DACS General Meeting
January 2013
Meeting Review:
Astronomy and Computers

By Richard Teasdale

The John J. McCarthy Observatory (JJMO) is an astronomical observatory located on the grounds of the New Milford High School. At the January general meeting, DACS members and visitors were treated to a detailed presentation on the operations of the observatory and the central role of its computers. The presentation was given by Marc Polansky, a volunteer at the observatory, supported by Bob Lambert, JJMO's Director of Volunteers. The evening provided a fascinating portrait of how much serious astronomy can be done by a small observatory run by amateurs and volunteers.

After a brief biographical introduction, Marc gave an overview of the computer equipment in use at JJMO. "Warp" is the image processing computer, which runs various image processing and celestial simulation software, much of it open-source. "Spock" is the machine that controls the telescopes and cameras, and runs software to control and rotate the dome of the observatory. "Data" is the administrative computer. Marc also described the functions of more specialized machines, the data network, the server on which observational data are stored, and the time server, which is critical to the accuracy of many astronomical observations.

Marc described the software used on the Spock telescope-control computer. The Sky 6 is a virtual planetarium program which is used to orient the telescopes to specific points in the sky. DomePro controls the observatory's dome so that the opening is always aligned with the telescopes. CCDSoft operates the cameras and filters, and transfers observational data to the server. Skynix captures video streams from a webcam.

The JJMO uses three telescopes for astronomical observations. There is a Meade 16-inch reflector, a Takahashi 106mm refractor, and a Meade 5-inch refractor. Reflecting telescopes use a concave mirror to focus the light received from the target, while refractors use a lens. The numbers refer to the diameter or aperture of the mirror or lens. The larger the aperture of the telescope, the greater its capacity to collect light and thus the greater its resolution and the further out into space it can potentially "see".

One of the specialized computers used by JJMO is built into the telescope mount. Its main purpose is to continuously re-adjust the orientation of the telescopes so that an object remains steady in the field of view and does not "drift" with the rotation of the earth. The same purpose is served more accurately by another specialized computer, the STV Autoguider, which uses a small CCD camera to monitor particular stars in the field of view and issue commands to the telescope mount to correct for drift. Marc showed us the value of the Autoguider by displaying images of a galaxy taken with and without it turned on, the "with" image being markedly clearer.

The Warp computer runs various software to process images captured by the telescopes. Marc gave us a detailed description of the steps involved in capturing and processing an image - a process that is not as straightforward as one might think.

We saw a number of examples of astronomical images produced at JJMO. In order to illustrate the difference between the Meade 16-inch and Takahashi  telescopes, Marc showed us images of the Triangulum spiral galaxy taken with each. He explained the use of filters and the process called "binning", an image enhancement technique which can produce brighter images.

Marc explained the significance of the different colors seen in images of astronomical objects - basically color correlates with temperature - blue objects are hot and red are (relatively) cool. The temperature of a star indicates much about its age and position in the stellar life-cycle.

To illustrate the results that image processing can produce, Marc gave us a slide show of some of his favorite images produced at JJMO, including the Eastern Veil nebula, the Pelican nebula, the Dumbbell nebula, the Running Man nebula, and the Horsehead nebula.

JJMO is an active player in the observation of asteroids, a.k.a. minor planets, within earth's solar system. Observatories world-wide contribute to an online database of objects (www.minorplanetcenter.net) that are observed to be moving relative to the stars. These objects are then subject to further scrutiny by anyone in order to elucidate their sizes, orbits, and other characteristics. JJMO is a member of the International Astronomical Union (IAU) and has the distinction of having received an observatory code from the IAU. Codes are given only to those observatories which have demonstrated the reliability of their data and there are only about 1,100 such world-wide. JJMO uses software called Astrometrica to analyze images of minor planet objects and to prepare submissions to the Minor Planet Center database. This is an area of research in which JJMO's time server plays a critical role because of the need for accuracy of the time measurements associated with observations.

Another area of research in which JJMO participates is the search for exoplanets, i.e. planets that orbit other stars. There has been tremendous growth in this field in recent years and it now constitutes one of the most exciting areas in all of science. Detection of exoplanets is usually based on the observation of very slight reductions in the amount of light received from a star as a planet passes between it and the earth. The science of detecting these tiny reductions is called photometry.

Marc concluded his excellent presentation with an overview of the JJMO website.

Following the presentation, Bob Lambert gave us a guided tour of the observatory. Members had the opportunity to observe the planet Saturn via the Takahashi telescope. Although "seeing" conditions that night were poor, we easily saw Saturn's rings.

Members who would like more information about JJMO are invited to attend a public open house which is held on the second Saturday evening of each month, at the observatory.