Planetary Astronomy Lab UROP

Summer 2009

Jessica Perez

Astrometry of GSC 1744:1814

Throughout summer ’09 I headed a project involving astrometry of GSC 1744:1814. The goal of the project was to improve on the star’s catalogue position by finding a more accurate right ascension and declination. Finding these offsets would improve upcoming occultation predictions. Since we already had offsets found using 40” and 42” telescopes, we focused on gathering much more data using the 14” telescope at Wallace.

Using Pier 4 at Wallace Astrophysical Observatory, I took images of the star while making adjustments so that it would remain centered in the frame. The raw data collected at Wallace was then flattened and biased before being run through an astrometry pipeline comprised of three Mathematica notebooks. The pipeline uses a network of stars to find the coordinates of our target. Because the network is only a limited number of stars, centering is crucial so as not to lose too much of the network. The outcome is a new position and offsets from catalogue.

By comparing data gathered on a 40” and on a 42” telescope to the data gathered on our 14”, we found that the plots generally agree with one another. While the data from the 14” was not as good as what was acquired on the larger telescopes, we were able to get much more data on the 14”. Having more data to work with helped lower the margin of error and better find the offsets.

The top graph is a plot of RA offset per frame and the bottom graph is a plot of DEC offset per frame.

Observing run in Chile

For a week in August I had the opportunity to join Susan Benecchi for a 3-day observing run at Las Campanas Observatory in La Serena, Chile. We used the 6.5M Baade telescope with both IMACS and MagIC cameras. While we were hit with rough weather for most of the run, we did manage to perform pinhole tests during the day with IMACS and gather data with MagIC on the last night.

During this trip I leaned how to operate MagIC and got to see how a run is organized. We had six programs that had been given time by MIT and had to schedule each night so that the program would get its allotted time. We ended up unable to stick to schedule due to weather and each night had to reevaluate and prioritize the programs. I also got to learn about LOIS, the system used to manage the instruments at Las Campanas and at Lowell Observatory.

After collecting data, I learned how to analyze each frame to find its limiting magnitudes. By using the smallest magnitude we were able to determine if the object we wanted to observe was possible to see in the frame. While we did not get the time to collect all the data we wanted to, we were still lucky to have a small window of time to observe. I’m glad I got to experience how a large observational facility runs and interact with the telescope operators.

Before starting this UROP I had little knowledge of how to run the telescopes or how to reduce data. I quickly learned how to run the software pertaining to controlling the mounts and operating the cameras. I also learned how to reduce data using IRAF in preparation for analysis. Through my trip to Chile I got to work with other telescopes and systems and familiarize myself with them.