AAVSO Observing Programs

Although the procedures followed by the observers in the AAVSO observing programs are standardized, each observer chooses his or her own areas of interest and targets. Approximately 650 observers from about 40 countries participate in our observing programs each year. These observers from around the world come from all walks of life, range in age from 10 to 90, cover the spectrum of experience from novice to expert, and use equipment ranging from the unaided eye to binoculars to telescopes of all sizes, some with photoelectric or charge-coupled devices (CCD) or driven by computer. Observers may participate in one observing program, or be active in several of them. An observer may make 1 observation or 10,000 or more in a year, and may concentrate on one type of variable, many types of variables, the Sun, and/or searching for novae or supernovae.

Each observerÆs contribution, whether large or small in quantity, is very valuable and is highly appreciated. In the AAVSO the quality of the observations is most important, not the quantity.

Visual Observing Program
Visual observations of variable stars make up the largest component of the AAVSO International Database. There are approximately 4,000 variables in the AAVSO visual observing program. These stars are primarily large-amplitude (visual range greater than one magnitude). The types of variables include pulsating (Mira, semiregular, RV Tauri, R Coronae Borealis, Cepheid, symbiotic), eruptive or cataclysmic (dwarf nova, nova, recurrent nova, novalike, supernova), nebular (T Tauri, flare), irregular, and suspected variables. With a few exceptions like eclipsing cataclysmic variables, they do not include eclipsing binaries or RR Lyrae stars; these stars require special observational procedures and are covered under separate observing programs.

The visual observing program also receives some observations of program stars made using techniques other than visual. Observations used with a charge-coupled device (CCD) or photoelectric photometry (PEP) instrumentation complement the visual program very well. These observations have been reduced by an observer to a photoelectric (V), CCD (V), or unfiltered CCD magnitude, are processed and archived with the visual observations, and in the archives are tagged as PEP, CCD, or CCDV.

Photoelectric Photometry (PEP) Program
The purpose of this program is to monitor in the Johnson (V) band small-amplitude variations (range less than one magnitude) in bright, red stars in the visual observing program that also show large-amplitude variations over long periods of time; the photoelectric observations thus complement the visual observations. Some stars have been added to the program at the request of astronomers.

There are currently 60 stars in the program. Types of variables include semiregular, irregular, symbiotic, RV Tauri, and R Coronae Borealis. Special finder charts for each star are available, with the variable, a comparison star, and a check star indicated.

For more information on the PEP program, visit the AAVSO PEP Committee.

Four-Color Charge-Coupled Device (CCD) Program
The purpose of this program is to perform ongoing BVRI CCD photometry on 8 red variables extensively observed with the Hipparcos satellite, originally in order to assist in calibrating the Hipparcos photometry. For each star a finder chart with four-color comparison star magnitudes is provided. These multi wavelength observations are being continued past the end of the Hipparcos mission for two reasons: in time, they will provide a unique and valuable multicolor database on these 8 long period variables, and they enable the evaluation of CCD data submitted by new CCD observers to the AAVSO.

For more information on the CCD observing program, visit the CCD Observing Program or the AAVSOCCD Committee.

CCD (V) Photometry of Faint Cataclysmic and Long Period Variables Program
The purpose of this program is to perform ongoing CCD(V) photometry (Johnson V band) of the faint portion (magnitude 15 or fainter) of cataclysmic or long period variables in the AAVSO visual observing program. The stars in this program are bright enough at maximum for the brighter portion of their light curves to be covered by visual observers, but they are too faint near minimum for visual coverage. There are presently 20 cataclysmic variables and 8 long period variables in the program, reaching magnitude 15 to 20 at minimum. For each star special finder charts are provided.

For more information on the CCD observing program, visit the CCD Committee.

Eclipsing Binary Program
The purpose of this program is to monitor the visual behavior of eclipsing binaries, primarily their eclipses, in order to determine or revise elements (period and epoch) where necessary. There are currently approximately 100 stars in the program. Stars may be added to the program as a result of general interest or at the request of an astronomer. Most of the observations for this program are made visually. However, some are made photoelectrically, and an increasing number are being made using CCD instrumentation.

For more information on the Eclipsing Binary Observing Program, visit the Eclipsing Binary Committee.

RR Lyrae Stars Program
The purpose of this program is to monitor the visual behavior of RR Lyrae stars in order to determine or revise elements where necessary. There are currently 40 stars in the program, many of them of small amplitude. Stars may be added to the program as a result of general interest or at the request of an astronomer. Special finder charts for these stars are available.

For more information on the RR Lyrae Stars observing program, visit the RR Lyrae Committee.

American Relative Sunspot Numbers
The AAVSO Solar Division was established at the request of the US government in 1944, when World War II caused the interruption of the publication of the Zurich Sunspot Number Index. Since 1944, the AAVSO has provided the scientific community with the American Relative Sunspot Number Index. The daily and monthly numbers of this index are calculated from sunspot observations reported monthly by AAVSO solar observers around the world.

Each month the American Relative Sunspot Numbers are published by the AAVSO in its Solar Bulletin, and are disseminated to the National Oceanic and Atmospheric Administration (NOAA) and other institutions and individuals. The reduced data from 1944 to the present are available from the AAVSO in electronic or hardcopy form.

For more information on the Sunspot Observing program, visit the Solar Division.

Sudden Ionospheric Disturbances (SIDs)
Since 1956 (the International Geophysical Year), the AAVSO has had a program for the indirect detection of solar flares through the electronic monitoring of very-low frequency radio stations for sudden signal changes, indicating sudden ionospheric disturbances and so solar flares.

The Solar Division welcomes advanced amateur astronomer participation in the SID program. SID monitoring equipment can be constructed in a few hours by anyone with minimal electronics background. Components are easily sourced and many SID program participants are available to answer construction and operating questions. Only a few SID monitoring stations are presently located outside the United States. Additional European, Asian, and Pacific locations would be particularly welcome.

For more information on the SIDs program, visit the Solar Division.

Nova Search Program
The AAVSO has had a visual Nova Search program since the early 1930s. An observer who is interested in searching for novae is initially assigned specific areas of the sky to observe. Once he/she has searched these regions, he/she can move on to other areas, thus encouraging a thorough coverage of the sky. If a suspect object is found, it is checked against one or more atlases, and if verification by another observer is needed, AAVSO headquarters and/or committee chair are often contacted for assistance. If the object proves to be new, AAVSO headquarters is informed so that the scientific community may be alerted and the nature of the object determined.

For more information on the Nova Search Program, visit theNova Search Committee.

Supernova Search Program
The AAVSO has had a visual Supernova Search program since 1973, when such a program was instituted within the Nova Search Committee. The AAVSO Supernova Search Committee itself was established in 1987.

Taking part in the Supernova Search Program requires a telescope capable of detecting stars as faint as 14th magnitude (at least) on a regular basis. Also needed is a collection of reference charts and photos showing the normal appearance of all the galaxies that the observer is currently monitoring.

The observer, who has memorized the appearance of each galaxy down to a certain magnitude, checks each galaxy as many times a month as possible, recording the date, time, limiting magnitude, and observing conditions. If a suspect object is found, it is checked against the reference photo. If verification by another observer is needed, AAVSO Headquarters and/or the Committee Chair are often contacted for assistance. If the object proves to be new, AAVSO Headquarters is informed so that the scientific community may be alerted and the nature of the object determined.

For more information on the Supernova Search Program, visit the Supernova Committee.

Search for Optical Counterparts of Gamma-Ray Burst Network
The AAVSO GRB Network consists of a worldwide network of observers dedicated to searching for optical counterparts of gamma-ray bursts (GRB's) through a coordinated rapid response network. What does this mean? Basically, they await word that a GRB has been detected (usually by satellite). When that word comes, they head to their telescopes and attempt to image the GRB using CCD cameras. Time is of the essence here and that is where the AAVSO GRB Network comes in.

Through a connection with GCN at NASA's Goddard Space Flight Center, notifications of recent GRB detections by orbiting satellites is distributed to the AAVSO network. Our network takes these notices and distributes them, in turn, to our members based on a set of filters each observer specifies. The distribution method is primarily via e-mail, cell phone, and pager. Depending upon the satellite that detected the GRB, the entire process can take from a few hours to a few seconds.

For more information on the Gamma-Ray Burst Network, visit the GRB Network page.