No. SETI@home writes its results to disk every minute or two.

If time resolution does not yield 64 or more time bins, or if the slew rate is out of bounds, the curve-fitting routine is not called. In the curve-fitting routine, if a Power of Time array has no bin above 3 sigma, skip that array. For each bin (i.e., each candidate Gaussian) if amplitude not above 3.2 sigma (mean recalculated to exclude peak) skip that bin.

Occasionally, a work unit will contain strong radio interference; these strong interfering signals typically come from satellites and radar from our own civilization. If the interference is very strong, the SETI@home program can not analyze that part of the spectrum, and after trying for a few minutes and detecting thousands of strong signals of earth origin, the program stops early in the processing and gets a new work unit. You will still get credit for the work done.

Earth is polluting space with radio and television signals that might be detected by nearby advanced civilizations, but it would be difficult for such a civilization to discover these signals if they only have Earth's current level of technology (eg: if they have an Arecibo like telescope and SETI@home like search).

Early TV shows like I Love Lucy and Ed Sullivan left the earth about 40 years ago, so have gone out 40 light years, reaching several thousand nearby stars. But these signals are relatively weak and SETI@home is not likely to detect the equivalent of Earth type TV transmitters, even on the nearest stars.

Earth's strongest transmitters might be somewhat easier to detect, such as those emitted by military radars, or some radio telescopes. The Arecibo telescope transmits very powerful signals when it is used as a radar system to study planets, asteroids and the ionosphere. These radar signals are powerful enough to be detected 10,000 light years away by searches like SETI@home, except for three big caveats:

a) The Arecibo transmissions are in a very tight beam (they are not omnidirectional, like TV and military radar), so they only cover a very small part of the sky at once (about a millionth of the total sky). It's is unlikely another civilization will be within one of these narrow beams.

b) The Arecibo transmitter's oldest signals left Earth about 30 years ago, so have only travelled 30 light years.

c) SETI@home is not searching the band of frequencies that the Arecibo transmitters utilize (although our older SERENDIP III program did survey one of those bands).

Click on the SETI@home icon in the Menu Bar and select Launch.

Macintosh dial-up Internet software comes in 2 flavors, Open Transport and FreePPP. On OS 9, Open Transport is called "Remote Access". If you are using Open Transport (OTPPP or "Remote Access"), then:

1) Under the Apple menu, select Control Panels and PPP ("Remote Access" in OS 9). make sure it has the correct phone number of your ISP, login name and password. To connect unattended, you must have "Save password" set.

2) Press the "Options" button, then select the "Connection" tab. Set "Connect automatically ..." and "Disconnect if idle for xx minutes". Set the disconnect delay to whatever number you wish.

3) You may also set the "prompt every xx minutes" checkbox if you wish. If the computer is unattended, so there is no response to the reminder, it will go ahead and disconnect after a few minutes.

If you are using FreePPP, then:

1) Find and open the FreePPP Setup application. Select the "General" tab.

2) Set "Allow applications to open connection" and "Disconnect if idle for xx minutes". Set the disconnect delay to whatever number you wish.

These are disabled while SETI@home is transferring data over the Internet, as they could interfere with the transfer.

Yes. Move the SETI@home icon out of the System Folder : Control Panels folder, to another location (such as the desktop), and restart your Macintosh. You can run SETI@home as a stand-alone application whenever you wish. But if you have another screensaver installed, SETI@home will run very slowly when the other screensaver is active, and the other screensavers animation may be sluggish or jerky.

Response to user input may be a bit sluggish on Macintosh models with slower processors (prior to G3), or with less than 32MB of physical RAM. You may sometimes need to hold the mouse button over the Menu Bar for a few seconds before getting a response.

SETI@home will not launch if another application has a modal dialog frontmost. The Standard File (Open and Save) dialogs are examples of modal dialogs. You must dismiss the modal dialog for SETI@home to launch.

Different portions of the same work unit can vary greatly in speed. If progress seems to freeze, be patient and let it run overnight. It may have gotten past the slow spot by then.

Here are some suggestions:

• Each time SETI@home launches, it optimizes itself for the current monitor color depth (256 colors, Thousands, Millions). If you change the color depth while SETI@home is running, it may slow things to a crawl.

• It should run reasonably at any screen depth, but it will run somewhat faster at lower screen depths (256 colors) than higher ones. Screen resolution (800X600, 1024X732, etc.) should have negligible effect on speed.

• In screensaver mode, SETI@home runs fastest if the screen is blanked, so for maximum speed set the preferences to blank the screen after a short time.

• In application mode, SETI@home runs fastest if its window is collapsed, using the Windowshade feature under OS 8.0 and later.

• Many Macintosh models are equipped with the Energy Saver Control Panel. This can put the computer's processor, hard drive, and monitor in a low-power sleep mode if the mouse and keyboard have been idle for a period of time. Although SETI@home can continue to run when the computer is in sleep mode, it will run much slower. You may want to change the settings in the Energy Saver Control Panel to let SETI@home have more time. Some people prefer to have the computer never sleep so it can analyze more signals, while others prefer to save electricity. The choice is up to you.

Dial-up Internet software comes in 2 flavors, Open Transport and FreePPP. If you are using Open Transport (OTPPP), then:

1) Under the Apple menu, select Control Panels and PPP. make sure it has the correct phone number of your ISP, login name and password. To connect unattended, you must have "Save password" set.

2) Press the "Options" button, then select the "Connection" tab. Set "Connect automatically ..." and "Disconnect if idle for xx minutes. Set the disconnect delay to whatever number you wish. 10 minutes is a good value.

3) You may also set the "prompte every xx minutes" checkbox if you wish. If the computer is unattended, so there is no response to the reminder, it will go ahead and disconnect after a few minutes.

If you are using FreePPP, then:

1) Find and open the FreePPP Setup application. Select the "General" tab. (If you don't see the "General" tab, click the small triangle in the lower left corner.)

2) Set "Allow applications ot open connection" and "Disconnect if idle for xx minutes". Set the disconnect delay to whatever number you wish. 10 minutes is a good value.

1) From the Start button, select "Settings" and then "Control Panels". Open the "Internet Options" Control Panel.

2) Select the "Connections" tab. Make sure the desired "Dial-up networking" selection is set as the default. (The set default button will be grayed out if you select the current default in the list.)

3) Set "Always dial my default connection".

4) Select the correct "Dial-up networking" from the list, and click on the "Settings..." button.

5) Another dialog box "xxxx Settings" appears. Press the "Advanced" button.

6) The "Advanced Dial-Up" dialog will appear. Set "Disconnect if idle for xx minutes" Set the disconnect delay to whatever number you wish. If you wish, you may also set "Disconnect when conection may be no longer needed.

If you set "Ask me before connecting" in the Preferences dialog, SETI@home will display more detailed information for many errors.

For Windows 95 and 98, do the following steps:

1) From the Start button, select "Settings" and then "Control Panels". Open the "Internet Options" Control Panel.
2) Select the "Connections" tab. Make sure the desired "Dial-up networking" selection is set as the default. (The set default button will be grayed out if you select the current default in the list.)
3) Set "Always dial my default connection".
4) Select the correct "Dial-up networking" from the list, and click on the "Settings..." button.
5) Another dialog box "xxxx Settings" appears. Press the "Advanced" button.
6) The "Advanced Dial-Up" dialog will appear. Set "Disconnect if idle for xx minutes" Set the disconnect delay to whatever number you wish. If you wish, you may also set "Disconnect when conection may be no longer needed."
7) Close the "Internet Options" Control Panel.
8) Double-click on "My Computer", and then on "Dial-Up Networking". Double-click on the default "Dial-up networking" icon. Make sure the "Save password" box is checked. If not, check it and click on "Connect", then "Cancel". Close the dialog.

For Windows NT do this: 1) Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
2) Click More, and then click User preferences.
3) In the Enable Auto-Dial By Location dialog box, select each location for which you want the automatic dialing feature to operate.
4) Click OK and then restart the computer.

No. Due to our new security measures to prevent falsified results, if a work unit has been partly completed by a different version of SETI@home, the progress will be reset to zero and the work unit will be processed from the beginning.

After each pass over the data, SETI@home does a preliminary check to see if the data's properties indicate a possible gaussian curve. If not, it saves time by skipping the gaussian analysis. For some work units (those with slow slew rates), no gaussian fit calculations are done for the entire work unit, so this area of the display remains empty.

There are several possibilities. If you have SETI@home set to connect automatically to the Internet, it may have returned the result and gotten a new work unit. (If a work unit has too much radio interference or RFI, then SETI@home may request a new work unit much sooner than usual.)

If SETI@home's processing was interrupted abnormally by a system error or power interruption, its output files may have been corrupted. In this case, SETI@home will restart the work unit from zero automatically.