About astrodork

Putting the "antic" in "Hyper-Pedantic" since 1996.


Hit up the local auction and did some stargazing this weekend.


I made a nice score on a pretty rare vintage Sansui matched set – an AU-888 (amp) and TU-888 (Tuner).

I hear they never imported these to the US so they’re pretty unusual. So cool !


We had the invasion of the annoying coital racoons last night- Elena spotted them skulking up on the deck and kinda freaked out. We ran them off with floodlights and the pellet gun- and managed to view some of the carbon stars in my little 100 carbon stars project. They include:

WZ Cassiopeia

La Superba

SAO 46574 (Hercules)

We also broke out the webcam and got acquainted with the image capture and processing software- our first CCD Lunar Astrophoto.

I believe this is the Cremona crater just left of center.

Celestron 8″ SCT Observing log (July 30/2011)

Elena and I had a lengthy session Saturday night. After a fair amount of time rebooting and tweaking we got the interface between our Celestron SCT and the laptop running Stellarium working.

One of the primary goals was to locate the carbon star Tau Lyra that had eluded us last time. Didn’t take long to find it this time around- it was a deep red and looked like a gem.

I played “computer operator” while Elena was at the eyepiece so that she wouldn’t spoil her night adaptation looking at the computer screen. This session was by far the most objects in the shortest time I have ever observed- we literally were running out of stuff to look at in Portland’s suburban (light polluted) sky.

We also saw:

(Europa, Ganymede, IO, Callisto)


Wild Duck Cluster





95 Hercules

17 Cygnus

Photo coming soon


Focuser hack

One of the problems with focusing a telescope at high magnification is that even the slightest touch on the most sturdy mount will still shake the scope a little bit- making the image blurry for a few seconds every time.

In this hack we will be making a little cap to fit over the focuser knob on my 8″ Celectron SCT.

Parts needed:
7/8″ inch rubber cap- probably designed for the end of a table leg or ??
A piece of stiff wire- a coat hanger will do nicely.

Years ago a salesman at Scope City in San Diego showed me this little trick- and even gave me a few extra caps. I still have 3 of them.

Bend your wire into an apropriate handle shape and length as desired.

Stick it into the cap thusly.

And attach to the telescope.

This reduces the vibration transferred to the scope by a -lot-.

Celestron 8″ SCT Observing log

Elena and I have been stargazing this week. We attended the SW Washington Astronomy club meeting on Friday and broke out the new telescope Saturday night.

July 23, 2011.
First Light in scope @ 8:22 PM

Performed alignment on
Polaris  and Arcturus

First Deep Sky object: M57


Collinder 339

Attempted (but didn’t see)
HIP90883 aka Tau Lyrae aka SAO 67087

We’ve got the interface working to use the laptop with the telescope so we’ll be sure to visit that carbon star (Tau Lyrae) on the next clear night.

Little known “feature” of the Hale 200″ Telescope at the Palomar Observatory

In 1985 or so I took an Astronomy class at Palomar College. I was 17, and if I recall correctly I got a “C” in the class. Like most people I had no idea that “Astro 101” was going to be an introduction to the chemistry, physics and spectroscopy of stellar systems. I was probably in a bit over my head.

The cool part about the class, one of the few that I actually learned something in, was the Field Trip to Mt. Palomar.

By the 3rd week the class size had dwindled considerably and the instructor offered us a unique opportunity- a group of 6 of us were given a tour by one one of the engineers who maintain the facility. We got the low-down and inside scoop on the facility; for example: the dome that encloses the Hale scope has a little billiards room;  and he advised “never take on an astronomer at pool- there are too many cloudy nights and they know all the angles”.

Another lesser-known feature is the giant concrete and rebar disc that was used during the construction of the mechanical portion of the telescope- used to simulate the weight of the large primary mirror that was being ground and figured in Los Angeles at the time. When the glass arrived the counterweight was dragged outside where it sits to this day. It makes a great place to sit in the sun and eat lunch. It measures about 24″ thick and at least 18 feet across- a good deal longer than a car.

The amazing super-cheap Green Laser Pointer (Bonus- it looks like Buck Rogers’ Laser Pistol)

Design Specifications:

1. Cheap
2. Must allow laser to be switched on (without holding the button) for 0-2 minutes, the max recommended duty cycle for this laser pen is 3 minutes.
3. Must use easily and cheaply replaceable laser pointer pens for when I forget to turn them off and the burn them up. (hasn’t happened so far).
4. Did I mention cheap? Bonus if it looks cool.

You’ll need:
Green Laser Pen pointer. Price varies greatly- I got several from Amazon for $6.50
A hand drill and…
A small bit ~5 MM
A 1″ bit.
Something to cut PVC plastic with.
(I used a Dremmel rotary tool, you can use a hack saw or something similar. If you find a flat plate of PVC (Maybe a light-switch cover?) your job is nearly done.)
Sandpaper / emory board for roughing up the PVC and smoothing seams and imperfections.

A hair dryer, or heat gun
A pot from the kitchen the approximate outer diameter of your scope’s tube. (If you want your mount plate to follow the curved contour of your scope.)
A small hammer and finishing nail


I got everything I needed at Ace Hardware

Lasco PVC Insert Tee 1″ x 1″ x 1″
ACE Hardware:

O ring
3/4″  Outer Diameter (OD)
1/2″ Inner Diameter (ID)
1/8″ Thick
Ace Hardware- $.50

Socket head cap screw

5 mm x 20 mm x 80 thread pitch
$.78 ea (need 4) at Ace Hardware.

5 MM x 80 pitch
Ace Hardware- $3.99
Used to thread the holes for your cap screws.

PVC rectangular fitting
Just about any rain gutter fitting will do. I got mine at… yep you guessed it- Ace Hardware for $2.19

Krylon “Fusion” paint (sticks to plastic)
I chose satin Black for $4.99 a can @ Ace Hardware

PVC cleaner, primer and glue (used to assemble irrigation systems and other PVC systems). If you need to buy it it’ll run you about $10 for enough glue to make a few thousand laser pointer mounts.


I construed my mount to attach to the accessory location of my Celestron 8 inch SCT using the mounting screws and holes often occupied by a piggy back camera mount. It would be just as easy to mount the finder to the scope using sticky tape or some other method.

I used the following process for assembly.

Cut the PVC mounting plate to size and drill a 1″ hole in the middle of it.
(To find the exact center you can draw a diagonal line from corner to corner- making an X in the center of the plate.)

Note: I’ve already drilled and glued the PVC plate to the T insert in this photo.

Gather your plate, heat gun and cooking pot. Might as well grab the oven mitts too.

Use the heat gun / hair dryer about 3/4 inch from the PVC plate for 1 minute or so. (1000 watt setting) The PVC will become soft enough to bend- obviously you don’t want to overcook it to the point of it turning to goo, or burn your fingers.

Bend the PVC over the outside of your cooking pot and let sit for a few seconds to cool. Repeat if necessary- when the PVC is fully cooled it will be rigid again.

Assemble your

PVC cleaner, primer and glue
T insert
Cooled mounting plate

I like to rough up the surfaces before applying the primer and glue for PVC. The adhesive seems to fuse the plastic at the molecular level. This is probably not recommended when you are making water-tight connections- but as you’ll see the fit between the mounting plate and the T insert is not perfect. I used my emory board and sand paper to give the mounting plate a slight chamfer to match the angled base of the T insert. When I dry-fitted the 2 components before gluing the T insert protrouded through the base of the mount plate 1/8″ or so. This is no problem- I sanded it down to flush after it was glued and cured. My joint was far from perfect- there were tiny gaps but the adhesive seems to have done a good job of fusing these parts together nonetheless. Give it a shot- maybe you’ll get lucky the first time too.

Cutaway cross section of joint.

You may ask “Is this joint going to be strong enough?” I had the same concern- and was pretty surprised by how solid it was after the glue cured- I imagine my little pointer will still be bonded 100 years from now- no problem.

Dry-fit your parts and practice getting them squared and aligned. You want your T Insert to be aligned as closely as possible to be perpendicular to the plate, and oriented the right direction. This design has the ability to fine-tune the laser direction (as we’ll see later) but it’s important to start off as squared as possible.

When you’re ready to glue:

Clean all the parts with the PVC cleaner. (My little kit of PVC adhesive has cleaner, primer and glue).
Get the primer and glue ready-
Dab the primer to both parts, the T Insert and mount plate.
Quickly dab the glue on the T Insert and fit it to the plate. You’ll have a few seconds to wiggle everything into place as the glue begins it’s chemical reaction. Once everything is square set the item down on a stable surface and let it cure for a couple of hours. If everything worked you’ll be surprised how solidly it bonds.

Now it’s time to drill and tap the holes for the Socket cap screws that will  hold your laser in place, provide for fine adjustments of the beam, and act as the “switch” to hold the laser pointer button down.

Gather your small drill but (~5 mm), drill, tap and cap screws. It’s better for your drill bit to be a smidge smaller, rather than larger, than 5 mm.

I also used a finishing nail and small hammer to tap a pilot mark in the T Insert before drilling. You don’t need to pierce the tube- just a little indentation for the drill bit to catch as you start to drill the holes.

You will be drilling and tapping 2 holes along the dorsal line of the T insert. One at each end. You will also be drilling and tapping 2 holes at about 120 degrees left and right of the rearward screw. See image.

In the above image you can see the laser holder drilled and tapped with the screws threaded into their holes. I used my laser as a guide to align the hole for the power button screw. You’ll need to remove the pocket clip from the laser if it has one.

You can also see in this image the O ring is affixed to the laser pointer. This holds the front of the laser in place, centered within the holder, and acts as the pivot that allows the adjustment screws to move the laser up, down, left and right.

I’m going to assume at this point that the reader knows better than to look into the laser while it’s illuminated- cover the aperture with opaque tape while you insert it into the holder tube- it’s a snug fit and the O ring can roll over the button-turning it on !

Helpful hints:

Insert the laser into the O ring,  then into the holder with the screws removed from the holder. Adjust it to be more or less centered- look into the “button hole” to align it as below:

Here you can see I have the laser partially assembled with the forward screw removed- look into the hole to get the button aligned. When you thread the front screw and tighten it it will push the button and turn the laser on. Back it off a few turns to turn the laser off. If you over-tighten the laser switch screw it will move the laser slightly out of alignment.

Here’s the unit assembled and tested- looks good and almost ready for paint.

At this point your process may vary- depending on how you intend to mount the unit to your telescope. In my case I removed the laser from the holder and found the locations for my mount screws on my telescope. I drilled one side as a hole- and the other as a slight channel- allowing me a little wiggle room to rough-align the mount bracket to the scope before tightening everything down.

If you’re planning on using sticky tape I recommend not painting the bottom surface of your mount- the raw surface will make a better surface for the tape to stick to.

I lightly sanded everything before applying a couple of coats of black paint- just to clean up the seams and burrs where the PVC components were molded at the factory.

When everything is dry- reattach and align to the scope just like any other finder using the 3 rearward screws. Be sure to only make small adjustments- and do not leave your laser powered on for an extended period.

Notes for future projects and improvements:

Smaller cap screws. the 80 thread pitch works well- but 4 mm screws would look a bit less clunky.

A clear template to mark the locations of the mount screws on the scope would have made transferring them to the mount plate prior to drilling easier.