Friday, June 16, 2023

Finally, Dark Sky and Reasonable Temperatures

Astronomy has taken a back seat for many months because we have been having atypically cloudy weather, at least at night, for pretty much all of spring.  After the 911 call last Halloween, I have refused to go out in freezing or below weather.  My wife was teaching and I would rise with her at 6:00 AM to make her breakfast. Late nights were not practical.

Tonight was in the 60s so a light jacket was enough.  The evening started out with the 0x Telrad refusing to stay in position after I adjusted its point of aim to match the telescope.  One of the screws that holds the mounting base in place was loose.  Why?  I looked in and saw that one of the screws had no nut holding it in place.  The other screw had two nuts on the screw.  How did I screw that up?  (Or is that nut that up?)

The goto Losmandy mount that I have struggled with since 2021 was confused by not being terribly precisely aimed at north and with the wrong time zone.  Tonight, I aligned it on Vega* and told it to take me to M57, the Ring Nebula, and it got me to at least the correct spot a few degrees away.  You really need more than one star to get accurate pointing so I am not whining. 

.* I needed binoculars to verify that it was Vega.  At the old house this was never required.

In the past, I have used a Meade 9x60mm finderscope to get myself on M57.  M57 is not visible through it but it is enough light to get the two stars in Lyra (beta and gamma?) that you use to position on M57.  M57 is about 40 percent of the distance between beta and gamma, closer to beta, I think.  

The Telrad has no light gain over the naked eye and in these increasingly light polluted skies, beta and gamma are pretty much invisible until it gets much later than I have the energy to stay awake.

I am also pondering a way to get the eyepiece closer to the ground.  I climb a very nice ladder to the eyepiece but in the darkness, descending is a bit scary.  The steps are a bit farther apart than I expect and it always feels like I am going to fall.

The casters on which the Losmandy mount rolls put the mount higher than it should be.  The original Losmandy tripod had hollow square legs 1.00" inside.  The Scoperollers I made for the early tripods just slid inside (0.95" was the dimension of the insert) adding only about the diameter of the casters to the height.  Losmandy changed the design a while back that certainly makes the inner legs stiffer but there is no longer a nice square tube into which to slide.  The inner legs are 1.25" square on the outside.

For the later tripods, I built an assembly that slides on the outside of the inner legs.  To get a good grip on the inner legs requires extending the inner legs several inches.  This puts the mount about a foot higher in the air and thus the eyepiece.  I wish that I could figure out a solution that adds less height.  Perhaps making a sleeve that locks onto the outer leg assembly so I do not need to extend the inner legs.

That would get the eyepiece only about 6" above my eye standing at ground level.  Less steps is less scary.  I guess I need to measure the exterior dimensions of the outer legs.  The American in Poland who bought ScopeRoller might want to consider a similar change.

The outer leg is not square.  The sleeve needs to be >1.45" x >2.013" (and that largely because there is fastener that sticks above the surface.  (I suspect it is a stop to prevent the lower leg from sliding completely out).  The lock knob that holds the inner leg in position has to be unscrewed.  Rectangular aluminum tubing is available.  Finding some that is close enough to just barely slide over this will be a slight challenge.

The closest that I can find is 2" x 3" x .25" wall.  That would give interior dimensions of 1.5" x 2.5": a little big.  A solution is to make a .4" shim of acetal held to the wider interior dimension by several screws.  This would give 1.5" x 2.2", which would be a good fit.  Not a press fit, but tight enough for a couple of screws on each side to hold it on.  The acetal would also reduce slide of metal on metal; the screws pressing on the acetal will depress it enough for a mar-free surface on at least one side.  

1 comment:

  1. "I climb a very nice ladder to the eyepiece but in the darkness, descending is a bit scary."

    Red LEDs on the steps so you can see them but not mess up your night vision?