35 replies to this topic

[Rustler46]

During the last two days I painted the interior walls with dark, flat paint. This will reduce reflections of local light pollution, that would otherwise be directed at the observer. A 9-inch roller made quick work of covering the majority of the flat, open surfaces. Next day I used a brush to cover the edges and hard to reach surfaces. When done a full gallon of paint had been consumed. The color was supposed to be a dark gray, but ended up having a dark purple cast. Nonetheless it will serve the purpose of darkening all exposed surfaces, helping to retain some semblance of dark adaptation.

 

 

West wall

 

Clear Skies,

Russ

 

 

 

 

[Rustler46]

After raising the height of the pier, I will be establishing a new "home" position for the mount. This position is where the telescope parks just before powering off the Losmandy G-11 mount. When in home position the OTA sits between two of the metal rafters with about 4 inches of clearance below the roof purlins. This will allow clearance for sliding the roof closed with the TG365 cover in place.

 

The reason for changing the home position is that the OTA is now above shoulder height, making it easier to walk around inside without bumping head or telescope. Also the counterweight intrudes less on the walking space on the west side. I'll see how this works in practice.

 

 

The OTA is sloping downward at about the same angle as the roof.

 

The flag hanging from the counterweight helps prevent running into that in the dark.

 

Tonight I hope to polar align the mount. The previous alignment was disturbed when raising the height of the pier. The "Polar Axis Correction" routine in the Losmandy Gemini-1 will be used for this. So after cold starting and aligning on 5-10 stars, the telescope is pointed at a star near the celestial equator and the meridian. When the routine is started, it offsets the star from its previously centered location in the FOV. The mechanical altitude and azimuth controls on the mount are used to recenter the star and polar align. This process may need several iterations to fine tune polar alignment. Previously the error in polar alignment was less than 5 arc-minutes in either altitude or azimuth. 

 

Edit:

Before running the alignment routine the mount was about 1/2 degree off in azimuth. This is to be expected since that error easily results from how far the pier's upper flange was threaded on the 4-inch pipe. Surprisingly there was considerable error also in elevation. This tells me that parts of the extended pipe and its coupling had some error in the threading, resulting in the flange being tipped a bit in elevation.

 

In any case I got rid of most of the error running the alignment routine. One more iteration should get it back to close polar alignment. As I recall it now is within 8-10 arc-minutes of correct.

 

Clear Skies,

Russ

Edited by Rustler46, 31 July 2024 - 06:20 PM.

[Rustler46]

I have decided to reduce the cross section of the upper wall ventilation openings. This will reduce wind-blown rain entering inside the structure. So some 7-inch wide strips on aluminum have been added as shown.

 

Northeast corner

 

Northwest corner

 

Inside view

 

The roof overhang was designed to be just 12-inches to help reduce the roof's overall weight. Of course one consequence is the possibility of rain blowing in through the upper vents. But having adequate ventilation is very important. So I hope the flashing I've installed will help make the observatory as functional as possible. Certainly Ocean Observatory as home for my Celestron-11 has proven its worth. I am thoroughly enjoying it.

 

Clear and Smoke-free Skies to All,

Russ

 

[Rustler46]

Tonight I had clear skies with gibbous Moon low in the south next to Antares. I decided to use the evening fine tuning polar alignment. Previously I had used the Losmandy Gemini-1 software utility "Polar Axis Correction" to bring the error from around 1/2 degree (30 arc-minutes) down to less than 10 arc-minutes. So tonight I started with another round by aligning on around 10 bright stars to allow the amount to build a model of the polar alignment error. Then I chose a star near the meridian and the celestial equator. This was carefully centered at 364X. When "Polar Axis Correction" was started, that star was automatically offset from the FOV center. Using the mount's mechanical adjustments for altitude and azimuth I recentered the star. After this I had to align on another 10 stars, which showed the error was 1 arc-minute in elevation and 2 arc-minutes in azimuth. That is way more accurate than it needs to be for anything other than long exposure astrophotography. But since I had the capability of doing an accurate polar align, it seemed best to do it.

 

I'm quite pleased how increasing the pier height by around 8 inches has given access to more objects low in the south. For the most part this is only an issue during summer and winter when the Milky Way is due south. It also makes for more comfortable viewing of objects near the zenith. The raised pier places the eyepiece 8 inches higher.

 

Best Regards,

Russ

[Rustler46]

Now that my Celestron-11 is now functioning quite well in its own simple observatory, I finding that I can easily setup for observing. At the end of a session, closing up is similarly a breeze. Perhaps 5-10 minutes before or after a session is all that is needed. At least in this non-rainy, dry season in Oregon, I keep most all of what is needed for each session right in the observatory. My iPad running SkySafari is carried from and to the house. No more carrying counterweights and shaft, attaching these to the mount. Then another trip to the garage for the OTA, plugging everything in. Another trip brings eyepieces, star atlas, etc.  All that extra work is done away with the simple observatory

 

When I unlock the observatory, there are 4 nylon straps holding the roof securely upon its sloping ramp. These are quickly removed and a quick pull of the rope opens the roof wide to the sky. Even if there is no wind at the time I always strap the roof to its ramp in the open position by two straps - one on each side. Then the Telegizmo 365 cover is removed, eyepiece inserted and mount powered on. A one star align is all that is needed to be in business for go-to operation. In this case the previously established mount model is used. This includes polar alignment error, the very small errors in orthogonality of the Losmandy mount and other geometric factors are included. Of course time of the night and geographic location all figure into the mix. And 5-10 alignment stars were used in the last "cold start" of the mount. Once that has been done, then subsequent "warm restart" boot-ups of the mount just require centering a single star, that has automatically been put in the FOV. 

 

The only time I need to go back to a "cold start", with alignment of 5-10 stars is if I further I improve the polar alignment by adjusting where the polar axis is pointed. That I did last night, with polar alignment closer than I've ever gotten before. It takes more time to describe what I do than to actually get to observing each night.

 

So this brings me to why I'm adding this reply. Now I'm considering what kind of astronomy I want to pursue. My observing site most moonless nights is around Bortle-5, 20.33 mag./arc-sec². With ease of getting on with observing, I can take advantage of infrequent clear nights. Even if I'm quite tired from other events in the day, I find myself more frequently getting on with even a brief observing session. 

 

In the past I've been involved in quite a bit of astrophotography, both long exposure and planetary. In recent years I've virtually ceased with that, being more into visual observing. But it would be easy to get back into AP or EAA. Certainly with the gas giants coming back into the evening sky, planetary imaging may be in order. Also I have enjoyed observing double/multiple stars, both with the C-11 & piggy-backed AT115EDT refractor. 

 

So there are a number of different avenues I may want to travel, now that my simple observatory makes observing so easy. The time, energy and money expended over the last 1/2 year or so has been well worth it. I highly recommend a similar course for others whose circumstances permit. Yeah, light pollution is an irritant. Weather is something to be endured. But I'm thoroughly enjoying this phase of my long-time astronomy adventure. At 78 years of age, the sky is still the limit. 

 

All the Best,

Russ

[Exnihilo]

Very inspiring Russ, thanks!  What sort of continuous observing efforts have you done, maybe for a single object night-to-night, or a specific class of objects?

 

I’m about to turn 65, but might still be working for a few years. I currently live in hot, light-polluted Phoenix but still get out observing quite a bit in the fall/winter.  At least we have a lot of clear nights. Maybe when I retire I can move someplace darker and cooler. 

[Rustler46]

Very inspiring Russ, thanks!  What sort of continuous observing efforts have you done, maybe for a single object night-to-night, or a specific class of objects?

 

I’m about to turn 65, but might still be working for a few years. I currently live in hot, light-polluted Phoenix but still get out observing quite a bit in the fall/winter.  At least we have a lot of clear nights. Maybe when I retire I can move someplace darker and cooler. 

Thanks for your comment, Paul. In the distant past I was involved in observing variable stars for AAVSO. This was a years long effort involving photoelectric photometry. But after that, I donated all of the electronic equipment to my college. Nowadays if I got back into that activity it would be using a digital camera, not the photon-counting rig I had back in the day. And I would limit myself to following a limited number of stars. There are thousands of variable stars needing ongoing data collection. Here's where the amateur with an observatory could be of great help to the professionals. But personally I would very much limit how much I'd be involved in variable star observing. In a sense it can be a consuming passion that risks taking away the joy one derives in amateur astronomy. At least that's how I view things.

 

So there are lots of avenues for this old astronomer to pursue. I never tire of viewing the same showpiece DSOs. Perhaps focusing on tiny planetary nebulae would be an interesting project. The C-11 has enough aperture and resolving power to make that productive, even under light polluted skies.

 

I hope your own path in astronomy continues to inspire you.

 

All the Best,

Russ

Edited by Rustler46, 16 August 2024 - 02:37 PM.

[Rustler46]

Recently I've a night where double stars were my quarries. See Eight Doubles in Aquila. This is a follow up set of observations for those first done in September, 2022. There was a mystery as to why the C-component in STF 2489 is not visible as it was with a much smaller telescope 2 years ago.

 

After viewing these, I decided to do a careful collimation, since it was off far enough to have irritating flares. This was about the best I've ever gotten collimation on the C-11. Even the little Poisson dot in the middle of the secondary shadow was carefully centered. Views of Schroeder's Valley and Aristarchus on the near full Moon were spectacular. So seeing must have been very good. My wife Renee enjoyed the view with me. Before closing down I noted a bright "star" in the southeast. Wow, Saturn is back! So at 364X with the APM SuperZoom gave a spectacular. We both were able to see 4 moons along with the nearly edge-on rings. A nice way to end a night of good seeing and spot-on collimation.

 

Three nights later I'm again viewing double stars, this time in Sagitta. This time there is poor transparency, variable clouds and good seeing. Sadly the collimation is not perfect as it was just last Friday. This has been a pattern with my old Celestron-11. It just doesn't hold collimation. I suspect it is due to the lock ring holding the secondary mirror assembly needs to be tightened. This can only be done with the corrector plate removed from the OTA. But doing so would give a good opportunity to clean the inside of the plate. After some 16 years the inside is scummy. My 1985 Super C8 Plus holds its collimation so well, that I seldom even check it. It's always right on. 

 

So I'll in the course of time, I'll remove the C-11, with my AT115EDT APO refractor being mounted in the honored position of my "simple observatory".

 

Clear Skies,

Russ

[Rustler46]

Sadly the collimation is not perfect as it was just last Friday. This has been a pattern with my old Celestron-11. It just doesn't hold collimation. I suspect it is due to the lock ring holding the secondary mirror assembly needs to be tightened. This can only be done with the corrector plate removed from the OTA. But doing so would give a good opportunity to clean the inside of the plate. After some 16 years the inside is scummy. My 1985 Super C8 Plus holds its collimation so well, that I seldom even check it. It's always right on. 

I inquired about this issue on the Cats & Casses forum. So it appears there are 3 reasons for easily losing collimation. They are:

• Secondary cell holder loose at corrector lens
• Primary mirror not securely held by its locking ring
• Loose bolts attaching metal tube to front and rear cells 

So it sounds like soon I'll demount the C-11 for a while to deal with the collimation issue. This will give opportunity to clean the inside of the corrector. My AT115EDT APO refractor will take up observing duties in the meantime.

 

CS,
Russ

Edited by Rustler46, 22 August 2024 - 03:46 PM.

[Exnihilo]

Russ, please keep us up to date, we’re enjoying reading about how it’s going. I’d still love to have a roll-off roof type observatory someday.

[Rustler46]

Russ, please keep us up to date, we’re enjoying reading about how it’s going. I’d still love to have a roll-off roof type observatory someday.

Thanks for your comment, Paul. So here's an update on things. After reading How to remove and clean a corrector plate in this forum , I've decided to leave the C-11 on its mount for now. This will allow for supporting the OTA at a correct orientation while I service the big cat. While the corrector is removed for cleaning, I can access the primary mirror for cleaning and for tightening its lock ring.

 

In the meantime, I had another opportunity last night to use the C-11 for observing some double stars in Sagitta. At the beginning of observing the collimation was slightly off from the near perfect alignment a few days ago. The telescope was pointed high in the sky on Altair. So with dew shield in place, I was able to access the colllimation knobs to bring it back to perfection. That goes a long way toward preventing irritating flares around the focused star image.

 

Dew was a problem last night, even with the dew shield in place. So I used a hair dryer to clear that away when it became a problem. I need to reinstall my DewBuster system. That keeps dew a bay, with the negative effect of heat input while trying to cool the OTA to ambient temperatures. A better solution is for a small fan blowing air on the front of the corrector. For my C-8 that has worked wonders in dew prevention. With a fan, almost no heat has been needed to prevent dew. I'll report on that in the course of time.

 

Best Regards,

Russ

Edited by Rustler46, 29 August 2024 - 02:50 PM.