A Small Fixer-Upper: The Gettysburg College Observatory

From Left to Right – Jamir Wesley, Sophia Marrone, Ethan Foote, Professor Milingo

Project Synopsis

Located just past the Painted Turtle Farm, the Gettysburg College observatory has been on our campus since 1967. In the past few years the observatory hasn’t been used much, so our goal this summer is to create a user manual for future research students so they can have a step-by-step guide on how to use the observatory.  In the past, the Gettysburg College Observatory has been used for many research projects including variable star research, binary star research, exoplanet transits, follow-up photometry of supernovae, and asteroid astrometry (carefully measuring the changing positions of asteroids to better understand and predict their orbits).   The Gettysburg College Observatory is a designated Minor Planet Center with the International Astronomical Union.

The Gettysburg College Observatory

Our jobs this summer also include making sure everything at the observatory is functioning well, checking the telescope’s abilities, its limits, and generally just cleaning up to make it a better space to work in.  There are three rooms at the Observatory – the classroom, the dome, and the warm room. The classroom is a large space that holds our smaller telescopes which are used on piers just outside the observatory. We also keep all extra equipment in this space because it is much larger than the dome or warm room. 

Jamir working in the observatory classroom.

The dome is where the telescope is. The telescope is a 16-inch reflecting telescope. Attached to the telescope is a CCD (Charged-Coupled Device) camera.  While we do not have a spectrograph, which would be used to identify energy that is absorbed or emitted from an object as a function of wavelength, we do have a filter wheel which allows us to do photometry. Photometry is the measurement of how much light comes out of an object within a given wavelength band. These filters also allow us to combine different images to make a  colorful picture, also known as astrophotography. 

The last room in the observatory is the warm room. All observatories have a warm room where the computers that control the telescope and the camera are kept at a regulated temperature to prevent damage to the electronics and keep the astronomers comfortable. Typically, observatories are located in dry areas that tend to get cooler at night so these rooms are known as “warm rooms”. Our warm room holds our two computers, the CCD computer that controls the camera and the Telescope control computer that controls the telescope. This room is not only heated in the winter but air-conditioned in the summer, which gave us a nice break from the heat while working. 

Ethan in the warm room

The two pieces of software that we use to observe are MaxIm DL and the ACE controller. MaxIm DL is the software that controls the CCD camera and allows us to collect digital images and different calibration frames with our telescope. The ACE controller software is the system that controls the movement and tracking of the telescope and dome. Our first step in making sure the observatory was in working condition was to check to see if these programs are still functioning and communicating with their respective hardware. In addition, there are many components in the observatory that had to be checked such as the dome. In the dome, there is a box that opens and closes the dome slit and also rotates the dome.  We tested this box when we first got into the observatory and found that it was working properly. The dome slit can also be opened from the telescope control computer through the ACE software which allows the telescope and dome to communicate with each other.  It’s necessary that the dome knows where the telescope is pointing so it can follow while the telescope tracks an astronomical target.  

After checking the dome we checked to see if the telescope control system, camera, and filter wheel were all working properly. As stated previously, the telescope has not been used for a few years so we had to make sure everything was working as expected. During our time we found that one of the photometric filters that we use to take images had become damaged from humidity and age, therefore making it unusable.  We’ve ordered a replacement that will be shipped in August and will be in place shortly after. 

This is an image of the 16” reflecting telescope in its dome

In addition, we must create a proper focus and flat routine to get good quality scientific images. Proper focus is important because it helps to get a clear image when using the telescope for research. It is very challenging to get a perfect image given the humidity in our area and the light pollution coming from town. Finding a flat routine is also very challenging due to the time frame since flats are meant to be done during dusk (shortly after civil twilight when the sun is 6° below the horizon).  Flats are calibration frames that allow us to characterize the response of the pixel array in the camera. You have to take many of these frames in a short period of time in every filter that will be used for the night, so one of our goals includes designing a smart and efficient process for taking flat field images. 

Since the observatory is only made up of sheet metal and plaster and doesn’t get much attention, we have spent much of our time cleaning it up.  We also spent some of our time updating the warm room (which is the main place we work) and taking down old corkboards and replacing them with whiteboards. There are also many creatures that find their way into the observatory so we worked with facilities to combat the flies, wasps, and mice within the observatory (this is common at observatories since they’re in remote locations).  With that overview, we’ll introduce ourselves and go into a bit more detail about our work.  

Who We Are

My name is Jamir Wesley and I am a rising sophomore majoring in Physics and Environmental Science, hopeful of becoming a professional engineer by 2030. I’ve always wanted to be an architect from a child and I think I’ve found my groove here through these programs offered at Gettysburg College! My favorite part about our research so far has been all the stargazing! I’ve lived in Philadelphia for my entire life and have never gotten a clear view of the night sky! I’ve recently seen the big dipper for the first time and cannot get it off my mind! I hope that writing a user manual for the observatory’s telescope will provide me with a background into how large telescopes function. I believe that this research is important because the science behind telescopes and their observations are so important to fields beyond astronomy. 

My name is Sophia Marrone and I am a rising sophomore majoring in Physics and Studio Art. I grew up in West Chester PA and I plan on becoming an architect. I have always been interested in space ever since I was a little girl, especially after I was given a book on astronomy which inspired me to go into Physics. After research this summer I have developed more of an understanding of how to stargaze and utilize telescopes. I find it interesting to look up into the sky and be able to point out the constellations to my friends and family. My favorite part of the research has been learning how to use the different types of technology in the observatory. There are many different computer programs we have to use to work the telescope and the camera that captures images.  I find it fun to work with them. While there are some interesting troubleshooting problems, I like to sit down and find answers! 

Hello! I’m Ethan Foote, a rising sophomore and an aspiring Physics and Math double major. Astronomy is a special topic for me because it never ceases to capture my imagination. So far my favorite part of our project was the moment my brain finally was able to contextualize the sky, where not only could I see the constellations, but I could also understand where they were going to move and why. This came from our usage of different spherical coordinates for astronomical objects that were confusing at first but helped lead to a better understanding, especially in the context of how it changes due to the Earth’s rotation. Now of course operating our large telescope has been quite fun as there’s that feeling of grandeur getting to use something that can absorb information from distant objects in space. I look forward to being able to combine all that I have learned to observe some celestial objects for science!

SIMBAD and Aladin, Focusing the Telescope, and Calibration Images

During our research experience, we’ve learned about many resources that have helped us prepare for observing. The darkest hours that are void of clouds and low in humidity make it great for observing at the Gettysburg College Observatory. While Weather Underground provides us with great forecasts of cloud cover and humidity in our community, Clear Dark Sky gives us forecast information regarding all things useful for astronomical observing like cloud cover, humidity, seeing (related to atmospheric turbulence), and more.  We also used two tools, the SIMBAD astronomical database, and the Aladin sky atlas, to help us while observing.  SIMBAD is an online astronomical database that allows us to look up the coordinates, basic data such as brightnesses in various filters, other physical measurements, and links to published peer-reviewed papers for astronomical objects. Aladin is an interactive sky atlas, powered by SIMBAD and other astronomical databases, which allows us to generate finding charts so we can identify targets while we’re observing.  One vital characteristic of the targets we identify is their brightness, which we have to consider when taking images.  A very bright star, those we may find with the naked eye, may saturate the CCD camera giving us an image that we can’t use for scientific purposes.  One of the projects we all worked on used SIMBAD and Aladin to create a list of stars that could be used to focus the telescope.  So these were stars that had to be bright enough for a short exposure (a few seconds) but dim enough to not saturate the camera. We needed enough stars that we could use throughout the night to check how the focus changed with temperature. Focusing on the telescope is just one part of the observing process, we also worked on obtaining calibration frames – such as bias frames and flat field images – that allow us to remove the instrumental signatures from our scientific target frames (the astronomical objects we’re interested in studying).  

A Day In The Life

A day for us begins with a debriefing in the morning in Master’s Hall. Our discourse often starts with checking in and talking about how things are going, then what work we have to do, and if the weather forecast is favorable for observing. Due to a longstanding pause in research at the Gettysburg College Observatory, our mornings are often filled with ideas on how we may be able to bring new life into the observatory. Although these conversations often include requests for pest control and computing support; we also determine when and how we should prepare for the rest of our day while considering the weather, cloud cover, and humidity. 

The greatest part of our work has been concentrated on creating a welcoming environment in the Gettysburg College Observatory!  Aside from critter removal (which is constant at most observatories, ours is no exception), we’re working to make the Observatory into a friendly space for astronomical research projects with students. Within the past two weeks, we’ve spent time searching through online databases to compile a directory of observable stars present during the summer nights. We’ve captured images of the faintest stars noticed by our eyes at night and have so far examined how changes in humidity and temperature change the telescope’s focus.  This allows us to direct students using our telescope on how to properly focus the camera images throughout the night.  We are also spending some time with the small hand-operated telescopes at the Observatory so we can host open house observing nights and possibly start an astronomy club!

This image shows a search for focus stars using SIMBAD

We think it is fair to say that our research journey this summer has been no simple task. With each day we all have persisted through unique problems and unforeseen challenges and we will continue to do so until the end.  We’re excited for the future of the observatory and the students who will work in this space with the help of our observing manual. A day in the life with our team is full of wonder for what the next day (or night) may bring!

More About Our Focus Routine:

Creating a focus routine for the telescope has been a unique challenge. For us to focus the telescope we need to take a series of images of a star, with a particular magnitude range, with a lack of other bright stars in its proximity, so that the camera can take a clear picture of that isolated star.  From there the camera control software takes a slice of pixels from the image that includes the most illuminated pixel, creating a graph that charts brightness by pixel position. That graph should create a bell curve shape. The computer then finds the width of that curve at half of the max brightness. Full Width at Half Max, or FWHM for short, allows us to quantify the focus. The smaller the FWHM the better the focus, we found that a good focus has a FWHM in the ballpark of 9 to 7 pixels. However, there is no absolute standard for a ‘good’ or ‘bad’ FWHM as the maximum focus will vary depending on temperature, humidity, and the seeing conditions (how much the atmosphere smears out an image while we’re exposing).

MaxIm DL 5 which we use to take images of the sky

In an effort to help future observers know where to start with a good focus position, we are creating a chart of the best FWHM we found at every temperature. We want to have this guide to reduce the time it takes to reach a good focus.  Good observing conditions can be few and far between in the mid-Atlantic, so the time in the observatory needs to be used diligently.   We are creating a simple focus chart that accounts for variations in temperature.  We focus the telescope by moving the secondary mirror of the telescope with a small motor.  The position of this secondary mirror can be read as an encoder position on the motor.  We’ve spent a lot of time during clear nights changing the secondary mirror position, taking an image of the target star, and measuring the FWHM over and over to determine the lowest FWHM.  Our work (and work continued into the colder months) should allow future observers to quickly adjust the focus throughout the night while observing.  We will continue working on this focus routine until we gain a clear understanding of what affects how well-focused our images are.

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