The Astronomy hobby thread

[Bob Kontak]

Originally Posted by flatbutt

Webb is on it's way!

So I wake my ask up at 6:30am Christmas morning to watch the launch. That was a scintillating 20 seconds as the clouds ate it up from view.

Anyhoo, I find this NASA website "Where is Webb" It gives current data about speed, distance traveled and distance remaining, percent complete. Basic stuff.

https://webb.nasa.gov/content/webbLaunch/whereIsWebb.html

The orbit where Webb is headed is Lagrange (point) 2. Now Lagrange is pretty cool and has to to with gravitational balance and i am still reading about it. I think it means Webb will be a million miles towards Mars but stay in lock step with the Earth around the Sun.

Here's the diagram:



Here's the reason for the post. The (a) rocket has to get up to circa 17k MPH to orbit. I'm assuming it did that. Now it's on the way to the L2 point, more than half way to the moon.

This morning it was moving away from earth at 1.0551 miles per second. That's slightly over 3,600MPH. What happened to the 17K MPH?

Also the spacecraft is slowing down. Now it's 0.93 miles per second at 5:00PM.

What gives with the "slow" speeds? I'm guessing way easier to slow down?

Apollo took a couple days to get to the Moon so they weren't going 17k MPH either. Correct?

[masraum]

Originally Posted by Bob Kontak

This morning it was moving away from earth at 1.0551 miles per second. That's slightly over 3,600MPH. What happened to the 17K MPH?

Also the spacecraft is slowing down. Now it's 0.93 miles per second at 5:00PM.

What gives with the "slow" speeds? I'm guessing way easier to slow down?

Apollo took a couple days to get to the Moon so they weren't going 17k MPH either. Correct?

Nope, the 17k mph is almost certainly correct. Also the speed moving away from the earth (including the deceleration) is probably correct.

Imagine that you've got a weight on the end of a 6' string , and you're holding the string and spinning the weight around above your head, maybe 36 feet per minute in a circle. Also imagine that there's a tree 8' away. If you start slowly letting more string out, say 1" of string every 5 seconds. That would mean that the weight on the end of the string was approaching the tree at 1 foot per minute, but the weight on the end of the string is spinning at 36 feet per minute.

That's how Webb is approaching at one speed, but going another. Also, as the distance from the earth increases, the circumference of the orbit also increases, which means that it takes longer to complete and orbit and therefore the orbits are getting larger at a slower rate.

[Bob Kontak]

Originally Posted by masraum

That's how Webb is approaching at one speed, but going another. Also, as the distance from the earth increases, the circumference of the orbit also increases, which means that it takes longer to complete and orbit and therefore the orbits are getting larger at a slower rate.

You're killin' me, Smalls.

I'm workin' on it but, damn.

[flatbutt]

Originally Posted by masraum

Nope, the 17k mph is almost certainly correct. Also the speed moving away from the earth (including the deceleration) is probably correct.

Imagine that you've got a weight on the end of a 6' string , and you're holding the string and spinning the weight around above your head, maybe 36 feet per minute in a circle. Also imagine that there's a tree 8' away. If you start slowly letting more string out, say 1" of string every 5 seconds. That would mean that the weight on the end of the string was approaching the tree at 1 foot per minute, but the weight on the end of the string is spinning at 36 feet per minute.

That's how Webb is approaching at one speed, but going another. Also, as the distance from the earth increases, the circumference of the orbit also increases, which means that it takes longer to complete and orbit and therefore the orbits are getting larger at a slower rate.

Also, one must consider that there is a difference between orbital velocity and escape velocity (which is indeed 17k mph). Orbital velocity being the speed that is required to reach extended orbit of a planet or star whereas escape velocity is the speed that is required to escape Earths gravity well.


Webb is nearly 200,000 miles out already!

[Bob Kontak]

I think orbit is 17k and escape is 24k MPH.

Originally Posted by masraum

That's how Webb is approaching at one speed, but going another.

Finally sunk in. Thanks.

[flatbutt]

Already reached the Moon.

[Hawkeye's-911T]

I think orbit is 17k and escape is 24k MPH.

While maybe not relevant to Bob's topic - those speeds are positively glacial when compared with the speed of the Parker solar probe. Depending on which source you've used, Parker clocks in between 360 to 430,000 mph. Granted, Parker was the beneficiary of a few gravitational boosts to achieve this speed.

All-in-all, this is pretty cool stuff.

Cheers
JB

[Eric Hahl]

Santa showed up with some astro-imaging gear today.

[flatbutt]

Originally Posted by Eric Hahl

Santa showed up with some astro-imaging gear today.

Very nice! Very $$$$ too. AMHIK

Piers are still back ordered. I'm going to give in and pour my own.

[Pazuzu]

Originally Posted by Eric Hahl

Santa showed up with some astro-imaging gear today.

Do you know how many t-rings, off-axis guiders, illuminated reticle eyepieces, Kodak Tri-X film and Nikon F-bodies with manual triggers you could have bought for that kinda money?

A lot. A lot of them. And you'd be imaging like a MAN. A Hairy chested MAN. Sitting out there in the cold, hunched over, eyes filled with tears, guiding like a MAN. Waiting two weeks for Fox Camera to tell you that none of your pictures are any good, just fuzzy blobs and dust specks, so they didn't process any of it. MANLY imaging.

Freaking red crap. Astronomy accessories should be black and steel and be hard to use.

[flatbutt]

HA! I've had more than one contact sheet come back to me a perfect black page. Of course, that was eons ago using an F2 that weighed so much my counter balance was a volks wagon!

[Eric Hahl]

Mike, I've had all those and done that. Even though this setup can be controlled remotely from the house I'll be using it out in the field so I will be up all night with it at least.

[Pazuzu]

Originally Posted by Eric Hahl

Mike, I've had all those and done that. Even though this setup can be controlled remotely from the house I'll be using it out in the field so I will be up all night with it at least.

Keep an eye on the forums for info about that ASIAir. I had a customer who used one, the version of PhD that is loaded on there (maybe, or one you can put on there?) is different than the Windows version. I had his mount and it worked great using the laptop interface, but he took it and put it back in his dome, put the ASIAir on, and had horrible results. I took it back, checked out fine, went back to him and again, bad results. Terrible tracking, random comm errors, etc. I asked for things like PhD logs, and apparently you can't get them from the red box o' doom (my name, but it it sticks, you can use it )

Just a warning.

[Eric Hahl]

For those interested in the solar systems movement through space...pretty interesting.
https://bigthink.com/starts-with-a-bang/earth-move-universe/?fbclid=IwAR3Z0MWv6bvEhUSibO6BFtapZDdT3qMmdwCmHRsz EbyjifQeYMWvUI90a_M

[flatbutt]

Asteroid tracking

https://www.virtualtelescope.eu/2021/12/30/potentially-hazardous-asteroid-7482-1994-pc1-close-encounter-online-observations-18-jan-2022/

[Eric Hahl]

So finally, all my gear arrived and we had a clear night last night. Set up in the backyard to do the initial testing of the equipment and see if I could capture anything. I did a fairly rough polar alignment, got close but not as close as I'd like.

Had a little bit of a rough time figuring out the app to control everything but once I started figuring it out it went very smooth.



Got everything working and sent the scope to Orion, turned on the tracking and started some captures. This shot is about 12 different exposures, some 30 seconds, some 60, some 300 and a couple 600 seconds. Only had time to shoot a few bias and dark frames, no flats yet.

I'm really pleased and looking forward to getting to know this rig.



Gear used:
Scope: William Optics RedCat 71 (350mmfl) F4.9
Camera: ZWO ASI2600 color
Mount: iOptron GEM45

[targa911S]

I'm currently moving to digital. A whole new world. I haven't done any deep sky stuff yet. Using a Nikon D5300, shooting through an 8" MEADE Schmidt Cass. with clock drive. Same rig I used for the old cold camera stuff I did 20 years ago. Practice practice practice

[masraum]

Originally Posted by targa911S

I'm currently moving to digital. A whole new world. I haven't done any deep sky stuff yet. Using a Nikon D5300, shooting through an 8" MEADE Schmidt Cass. with clock drive. Same rig I used for the old cold camera stuff I did 20 years ago. Practice practice practice

Nice!

I'd love to do AP, but I barely have time to do A. Add the P and there's no way.

I've got an 8" Celestron SCT.

I took these with my cell holding it up to the EP. That's probably as close as I'll get to AP in the near future. OK, I do have an SLR and have considered getting some wide angle milkyway shots with that.

[Eric Hahl]

Nice, kinda wish I still had my old clock drive SCT.

[Pazuzu]

Originally Posted by Eric Hahl

Nice, kinda wish I still had my old clock drive SCT.

Which one do you want? I'm working on restoring my inventory to sell...

First model year (1981) Meade 2080, with the first year 2-screw secondary collimation and super sweet only-one-year wedge with early Alt-Az adjusters. Comes with an early Acu-Trac AC drive controller. The 2080 had a worm gear too, not like the early C8s with spur gears!

First year (1988) Meade LX-6, the first DC powered Meade, first f/6.3 Meade model, with the FULL WORKING dual encoders and full hand paddle with digital readout...

First Year (1987) Celestron Powerstar, the first Celestron DC powered mount, with RA and Dec control using Vixen sourced stepper motors, and a kick-ass hand controller with focus and reticle control, speed control and a map light...

Each with era-correct cases, tripods and wedges. Weeee!!!