16" Mirror Cell Work Started

This afternoon I started work on the mirror cell for the 16" scope.  It is designed just like the 12.5" mirror cell with some added holes for air flow.  I am adding a fan to blow onto the back of the mirror cell as well as two that will blow on the surface of the mirror.

Throughout the week, I hope to finish it up.  Fellow ATM Tim Scott is making the triangles and bars for me (thanks Tim!).  I should have the mirror box finished over the next couple weeks.  About that time, the new secondary and spider should be ready from Protostar.

I also ordered some split bolts from Obsession Telescopes and some muffin fans from Startech.com.

Slow but steady progress...

Last week I ordered a Protostar 3-vane spider with built in dew control and a 2.6" secondary mirror.  That should show up in the next couple of weeks.  I also ordered the aluminum for the triangles and bars for the 18 point mirror cell.  A good friend of mine will be making those items for me (he can do a much better job than myself).  This week I hope to get the mirror cell started and hopefully finish it by the end of next week.

I am still fighting with myself on how I want to do the secondary ring.  I like the look of the single ring, but having two rings (like most truss dobs) opens up some more possibilities.  Like using a light shroud without having it custom made.  I will probably go with what I know and stick to the single ring design.  The 12" is just fine and I have no problems with it.  I think I loose some contrast, but not enough to cause major problems.

My goal is to finish most of the scope before winter hits.  I think I will be able to get it done by then.

September Nights

September is usually a great month in Ohio for clear skies.  The autumn skies provide a wealth of objects to observe!  If you get a chance to get out to a dark sky, please do.  In fact, many of us at the The Columbus Astronomical Society are planning to do just that!

The first thing you will notice when looking overhead is a glowing stream of light broken up by dark lanes.  This is our very own galactic home, the Milky Way.  What you are seeing is the combined light of billions of stars and in some places, obscured by intergalactic dust.  Take a pair of binoculars and sweep this region of stars and you will see thousands of stars across the field of view.  Occasionally, you may see clumps of stars together.  These stars usually are part of a galactic star cluster.  When stars are born, they hang around together during their early years.  Bound by gravity, they eventually start to drift off to form their own paths in the Milky Way.  About 5 billion years ago, this happened with our Sun.

Towards the south east during the evening, you may notice a bright star.  This beacon is Jupiter, the king of the planets.  With those very same binoculars, you can see Jupiter's orb and one of more "stars" close by in a line.  Those stars are Jupiter's moons, Io, Europa, Ganymede, and Callisto.  If you are so inclined, make a little drawing log and draw the positions of the moons in relation to Jupiter.  Galileo did the same thing 400 years ago!!

Towards midnight, the Milky Way starts to slide towards the west and the sky changes towards the autumn sky, dominated by Pegasus and Andromeda.  Pegasus is comprised of what is called the "Great Square" and Andromeda looks like a tilted Christmas Tree off to the side.  Andromeda holds a treasure called the Great Andromeda Galaxy.  This galaxy can be seen with the naked eye in dark skies.  And is very visible in binoculars.  Some day, billions of years in the future, Andromeda and our Milky Way are going to merge together.  Don't worry though, our solar system will probably come out of the merger unscathed.

Look towards the east and you will notice a grouping of stars.  This grouping of stars is called the Pleides, or the seven sisters.  A very nice object in binoculars.   Towards the northeast, there is a bright star called Capella, the brightest star in the constellation of Auriga.  Capella and the Pleides are part of the winter sky where Taurus and Orion resume their yearly battle above the frigid landscape below.  But that is for another time.

Clear skies and I hope you take time to look up and notice the Universe above you.

Two Observatories Saved from Wildfires

Thanks to the efforts of brave firefighters, two historic observatories have been saved from the wildfires in California.

Story

Bearings done

I finished the bearings.  They are 21" in diameter and 1" thick.  On the 12.5", I routed some holes to give it a nice look.  With these bearings, I decided to try something different.  The bearings are made from two 1/2" pieces of baltic birch plywood.  I routed similar holes only one of pieces and left the other solid.  I think it looks nice.  I sanded them so that they are perfectly matched.  I plan to work on the secondary ring this week.

Also, I will not be painting these like I did on the 12.5".  I plan to keep it natural by putting a layer of clear enamel over it.  I think it will look good.  The rest of the scope will be the same however.

16" Build officially started

Today I started cutting wood for the bearings.  The bearings are 21" in diameter and will be 1" thick.  Pictures to follow tomorrow when I finish up the bearings.

16" Mirror Arrives safely

I picked up the packages that contain my 16" mirror, spider, secondary, focuser, and a little surprise: A Meade Coffee Cup!! (Thanks Richard).  You know, you don't really think about how big something is until you get it.  When I pulled the mirror out, it was kind of overwhelming to see it.  I did get a tape measure out and confirm that it indeed is 16" wide (instead of 18 or 20, hehehehehe)

The secondary was larger than I expected.  I measured it to be about 3 5/8" wide.  Pretty big for visual use, but not big enough to cause a problem (you want to stay between 20% to 25%).  I measured the spider and it is just about the right size for my purposes.

Now the fun begins!  I will start with the secondary ring and bearings, and then onto the mirror box.  I need to start getting stuff together to sell so that I can afford the truss system.  This is where I learn patience.  Pretty hard to do when there is a nice 16" mirror waiting to reflect some photons.

Cannot wait to start cutting wood!