APOD, a chinese CubSat has been in Space since late 2015. One of its satellites carries a VLBI beacon. Since then, several efforts were undertaken to observe APOD.

We have had several attempts in observing APOD with the AuScope antennas in Hobart, Katherine and Yarragadee. Due to the long baselines, the tracks are relatively short. Our attempts here at the University of Tasmania to correlate the data have not really been successful so far. However, in November we will intensively try to collect more data. This includes an optimised tracking (continuous tracking should be possible with our antennas) and the observations themselves. Andreas Hellerschmied from Vienna will visit us and Tim Natusch from Auckland has also agreed to support us by providing the Warkworth antenna. Hoping to report on successful observations soon.

Friday, Nov 11: tracking tests with Ho26m. Some tests using ISS signal; S-band beacon (2270) clearly detected, stable throughout track. Sattrack worked smoothly after drive PC reboot. Testing AzEl track for APOD of the next day. Found we can only do one side of the track (up to about 30 deg elevation).

Saturday, Nov 12 (316b): Morning: APOD track with Ke and Yg. Blocks of quasars before and after (10 min). 5 min break between quasar and sat. AzEl files are manually loaded via antenna control HMI. Quite stressy but works. Signal (carrier and DOR tones) was clearly visible in spectrum analysers, both in S-band and X-band. DOR tones also visible in autocorrelation (0.25 sec of data). Carrier might be saturating.

• 216a (KeYg, 2016-11-11, 22:15:00 - 22:39:1010 UT)
• 217a (HoHbKe, 2016-11-12, 09:34:00 - 10:15:33 UT)
• 217b (HbKeYg, 2016-11-12, 21:35:00 - 22:09:49 UT)
• 218b (HbKeYg, 2016-11-13, 10:48:30 - 11:14:27 UT)
• 218c (HbHoKe, 2016-11-13, 21:01:00 - 21:26:59 UT)
• 218d (KeYg, 2016-11-13, 22:35:00 - 22:57:55 UT)
• 219a (HbHoKeYg, 2016-11-14, 10:00:00 - 10:40:05 UT)

Saturday Nov 12 evening 317a: tracking with Ho, Hb, Ke. Quasar recordings and tracking successful. No recordings during for Ho and Hb, Ke started late; so no overlap. Ho signal looked good an stable (S-band). Hb (x-band) highly variable (about 1 sec). Ke variable as well (in s-band) at high elevations.

Sunday morning Nov 13, 317b: ke overhead track, couldn't keep up at high elevations. Yg looked good, appeared to be stable throughout. Hb didn't look too good, weak and unstable at s-band, even at low elevation.

Files (VEX, tracking data, etc.) related to these sessions are provided on the VieVS server via SFTP:

• vievs.hg.tuwien.ac.at
• user: sorts
• directory: /home/sorts/apod/2016/

Please contact Andreas Hellerschmied, if you need the password)

• Unordered List ItemThe tracking files have to be loaded by the antenna control system which takes some time. Therefore, there is a gap of min. 5 minutes between blocks of quasar observations and satellite scans in the schedules
• Basical the S/X APOD signals are visible on an attached spectrum analyzer. This can be used to confirm that the antenna is on source during tracking.

• Antenna control with direct AzEl input.
  • Format: Azimuth Elevation Position_Angle MJD time
    • First line: number of tracking points (integer)
    • Remaining lines: one line per tracking point, TAB delimited, all integers:
    • Azimuth and Elevation are in degrees x 10000, Position_Angle should always be 0 (not used), MJD is the modified Julian Day number, and time is the number of milliseconds since the start of the MJD

Comments:

• Investigating the signal spectra during tracking a periodic variation in the signal amplitude is visible at higher elevations (more pronounced at X-band than in S-band)
  • This is probably caused by the antenna tracking system (still “stepwise”?)

• Antenna control with direct AzEl input.
  • Different format than used for KeYgHb
  • There is a scrip to convert AzEl files written in the format used for KeYgHb to the Ho-specific format (still AzEl positions)
  • AzEl values should be within 0 to 360 deg

Comments:

• If the satellite becomes too fast track (high elevation) the antenna has problems to catch the track again
  • If there is a rise and set section and the satellite is not observable in between =⇒ Only observe one of the sections.