I am using GMAT to propagate satellite motion with Jacchia-Roberts atmosphere model. Here is a formula used from this model which is then used to estimate the variation in drag on a spacecraft due to heating by solar activity:

$$T_c(K) = 379 + 3.24\cdot F_{10.7} + 1.3[F_{10.7} – \overline{F}_{10.7}]$$

in which $F_{10.7}$ and $\overline{F}_{10.7}$(the average daily solar flux at a 10.7 cm wavelength for the day of interest and 81-day running average of $F_{10.7}$ centered on the day of interest, respectively) are used.

I would like to ask; where does GMAT take this coefficients from and where can I find the $\overline{F}_{10.7}$ in order i would like to implement Jacchia-Roberts?

As it is seen from definition, a values not only before but also after this day will be needed to calculate $\overline{F}_{10.7}$ but I couldn't find a resource in the internet providing me such information.


1 Answer 1


Here is a NASA repository of space weather data, including f10.7.


I would bet GMAT gets its data there or a similar site.


Apologies everyone for the lacking answer, I'm new to StackExchange. That original link actually only has historical data, so it probably isn't the best source.

I found this old GMAT forum post (http://forums.gmatcentral.org/viewtopic.php?f=3&t=43555) that says GMAT gets solar weather data from CSSI/Celestrak: https://celestrak.org/spacedata/. This post is old, so I can't guarantee that's still what GMAT uses, but that's also the source my company uses for space weather data for operational OD so it's probably a safe bet anyways.

This has historical and a few months of daily predictive data you could use, including f10.7 and other common space weather indices. Hope this helps.

  • 1
    $\begingroup$ @AlexJohnson It's nice to accept answers if they really answer your question or solve your problem. In this case though, with a link-only answer, it's better to hold off and not accept until the answer is brought up to SE standards. I usually wait a few days to allow for the possibility of more answers; sometimes when people see an answer that's accepted quickly, it deters them from taking the time to write an even better answer, and then future readers miss the opportunity to read it. $\endgroup$
    – uhoh
    Commented Aug 8, 2018 at 11:15
  • $\begingroup$ it looks much better now! By the way if you make a change that addresses someone's comment, leave a short comment with the @ sign in front of their user name. That way they get a notification and will know that you've addressed the issue. In this case I just found this by accident. Looks much better now! $\endgroup$
    – uhoh
    Commented Aug 14, 2018 at 15:53

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