Hodgepodge

In the end it is a Celestron C8 telescope drive and forks containing custom electronics, a Meade heavy duty wedge from an LX-90, a hand-made tripod, holding a Televue 76mm APO telescope, using a Vixen style dovetail base, with a Baader film solar filter.

It is tempting to call it Frankenscope after the similarities with the classic monster.

Hodgepodge
Hodgepodge setup on the side of Mauna Kea with the TV-76mm and Telrad on the plate

To further add the the Mary Shelley plot similarities, much of this was revived from the junk pile. I very nearly decided to toss the drive and fork, they were that bad, peeling paint and rusty bolts. A great deal of work was necessary to re-animate these components.

The wedge came from a telescope that was killed in an unfortunate incident with an aquarium heater. The heater was used to de-humidify the OTA and prevent fungus on the optics. Note: Aquarium heaters are not made to operate out of water.

Hodgepodge
The Hodgepodge mount assembled for the first time

Several new aluminum parts were machined from scraps, some of which were scavenged when the observatory shop was being cleaned out and a lot of metal stock was tossed.

Many of the electronic components used to build the drive corrector were also scavenged parts from dead electronics, this includes the 1.8432MHz crystal that forms it’s beating heart. This heartbeat keeps the mount turning at exactly sidereal rate.

Yeah, you could call it Frankenscope.

But I will call it Hodgepodge.

The Sun on Eclipse Day

A few days ago I looked at the solar imagery from the spacecraft and ground observatories and feared that our Sun would be completely spotless for next week’s solar eclipse. The one sunspot visible had just rotated out of view, not to return until well after the eclipse. There were no other sunspots apparent.

SOHO Sunspots Aug 15, 2017
SOHO sunspots on Aug 15, 2017 showing the newly formed AR2671
Our Sun has served up a very nice surprise. A complex and energetic sunspot group has formed. Better yet it will be just about mid-disk when the Moon arrives.

Sunspot group AR2671 formed on the eastern limb of the Sun over the last couple days. It has even produced a few c-class solar flares to show it has some vigor.

Better yet… This sunspot group will be a boon to eclipse photographers across the US. The pattern of dark spots will make the difficult task of focusing a telescope on the Sun far easier. These spots will provide a focus target to untold telescopes.

The only question now is will the group last for five more days? Will is grow or shrink.

The Sun on Eclipse Day

OK… I am going to have to retract this post… The Sun has served up a surprise… Will it last a few more days?

What will the Sun look like when eclipse day arrives on August 21st?

Very quiet!

Sun on Aug 10, 2017
The Sun as it appeared August 10, 2017 with sunspot AR2670
There is only one major sunspot group visible at the moment. The large spot AR2670 has been visible for a couple weeks now, crossing the face of the Sun since the beginning of the month.

I observed this spot several times while training some folks at the observatory to use a solar setup and while testing my eclipse telescope.

AR2670 is now disappearing from sight as it rotates over the limb, maybe it will be back in another couple weeks for a third appearance.

Checking the SOHO image archive and the GONG farside maps shows there is nothing else, no significant solar activity that will appear before the total eclipse in eight days. Nothing hiding on the farside to rotate into sight.

There is a slim chance of something new developing over the next week. However, we are approaching solar minimum, a quiet Sun is to be expected. Indeed, I expect we will have an almost featureless solar disk on eclipse day.

Update 14 Aug 2017: With one week to go a new spot has appeared! I do not see that is has an AR designation yet, but this new spot should be in the middle of the Sun on eclipse day if it lasts for the week. It may not be big or pretty, but it will at least give everyone something to focus cameras on in preparation for the main event.

Update 15 Aug 2017: The new sunspot has been designated AR2671 and has already produced some C class flares. Looks like has the energy to develop a bit more. At least one small sunspot for the eclipse?

Two Solar Film Filters

When travelling to an eclipse, one solar filter is not enough. I need a backup!

Two Solar filters
A Baader film solar filter beside an Orion Safety Film filter, both for the 76mm refractor
This is particularly true as my primary filter is a Baader film filter. While a very nice and effective filter, it is also very thin film, and easily damaged. Thus I have borrowed a second filter (Thanks Chris!), the borrowed filter being an Orion E-Series Safety Film filter.

Having the two filters available for use mean I must choose between them when the moment is critical. Which is better? Some testing is in order to find out.

The two filters appear very different, the thin silver film of the Baader quite different than the thicker black polymer film of the Orion filter. Both filters are safe to use and provide decent solar viewing. Both provided pleasing solar images using my Televue 76mm APO telescope at low and medium power.

Stepping beyond basic use I do find that they perform quite differently. So differently I felt some notes are in order.

Continue reading “Two Solar Film Filters”

Eclipse Observing Checklist

For this solar eclipse I will be in the middle of central Oregon, a long way from any stores, much less an astronomy equipment store. I will have to have everything I need on-hand, nothing forgotten, nothing overlooked.

A checklist is certainly in order!

The checklist below was compiled as much for myself as anyone who might read this posting. Actually writing the checklist out is quite useful as a personal double check. I need to consider that we will be camping for several days prior to the eclipse, that time will be spent hiking, stargazing, or simply relaxing in the forest with family.

Continue reading “Eclipse Observing Checklist”

Telescope Moonrise

A tricky shot, taking very precise timing and navigation. I can not claim credit, Sean Goebel did the planning. I just supplied scouting information and came along for the ride.

Mauna Kea Telescope Moonrise
The Moon rising directly behind the telescopes on the summit as seen from near Waikoloa
Sean has been after this photo opportunity for some time. For months he has messaged me to check on the weather over the Waikoloa area each time a full Moon is available. As he has to drive across island to reach the correct locations, a look ahead at the weather can save a great deal of wasted time.

Given that this only involved a fifteen minute drive from the house for me… Why not? Give it a try. Besides, I already had a suitable telescope loaded in the vehicle.

Continue reading “Telescope Moonrise”

Old School Drive Corrector

Telescope clock drives from the 1980’s or earlier often used AC synchronous motors. These commonly available AC motors are used to power timeclocks, record player turntables, and telescopes, anyplace a motor needed to run at a very accurate speed.

Sidereal Drive Platform
A Celestron telescope drive configured as a sidereal rate tracking camera platform
The speed of a synchronous motor is set by the frequency of the powerline, in North America and many other places this is 60Hz. As the frequency must be synchronized for every power station on the grid the frequency is quite accurate, a feature exploited by clockmakers and telescope builders. Once found everywhere these motors are less common, but are still around.

Drive Correctors

It was the common use of these motors in telescope drives that led to the invention of the drive corrector, a device that was once a required piece of kit for serious amateur astronomers. Drive correctors like this were needed when operating from a battery at some remote location, generating AC from a 12Vdc car battery.

You also needed a drive corrector for guiding while doing astrophotography. The corrector could speed up or slow down the telescope drive a bit to correct the telescope drive speed and stay on target, something not possible with the fixed 60Hz of the mains supply. Thus the term drive corrector.

Continue reading “Old School Drive Corrector”