5 replies to this topic

[sternenhimmel]

CRS-32 re-enters tomorrow along the California coast -- it will be visible formt he bay area down to LA. People in LA, especially Long Beach may even hear the sonic boom.

For me here in Monterey, it will be directly over head re-entering the atmosphere, and I wanted to see if there's any way to get my AM5 mounted scope (382mm focal length) to track it. I know I can use the AM5 in alt-az mode, but I only have the rather inperceise hand controller that comes with it, no fancy joystick or anything. I'm hoping there's a way to use the guide scope feed to auto track it -- it's going to be brighter than any other objects in the sky.

[triplemon]

Uh - might want to start by tracking the ISS at night. Or some airplanes during the day. To get some feeling how easy (or difficult) it is to track a moving object.

 

In general - unless you have VERY specialized software, automatic tracking will be impossibly hard. As the object may head in a slightly different direction or at a slightly different speed than what a pre-caclculated track that steeers the scope is. So you have to constantly make guiding corrections at rapid pace in both directions. As the sattelite tracking software (which usually is nothing but rapid sucessive slews) will not learn from your past guiding inputs and adapt the general track heading and speed to remove the constantly increasing offsets. Not even talking about initial aquisition - where you could be further off than the FOV of even a 8x50 finder.

 

Last - the actual track and timing during re-entry is a lot more variable than the orbital segments, due to upper atmosphere density changes  So you won't find any very good prediction ahead of time (simple TLE won't do - speed is rapidly changing), these re-entry vehicles do really actively navigate during reentry. And being a few seconds off in timing - that can be several degrees in the sky. Thats the biggest problem with initial aquisition.

 

I find it easier to track in a all manual dob. Once you get the hang of it, manual tracking at 50-60 power is definitely possible.

 

I think there are solutions to use a wide FOV camera-based auto-guider (or even better - two separate ones for coarse and fine guidance), but when I last looked into that maybe ten years ago it was all still in its infancy and required a lot of McGyvering to make it work.

Edited by triplemon, 23 May 2025 - 08:25 PM.

[RalphMeisterTigerMan]

That should be pretty cool! Looking froward to watching some posts on the Tube of You!

 

Clear skies and keep looking up!

RalphMeisterTigerMan

[Al Berman]

I'm hoping to shoot the reentry tonight with my Sony A1 and 200-600. You mentioned it will be passing directly overhead in Monterrey. May I ask where you found the trajectory so I may carefully plan here in Los Angeles?

[sternenhimmel]

So we went out and caught it last night -- the thing was hauling a** though and there would have been zero chance of tracking it at my skills. I didn't even bother. It was moving cosiderably faster at our location than it was by the time it was over LA. 

However, it was spectacular, and way cooler than I expected. Basically imagine the brightest meteor you've seen, but orange, and making its way across the entire sky leaving a smoke trail. 

I did try to take a long exposure with my Sony A6700, but the camera is new to me still, and some headlights ruined my shot anyway. Note for people here -- the A6700 (and maybe all sony mirrorless cameras) require an equal time to process as your exposure length when shooting in bulb. So if you shoot for 60s, you can start your next exposure for 60s, which is really a bummer. 

Here's a photo my partner took on her phone just as it started coming over the horizon. This is not a long exposure (well maybe 1s), the trail is the smoke trail. 

Oh, we also heard the sonic boom!
 

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Edited by sternenhimmel, 25 May 2025 - 01:58 PM.

[areyoukiddingme]

Easy to keep track of in binoculars, or a short refractor manually. I imagine next to impossible with a motorized mount.