Multicolor Microvariability Observations of BL Lac Object: 1ES 1959+650
Whitney Wills
Advisor: Michael Carini
Western Kentucky University
Bell Astrophysical Observatory
Manufacturer: Group 128Primary Diameter:0.6mf-ratio: 11Design: True CassegrainStarted building process in 1975
Bell Astrophysical Observatory
• Refurbishment 1999-2000
• Apogee Ap2p CCD camera
• Image scale: 0.59arc/pixel, binned 2x2
Major Projects at Bell
• AGN Monitoring – Dr. Michael Carini
• Transiting Extra Solar Planets – Dr. Charles McGruder
• Monitoring of Wolf-Rayet Stars – Dr. Sergey Marchenko
• HOU – Dr. Barnaby– Jupiter and Saturn Week
2002-2003
Observations
• Student run sessions from WKU’s campus or onsite
• Exposures of 180sec in V and I filters
• Continuous monitoring for approximately 8 hrs
What are Active Galactic Nuclei?
1 Normal Galaxy
Normal Galaxies
Spiral: M31
Elliptical: M87
Irregular: LMC
What are Active Galactic Nuclei?
1 Normal Galaxy
+ 1 Super Massive Black Hole at Center
Super Massive Black Hole
What are Active Galactic Nuclei?
1 Normal Galaxy
+ 1 Super Massive Black Hole at Center
+ 1 Accretion Disk
Accretion Disk
What are Active Galactic Nuclei?
1 Normal Galaxy
+ 1 Super Massive Black Hole at Center
+ 1 Accretion Disk
+ 2 Relativistic Jets of Material
Relativistic Jets
What are Active Galactic Nuclei?
1 Normal Galaxy
+ 1 Super Massive Black Hole at Center
+ 1 Accretion Disk
+ 2 Relativistic Jets of Material
=AGN
Active Galactic Nuclei
What are BL Lacertae Objects?
The most extreme example of an AGN
Highly variable polarization
Featureless optical spectra
Highly variable continuum emission at all wavelengths
LBL vs. HBL
Urry, C.M., Advances in Space Research, Vol. 21, Issue 1-2, p. 89, 1998
Why Study Them?
Featureless continuum means continuum radiation is the only diagnostic
Models of AGNs need data
External Compton scattering model
Radio and optical radiation up-scattered to gamma-ray radiation
Predicts wavelength dependent lag
Short timescales--microvariability
Microvariability
• Variations with timescales of hours
• Provide the tightest constraints on the size of the emission region
Reductions
Image Reduction and Analysis Facility (IRAF)Removed background and thermal noise from the pictures (Bias and Dark levels) and removed non-linearity (flat field) Measured the brightness inside a circular aperture centered on the star
Before Reduction
After Reduction
Finding the Aperture
Used an image examiner tool in IRAF
Found the full width, half max of the point spread function of the object and each of the comparison stars
Took the average of the fwhm and used it as the aperture radius in a parameter in IRAF
Calculating Differential Magnitudes & Errors
Using the Phot tool in IRAF, magnitudes were foundUsing these magnitudes, the difference between the object and comp stars were foundThis new differential magnitude was then plotted against the UT time The standard deviation between each of the images was used for the error
OJ 287
1ES 1959+650
Light Curve – 1 ES1959+650 I Filter
I 1959 fwhm=4.6
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
04:48:00 05:16:48 05:45:36 06:14:24 06:43:12 07:12:00 07:40:48 08:09:36 08:38:24 09:07:12ut time
dif
f m
ag
Light Curve – 1ES 1959+650 V Filter
V 1959 fwhm=4.25
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
04:48:00 05:16:48 05:45:36 06:14:24 06:43:12 07:12:00 07:40:48 08:09:36 08:38:24 09:07:12
ut time
dif
f m
ag
Conclusions
Need more data!
Need to increase the exposure time to 240 seconds
Opportunities
Work with 0.6m telescope that included gathering data and troubleshootingActual experience with software professional astronomers use (IRAF)Experience presenting research at conferences at and away from WKU: Argonne Undergraduate
Symposium (2002 & 2003)
Women in Astronomy II Conference
2003 Summer AAS Meeting
Sigma Xi – Honorable Mention
Posters at the Capital (2002 & 2003)
WKU Student Colloquia Invited Speaker at
NSSTC
Acknowledgements
Telescope Operators: Dr. Michael Carini Dr. David Barnaby Whitney Wills
Data Analysts: Dr. Michael Carini Whitney Wills
This project has been supported by NASA, the Kentucky Space Grant Consortium and the Applied Research and Technology Program at WKU
Questions?
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