Jeffrey R. Charles
2454 E. Washington Bl.
Pasadena, CA 91004
(818) 398-4573

References & Publication Abstracts


Brief Publication Abstracts


Addresses of Former Employers

Jeffrey R. Charles;
Selected Publications & Presentations; Brief Abstracts;
In alphabetical order:

ALAT - Airborne Large Aperture Telescope. ALAT is a proposed ~3 meter optical telescope (or array of telescopes) on a multiple function high altitude lighter than air platform (MLAP). ALAT is envisioned to be used for astrophysics and as an airborne relay for deep-space optical communication (ARDOC). It is envisioned that beamed microwave power will be utilized to facilitate long term station keeping at altitudes up to 22 km. In addition to carrying optical telescopes, the ALAT platform is envisioned to house inflatable antennas, carry broadcast and cellular communication payloads, surveillance payloads, and serve as a platform and test bed for other small and moderately sized high altitude projects. In the process of this work, I determined that there would be useful "spin-off" applications for much of the technology developed for ALAT, particularly in regard to antenna feed systems and composite and inflatable structures. I first presented the ALAT concept at the Jet Propulsion Laboratory in 1993. In 1995, I presented an abbreviated version of this paper at the JPL "Innovative Space Mission Applications of Thin Films and Fabrics" miniconference. Most of this paper was published in the proceedings of this conference. Click here to see a "view graph" version of the ALAT airborne telescope paper.

All-sky Reflector with "Invisible" Axial Camera Support Strut. This work began as one of my first amateur optical projects. The primary requirements were to obtain an uninterrupted view of the entire horizon on a circular photograph, and to do so at a very low cost. At the time, adequate instrumentation was not available, so I invented, fabricated, and patented, the axial strut wide angle reflector. The concept is to "hide" the support strut in the central part of the photo that would typically be obstructed by a secondary mirror or by the camera. In addition to covering aspects of the initial project, this paper also addresses the application of the axial strut concept to other tasks, such as photographing the night sky. The paper also includes information about how individuals can build their own axial strut reflector with simple tools and materials. An abbreviated version of this paper was incorporated into an article in the April 1987 issue of Astronomy Magazine. Click here to see full axial strut reflector paper.

Astrophotography with a Small Telescope. This paper is about "pushing the envelope" with a small telescope in order to obtain photographs of celestial objects that are normally reserved for larger instruments. Borrowing material from the instruction manuals I wrote for my Versacorp optical instrumentation, this paper also includes the first step by step instructions for taking off-axis guided photographs ever published. It was presented and published in 1988. This paper is not presently posted.

Cultural Realities at Your Eclipse Destination; When Caution may be in Order. Being informed about a foreign country and the way its cultural issues can affect a member of a total solar eclipse expedition is very important to the eclipse traveler; particularly if traveling alone or in a small group. The influence that undesirable cultural issues can have on an expedition member tends to be somewhat proportional to the degree in which that member is exposed to the culture. This paper addresses problems myself and others experienced in Latin America and other areas, and suggests how other eclipse observers may avoid similar problems. I presented eclipse information at Bolivian schools and universities in 1994, so my "exposure" to that culture was substantial. This paper has the potential to be controversial or " politically incorrect" because it dares to addresses the effects that cultural issues such as racism, extremes of rich and poor, oppression, and armed conflict can have on the traveler. In doing so, it by necessity calls attention to these "undesirable" cultural factors. I make no apology for this because avoidance of "undesirable" people and cultural factors is the best way to prevent being affected by them. One usually can't effectively avoid something without first knowing that it exists. Click here to see the full paper.

Getting Your Film & Equipment Through Airports and to Your Eclipse Site. This paper deals with travel preparations for total solar eclipse expeditions. Recent developments have increased the likelihood of rigorous and time consuming security checks at U.S. airports; however, observing total solar eclipses usually involves international travel, and many international airports already have rigorous and time consuming security procedures to enhance passenger safety and to discourage drug trafficking; therefore, it is important to be prepared to cooperate with these security measures. An important part of this preparation is in how you document and pack your instrumentation. International travel involving the transportation of eclipse equipment requires planning, documentation, mobility, vigilance, and the task of getting film and magnetic media through unfamiliar security checkpoints. In some situations, even the selection of proper attire will have an effect on how one is treated by airport personnel. In rare cases, an airport employee who is on a power trip may act unreasonably, and this paper suggests how one can deal with such situations without being walked on. Other considerations are also addressed, including ground transportation to a suitable eclipse site and cultural factors which could potentially affect local travel. Click here to see the full paper.

Predicting the Appearance of the Lunar Umbra at Future Total Solar Eclipses. The primary purpose of this ongoing project is to obtain and analyze data that will facilitate predicting the appearance of the lunar umbra at future total solar eclipses. Before, during, and after the total phase of the eclipse, the lunar umbra can usually be seen as a large dark area in the sky. Direct sunlight is absent within the umbra, so the normal blue color of the sky caused by atmospheric scattering is absent as well. From a distance of ~50 km or more, the diffuse umbral boundary can appear to be surprisingly well defined. This implies that the atmospheric scattering which makes the umbral boundary visible is stronger at certain altitudes. Thus far, my experiments show two prominent altitudes for this scattering in a cloudless sky; ~14.6 km and ~22 km. The latter figure corresponds to an altitude in the lower stratosphere at which relatively high concentrations of ozone and volcanic material are present. Additional effects are observable during totality; sunlight that is scattered or reflected to the observer from outside the umbra will often to appear yellow or orange due to atmospheric scattering.

To collect data at various total solar eclipses for use in the study of the umbral boundary, I designed and fabricated the instrumentation required to take 360 degree panoramic photos of the twilight conditions typically present during totality. Time indexed video and other cameras were also used to collect data, as was a light meter. This work requires good weather conditions and good site selection. The weather was not favorable for all observed eclipses, but after I observed my third eclipse in 1994, I had enough data to calculate results and prepare a presentation. Results of this work were first presented in 1995. Click here to see the umbral prediction paper.

Steps to a Successful Eclipse Expedition. Based on my experience at various total solar eclipses, this article presents recommendations for how to successfully complete several eclipse projects during the typically brief one to five minute duration of totality. As would be recommended for any tasks which must be well organized; planning, documentation, practice, and relative simplicity are stressed. This paper was presented at the Riverside Telescope Makers Conference in May, 1996. It includes some eclipse photography information from my 1991 presentation entitled "Gadgets & Techniques for Total Solar Eclipse Photography". Click here to see full eclipse paper.

Click here for a list of more articles, papers, & publications.

Click here to see my EclipseChaser web page; a compilation of documents and images relating to total solar eclipses.

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Jeffrey R. Charles;
Personal and Professional REFERENCES:
June 2, 1996.

Samuel Zingales (former supervisor at JPL)
Jet Propulsion Laboratory
ms 161-213; 4800 Oak Grove Drive; Pasadena, CA 91109-8099
(818) 354-5454

Dr. Chien-Chu Chen
Jet Propulsion Laboratory
ms 161-260; 4800 Oak Grove Drive; Pasadena, CA 91109-8099
(818) 354-7738

Riley Strickland
Jet Propulsion Laboratory
ms 238-438; 4800 Oak Grove Drive; Pasadena, CA 91109-8099
(818) 354-9264

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Jeffrey R. Charles;
Addresses of Employers for Previous 10 Years:
(Self-employment addresses at Versacorp not shown)

1995 Employer:
Telos Inc.
320 N. Halstead Street, Suite 260
Pasadena, CA 91107
(818) 351-2341
Admin. Contact: Denise Pothoff
Relevant Supervisor: Samuel Zingales (at JPL)

1992 to 1995 Employer:
PRC Inc.
2500 E. Colorado Blvd.
Pasadena, CA 91117-0008
(818) 564-0725
Admin. Contact: N/A (PRC TSEP office was closed in 1995)
Relevant Supervisor: Samuel Zingales (at JPL)

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