Questa sezione contiene le risposte alle domande più comuni che ci vengono rivolte dagli utenti, sia in riferimento alle possibilità di Perseus che al suo utilizzo. Se non trovate risposta alle vostre domande, non esitate a scriverci a info@perseus.it.

Q. Considering that I have only three installations available, what should I do when I change my PC or OS?

A. If you want to install Perseus on another PC or OS, you have to use the program's uninstall function in order to get your uninstallation code. When you tell us (by phone or using this web page) this code, your uninstallation will be recorded. After that, you'll be able to install Perseus again, using the same procedure you used the first time. You can repeat this process every time you want.
Please, TAKE NOTE OF YOUR UNINSTALLATION CODE when you get it, in order to use it when you'll record your uninstallation.

Q. What if the system crashes unrecoverably and it is not possible to get the Uninstallation Code?

A. If this is the case, contact us by email or phone and we will provide an additional possibility of installing the software. Please supply the serial number that you found on the CD case or in the user's manual. If you have other active installations (for example on another PC), please supply also the activation codes of those copies. To see them, start Perseus and choose "About Perseus" from the Help menu.

Q. I inserted the serial number but there is an error. Why?

A. You must type the serial number without spaces, with hyphens and taking care not to confuse "B" with "8" or "O" with "0"; serial numbers can contain only the digits from 0 to 9 and the letters A, B, C, D, E, F.

Q. Since it is necessary to activate the software using the website, can I install Perseus on a PC that is not connected to the Internet?

A. You can install Perseus without problems from the installation CD, or even from a USB key where the CD has been copied to. To complete the activation, you can copy the temporary code and the activation code between the installation PC to another PC connected to the Internet using pen and paper. You can choose to make a manual activation to get the temporary code, then cancel it and start Perseus (up to 20 times). When you have the activation code, choose the manual activation again; the temporary code will not change.

Q. I reinstalled Perseus on the same PC, but the old activation code does not work anymore. Why?

A. The temporary and activation codes contain a random component, and they do not repeat and are not reusabee, even if they are generated on the same PC with the same serial number.

Q. Can I keep two installation of Perseus on the same PC?

A. Only if one is an installation of Perseus Light Edition and the other is an installation of Perseus Level I, II or III.

Q. It is required to insert the original CD in the PC in order to use Perseus?

A. No. You can use Perseus without CD if you made a complete installation; otherwise you have to use the original CD or a backup copy.

Q. Why does Perseus slow down while zooming or engaging RealDeep?

A. If you have selected the Minimum or Medium option during the installation, Perseus will read some data from the CD-ROM. This will cause the slowing down, which is due to the access time to the CD data. You can disable the CD access; in this case, Perseus will use only the data already installed on your hard disk.

Q. What's the time period I can use with Perseus' simulations?

A. It depends on the subject of simulation. Planets' motion is calculated with an error of some hundredths of a second on a period which goes from about 1000 B.C. to about 3000 A.D. Out from this period, precision gets worse; you'll have nonsense results out of the 5000 B.C. - 5000 A.D. period. The precession of equinoxes has similar limits. The extrapolation used to obtain future values of ΔT becomes inaccurate in brief time intervals; by the way, on this site you'll get continuously updated data. Data referred to the past are based on the chronicles of the past eclipses, and they're obviously affected by some inaccuracy. Stars' position are calculated using their proper motion. Precision is subject to the time distance from the twentieth century, when the positions have been measured, and to the uncertainty of the stars' proper motions. The more these parameters increase, the more the position's inaccuracy will grow. Perseus will not let you go out of the time span 1,000,000BC-1,000,000AD (1,000BC-3,000AD for the Light Edition).

Why can't I see any RealDeep object printed?

A. With some printers you'll have to change the print settings, in order to have the RealDeep printed. Usually you'll need to use a darker setting. Considering that it depends strictly on the printer's features, you'll probably need to make some attempts before finding the proper setting.

Q. Where do I find the USNO-A catalogue?

A. The USNO-A catalogue is available on the USNO site. The downloading instructions are on this page: http://ftp.nofs.navy.mil/projects/pmm/a.response. You'll have to use a FTP client to download it. The complete catalogue's size is about 6.6 GB (approximately the content of 11 CD-ROMs). Considering the huge size of the catalogue, we recommend you to download only the files related to the sky zone you are interested in. The USNO-A catalogue can be freely copied without paying fees, but nobody can make money of it. We suggest that you get it by asking someone who has it already, and is willing to copy it for you.

Q. Can I move my customized objects' descriptions from one PC to another?

A. Yes, you need only to move the DESC.DAT file, located in the DATI folder of Perseus (usually C:\Program Files\Perseus\DATI).

Q. In the scripts available on this site I can see simple lines drawn on the simulation. How can I get them?

A. Lines in scripts are obtained just by inserting an empty text.

Q. Perseus works with Windows Vista?

A. Perseus works with Windows Vista from version 1.8. If you have a previous version you will have to download the update from the patch page. If your version is lower than 1.5, you will have to download also the patch to version 1.5.
In order to install Perseus follow this procedure:
- obtain administrator rights;
- install Perseus by executing Setup.exe from the CD-ROM;
- if the version of Perseus is lower than 1.5, install the patch 1.5;
- if the version of Perseus is lower than 1.8, install the patch 1.8 after the patch 1.5.

Q. During the installation of level I-II-III, the installer hangs with the error C:\Program Files\Perseus\DATI\SECT11_.TAB An error occurred while trying to rename a file in the destination directory: MoveFile failed; code 32.

A. This error can be due to a defective CD, but also to system problems. You can try with this procedure:
- copy the entire contents of the CD in a folder on the hard disk;
- obtain administrator rights;
- install Perseus executing Setup.exe from the folder where you copied the CD;
- if the version of Perseus is lower than 1.5, install the patch 1.5;
- if the version of Perseus is lower than 1.8, install the patch 1.8 after the patch 1.5.
In some cases, you will have to do the installation procedure starting the system in safe mode.
If the CD copy procedure fails, write to us at info@perseus.it.
In any case, it is permitted (and suggested) to make a backup copy of the installation CD.