Almaden Observatory

Equipment and Construction

This page describes the current status of the Observatory.  Since initial operation in 2010 I have had a constant string of upgrades as I have tried to improve the operation of the observatory and improve the picture quality.

Equipment

Optics

Guide

Filters

Weather

All Sky camera

My Boltwood II weather sensor is good at detecting weather that is potentially dangerous to the observatory.  It is not as good for sensing high clouds.  My original solution was to use a surplus Orion StarShoot Autoguider with a Tamron lens (originally intended for security cameras.  I attached this to the bracket at the top of the telescope. I can now monitor the sky and confirm there are really stars up there.

I knew clouds were a possibility when I opened, but this confirmed it.  At this point the Clarity was still saying the sky was clear.  Shortly after this picture was taken the clouds were thick enough that it triggered a weather alert.

While the Orion camera did provide some visibility it was not designed for this purpose and was not sensitive enough, and only provides a view through the slit.

I had previously considered an true all sky camera. At the time all of the cameras required either a serial connection to a dedicated computer or a USB connection. Either of these would mean dedicating one of my PCs. In the 2018 NEAF Starlight Express announced a product using a Raspberry Pi in a weather proof enclosure. This permits the computer to be dedicated and close enough to the sensor so USB makes sense. While the unit had wireless capability I selected a location close to the master hub for my house which permitted a twisted pair connection.

This shows the camera installed near the observatory (looking west). Since most of my north sky is dominated by trees, the camera is tilted so more of the south is captured. The result is that virtually my entire sky is in the field of view.

I knew clouds were a possibility when I opened, but this confirmed it.  At this point the Boltwood was still saying the sky was clear.  Shortly after this picture was taken the clouds were thick enough that it triggered a weather alert.

Site Description

Tour of the Observatory

Note old filter wheel

Horizons

Horizons at Almaden Observatory

Not Ideal.  3 streetlights are visible plus the neighbor to my north has backyard lights.

Quality of the Site

Light Polution at Almaden Observatory

Not an ideal location for an observatory. The chart marks downtown San Jose. I am south so at least in the pink area.  This is why I am going to focus primarily on Narrowband.

Video of the Observatory.

Guiding Using IR

One of the presentations at NEAF 2017 was for a device that did full aperture off axis guiding by reflecting the IR and passing visible light.  While that particular device was not interesting to me it gave me the idea that I could improve my guiding by inserting an IR filter (really a Halpha high band pass) in front of the guide camera. Since longer wavelengths of light are less seeing affected this would reduce the jitter of the star images.  It also had the second effect of decreasing the brightness of the star which meant that I had to increase the exposure time.  Increasing the exposure time meant that I averaged the true star position over a longer interval.  Together they gave a better measure of the true star location.

In addition I reduced the aggressiveness of the correction in Maxim.  This had a side effect in ACP. Since the default behaviour of ACP is to move the mount during dithering by making a guiding correction, I was finding it potentially took too long for the mount to settle in its new location.  Since I have a mount with absolute encoders it was faster to shut down guiding, have ACP dither by moving the mount with a seek, and then restart guiding.  This involved some programming.

Upgrade Saga

Summer - Fall 2017

Since the equipment has a few years on it now it started showing its age.  Two problems one with the camera and one with the focuser were both moisture related. Both parts got a trip to Upstate New York.  During the winter I double bagged the equipment with desiccant pouches and only ran once during a period of low humidity.

October 2017

I finally decided to convert to an Optec EL panel. While some observers really distrust these, my own experience is that any kind of sky flats do not give good results.  So far the EL panel is at least as good as the LED box I built.  The EL panel has the distinct advantage that ACP is able to manage the brightness so I can set a run of the entire filter set and then have ACP shut the panel off.

April 2017 - May 2017

During NEAF I decided to get the CenterLine that I originally tried to order in 2013.  This will allow an L filter for faster focusing and pointing.

I also switched my sV filter for an sB.  This allowed for the eventual conversion to an EL panel.

Finally I inserted an Halpha bandpass filter on my guider and improved my guiding by guiding in IR. I am back to using guiding to assist tracking.  I do note that adjustments are rarely required.

December 2015 - March 2016

Tube sag due to the heavy instrument package has been a concern since day 1.  In early December I tried to reinforce the focuser extension tube using a Parallax ring.  Unfortunately when I measured the results I had made the system significantly worse!! After some advice from the AP maillist I narrowed the cause back to the Parallax rings used to hold the scope. I installed more than 4 years ago. They never fit properly and thus the scope was never square to the declination axis.

I have now replaced scopes's Parallax rings with Takahashi rings.  These exactly fit my AP mounting plate unlike the parallax rings which required me to oval the holes. I added support to the focuser extension but this time with ADM rings.  These provide better support to the heavy instrument package.

Due to El Niño the scope has been in the house since December.  I was not able to resume full operation until April.  The good news is that the scope is now tracking perfectly.  For most of the time since April I have not used active guiding.  As of June I turned it back on, but only on a "Best Effort" basis.  If it has problems I revert to self guiding.

October 2015

After talking with the AP folks at AIC I bought an AP sourced Baader Varo Finder kit and put my SBig STi back to work.  Initial tests are mixed.  (although the situation improved in 2017) I got excellent results near the equator, but poor results for M 81. 

Summer 2015

After much deliberation I decided to go ahead and purchase the 1100AE.  The absolute encoders have dramatically improved my tracking performance.  Also the 1100AE is better suited for remote operation since the 1100 eliminates cable tugs. The encoders permit setting a hard limit and provide a means to recover from a "lost scope" condition.

February 2013 - April 2014 Upgrade

It seems like I am doing something each February.  In 2013 I planned to replace the first generation SBig 8300 with a camera that had a better cooler.  Little did I know that this cycle would take 14 months.

I settled on a FLI Proline 16803.  The primary goal was to improve the cooling, but the 16803 will also give me a greater FOV at the cost of less resolution.  As a part of this I also had to replace the filter wheel and chose to get a more robust focuser.  Due to weight concerns I initially bought a CFW-4-5. With this filter wheel I could only configure my system for either Narrowband or Nb4Stars + Hydrogen, but not both.  The order took FOREVER and once it arrived I had to redo the optical path because the camera/filter wheel.focuser was too heavy for the CAA. 

The Orion ST-80 even with the new focuser had enough wiggle to wreck my tracking.  Thus I replaced the guide scope with a simpler and lighter Hutech that screws together.  After experimenting with several guide cameras I ended up with an Orion SSAG.  The images are noisy, but the camera is very sensitive and has very small pixels. Thus it is perfect match to the Hutech (Orion sells a similar scope, but with a "design to cost" mount).

The limitations of the CFW-4-5 proved too much for me.  Thus I ordered a CFW-5-7.  This allows all my of Narrowband and NB4Stars filters to be used at the same time.  I also replaced the CAA with a custom extension built by precise parts.  While this prevents me from easily changing the camera angle, eliminating the CAA makes the system more rigid.

I also took the time to redo the lower shutter system.  Now it works reliably.

During the summer of 2013 I analyzed some of the initial photos in this new configuration.  Sadly it looked like a mishap I had with the scope 2 years before had damaged its optics.  So the scope took a journey back to Japan.  It returned in April 2014.  Once everything was together and running the system now works perfectly.  I have perfect guiding, wide field in focus across the entire frame, and all of my filters.

March 2012 Retrofit

I replaced the wheels the dome rides on with rollerblade wheels.  This allows the dome to turn silently; however, it turns so easily now that it bounces when it stops.

Replaced G-11 with AP 900

Replaced Pier Tech with ATS Pier

February 2011 Dome Channel Retrofit/ Dome Rotation

NOTE:  These instructions are for an older version of the retrofit.  Some of the techniques might apply, but check the Exploradome mail list for up to date info.

This page describes retrofitting the dome with the new wheel channels.

Feb - November 2010 Construction

This web album shows the observatory under construction