Phoranso uses the UCAC4 catalog both for astrometric measurements to calculate the position of the stars in your images and for photometric measurements to extract precise brightness information in various wavelengths (bands) for stars in your images. 


When launching Phoranso for the first time, it will prompt you either to download the UCAC4 catalog or, if you already have the catalog installed on your PC, to specify its location in Phoranso.



UCAC4 star catalog not installed on your PC


If the UCAC4 catalog is not yet installed on your PC, Phoranso can download the complete catalog for you. Go to Tools → Download UCAC4 catalog. Phoranso offers two download methods; both contain identical contents, so you may choose whichever you prefer. When in doubt, select From Google Drive.


Option 1: Download from Google Drive 

  1. Choose From Google Drive to download the UCAC4 catalog directly from an external Google Drive repository.






  1. Follow the instructions shown in the dialog box. Open your Documents folder and navigate to the Phoranso directory. Inside it, create a new folder named UCAC4. 

    Next, click the Google Drive link in the dialog box. This will open your web browser and take you to a Google Drive location containing all required UCAC4 files and folders.

  2. Download the entire contents of that Google Drive folder into your newly created UCAC4 folder. Keep in mind that the UCAC4 catalog is approx. 12.5 GB, so the download may take 15 to 50 minutes, depending on your Internet speed. 

  3. When finished, the contents of your UCAC4 folder should match the structure shown in the figure at the bottom of this section. You can then close the dialog box.

  4. After completing the download, continue with the instructions in the next section UCAC4 star catalog already installed on your PC. 



Option 2: Download the UCAC4 catalog from an FTP Server


  1. Select From FTP Server to download the UCAC4 catalog files from an external FTP Server.




  1. Press OK to start the download. While the download is ongoing you can continue to interact with Phoranso. Each time a new UCAC4 file has been downloaded to your PC, you will see a short message appearing in the dialog box. Notice that some UCAC4 files are extremely large, so it can take a long time between successive message updates. 

  2. When the installation on your PC has completed, the below message appears:



  1. You should now proceed with the instructions provided in the below section UCAC4 star catalog already installed on your PC.



UCAC4 star catalog already installed on your PC


  1. This section applies if the UCAC4 star catalog is already present on your PC, or if you have just completed downloading it using one of the options described above.  

  1. Open the File menu and select Settings . In the dialog that appears, switch to the Catalogs tab, as shown in this image:



  1. In the upper part of the window, under Photometric Catalog, you will find the field where you can specify the location of the UCAC4 Folder on your PC. Click the button with the 3 dots next to the UCAC4 Folder location field. This opens the Windows folder selection dialog. 

    Navigate to your UCAC4 folder, select it, and click OK. The folder path will be automatically updated. You may now close the Settings dialog box - your changes are saved automatically.



Important

You have to ensure that your already installed UCAC4 catalog has the exact same structure as shown in the image below.  Your u4b subfolder has to contain exactly 900 items, while the u4i subfolder has only 1 item (file u4index.unf). If your UCAC4 installation deviates from this structure, you will have to go through the above installation step to ensure proper working of Phoranso.