The 200" Hale Telescope on Palomar Mountain v2.0 by Selden Ball © December, 2007. All rights reserved. ================================ This Addon is designed for use with Celestia v1.5.0pre4 or later. It provides an interactive CMOD model of the 200" Hale Teleseope and its dome on a digital elevation model of Palomar Mountain. If you restore this Zip file into Celestia's Extras directory, it should recreate all of the directories and files necessary for it to work with Celestia v1.5.0pre4 or later. The telescope's models and scripts are large and complex. Celestia pauses for several seconds to load them when the telescope first comes into view. While running, I get about 20-30 frames/second on a rather fast system. It may run much more slowly for you. A low resolution version of the model of the telescope is included. Selecting that may help. Functions ========= The included SSC catalogs and Scripted Orbits and Rotations cause the telescope to track the currently selected object and the dome to turn with it. The field of view images represent what can be seen by the Palomar Large Format Camera described at http://www.astro.caltech.edu/observatories/palomar/lfc/lfc.html and by the PHARO (Palomar High Angular Resolution Observer) camera described at http://astrosun2.astro.cornell.edu/research/projects/PHARO//pharo.html The included HTML (Web) file contains Cel:// URLs which will take you to viewpoints around the telescope. The scripts included in the scripts subdirectory can be used to configure the telescope for observation and to display the various paths that light takes through the telescope. Telescope control commands are implemented which enable you to move some of the components of the telescope and of the observatory. Scripts invoking the individual commands are in the folder hale_commands. (The commands themselves are defined as OpenCluster deep space objects in 00_hale_commands.dsc) To give a telescope control command while Celestia is running, you can either select the appropriate one-line script in hale_commanad, or you can type the appropriate command directly to Celestia in the form [return]command[return] where "command" is the name of one of the objects defined in hale_commands.dsc ( This is exactly the same method that you could use to select for viewing any astronomical object in Celestia.) If you type a recognized command, the Hale control scripts will promptly start executing it and reselect the original object. Any object selection which is not recognized by the control scripts will be ignored by them and will be left for Celestia to select. All of the commands are either multi-word strings starting with "Hale_" or their 3-5 character synonyms starting with the letter "H". These commands allow you to + separately hide or reveal + the dome and its base + interior fixtures of the dome + low or high resolution versions of the telescope's plinth, yoke and optical assembly + the laser system sometimes used with the adaptive optics + any of the five light paths and animated photons along them + an observer taking pictures at the prime focus + the large format camera + the laser launch telescope sometimes used with the adaptive optics + open and close the dome's doors (The dome and windscreen track the telescope's movements automatically. This means that they're defined in SSC files, not Lua scripts.) + raise and lower the cover of the primary mirror + raise and lower the Cassegrain and Coude secondary mirrors + raise and lower the central Coude flat and its crane + rotate the central Coude flat to direct the Cassegrain light path through the East trunnion into the East arm for observing with the East Eschelle Spectrograph. + raise and lower the Coude Bridge which is needed when using the Coude light path to observe objects which have a Declination greater than +50 degrees. + raise, lower and stop the elevator which provides access to the prime focus + move the overhead crane backward and forward + raise, lower and stop the crane's hook Commands are *not* available to rotate the dome and to raise and lower the windscreen. Their motions are defined using static Reference Frame directives in the SSC catalogs. Their manual control functions will have to wait for v3 of this Addon. Operational Notes ================= Although the URLs on the Web page "hale_telescope.html" will take you to reasonable locations, in most cases you'll find your view blocked by the observatory dome. To see the telescope itself, you must type some commands in the form [return]command[return] or select the corresponding scripts in the folder hale_commands: You could either + open the dome doors and then peer inside Hale_Open_Door or + hide the dome entirely Hale_Hide_Dome and you'll probably want to + hide the internal support structure Hale_Hide_Internal Accuracy Limitations ==================== This Addon is representational rather than realistic. References for many of its components are limited or unavailable As a result, the models of the telescope and its dome are incomplete, many details have been omitted, and some aren't quite right. (If you can provide reference pictures for incorrect details, the author would be greatly appreciative.) The low-polygon models of the telescope, yoke and plinth don't exactly match their high-polygon versions. The model of the mountaintop is relatively low resolution and doesn't exactly follow the topographic contours. The telescope and dome turn continuously despite the time of day: The yoke turns to orienations which are impossible for the real telescope. Appropriate motion limits will have to wait for v3 of this Addon. In order for the telescope's operation to be visible, the sun needs to be up, so the scripts show the telescope moving during Celestia's daytime. Normally the real telescope's dome would be closed during the day in order to provide a constant temperature, ensuring the stability of the shape of the primary mirror. Functional Limitations ====================== The SSC catalogs and Scripted motion Lua modules were developed using Celestia v1.5.0 pre3 and pre4. They cannot work with earlier versions of the program, and may need to be modified for use with later versions of Celestia. When the telescope model is pointed down toward the Earth, some of Celestia's orientation calculations fail because the axes of some of the coordinate systems become parallel to one another. This causes the dome to abruptly tilt. When the model is pointed toward other objects, the dome is horizontal as it should be. But pointing the telescope down toward the ground is not particularly useful, anyhow ;) In order for the commands to work, Celestia must be Following or in SynchOrbit around Hale_Position or some other telescope component. Telescope Constraints ===================== Some, but not all, movements of the model have been designed to match some of the real telescope's limitations. For example, the movement of the laser trolley is limited: NGSAO (Natural Guide Star Adaptive Optics) observations are limited only by the telescope declination limit for tracking of .. < 88º, and hour angle limit of -6h40m < HA < 6h40m. However, in LGS (Laser Guide Star) mode, agreements with the Federal Aviation Administration and the design of the laser beam transfer optics limit PALMLGS observations to the elevation range 20º < el < 90º, and declination range -11.6º < .. < 65.2º. Ref: www.oir.caltech.edu/twiki_oir/pub/Palomar/SWIFT/ICDs/SWIFT_ICD_v02.pdf The declination limits of the telescope's optical tube model are not enforced, however. For example, it'll happily point toward the south pole, going into the south pillar. The laser light beams will still point toward the trolley, too, penetrating through "solid" materials. Credits ======= Surface textures of Neptune and Uranus were derived from adaptive optics pictures taken by, and are used with the permission of, Don Banfield (Cornell). Credits: Don Banfield (Cornell), PHARO Team (Cornell), PALAO Team (JPL). Of course, none of this would work without Celestia :) http://www.shatters.net/celestia/ The scripted control functions are written in Lua. http://www.lua.org/ The rotation modules used to orient the telescope make use of routines taken (with permission) from the Lua Edu Tools for Celestia. Thanks, Vincent! http://vincent.gian.club.fr/celestia/Lua_Edu_Tools.zip The models included in this Addon were created using Anim8or, a free 3D design program written by Steve Glanville. Visit http://www.anim8or.com/ for more information. The designs of the models were based on 1. photographs provided by Scott Kardel, Palomar Public Affairs Coordinator 2. pictures and movies on the Palomar Web site at http://www.astro.caltech.edu/palomar/ ) 3. photographs of the telescope's construction found on the Web in the Caltech Institute Archives at http://archives.caltech.edu/ 4. drawings of the telescope by Russell Porter as published in _Photographic Giants of Palomar_, Fassero and Porter, Westernlore Press (1947) and on information found in the books 5. _The Perfect Machine: Building the Palomar Telescope_ by Ronald Florence, Harper-Collins Publishers (1994) 6. _Palomar, The World's Largest Telescope_ by Helen Wright, The MacMillan Company (1954) 7. _The Glass Giant of Palomar_ by David O. Woodbury, Dodd, Meade & Company (1940) and on information found in the articles 8. "Optics of the 200-Inch Hale Telescope" by John A. Anderson, 1948pasp 60 221A 9. "Engineering Aspects of the 200-Inch Hale Telescope" by Bruce Rule, 1948pasp 60 225 (pasp = Proceedings of the Astronomical Society of the Pacific) The following Web sites also provided useful information: http://www.astro.caltech.edu/palomar/200inch/lfc/index.html http://www.astro.caltech.edu/observatories/palomar/lfc/lfc.html http://ao.jpl.nasa.gov/ http://astrosun2.astro.cornell.edu/research/projects/PHARO//pharo.html (and other Web sites too numerous to mention.) The "7.5 minute" DEM and topographic maps that this Addon uses were originally created by the USGS. DEM models were obtained from http://geogdata.csun.edu/ Topographic maps were obtained from http://archive.casil.ucdavis.edu/ They were translated into Celestia's CMOD format using 3DEM and a home-grown Fortran program. ImageMagick and netpbm were used to crop, scale and translate the topo map and other images into JPEG format. 3DEM, ImageMagick and netpbm are freely available. Visit their Web sites at http://www.visualizationsoftware.com/3dem.html http://www.imagemagick.org/ and http://netpbm.sourceforge.net/ Copyright and license ===================== This Addon, its models and accompanying documents were created by Selden Ball for use with Celestia and are copyright © December, 2007. All rights reserved. License: This Addon may be freely redistributed for educational purposes so long as all of the provided files are included. This Addon may not be used for any commercial benefit without explicit written permission from the author. Selden Ball December, 2007 http://www.lepp.cornell.edu/~seb/