ASRG SETI at UK
Where We've Been Looking Lately
Data are retained and analyzed for approximately the past month. We try to concentrate our efforts on the most recent files because any signals there are the most likely to be confirmable by other stations. You can see where we have been looking lately by monitoring U Kentucky ASRG SETI Data.
We are using posts to U Kentucky ASRG SETI Data to "announce" the availability of new data files for analysis. You can find these posts in Netscape by pointing your browser at U Kentucky ASRG SETI Data. 28 Mb (one hour long) files, 7 Mb (15 minutes long) files and 2 Mb (5 minutes long) files are listed on U Kentucky ASRG SETI Data.
Users can determine file size from the file names: one-hour files have names in the format date_time_utc.wav, where time is the starting time of the one hour period, while the 15-minute files and 5 minute files have names in the format date_time_utc_1.wav, date_time_utc_2.wav, date_time_utc_3.wav, etc., where the number indicates how many quarter-hours have past since recording began. You can also get a complete list of files and their sizes on the servers by deleting the file name from the hyperlinks.
Before making a post reporting an unusual signal (from SETIEasy, for example), go through the checklist for Detecting Terrestrial Interference and Spectral Artifacts. Most of the internally generated noises in the system are too small to be detected in files in the 8-bit data format. In 16-bit data files, however, small CW signals are common. In addition to checking suspect signals against the Known Interferences Log, each time a data acquisition run begins the antenna is turned off for at least two minutes while "data" are recorded. These data are used to identify internal system noises that may arise at particular combinations of time, frequency, and drift. In this way, interferences can be easily and quickly distinguished from more interesting signals. While programs like SETIEasy can calibrate on test data segments and ignore most interference automatically, with other programs ignoring locally generated interferences is not quite as simple. CW signals in ASRG data posted online are checked before being copied onto the data servers, so any such signals appearing in the posted files were already noted in the test data segments and/or Known Interferences Log. Students should examine the posted data files for more unusual signals in mind, particularly modulated ones that might not be easily detected by computer programs.
On U Kentucky ASRG SETI Data the posts look like
(Note that these are all 5-minute files.) The top post in each thread contains a file name, while subsequent posts are made beneath each file post to mark certain files as "Downloaded" or "Completed." To download the file in recent versions of Netscape or Internet Explorer, one need only right-click on the hyperlink in the lower frame and select "Save As" or "Save Link As" to download and save the file for analysis on your own computer. When you complete an analysis, it helps to describe the software and parameters employed. For example, posting "Completed SETIEasy v1.33, dechirps = -0.1 to +0.15 in 0.01 steps" or "Completed CoolEdit dechirps 20% to 120% in 1% steps" lets others know what you did to get your result, and what other tests remain to be applied.
There is also an ongoing discussion of the ASRG's SETI data and analysis techniques on U Kentucky ASRG SETI.
Note for those who have expressed an interest in discussing SETI-related topics: most such discussion occur on the newsgroups sci.astro.seti and alt.sci.seti