The Astronomy hobby thread

[Pazuzu]

Originally Posted by flatbutt

I have had issues getting my AVX to track well enough for stellar pix, but at 33 milliseconds....

This AVX is one of the 3 that I have in the shop, all will be Blueprinted then sold.

I rebuilt/Blueprinted a CG-4 and have it autoguiding at sub-arcsecond RMS...about 50 arcseconds of periodic error, but it's smooth and simple and guides out just fine. For a $200 mount.

[Pazuzu]

OK, many of you already know, but we are 2 weeks out from the Great Conjunction, when Jupiter and Saturn will appear within a 10 arcminute circle...that's small enough that even cheap planetary cameras on scopes up to 8 or 10 inches will be able to image them at once.
Closest approach is Dec 21, but Dec 20 is pretty good. Dec 22 they've started to move apart, and they're "too far" apart before and after then.
West-Southwest sky, as soon after sunset as possible, the two brightest things in the low sky will get closer and closer over the next 10 days, until they meet on Dec 21.

A 25mm plossl eyepiece on an 8 inch f/10 SCT gives about a 35-40 arcminute circle field of view. So, with an eyepiece you could still go with a 12mm eyepiece for about 160x power and clearly get both planets and the moons. With a ccd, the field of view is 135(A/B) where A is the chip size in mm and B is the scope focal length in inches. The same 8 inch f/10 SCT with a NexImage5 camera (about 5mm chip size) will be too tight at around 9 arseconds, adjust to your equipment accordingly.
https://astronomy.tools/calculators/field_of_view/
Shoot for a field of .25-.4 degrees across.

[flatbutt]

Originally Posted by Pazuzu

This AVX is one of the 3 that I have in the shop, all will be Blueprinted then sold.

I rebuilt/Blueprinted a CG-4 and have it autoguiding at sub-arcsecond RMS...about 50 arcseconds of periodic error, but it's smooth and simple and guides out just fine. For a $200 mount.

Are you Axis2?

[Pazuzu]

Originally Posted by flatbutt

Are you Axis2?

Axis Squared, yes. It's not squared as in the mathematical process, it's squared as in "set to be orthogonal"

[GH85Carrera]

I was in my back yard last night and noticed how bright the two planets are, and how close together they were. In the movies two bodies aligned like that is usually the start of an apocalypse or some great disaster from the combined gravity of the two largest planets. The facts that humans have more gravitational effect on one another than Saturn and Jupiter combined will have on Earth is never mentioned.

[flatbutt]

Originally Posted by Pazuzu

Axis Squared, yes. It's not squared as in the mathematical process, it's squared as in "set to be orthogonal"

Check your PM

[masraum]

Originally Posted by GH85Carrera

I was in my back yard last night and noticed how bright the two planets are, and how close together they were. In the movies two bodies aligned like that is usually the start of an apocalypse or some great disaster from the combined gravity of the two largest planets. The facts that humans have more gravitational effect on one another than Saturn and Jupiter combined will have on Earth is never mentioned.

Jupiter is putting on quite a show. Usually Saturn also seems very impressive, but it's the poor cousin right now. What's even crazier (to me) is that Mars is putting on more of a show than Saturn. I'm used to Mars being the unimpressive one.

[flatbutt]

Well Saturn averages approx 850 million miles away from us. I'm amazed every time I see it.

[Eric Hahl]

Typical northwest skies here. Can't see anything through the clouds and rain

[masraum]

Tomorrow we are closing on our home. I'm currently very near downtown Houston, so probably Bortle 9 skies. The new place is 80 miles away, and per this site
https://www.cleardarksky.com/maps/lp/large_light_pollution_map.html


approx
Artificial / Natural Sky Brightness: 0.58 to 1.00
Sky Brightness - mags / sq arcsec - V Band : 21.51 to 21.25
Bortle Scale: 4
Description: Zodiacal light seen on best nights. Milkyway shows much dark lane structure with beginnings of faint bulge into Ophiuchus. M33 difficult even when above 50 degrees. Limiting magnitude about 6.2 to 6.5.

[flatbutt]

The pairing is fairly low, maybe 30 degrees so low level stuff will interfere and they are setting early too.

[masraum]

Originally Posted by flatbutt

The pairing is fairly low, maybe 30 degrees so low level stuff will interfere and they are setting early too.

It's a bummer for sure, but I think I can get to a place where I'll be able to see them. Thank goodness it's happening in the dead of winter.

[Rtrorkt]

Newbie here. Have a 5" Nexstar and can't get it to align properly. I believe I have the north alignment right, though I am unsure of that. Is there a simple way to know that the tube is pointed in the right direction as I do the first alignment to north. Is the support to the left or right of the tube?

I thought if it was off 180 degrees then the three star alignment would be as well. It did not seem that way.

If someone can help, it would be much appreciated.

[flatbutt]

I don't have a single arm mount so IDK how that would effect alignment. Are you doing a polar alignment or just pointing the OTA north? Do you have on board GPS?

Nexstar has onboard software to guide you through the process. Try putting Sirius or another known bright star in the crosshairs and have the computer take over from there. IIRC only mag 2.5 or brighter should be used for alignment on a Nexstar.

This is what I do on my CPC800
Solar system align. Center/align the moon (if Jupiter not yet visible).
GoTo Jupiter. Should be close enough after GoTo to locate it in the finder scope.
Press Align, then choose “Replace” and Unassigned.
Center/align Jupiter. (now you have a two “star” alignment).
GoTo Altair. Press Align. Choose “Replace” and Moon.
Center/align Altair with high power eyepiece.
GoTo Arcturus. Press Align. Choose “Replace” and Jupiter.
Center/align Arcturus with high power eyepiece.

[Rtrorkt]

Thank you. It is just a small stand alone telescope with a hand held input unit. It is not connected to any computer. It does the alignment automatically, I am just following the steps. First is north, then date, time, time zone latitude and longitude that I am getting from my phone. At that point it picks 2 stars.

I am a bit impacted by foliage so getting the stars is a bit of a struggle. It seems to first want Vega and the moves on from there.

Since I know the longitude and latitude are correct 33 degree 42 min N and 111degrees 45 min west (I am assuming the + on the longitude is for northern hemisphere), the screw up may be when I align to north I may be 180 out of phase. Just don't know what side of the tube the support is on. When pointed North is it left or right
Unit is a Nexstar 5. Got it free, so no manuals with it

[flatbutt]

Originally Posted by Rtrorkt

Thank you. It is just a small stand alone telescope with a hand held input unit. It is not connected to any computer. It does the alignment automatically, I am just following the steps. First is north, then date, time, time zone latitude and longitude that I am getting from my phone. At that point it picks 2 stars.

I am a bit impacted by foliage so getting the stars is a bit of a struggle. It seems to first want Vega and the moves on from there.

Since I know the longitude and latitude are correct 33 degree 42 min N and 111degrees 45 min west (I am assuming the + on the longitude is for northern hemisphere), the screw up may be when I align to north I may be 180 out of phase. Just don't know what side of the tube the support is on. When pointed North is it left or right
Unit is a Nexstar 5. Got it free, so no manuals with it

Cloudynights.com has OTA specific groups. They can help, I promise.

https://www.cloudynights.com/forum/90-celestron-computerized-telescopes/

Also:
https://www.manualslib.com/manual/1031639/Celestron-Nexstar-5.html

[Rtrorkt]

Thank you. I have just found an on line manual that says the direction of the tube is not important when aligning. Will give it another shot tonight.

Appreciate the quick responses

[Eric Hahl]

From photos on the interwebs...it looks like when pointing north in the norther hemisphere the arm would be on the left side of the tube.

[flatbutt]

Not a backyard target but day-um!

https://www.techtimes.com/articles/255266/20201221/nasas-hubble-telescope-proves-albert-einsteins-molten-ring-theory-right%E2%80%94intense.htm

[Rtrorkt]

Originally Posted by Eric Hahl

From photos on the interwebs...it looks like when pointing north in the norther hemisphere the arm would be on the left side of the tube.

thank you. assuming the clouds go away, will try that tonight.