Global High Resolution H-alpha Network


1. There are *FL and *FR file in my downloading list, what the names refer to?

FL files are dark and flat corrected images. FR files are FL images with Limb-darkening correction.
For more detailed filenaming, please see the format page.

2. How long does it take to process my request?

It depends on how much data is requested. Typically, an image sequence of
4GB (within a period about 11 hours with 1 minute cadence) will be ready in 2 business days.

3. Why I get *.GZ files instead of original FITS files?

In order to reduce the image size, we compress FITS files to GZ files.
This will save more than 25% of online storage. For some WINDOWS users,
the IDL/SSWIDL may not be able to read GZ files. If this is the case,
please un-compress all the files using WINZIP, WINRAR or other third-party

4. I got difficulty downloading the data. Could you provide FTP or other solutions?

Currently we do not offer FTP download for security concern. For data less than
4GB, we could burn CDs or DVDs.

5. How to figure out the observing period for each station?

One can find the time difference for each station to UTC through GHN's timezone page.
Our stations observe the Sun in daytime (varies upon the season in North Hemisphere) if the local weather is clear.