LONG TERM MONITORING OF BL LACERTAE OBJECTS WITH THE BELL OBSERVATORY AT WESTERN KENTUCKY UNIVERSITY

by

Whitney Wills

08 August 2003
Socialization : 10:15 a.m.
Presentation : 10:30 a.m.

Active galactic nuclei (AGN) are some of the most energetic objects in the Universe. They are composed of an ordinary elliptical galaxy with a super massive black hole at the center. A disk of material, called an accretion disk, surrounds the super massive black hole, and jets of material moving at nearly relativistic speeds are emitted perpendicular to the disk. In the BL Lacertae class of AGN jets are pointed almost directly along the line of sight, resulting in large amplitude, erratic brightness variations. Our primary goal is the monitoring of the brightness variations of BL Lac objects and using these variations to investigate the physics at work in these objects. BL Lacs are the most extreme example of an AGN with highly variable continuum emission as one of their defining characteristics. We have undertaken a program to monitor these continuum variations by using the Bell Observatory 0.6m telescope. Undergraduate students run the sessions from WKU's campus via the Internet or on-site. The telescope is equipped with CCD camera, which is used to obtain data that is then transferred to WKU's campus where it is archived and analyzed by undergraduate students.

Biography of the speaker: Whitney Wills is a senior in her final semester at Western Kentucky University as a physics major, math minor and astronomy minor. In high school she worked with the Goldstone Apple Valley Radio Telescope (GAVRT) for two years through her astronomy teacher, Mr. Eric Thomas. For the past three years she has been involved in active galactic nuclei (AGN) research with Dr. Michael Carini at WKU. At Western she observes at the local 24" Bell Telescope and also reduces the data pertaining to the AGN project. She also constructed and maintains an observatory website that the observers use during their sessions. It includes object coordinates, star charts, focus stars, offset stars and images from the telescope for each object. She has also been the Communications and Executive officer of the Hilltopper Astronomy club.




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MULTICOLOR MICROVARIABILITY OF SELECTED BL LACERTAE OBJECTS

by

Lindsay E. Hopper

BL Lacertae objects are the most extreme members of a class of objects known as Active Galactic Nuclei. The defining characteristics of BL Lacertae objects are large amplitude continuum variability at all wavelengths, a featureless optical continuum, and large amplitude, highly variable polarization. Microvariability is defined as variations on the timescale of hours and represents the fastest variations observed in these sources. Through light travel time arguments, these fast variations provide a means to estimate the maximum size of the emission region responsible for the microvariability. Using the 42 inch Hall telescope at Lowell Observatory and the Bell Observatory 0.6 meter telescope at Western Kentucky University, we observed the objects PKS 0716+714, BL Lacertae, OJ 287, and 3C 66A for microvariability. Both 0716+714 and BL Lacertae were observed in the B and I filters, while OJ 287 and 3C 66A were observed in the V and I filters. These observations allow us to set limits to the size of the emission regions responsible for any observed microvariability and determine what, if any, amplitude difference and/or lags exists between the variations at widely separated optical bands.

Biography of the speaker: Lindsay Hopper recently obtained a Bachelor of Science degree from Western Kentucky University with a double major of physics and mathematics. She is currently working as a technician at the Applied Physics Institute of WKU on developing new technology for homeland security. Her past research projects include nondestructive analysis, modeling the stratosphere, and flow instability. She also served for two years as the technical officer of the Hilltopper Astronomy Club.




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