Astronomy Archives - Page 71 of 75

June 10, 2015June 10, 2015

My new OTA is here! My new OTA is here!

After 13 years of using mostly the same 8″ Celestron SCT, I’ve just upgraded to a new (to me) C9.25. It is a 2008 model in what appears to excellent condition with Starbright XLT coatings. It has the dovetail plate and it appears that the JMI Motofocus I used on the C8 will work here too. Now to list the C8 OTA and see if I can fund part of the upgrade.

May 28, 2015December 16, 2020

Jupiter 5/28/2015

Wednesday evening, during a rare clear night in May, I was able to capture this sequence of events happening on Jupiter. At the very start you can see Jupiter’s moon Ganymede over to the left and its shadow on the face of the planet. Almost immediately you will see the shadow of another moon, Io, appear on the right and start chasing the shadow of Ganymede. Each frame represents 2 minutes of real time and the entire sequence is an hour and 40 minutes long. As you watch, you will also notice the Great Red Spot moving along with the shadows and if you look closely you might notice Io itself transiting the disk of Jupiter but it is not nearly as obvious as the shadow. You might also notice the difference in the size of the shadows. Ganymede is the most massive moon in the solar system while Io is quite a bit smaller. Eventually Io leaves the disk and becomes visible against the black background. Finally at the end the two shadows merge as Ganymede eclipses Io. Jupiter was dropping into the trees as this happened so I was not able to capture the end of the eclipse when the two shadows separated. I want to thank my friend Carl Freyaldenhoven for bringing this event to my attention. The images were taken from my backyard in West Little Rock.

May 25, 2015

Telescope Makeover

In the latest episode of Extreme Makeover: Telescope Edition, Jim makes more rings, a box, and something to put in the box. First, I made two plywood rings that will be the basis of the secondary cage which holds the secondary mirror, the focuser, a finder, and maybe a soda. Next I worked on the mirror box and primary mirror cell which I started on yesterday. You can see the cell sitting in the open box, the back side of the cell with its collimation screws salvaged from the original tube, and finally the cell back in the box with the upper surface of the box.
Next up, not necessarily in this order will be to finish the cell and mae it with the primary mirror, construct the secondary cage, build the truss arms, assemble, determine the balance point so that I will know where the previously covered altitude bearing will be attached then build the rocker box, sand, paint, get the soda from its place in the secondary cage and enjoy.