CHOICE Course Descriptions

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Most courses are available to AAVSO members AND the general public. The fee for AAVSO members is $35.00 click here. Non-members pay $60.00 click here. Registrations are available on a first-come, first-served basis.

The following is a brief description of each course currently offered in the CHOICE curriculum:


CCD Photometry Part I

This course will use the first half of the AAVSO Guide to CCD Photometry and will provide motivation and scientific background for doing photometry with a CCD.  Topics covered include system testing and basic image calibrations from bias and dark frame subtraction to flat fielding. Students are strongly encouraged to have their own CCD/telescope ready to take calibration and light frames along with their own image processing software, with which they should be familiar. Images for analysis will be provided if the student is unable to obtain their own for any reason. A cooled monochrome camera is required. A cooled 16-bit monochrome CCD is recommended. One-shot color cameras are not suitable for this particular course.

Important-please read: Camera and software requirements and recommendations

If you have any questions about the course please click here to send a message to the instructor via the photometry forum.


CCD Photometry Part II

This course covers chapters 5, 6, and 7 of the AAVSO CCD Photometry Guide.

Prerequisites: Experience with basic CCD imaging and image calibration. CCD Photometry (Part I) is strongly advised but not required. You will also need working knowledge of the photometry tool in any of the standard CCD image processing programs. Knowledge of VPhot will be very helpful.

This is an observing course. You are strongly encouraged to have the use of a functioning telescope and camera system and the ability to produce calibrated images of assigned fields. You will need, at minimum, a photometric Johnson V filter, and one other photometric filter, preferably Johnson B. For observers transitioning from RGB tricolor imaging, you may use your RGB filters for the exercises, including transforms, but you will need photometric filters if you decide to continue doing CCD photometry.

If you are not able to make your own images for any reason, or you do not yet have a suitable camera, the instructor will provide images for you to use.

For students continuing from CCD Photometry (Part I), detailed instructions on how to do the exercises using VPhot will be provided. By the end of the course you should have a decent working knowledge of VPhot.

Important-please read: Camera and software requirements and recommendations

If you have any questions about the course please click here to send a message to the instructor via the photometry forum.


Developing A Visual Observing Program

This four week course is designed to help visual observers get the most enjoyment and scientific return from the observing programs they develop, based on each individuals’ equipment, observing conditions and interests. To successfully complete this course you must provide in writing, two documents.

1) A complete observer profile (a sample is provided)

2) A list of stars appropriate for your primary observing equipment, observing site and conditions, frequency of observing sessions, scientific merit and fun factor (a sample is provided).


DSLR Photometry

This course will utilize the AAVSO DSLR Observing Manual as its guide. This manual is a basic introduction and guide to using a DSLR camera to make variable star observations. The target audience is first-time beginner to intermediate level DSLR observers, although advanced observers may find the content useful as well.

Important-please read: Camera and software requirements and recommendations


Exoplanet Observing

This course is designed to provide participants with the basics of how to conduct their own exoplanet observations. With the flood of targets coming in from the currently running TESS (Transiting Exoplanet Survey Satellite) mission, this course offering is especially timely.

The first half of the course will cover the fundamentals of high precision photometry, as well as the various phases of an exoplanet observation. The second half will review the use of AstroImageJ (AIJ) for image reduction and exoplanet transit modeling. In addition, the future of exoplanet observing using small telescopes will be discussed, as well as ways in which amateur astronomers can contribute to exoplanet research, including contributions to the TESS mission.

The course will use “A Practical Guide to Exoplanet Observing” as its primary text, as well as a set of sample exoplanet observations, both of which can be found at Videos created by Dennis Conti are associated with each week's module. Participants will take a quiz after each module that assesses your understanding of that week's videos and written materials, and your practice with the transit-fitting software (AIJ). Participants must successfully pass each quiz to successfully pass the course. A private forum will be available to participants in order to communicate with each other, as well as the instructor.


Observing and counting sunspots

For centuries after the first telescopic drawings of the Sun were made, observing and counting sunspots remained, and still is, one of the most important methods for monitoring the activity of our nearest star. This two week course will provide the fundamentals of visually observing, monitoring, and recording sunspots, with the aim of involving participants in the determination of the American Relative Sunspot Number (RA), a simple and effective index of the solar photospheric activity. It has been recorded by AAVSO since 1944 with the purpose of maintaining a long-running and consistent database for the use of solar researchers world-wide.

The course will focus on several topics such as equipment, safety issues, basic concepts about sunspot activity, morphology of sunspots and sunspot groups, and recording and reporting observations. Counting sunspots requires some basic knowledge on how sunspot groups appear, develop, and decay, thus, some time will be devoted to sunspot groups classification.

The course will consider only white light observations of the Sun. They can be carried out with only a very modest telescope and a commercial solar filter and do not require any expensive equipment. Narrowband (e.g. H-alpha) observing and imaging are outside the scope of the course.

There are no prerequisites for participating. The course is open to everybody, even to absolute beginners in solar observing. However, more experienced observers may be interested to join for discussing in detail some of the topics and for contributing to the course with their own experience.

The AAVSO Solar Observing Guide will be used as the reference text.


Photoelectric Photometry in the 21st Century

This course will cover the techniques necessary for observers to produce highly accurate variable star observations using single channel photoelectric photometry (PEP).  We will cover the history of PEP technology and its continuing relevance today, as it fills a gap left by CCD and large automated surveys for precision photometry of bright stars.

Equipment and observing techniques will be presented as well as detailed discussions of data reduction and error source identification and correction.  Spreadsheet based tools for extinction, transformation, and data reduction to the standard system will be provided for use in labs using sample observation sets.  Specific techniques applicable to commercially available single channel photometers, such as the Optec SSP-3 and SSP-5 will be covered in detail.

Although this material and the exercises will be based on PEP observations, the underlying theory is applicable to all types of photometric measures, and may prove useful to CCD and DLSR observers who desire a fundamental understanding of photometric measurement.

The course will conclude with a module on designing your own PEP observation program.  Star and observation band selection will be covered, as well as discussions on how to balance the calibration observations needed for high precision with the science observations that are the final results.

The course will use the newly created Photoelectric Photometry Observing Manual as its primary text, but will augment this material with additional readings and tools available on the AAVSO website.

You must successfully complete exercises and weekly quizzes as well as a final examination to pass the course.


Photometry Using VPHOT

This course is designed to teach observers how to conduct photometry using VPHOT, the AAVSO’s cloud-based photometry reduction software. The main objective is to understand “best photometric practices” by independently conducting exercises which utilize VPHOT as the photometry tool. You will learn (1) how to upload and manage your image files, (2) how to create suitable sequences, (3) how to perform differential aperture photometry on single images and time series, (4) how to generate transformation coefficients using TG, (5) how to transform your magnitudes to the standard system, (6) how to save your analyses, and (7) how to submit your results to the AAVSO. You do not have to own a CCD or have your own images since sample images will be provided.

You should complete rigorous daily exercises, and must complete weekly quizzes as well as a final examination to pass the course.

This course is only available to AAVSO members. If you would like to join the AAVSO click here.


Variable Star Classification and Light Curves

This course is an overview of the types of variable stars most often observed by AAVSO observers. We explain the construction of light curves and phase diagrams. We discuss the physical processes behind what makes each type of variable and how this is demonstrated in their light curves. We link these salient features of the light curve to common observing practices for each type. Variable star names and nomenclature are placed in a historical context to aid in understanding today’s classification scheme.

You must successfully complete weekly quizzes and a final examination to pass the course.

Classification variable des étoiles et courbes de lumière

Ce cours constitue une base pour mieux comprendre les étoiles. Il consiste en un aperçu des types d'étoiles variables le plus souvent observées par les observateurs de l'AAVSO. Nous y expliquerons comment obtenir des courbes de lumière et des diagrammes de phases à partir de nos observations. Ceci nous permettra d'en déduire les processus physiques propres aux différents types de variables, leurs particularités, leur activité, leur température de surface effective et bien sûr, comment tout cela peut être démontré grâce aux courbes de lumière. Nous relierons également les caractéristiques de chaque courbe de la lumière aux pratiques d'observation courantes spécifiques à chaque type. La nomenclature des étoiles variables est mise dans un contexte historique afin d'aider à comprendre le schéma actuel de classification.

Nous espérons que vous ne verrez plus les étoiles de la même façon après avoir suivi ce cours.

Vous devez participer aux discussions par écrit et réussir tous les questionnaires hebdomadaires puis l'examen final pour passer le cours.


Visual Observing Basics

This course will use the AAVSO Visual Observing Manual as its primary text. We will cover variable stars, basic equipment, how to make observations and submit data, plotting VSO charts, planning an observing session and many other topics. This course is highly recommended for anyone just starting out in visual VSOing.

The course will last four weeks. There will be an additional two-week period in which to make observations, submit observations, ask questions in the forum and put what you’ve learned into practice. After the six-week period, those who have completed the quizzes, participated in discussions and submitted two positive variable star observations of sufficient quality to the AAVSO International Database will be awarded a certificate of accomplishment along with a badge on your website profile.


How to use VStar

This course is intended to provide participants with a systematic coverage of VStar's current functionality, an appreciation of the ways in which it can be extended, and how it can be used for variable star data visualization and analysis.

You’ll learn how to create mean plots, phase plots, and perform simple period analysis. This is not a course on statistics but relevant statistical concepts as they apply to the use of VStar will be introduced through reading and discussion.

You must successfully complete exercises and weekly quizzes as well as a final examination to pass the course.

VStar is written in the Java programming language, requiring at least version 1.6 to run on Windows, Mac OS X, Linux, and OpenSolaris.


Analyzing Data with VStar

This course is intended for VStar users who have taken and passed the basic CHOICE VStar Course, How to Use VStar. This course assumes that you already know the mechanics of using VStar. The objectives of this course are to provide participants with a better understanding of analysing data with VStar, what you are doing when you use VStar and why it works. That means the course explores basics of underlying theory, limitations of the analysis and valid conclusions one can draw from the results and conclusions that one cannot draw from the results.  The course will also afford ample practice in applying the various analytical tools VStar provides.

This will be achieved by guided reading, exercises (both illustrative and real-world), forum discussions, quizzes, and a final exam or project. The text for the course is Analyzing Light Curves: A Practical Guide, by Grant Foster, which will be applied to the use of VStar. Thanks to the generosity of the author, Grant Foster, the book will be provided in PDF format as part of the course materials for the August 2020 session of the course.

Discussion topics will be created in the course forum for all major course outline sections. Everyone can benefit from questions and comments in such forum topics.

This is not a course on statistics but relevant statistical concepts as they apply to the use of VStar will be introduced through reading and discussion. By necessity this course will use more math than the basic course.