Dear Friends:

Spectroscopic measurements provide wealth of information on plasma conditions, but often the experimental design and data analysis involves the knowledge of Non-LTE population distributions. The code FLYCHK, an extension of popular K-shell spectroscopy code FLY, has been developed to provide experimentalists with a simple tool to compute charge state distributions and spectra for a wide range of laboratory conditions. We hope this will contribute to making spectroscopic methods more accessible to those in the community and provide a simple to use tool for those outside the community who need NON-LTE radiative properties predictions.

In order to obtain access to the FLYCHK, which is now hosted at NIST and available via a website interface, one needs to send the following information to Dr. Yuri Ralchenko (mail below):

1. name

2. affiliation

3. address and phone number at work

4. e-mail

5. brief description of research interest

Note that indiscriminate execution will revoke your access.

Please contact us if you need any assistance with the FLYCHK calculations or have any feedback on the website interface itself. We appreciate your interest and hope FLYCHK will contribute to your research.

Dr. Hyun-Kyung Chung: hchung.hedp at
Dr. Yuri Ralchenko: yuri.ralchenko at
Dr. Richard W. Lee: dicklee at