Bonjour, let’s measure the time of an asteroid occultation!
A few days ago I decided to test the accuracy of different timing equipment as regards the preparations for observation and recording of the occultation of star TYC 1187-01197-1 by asteroid Arachne on Saturday November 8th 2014 by members of our club. Normand, Roger, Yvan and I hope to encourage all the members of our club to participate in this and other future asteroid occultation observations. What is needed is a telescope, a hunter’s eye, a chronometer and a reliable time source!
The available equipment for timing were:
1. Tim-10 GPS Video Time Inserter. A high-accuracy GPS devise (1-pulse-per-second) used for occultation observations. The GPS time signal is received through a Garmin 1-PPS GPS receiver, it is being corrected inside the devise and is displayed as an output stamp in each and every frame of the video signal of a CCD video camera. This was the base for my test.
2. Radio Clock, model « RMB 899 P » by Oregon Scientifics. A radio clock or radio-controlled clock is a clock that is synchronized by a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock. It was great to see that this devise can operate here in Laval, QC as it CAN be synchronised with NIST Shortwave Radio Station WWVB 60 near Fort Collins, Colorado.
3. Telephone talking clock. A time service by National Research Council Canada (NRC) .
If you dial 613-745-9426 on your home phone or even your mobile phone (as I did for the test) you can have a very accurate time source. Voice announcements of Eastern Time are made at ten-second intervals, followed by a tone whose beginning indicates the exact time. This service is available to the general public by dialling the Ottawa telephone numbers 613-745-1576 for English service and 613-745-9426 for French service.
In the following video the first scene is a general view of all the equipment for the test. You can see (from right to left): the GPS VTI devise, a digital voice recorder (top), my mobile phone (down), the Oregon Scientific Radio Clock and my camcorder. In the following scenes you can see the actual test. In specific:
You can SEE: 1. The GPS time line in UT (3rd row). Watch the count of seconds. The first and second rows are LOngitude and LAtitude 2. The Oregon Scientifics Radio Clock.
You can HEAR: 2. The Oregon Scientifics Radio Clock – quadruple (4) beep alarm sound at the beginning of each second 3. Telephone talking clock – a tick at each second and a voice announcement of time every 10 seconds.
Results: This was not an accurate measurement, just a visual observation. The inspection shows that in comparison with the GPS time line, both the SW Radio Clock and the Telephone Talking Clock seem to be well less than 0.1 second away. This is a very good result, since the maximum uncertainty of a a visual observation report should be no more than 0.5 seconds.
Another time source option: CHU Radio Station (not in my tests yet)
If you already have or if you can buy a SW radio receiver, you can have a reliable time source for your observations. Just synchronize your chronometer or mobile phone to CHU, in any of these three frequencies: 3330, 7850, and 14670 kHz.
CHU is the call sign of a shortwave time signal radio station operated by the Institute for National Measurement Standards of the National Research Council of Canada.
CHU’s signal is used for continuous dissemination of official Canadian government time signals. The CHU time signal and radio frequencies are derived from atomic clocks.
Click below to hear the sound file
Good luck and good timings to everybody!