With the shortened Kerbin day, how does that affect a geosynchronous orbit?

[Shiv]

Is it still a period time of 6 hours or is it a few seconds shorter now?

[LethalDose]

Is it still a period time of 6 hours or is it a few seconds shorter now?

Unless I'm screwing up my terminology (which is possible, the synodic/sideral thing messes with me), it just is a 6 hr period now. Before KSO was 6 Hrs and some-odd seconds.

Edited July 18, 2014 by LethalDose

[Shiv]

Before the update to get a geosynchronous orbit you set the orbital period to 6 hours, or so I was told by a couple of folks. I want to know whether the day length 'fix' has affected that. It seems it would because I believe they sped up the rotation of Kerbin to adjust it.

[Phoenix84]

What is this 'day length fix' you speak of?

The solar day and sidereal day cannot physically be the same. If one is changed, the other must as well.

Last night I just finished placing 24 GPS satellites in orbit and 1/2 day orbital period (2:59:60.0). This was with 0.23.5, so I hope I don't have to change it.

The sidereal day (planet rotation period) is exactly 6 hours. The solar day is 6h 50.8 seconds. Did this change?

[LethalDose]

Well, if they changed the rotational speed of kerbin, then they changed altitude and period of KSO, so if 6 hrs used to be right, now it's wrong. I'm trying to find where Harvester described the change.

[LethalDose]

Okay, here it is:

"Kerbin's Solar Day is now exactly 6 hours long (sidereal day is now 59 seconds shorter)."

So yes, the sidereal day is now 6 hrs (which is how I read this), so the synodic day is now shorter, probably by about 59 seconds, but I can't tell you exactly how long without substantially more math than I have time for right now.

But setting your orbital period to about 5 h 59 min should be really good until the numbers get redone.

To me, what's weird about this is the wiki said that the sidereal day was 6 h 0 m 50.8 s, so the sidereal day length should be 50.8 s shorter, not 59 s shorter.

Yep, screwed up synodic and sidereal. KSO should be 5h 59m 1s now, according to Harv's post.

Edited July 18, 2014 by LethalDose

[Phoenix84]

Okay, here it is:

"Kerbin's Solar Day is now exactly 6 hours long (sidereal day is now 59 seconds shorter)."

So yes, the Sideral day is now 6 hrs (which is how I read this), so the synodic day is now shorter, probably by about 59 seconds, but I can't tell you exactly how long without substantially more math than I have time for right now.

But setting your orbital period to about 5 h 59 min should be really good until the numbers get redone.

Thanks for the find.

So they made it like earth. It makes sense from a cultural and realism perspective. Just annoying with math now. I do recall a discussion about that a while back now.

Well, I'll just hyperedit the orbits to fix them then. I need to do that anyway to make sure they don't drift.

I'm curious to know how that will affect other orbits though. For example if I have crafts on an intercept course and such?

EDIT: The synodic day is the solar day (at least for Earth). The sidereal time is the shorter of the two.

EDIT2: I added this as you corrected your post.

This is explained as such (forgive me if you know this):

The sidereal time is the true rotation period of the planet.

The solar day is the time it takes for the sun to go from one point in the sky to the exact same point the next day.

However during the day, the planet is also revolving around the sun. This causes the sun to not be in the same spot if you follow the sidereal day. This discrepancy (for Kerbin at least), is about 59 seconds. This is about 1°, IIRC.

The wiki just hasn't been updated yet.

Blog post: http://forum.kerbalspaceprogram.com/content/296-KSP-First-Contract-(v0-24-0)-Complete-Changelog

Edited July 18, 2014 by Phoenix84

[Shiv]

Ah there it is. I knew they were planning on changing it but never saw an official figure. So we need to match our satellites to 5h 59m 1s now correct?

[LethalDose]

It makes sense from a cultural and realism perspective. Just annoying with math now.

Yeah, this. Someone complained that 6 hrs didn't make sense because it wasn't equal to a synodic day, so now we have to deal with wierd numbers. SIGH!!!

Ah there it is. I knew they were planning on changing it but never saw an official figure. So we need to match our satellites to 5h 59m 1s now correct?

Looks it. I wager it's correct to within .5 sec (assuming it's rounded to the nearest second). If someone has Kerbin's new radial velocity, we can get it with substantially more precision.

[Rhomphaia]

The info box in map view says "Rotation Period 5h, 59m, 59s"

for all other bodies the box lists the Sidereal Day