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?