Does anyone know the ascending node and periapsis for the ISS? This is for a MATLAB script. I cannot find it on the internet and figured that this would be a good place to ask.
You can find the recent data on Heavens-Above.
Epoch (UTC): 27 July 2018 17:07:00 Eccentricity: 0.0005177 inclination: 51.6392° perigee height: 402 km apogee height: 409 km right ascension of ascending node: 176.7268° argument of perigee: 353.8799° revolutions per day: 15.53762294 mean anomaly at epoch: 6.2290° orbit number at epoch: 481
Due to low orbit and resulting air drag, plus periodic reboosts, that data shouldn't be treated as fixed/long-term; the orbit changes over time a lot.
Coasting Arc #19 (Orbit 673) --------------------------------------- [...] Satellite: ISS Catalog Number: 25544 Epoch time: 18221.12611709 = yrday.fracday Element set: 918 Inclination: 51.6406 deg RA of node: 114.8775 deg Eccentricity: .0005396 Arg of perigee: 39.6633 deg Mean anomaly: 320.4914 deg Mean motion: 15.53822846 rev/day Decay rate: 1.67170E-04 rev/day^2 Epoch rev: 674 Checksum: 315
Note that I'm writing this answer on July 27, but the epoch of the data set quoted above is the 221st day of the year, which is August 10; it is the 19th set of predictions that's available as I look. As your other answer says, the orbit of the ISS is non-Keplerian because of its interaction with the atmosphere and occasional correcting boosts. Comparing different sets of orbital parameters might let you learn some interesting things about the way the orbit evolves over time.