A Battery Caddy for the AM5

The ZWO AM5 telescope mount is a great piece of kit… It integrates very well with software allowing easy computer control, just click and go. The mount tracks wonderfully allowing excellent astrophotos. It is small, does not require a counterweight for smaller ‘scopes, and precise polar alignment is a breeze.

A 3D printed battery caddy on the side of a ZWO AM5 telescope mount
A 3D printed battery caddy on the side of a ZWO AM5 telescope mount

The mount is not without issues… Without a camera integrated into the system the GOTO accuracy is awful, using the mount as a visual mount is frustrating. You really need to have at least a guide camera and the ASI Air computer connected to allow to plate solving and automatic correction of the position at the end of each slew to a new target.

Another issue is that the mount has no concept of cord wrap. It will happily spin around and around as you wander across the sky. In equatorial mode this is not an issue, in alt-azimuth mode this runs the risk of damaging your equipment if you do not notice the power cord getting wrapped up on the mount in the dark.

Yes, I did that.

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Binocular Solar Filter

One of the things I brought back from Oregon Star Party was a set of solar filters for binoculars.

A simple set of solar filters for my Nikon binoculars
A simple set of solar filters for my Nikon binoculars

The filters were from DayStar Filters who had a booth at the star party. I spent a while chatting with the gal running the booth and enjoying the hydrogen alpha views through the ‘scope they had set-up. The Daystar SS60 Hydrogen alpha ‘scope they had on sale was rather tempting.

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Battery Corrosion Again

Leaking alkaline batteries, the bane of our portable, battery powered existence. All too many times I have found myself repairing electronic devices damage by leaking batteries, or just junking the gear when the damage is too severe.

Corrosion damage in the base section of a Celestron 8SE mount
Corrosion damage in the base section of a Celestron 8SE mount

This time the device in question was just a bit too valuable to dispose of despite fairly extensive damage.

A Celestron Nexstar 8SE telescope.

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Testing a Mirror

As I have observed lately, most of the small telescope mirrors available right now are out of China, most of those produced by one company, Guan Sheng Optical or GSO. If you want a small mirror, say a 6″ or 8″ mirror, there is not a lot of choice, the mirror makers in the US generally do not do anything smaller than 10″.

Foucault knife edge test
A textbook Foucault knife edge test image on a 6″ f/4 mirror

The GSO mirrors range from decent to pretty bad, with no way of knowing what you will get when you order, just luck of the draw.

But how do you tell?

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My Telescope Sings to Me

OK, I did not expect this.

At the telescope in the driveway again
At the telescope in the driveway again

I have been observing from my driveway each evening this last week now that the Moon has left the evening sky. Pleasant sessions wandering through the stars and clusters of Scorpius, Sagittarius, and Ara.

The week has also featured gentle trade winds at the house, resulting in fickle breezes around the telescope which is mostly in the shelter of the house. I get some manini gusts that make it around the garage that really do not bother me but do keep the mosquitoes down.

These breeze have created an unexpected phenomena, they make my telescope sing to me.

It is a gentle and resonant low B note as the breeze plays past the front of the telescope. Much like blowing across the top of a beer bottle, the tube of the telescope resonates with the breeze. Apparently a Cave Astrola 8″ f/6 telescope is a tenor.

Sometimes quiet, sometimes quite notable, I listen to the telescope hum while I look up the next cluster to observe.

Now if you excuse me I need to chase the pigs out of the yard… Again.

Christmas Telescopes

We just received the Costco Christmas sales mailer. Every year there is a telescope featured, promoted as a gift. Not just slightly featured either, but included on the front page of the flyer, the first thing you see when you pick the mailer up.

Celestron Astromaster 130EQ
A typical inexpensive telescope, the Celestron Astromaster 130EQ

The telescope this year is a Celestron Astromaster 130EQ, the typical small reflector on an equatorial mount. The deal includes several eyepieces, filters, and a cell phone adapter for afocal photography.

Those of us with long practical experience just cringe when we see such telescopes. These cheap telescopes are usually more of a frustration to would be amateur astronomers than useful. Cheap ‘scopes have deterred more folks from the hobby than we will ever know.

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Unsafe Solar Filters on EBay

I though these things were gone!

Eyepiece mounted solar filter
DO NOT USE! A Solar filter meant to thread into a 0.956″ telescope eyepiece.
But no, in the world of cheap e-commerce, any product can be found, even those that are notably unsafe.

What are we discussing? Eyepiece style solar filters that screw into the threads on the bottom of the eyepiece, not at the front of the telescope like proper solar filters.

I actually have one of these things, found in a kit of equipment I was given. A bright red and very cheap pot metal casting with a small glass filter. I have never attempted to actually use it, I keep it as a example of the bad and the ugly. It is a vintage bit of gear, the type that was included with inexpensive Japanese refractors of the 60’s and 70’s, sized to be used with the small 0.965″ eyepieces of the era.

An eyepiece style solar filter available on EBay
An eyepiece style solar filter available on EBay
To my surprise I find out these things are still around… I was shopping for an inexpensive solar filter for a small telescope when I came across these eyepiece style filters on EBay. They are cheap too, less than $10 with shipping, just the sort of thing to attract a young or novice telescope user into trying a product that is potentially very dangerous.

Given that the risk you are taking involves irreplaceable eyesight, this is very serious.

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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.

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Restoring an Obsession

Obsession Telescopes are something of a standard in the astronomy community. David Kriege was one of the first to start building truss tube dobsonian telescopes commercially, bringing portable large aperture telescopes to the astronomy community. These telescopes were a bit of a revolution in the pursuit, with sizes unreachable only a decade before, when a 10″ or 12″ telescope was considered big. When I built my 18″ it is David Kriege’s book I used for much of the design, following in the footsteps of so many amateur astronomers.

20" f/4 Obsession Telescope
The restored 20″ Obsession telescope set up at hale Pohaku on the side of Mauna Kea

A 20″ f/4 Obsession donated to the observatory has presented a challenge and an opportunity. The telescope was the prized possession of Bob Michael having been ordered new directly from Obsession. The telescope is serial number 004 with a manufacturing date of June 1st, 1990. As David started Obsession Telescope in 1989, this is a very early example of his work. For many years Bob and his wife used this telescope to observe, completing the Herschel 400 and other observing projects. Unfortunately he was forced to give up astronomy due to age and glaucoma, donating his equipment to the observatory.

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The 1999 Losmandy Catalog

I have a pile of material that was donated to the observatory. While some of the gear will be used for outreach, a fair amount of the pile is not usable for this. ¬†With JoAnne reminding me about the stack in her warehouse it is time for me to sort it out and dispose of it. ¬†Among the pile was an entire crate of books… Astronomy textbooks, star charts, observing guides, and more.

A Driveway Telescope
The Losmandy G11 mount setup in the driveway for an evening of astrophotography

This pile of books included a full set of the classic Burnham’s Celestial Handbook, both volumes of Uranometria, and other treasures. After determining the observatory had no need for these I brought them to the last astronomy club meeting and gave them away. It was nice to see these books go to those who would appreciate them.

At the bottom of the pile was something that caught my eye, several old catalogs and manuals. These were just fun to read through. There are both Losmandy and Takahashi catalogs from 1998 and 1999, as well as a manual for a Takahashi FS Series refractor.

1999 Losmandy Catalog

The 1999 Losmandy catalog was particularly interesting. My old Losmandy G11 is a workhorse mount, one that has seen many adventures with me. The manual includes a price list, showing that it once sold for $3400, quite a bit more than the $1400 I paid for mine used in about the same era. Interestingly Losmandy still sells this mount and most of same accessories found in this catalog.

As I read I realized that this catalog may also be good to scan and post so that others may find this catalog a useful resource. I hope to scan and post some of the other items in the stack that might be good to save.