tumble period is approximately 3 seconds, which
means an angular velocity of 120 degrees per second.
Anik D2 was a comfortable 25 degrees above the local horizon, and was
also easily imaged. It also exhibited a tumble period, which was determined to
be about 4 seconds. The image of this satellite is shown in Figure 7.
Figure 7: An image of the Anik D2 satellite. From this 10-second exposure image, it is apparent that the tumble period is approximately 4 seconds, which means an angular velocity of about 90 degrees per second.
8: An artistís conception
of the Anik E series satellite. Image courtesy Telesat Canada.
Anik E1 was retired on January 18, 2005 (source: www.telesat.ca) after over 13 years of faithful service. I had tracked this satellite (along with Anik E2) many times before while it was active. On that night at Rideau Ferry, this satellite was 5 degrees below the western horizon, and therefore inaccessible.
Anik E2 is still active (source:
www.telesat.ca), but in a 2.3 degree inclination orbit, and therefore no longer
in a purely geostationary orbit. The satellite was located at an altitude of 36
degrees, and just 2 degrees south of another Telesat satellite, Nimiq 2. As
expected, the satellite was still very bright. The image is shown in Figure 9.
Figure 9: An image of the Anik E2 satellite taken at Rideau Ferry. You can see the slight inclination of the orbit by the slight angle the streak has to the horizontal. Its larger size is certainly apparent from its higher brightness compared to the previous Anik satellites.
Anik F1 was launched on
November 21, 2000 to replace the aging Anik E1 satellite and to assume all the
duties of its predecessor. As expected, it was very easily detected where it was
predicted to be. An image of the Anik F1 satellite streak is shown in Figure 12.
I discovered that another geostationary satellite was co-located with Anik F1,
as two horizontal streaks were in the image. I quickly determined that the
interloper was the newest Telesat satellite, Anik F1-R.
10: An artistís
conception of the Anik F1 satellite. Image courtesy Telesat Canada.
Anik F1-R is the first European-built satellite for
Telesat. Launched on September 8, 2005, it was placed in orbit to assume the
duties of Anik F1, which is now assuming its new duties of exclusively servicing
the South American continent.
Figure 11: An artistís conception of the Anik F1-R satellite. Image courtesy Telesat Canada.
Figure 12: An image of the Anik F1 and Anik F1-R satellites. Both of these satellites are currently active. The exposure time was 10 seconds. Note how both streaks are lying horizontally, indicating that they are indeed geostationary satellites.
Figure 13: An artistís conception of the Anik F2 satellite. Image courtesy Telesat Canada.
Figure 14: An image of the Anik F2 satellite.
is Canadaís first direct broadcasting satellite. For those who subscribe to the
Bell ExpressVu service, you are pointing your satellite dish to either Nimiq 1
or Nimiq 2.
Figure 15: An artistís conception of the Nimiq series satellite. Image courtesy Telesat Canada.
16: An image of the Nimiq
1 satellite. This satellite, along with Nimiq 2, is what Bell ExpressVu users
point all their satellite dishes to receive their direct-to-home satellite TV
Nimiq 2 was launched
to increase the Bell ExpressVu service to subscribers. This was also the final
satellite I tracked that night at Rideau Ferry, about 1Ĺ hours after I had
begun. Its image is shown in Figure 17.
Figure 17: An image of the Nimiq 2 satellite. The exposure time was 5 seconds.
The final results of this survey are shown in Table 1 below. Note how the phase
of the satellite does not solely determine the brightness. Other factors such as
distance from the observing site, size and reflectivity of the satellite itself,
and even the altitude of the satellite in the observerís sky can affect how
bright the satellite appears.
Table 1: The final results of the Telesat satellite survey at Rideau Ferry, October 30, 2005. The magnitudes of all the satellites were determined using CCD photometry, but only represent the ballpark brightness of the satellites, especially in the cases of the tumbling satellites.
Stay tuned for images of Anik F3, in which I will try to get images of its orbit insertion and final parking into its intended orbit slot. It is due for launch sometime during the latter half of 2006.
A special thanks to Robert Dick for his hospitality and permission to use his observatory grounds at Rideau Ferry for this experiment.
This page last modified: November 25, 2005