I searched for today's lunar eclipse data in Wolfram Alpha.
That gave me this result:
In their sources section they have Given some sources.
One of them is: https://eclipse.gsfc.nasa.gov/eclipse.html
My Question is Why the data umbral magnitude, penumbral magnitude are different ?Wolfram Alpha's source is Nasa gsfc site so why not same as NASA's data . I know that there is a little difference between those data but why not same as NASA's data ? I don't know much about this stuff so if i am missing anything let me know. Thanks :D
The data in Alpha was obtained from a previous iteration of the NASA site around 2009. Back then, the algorithms used to compute solar/lunar phenomena were likely based on JPL DE 405/406 ephemeris. Since then, they have likely updated to use the JPL DE 431 which is a much more precise ephemeris that wasn't available when we obtained the data from them. At some point we hope to update to use newer data, but the new structure of the NASA pages makes it hard to obtain the new data.