International Space Station

[Mills]

Wow , that was great !
Right on time .

 

[striker55]

Good sighting, nice and bright. And right on time.

 

[striker55]

Next sighting is this morning at 6:19:44, wsw to ssw, 16.6° elevation

 

[striker55]

Got to see it just before it went behind a neighbor house. Probably should have gone out the front door.

 

[Mills]

Boomer flashback;
1961

Mercury-Redstone 3 - Wikipedia

en.m.wikipedia.org

 

[oohrah]

You will notice that the visible passes will only occur less than a few hours after sunset or before sunrise. This is because ISS is still in sunlight at its altitude, and you can see it because you are in darkness.

However, if you want to monitor the amateur radio frequencies, you can do this on any pass, as there are at least four passes every day.

 

[BBL]

You can't keep up with it with a telescope, it moves too fast.

Thank you. I guess binoculars will have to do. Unless I can hold up the telescope while staring into the ocular and trying to aim it. Oof.

 

[striker55]

Thank you. I guess binoculars will have to do. Unless I can hold up the telescope while staring into the ocular and trying to aim it. Oof.

Yeah I tried binoculars, couldn't keep my hand steady.

 

[jmohme]

When I had a telescope I tried to figure when the ISS would pass in front of the moon to get a picture, never happened for me.

That is high on my list too.
In fact I was just out viewing Saturn and Jupiter through my 8 inch scope with friend and was talking about this very thing to her.

 

[BBL]

ISS is in a low earth orbit, 90-93 minutes or so orbital period, so it moves pretty fast. Use the lowest power/widest possible FOV on your telescope and be prepared to keep moving it to follow.

I just realized that the math does not add up.

This entry claims that the ISS will be visible 10 degrees above the horizon for nearly 7 minutes. That is 160 degrees across the sky in almost 7 minutes. That calculates to pretty much 15 minutes for 360 degrees.
If the ISS takes 90 minutes to orbit, wouldn't it spend 45 minutes over our half of the sphere and 45 minutes on the other side?
What am I missing here? Or is my astronomical ignorance showing here? (pun intended)

 

[striker55]

Another good sighting for tonight, high in the sky. This is a screenshot of tonight's flight.

 

[oohrah]

I just realized that the math does not add up.
View attachment 344430

This entry claims that the ISS will be visible 10 degrees above the horizon for nearly 7 minutes. That is 160 degrees across the sky in almost 7 minutes. That calculates to pretty much 15 minutes for 360 degrees.
If the ISS takes 90 minutes to orbit, wouldn't it spend 45 minutes over our half of the sphere and 45 minutes on the other side?
What am I missing here? Or is my astronomical ignorance showing here? (pun intended)

At the ISS altitude, it has about a 2000 mile footprint, in other words, it can see 2000 miles from its horizon to horizon. you are in its horizon for about 7 minutes with an overhead pass. That is about how much time you will get in a 90 minute orbit. So, you get 90/7 time of an orbit times 2000 = the circumference of the Earth. All these number are are approximate.

 

[Big Dipper]

I just realized that the math does not add up.
View attachment 344430

This entry claims that the ISS will be visible 10 degrees above the horizon for nearly 7 minutes. That is 160 degrees across the sky in almost 7 minutes. That calculates to pretty much 15 minutes for 360 degrees.
If the ISS takes 90 minutes to orbit, wouldn't it spend 45 minutes over our half of the sphere and 45 minutes on the other side?
What am I missing here? Or is my astronomical ignorance showing here? (pun intended)

The simplest explanation of the flaw in your logic is that your view point is NOT at the center of the orbit! The 160° is the portion of your visual sphere that ISS traverses, not the same as 160° of its orbit.

As a further example, your North and South horizon points are 180° apart (in your visual sphere). But those two points (maybe 5 or 6 miles apart physically) are not halfway around the Earth.

 

[striker55]

Best sighting this week!

 

[BBL]

Thank you for the explanations, gentlemen. I knew it was something simple. My ignorance shows.
We saw the ISS with our bare eyes and even with binoculars but it was just a burning bright dot.
I even caught it with the telescope about twice but only for maybe 1 second. Not enough time to figure out what I was seeing. Also very bright and blinding.
Did anybody get a good picture, by a chance?

 

[vmax]

I pick it up easy with my mobile rig, remember it's only 254 miles away when passing overhead.

Ans basically line of sight with no obstacles in between

 

[Mills]

Crystal clear for a 8:29 view tonight
West to Northeast

 

[Mills]

Right on time, spectacular

 

[BBL]

It was again very nicely visible last night (2030 CDT) and it was at good elevation of 51 degrees, passing NW to NE.
I liked the quick red phase as it went through the "sunset".
I gotta install the app.

 

[oohrah]

Tonight over Texas NNW to SE starting about 1944 local (confirm your location time) - watch the SpaceX Dragon Crew capsule chasing ISS (Dragon just launched this morning).