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Lightweight  Alt-Az Telescope Design Team



The combination of low-cost alt-az telescope control systems and affordable aerospace materials has reached the point where a revolutionary new class of lightweight, highly capable alt-az telescopes is emerging.  Similar to SCTs, this new class of alt-az telescopes will not only be used visually, but also for CCD-based scientific research and astrophotography.  Similar to Dobs, they will have larger apertures than SCTs, yet will be lightweight.  Unlike the visual Dobs but similar to giant mountaintop alt-az telescopes, this emerging class of precisely controlled telescopes will handle a variety of instruments mounted on field de-rotators with generous back focus.  The primary reason for developing lightweight alt-az telescopes with apertures larger than SCTs is to conduct research on and image (as well as view) fainter objects with affordable telescopes. 


The cost of alt-az telescope control systems has plummeted over the years.  Initially, control computers and telescope control electronics cost tens of thousands of dollars and filled entire equipment racks.  Today, Sidereal Technology makes a microcomputer-based alt-az telescope control system for about $1,000 that you can place in your briefcase with room to spare.  Meanwhile, the cost of aerospace materials has plummeted as their use has moved beyond aircraft and spacecraft to outdoor signs and building exteriors.  Given these two dramatic drops in cost, research-grade alt-az telescopes fabricated from lightweight aerospace materials are now economically viable.


An informal team has been established to facilitate the development, production, and use of lightweight, low-cost, research quality telescopes in the aperture range, primarily, of 0.5 to 1.0 meters (although both larger and smaller apertures are also of interest).  This team has no commercial aims per se, although one of its goals is to encourage the manufacture of this "new" class of alt-az telescopes and the various components that will go into them.  Thus we consider members from commercial firms to be central to our team, and hope that what we come up with will be useful to them.


Specialty Areas


As our informal team has expanded there has been, as might be expected, some specialization (although we all share an irrational love of telescopes and astronomy).  We have a strong optics section with Dave Rowe, Tom Krajci, Tong Liu (Hubble Optics), Rick Hedrick and Joe Haberman (PlaneWave Instruments), Gerard Pardeilhan (optician at Strasbaugh in San Luis Obispo) and John Hall (Pegasus Optics).  Steve Kennedy has an interest in the project.


We also have a strong control section with Dan Gray (Sidereal Technology), Dave Rowe (on large diameter brushless DC direct drive motors), Art MacCarley (EE chair at Cal Poly and control systems instructor), Helen Yu (EE professor at Cal Poly who also teaches control systems), Ty Safreno (President of Trust Automation in San Luis Obispo), and Russ Genet.  Mel Bartels has provided helpful inputs.


Although not directly part of our group, Elwood Downey (NM Tech University’s Magdalena Ridge Observatory 2.4-m Project Engineer) and Kevin Harris (EOS Technology’s 2.4-m Project Engineer) have made vital contributions to both the control aspects of this project for which we are most grateful.  Our visit to MRO, suggested by astronomer Chris Corbally at the Vatican Observatory's pioneering 1.8-meter alt-az telescope, was a major milestone in shaping of our ideas.


Our mechanical team is still in the formation stage, but already includes Richard Kay (President of Impact Bearings with six plants in the LA area), Jim Widmann (ME Professor at Cal Poly), and our Jack-of-all-trades, Dave Rowe.


Supporting University


Cal Poly (California Polytechnic State University, San Luis Obispo) is the first university to join our team.  The chairs of the ME and EE Departments at Cal Poly, Tom Mackin and Art MacCarley, are supportive of the project (as are ME and EE Professors Jim Widmann and Helen Yu mentioned above). They are challenging some of their best students with various aspects of lightweight alt-az telescope design.  George Roberts (President of Inca and a longtime supporter of Cal Poly's ME Department) is providing helpful overall advice to our team.  Rich Saenz the Physics chair and three of the astronomers at Cal Poly, Dave Mitchell, John Keller, and Michelle Ouellette, have been helpful in defining astronomical research applications.  Cal Poly would like to develop, site, and use a 1-meter alt-az telescope.  We have adopted Dave Rowe's conceptual sketch of the Cal Poly 1-meter telescope as our project's logo.


Remote Test Site


Tom Smith's Dark Ridge Observatory (DRO) near Cloudcroft is a willing test site for the team’s telescopes.  Tom, a very active team member, has contributed in many areas to the team’s deliberations.  A nuclear engineer, he worked with Russ on various astronomical projects in San Luis Obispo for several years and then took early retirement to set up his observatory in New Mexico.  He is busy pouring concrete and hammering nails for his control room and the roll-offs for his two 14-inch SCTs and his 20-inch alt-az telescope.  We plan on placing the 25-inch telescope, described below, at DRO for a couple of years after the telescope’s construction and testing at Cal Poly.


The 25-inch will eventually end up at Dave Rowe's Starry Ridge Observatory (SRO), also near Cloudcroft.  After Dave retires in about a year, he will be building his observatory (complete with a dome).  At both the Dark Ridge and Starry Ridge Observatories, time will be made available on the 25-inch alt-az telescope for Cal Poly students and others in the San Luis Obispo area (Cuesta College students, high school students, and advanced amateurs from the Central Coast Astronomical Society).


Advanced Technologies


Peter Chen (NASA Goddard SFC) keeps us in touch with developments on ultra-lightweight (carbon fiber) mirrors.  We have to restrain ourselves not to think too much about what a 2-meter telescope—that weighed under 300 lbs. and could be transported in a pickup and set up in half an hour—might achieve.


The possibilities for including some form of adaptive optics are also being considered.  The cost of piezoelectric devices has dropped significantly in recent years as has the cost of high-speed digital signal processors.




We have planned several workshops.  The first one is this coming Saturday (October 20th) in San Luis Obispo (SLO), the first of a number of SLO Alt-Az Workshops.  Dave Rowe, Rick Hedrick, and Richard Kay are coming up from LA to join the folks from Cal Poly (professors and students) and several local industrialists (Ty Safreno, Gerard Pardeilhan, and others) for an afternoon alt-az workshop in San Luis Obispo (with an optional lunch before hand and dinner afterwards).


Other workshops in this series will be scheduled at San Luis Obispo over the school year.  The initial goal of this series of workshops is the design and fabrication of the 25-inch alt-az telescope mentioned above.  The primary mirror is being supplied by PlaneWave Instruments, and work has already begun on this mirror.  Many of the components and materials are being funded by Dave Rowe (Starry Ridge Observatory).  The control system is being provided by Dan Gray (Sidereal Technology).  Dan is working on an advanced version of his control system that will handle direct drive brushless DC motors and very high resolution encoders.  Of critical importance, the telescope's structure will be designed and fabricated by a graduate Cal Poly ME student team in Jim Widmann's ME Projects class.  A key purpose of this series of workshops is to support Jim and his students.


This series of San Luis Obispo workshops is also firmly setting, as its goal, the development and eventual fabrication and operation of a 1-meter Cal Poly alt-az telescope.  We will carry along the design of this telescope as we work on the "pave the way" 25-inch system.  The optical plan for the 25-inch is a corrected hyperbolic Newtonian, while the plan for the 1-meter is a corrected Dall Kirkham with a tertiary folding flat.  The Cal Poly 1-meter telescope will, on completion, become a major research tool for Cal Poly.  We plan to site it at a dark, relatively fog-free location just over the coastal ridge—perhaps at Santa Margarita Lake (a SLO County park) which is just a 20-minute drive from the Cal Poly campus.


The following Saturday, October 27th, there will be an alt-az workshop in Dallas.  A number of us will be at this event, and we should get many helpful inputs from the folks in Texas (and others flying in).  Max Corneau is not only the local host for this workshop, but an active member of our alt-az developmental team.  There will be invited summaries of this workshop published in Astronomy Technology Today (Gary Parkerson, Editor) and in Amateur Astronomy (Charlie Warren, Editor).  Amateur Astronomy is featuring a special issue next year devoted to articles on various aspects of our alt-az developmental project.  Russ Genet will be the guest editor for this special issue.




Two major conferences are planned with a number of special focus sessions that will feature the team's work, including optical, mechanical, control, and other sessions.  The first conference will be in San Luis Obispo this coming June 20-22 (2008), and the second will be in Hawaii the following January 1-5 (2009).  See www.STARConference.org for details on both conferences.  The proceedings of these two conferences will be published as hardback books—part of the prestigious Astronomical Society of the Pacific's Conference Series managed by J. Moody (Russ Genet will be the editor for both volumes).


The Small Telescopes & Astronomical Research (STAR) Conference will, primarily, be a national conference with about 150 attendees.  We had a precursor to the this conference last year, the STAR Workshop.  A summary of this workshop was published in Astronomy Technology Today.


The Hawaii conference, Galileo's Legacy: Small Telescope Science 1609 and 2009, will be a major international event with over 250 expected.  It will open with a New Year's Eve inaugural talk by Rick Fienberg (Senior Sky & Telescope Editor) followed by fireworks to help launch the International Year of Astronomy.  There will be many special focus sessions related to alt-az telescopes and their use in scientific research.  Richard Berry, the former, long-time Editor of Astronomy, will give the Luau talk.  There will be tours of Mauna Kea before the conference and Haleakala after the conference.


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