Tracking Telesat's Past from Rideau Ferry

On the night of October 29-30, 2005, I attended Rob Dick’s 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 Telesat’s 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 Canada’s satellite communications infrastructure.

In the past, I had already tracked several of Telesat’s 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 A’s smaller size, lower reflectivity, and the light pollution in the Ottawa area.

At about 00:30 E.D.T., I began with Telesat’s first satellite: Anik A1. Anik A1 was the world’s 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 Earth’s 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%.

Figure 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 telescope’s 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! That’s 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 Earth’s rotation as the tracking instrument. In this way, the satellite’s 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.

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 telescope’s 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.

Anik B1 (the only Anik B series satellite), was located 45 degrees below the local horizon that night, and therefore could not be detected.

Figure 3: An artist’s 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 streak’s 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!

Figure 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 in 1983.

Anik C3 was 25 degrees below the local horizon, and therefore was inaccessible that night.

Figure 5: An artist’s conception of the Anik D series satellite. Image courtesy Telesat Canada.

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.

Figure 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.

Figure 8: An artist’s 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.

Figure 10: An artist’s 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 artist’s 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.

Anik F2 is Telesat’s most hefty baby, weighing in at 5950kg. It is the heaviest of all the Anik satellites launched to date. Its current duties are to provide the entire North American continent with advanced broadband services. An image of this satellite is shown in Figure 14.

Figure 13: An artist’s conception of the Anik F2 satellite. Image courtesy Telesat Canada.

Nimiq 1 is Canada’s 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 artist’s conception of the Nimiq series satellite. Image courtesy Telesat Canada.

Figure 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 service.

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 1½ 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 observer’s 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.

While I was imaging the Telesat satellites, I marveled at the fact that although I was detecting satellites that were approximately 39,000km from my location, they were created by a company that was located a mere 10-minute drive from where I live!

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.