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Our first step is to look into the data fields that are found on all client displays. The Data Info section seems to be a good place to start. Each of the entries here are detailed below.

From: 5 hr 20 min 59 sec RA, +20 deg 12 min 35 sec Dec

chart3.jpg (29097 bytes)This is the location in the sky where the Arecibo antennae was pointed when this work unit was recorded. From the sky chart used at Berkeley, the following map shows the position of this work unit in large scale.

The red point is the work unit location. It is in Taurus, just above Orion. That's nice because it is an easy place to find in the sky. Orion is The Hunter. The stars of Orion form an easy to recognize figure of a man. It may be the most recognized constellation in the sky. The work unit is just over his left shoulder just above the star Bellatrix. At midnight, in October, Orion is above the Eastern horizon.

A more detailed examination of the work unit location will be done later in this article. To start we are just checking the area in general.


 

Winter Milky WayIn this image, from Astropix, the work unit area is very close to the M1 label right of center. That is the famous Crab Nebulae. It contains a pulsar that is bright in the radio spectrum. The Crab Nebula has the coordinates  RA 5h 34m 30s, decl 22 01' 00" and that puts it about 3 away, to far to be detected by the antenna. It is far to early to start selecting candidate objects in our review of the spike but it is an interesting area.

 


Recorded on: Tue Mar 23   21:01:39 1999 GMT

chart4.jpg (68636 bytes)The Arecibo radiotelescope is not limited to looking for signals in the night. This work unit was recorded at 21:01 GMT, which is 5:01 PM in Puerto Rico. Puerto Rico uses the Atlantic Time Zone and is 4 hours behind GMT all year round. Daylight Savings Time is not observed in Puerto Rico.

In this image, taken from the SkyGlobe application, the work unit location   (small yellow X at center) is shown to be high in the East. The data block at upper left shows the work unit time, date and location. The location of the observatory is Latitude 18 20' 36.6" North and Longitude 66 45' 11.1" West.

Note that this is a view of the high Eastern sky. North is at the left here. In the above images, North was at the top. This chart is facing East and looking nearly straight up.

At lower left, the data block shows that the mouse cursor and work unit spike, at screen center, is at 78.1 degrees azimuth  and 79.4 degree elevation   from Arecibo.

It is interesting that the Moon is close to this location. The Moon could easily reflect radio signals from Earth. But it is not close enough here to be in the antenna's beam. A better calculation to be assured of the exact position might be warranted.

The little wavy lines to the left of the Moon is the location of M1, the Crab Nebula. It is also to far away to be involved in the work unit data.


Source: Arecibo Radio Observatory

Arecibo RadiotelescopeAll the data for the SETI@home project comes from Arecibo. This is a beautiful place. An aircraft carrier would fit inside this 1000 foot dish.


Base Frequency: 1.418994139 GHz

The SETI@home data is recorded from the output of a receiver riding piggyback at the focus of the Arecibo carriage house shown above the dish above. That receiver is tuned to a frequency around 1.42 GHz. At Berkeley, that digital recorded is fed into a splitter that converts it into a frequency spectrum. That spectrum is broken into 256 subbands. Each subband then has a base frequency associated with it. For this work unit, it is 1.418994139 GHz. On the client graphic display, that is the left side of the graph and is the radio frequency that matches 0 Hz on the graph.

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