John Ciccarelli (GW Carver HS of Engineering and Science, Philadelphia, PA)Ronald J. Maddalena (NRAO, Green Bank, WV)

During the summer of 2003, John Ciccarelli participated in an observing project that used the Green Bank Telescope to observe the Galactic Center at two radio frequencies: 5 GHz and 10 GHz. The collected data was transformed into Flexible Image Transport System (FITS) format images resulting in high-quality images that clearly show features previously found at other wavelengths.

The scientific research project resulted in a student-led research project that will analyze this region and its specific features to identify the emission mechanism of these radio waves. Students will use a variety of software programs to visualize the data collected including: Psi-Plot, Sky Image Processor, Hands-On Universe and FITSView. Once completed and refined, this project will be made available to other teachers through the NRAO’s web page. Ideally, this data can be compared to public-domain images in other portions of the electromagnetic spectrum to help students understand that this information coupled with other observations can explain how and why it is emitted.

Research Experience

The Galactic Center is a region of frequent study in radio astronomy. The millions of light years of dust and gas between the Galactic Center and ourselves force us to use low frequency telescopes to investigate what optical telescopes cannot see. In recent years, several new features have been more clearly mapped in the Galactic Center. This project attempts to succeed at a similar feat using the Green Bank Telescope at 5 and 10 GHz to map the radio sources Sgr A, the Galactic Center Arc, Sgr B, Sgr C, Sgr D, SNR G359.1-0.5, the Snake, the Mouse, SNR G0.0+0.1, as well as a number of new cometary HII regions, and extended thermal and nonthermal sources. Mapping of this region was done using the “basket-weaving” technique over the course of four consecutive nights. The mapped region spanned 4o x 1o (l x b).

Research Experience for Teachers at NRAO-Green Bank: Comparing the Galactic Center at 5 GHz and 10 GHz

The NRAO is operated for the National Science Foundation (NSF) by Associated Universities, Inc. (AUI), under a cooperative agreement

Classroom Application

The classroom application of this observation project complemented the study of electromagnetic radiation and cosmology in a high school level senior Physics II course. This class of fourteen students had to first become familiar with the scope and limitations of available astronomy and data reduction software before tackling the mass of data collected from the observations.

Following several preliminary exercises that improved their familiarity with the packages, students begin to process the data using the graphical software package Psi-Plot to convert the right ascension and declination coordinates embedded in the data from radians to degrees. Students then learn the meaning and purpose of calibration and antenna temperature and calculate the antenna temperature of each pointing and each polarization.

After these conversions the student is able to create three dimensional plots of the data to better understand that there are regions of higher radiation emission. Often, students see astronomical images and do not understand that shades in an images color palette directly correspond with radiation intensity. This feat is also attainable using certain astronomical imaging software, such as Hands-On Universe.

Using the FITS images created, the students can blink and compare the identified radio sources in the region to better understand whether the radio emission is caused by thermal or synchrotron radiation. Students can then learn how astronomers make inferences about the emission mechanisms inside our own galaxy and how models can be created to explain the occurrences in galaxies that behave similarly to our own.

Ultimately, this project will be revised using student and teacher feedback so that it can be made available for other teachers’ use in the classroom. Some considerations that could hinder its repeatability are access to licensed software, familiarity of data analysis and availability of computers.

RAdeg

Decdeg

Lant

-95.5-95.0-94.5-94.0-93.5-93.0-92.5-92.0

-31.5-31.0-30.5-30.0-29.5-29.0-28.5-28.0-27.5

34

35

36

37

38

39

40

Galactic Center at 10GHz (R)

Right Ascension (o)

Dec (o)

Ant

enna

Tem

prat

ure

(K)

-95.5-95.0-94.5-94.0-93.5-93.0-92.5-92.030.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

110.0