Photoelectric Photometry (PEP) Committee

Contact AAVSO (aavso@aavso.org) for more information.

Symbiotic System in Southern Crab Nebula (He2-104) In this symbiotic system, a red giant throws off material in a powerful stellar wind, and a white dwarf companion catches some of it. As a result, an accretion disk of material forms around the white dwarf and spirals onto its hot surface. Gas continues to build up on the surface until it sparks an eruption, blowing material into space. The eruptions have formed the shape of this nebula into an hourglass nestled within an hourglass. Image Credit: R. Corradi,Instituto de Astrofisica de Canarias, Spain; M. Livio, STScI, and NASA

What We Are

You have seen all the Messier objects, at least once. Maybe you have found many of the objects on the Herschel or NGC lists. Now, you are looking for a new challenge, but not one that requires driving for hours to find a dark sky site. You live near a large city or other area that precludes the steady seeing required for planetary work, and you are not sure you want to lay out the cost for a premium CCD camera. What can you do?

Consider photoelectric photometry! If you have a good 6 or 8 inch (or larger) telescope with a reasonable drive on an equatorial mount, please read on.

In recent years, advances in electronics and the availability of moderately priced photometers have brought PEP into the repertoire of many amateur astronomers. Used photometers can be found on eBay for about the price of a premium eyepiece. With such an instrument mounted on your telescope, you can obtain scientifically useful astronomical data. PEP measurements can even be done in bright, light-polluted areas and during bright phases of the moon. What you would be doing is photoelectric photometry of variable stars.

The AAVSO has developed a PEP observing program, targeting variable stars of all types that exhibit small amplitude variations, often less than one magnitude. Using your equipment, you can produce data as accurate as those generated in professional observatories. Professional astronomers use data produced by amateurs in papers published in the professional journals. The amateurs who provided the data are often given co-author status in the papers. But most important, you will be contributing new and valuable knowledge to the astronomical community.

Who We Are

The AAVSO PEP program has been operating since 1983 and the data archive contains over 45,000 observations. At any given time, we have 15-20 active observers, and they are scattered world-wide. We have observers in Sweden, Italy, South Africa and Australia. We would like to have more observers in the program, no matter where you are.

Dr. John Percy, University of Toronto, is our professional mentor and edits the PEP Newsletter. He has a long association with variable star research.

The Chairman of the AAVSO's PEP Committee will help you get started. He will advise you in any technical matters concerning photometers, telescopes and observing techniques. Finder charts for all stars in the program are maintained by AAVSO Headquarters and are available on the AAVSO web site. You will submit your observations directly to the AAVSO database using tools that are available on the web site.

More Information

• PEP Committee Chair: Jim Fox (makalii45@q.com)
• Infrared Photoelectric Photometry
• Catalog of Photoelectric Photometry Charts
• PEP Newsletters
• Current PEP Alert and Special Notices:
1. Special Notice #131 -- Long-term photometry of P Cygni
• Graph & Table Of PEP Observations (ca. 2000)
• Archive Of PEP Observations
• History & Operating Highlights of the AAVSO Photoelectric Program

References

• Astronomical Photometry: A Text and Handbook for the Advanced Amateur and Professional Astronomer by Arne A. Henden and Ronald H. Kaitchuck, 1998, Willmann-Bell.
• Astronomical Photoelectric Photometry Manual (Using UBV Photomultiplier Tube Photon Counting) - by Jeff Hopkins at Hopkins Phoenix Observatory Phoenix, Arizona. 31 May 2004