OALM Project Details
The efforts to discover NEOs have been concentrated in the Northern Hemisphere where there are already 6 big NEO surveys functioning. We got a grant to install a new observatory fully dedicated to the NEO survey in the countryside of Uruguay (South America). The requested grant will be used to buy a larger and more sensitive CCD.
The search for NEOs has been concentrated up to now in the northern hemisphere. Six dedicated NEO surveys programmes are already in place: 4 located in the South West of USA, one in Hawaii and one in Japan. None of the surveys mentioned above reach most of the southern sky, therefore more than 25% of the celestial sphere is not covered by any project.
Objectives and Methodology
Our main objective is the search for NEOs in the southern sky as well as follow-up observations to determine accurate orbits. With a larger number of known NEOs, we can improve the estimates of the chances that one could collide with the Earth. To search for moving objects we require a dedicated telescope and a CCD camera with a wide field of view. We will start our survey with a telescope in the lower range of the already existing surveys. Software for the automatic control of the telescopes will be installed. The discoveries of asteroids and comets will be communicated to the Minor Planet Centre of the International Astronomical Union and then to the rest of the astronomical community. Follow-up observations of the discovered objects will be done from other telescopes of our own institute as well through collaboration with colleagues of the SouthAmerican Spacegaurd Association, with telescopes in Argentina, Brazil, Paraguay and Uruguay. NASA is already supporting several NEO surveys located in the USA. In mid-1998 it was established the NASA's Near-Earth Object Program Office to help coordinate, and provide a focal point for, the study of those comets and asteroids that can approach the Earth's orbit. This new survey in the southern hemisphere as well as the follow-up capability would contribute to reach as soon as possible the NASA's goal of locating at least 90 percent of the asteroids and comets that approach the Earth and are larger than about 1 kilometre in diameter.
The research team
The institutes involved in the project are: the Dept. Astronomy (Fac. of Sciences) and the Observatorio Astronómico "Los Molinos" - OALM (Minister of Education and Culture). Their main research topic is the study of minor bodies of the Solar System. Some members of our group are members of several IAU Working Group, like the one in on Near-Earth Objects and the one on Comets and Distant; and of Spaceguard Foundation.
The staff of the project has large experience in observational research; they have performed observational runs in several telescopes of medium and large size. Our group has been involved in several search for asteroids and comets using telescope from the European Southern Observatory and the Cerro Tololo Inter American Observatory. The OALM has intense outreach activities for students and amateur astronomers.
The present status
The National Research Council of Uruguay (CONICYT) granted the OALM a small project to install a telescope to search for NEOs. The total amount of the awarded fund is US$27000. The money was used to buy a 46cm (f/2.8) telescope (Centurion 18“ by Astroworks). With further support from our home institutions (Universidad de Uruguay and the Minister of Education and Culture) we buy a PC and software. One of the members of our group (Dr. T. Gallardo) got a grant from the Planetary Society to buy a CCD ST9e that was used for our project. Nevertheless, the ST9 does not fully cover the available focal plane of the Centurion telescope. Detectors as large as 30x30 mm could be installed without considerable image distortion.
The telescope will be located in a dark area of the countryside, 200 km from Montevideo. We have support from the Local Government of the Province of Maldonado for the buildings. The construction will start in April. We have already got some further support from the National Telecommunications Company (ANTEL) and the National Energy Company (UTE) to provide us with telephone connections and alternative energy (solar panels).
In the mean time we have installed the telescope at the actual site of the OALM where we are testing the software, the hardware and starting our survey observations. The telescope and the CCD are controlled with the following software: 1) Astronomers Control Program to control the telescope and the dome, 2) MaxIm DL/CCD to acquire the CCD images and pre-processed them; and 3) Pinpoint to detect the moving objects as well as stars of varying brightness.
The telescope will be fully controlled from our home institute in Montevideo. Every afternoon we will submit the jobs for the night and the controller system will decide whether to open the dome and start the observational routines depending on weather conditions. Four frames of each field will be taken separated by half an hour. The software for detection of moving objects will analyse the images and produce a report. Next morning the report of the discoveries as well as the discovery images will be sent them back to Montevideo. After analysing the information we will submit the discoveries to the MPC.
As mentioned above we actually use a CCD ST9E for the image acquisition. The ST9E has a chip Kodak KAF-0261E thick, front-illuminated of 512x512 pixels of 20x20 micron. Though it is a blue-enhanced chip, the peak QE barely reaches 60% in the visible part of the spectrum. With a focal length of 127cm, the field of view becomes 28'x28" (0.22 square deg.). We plan to take 45 seg. exposures and 4 images per frame. Allowing for time to download the images and move the telescope, in two hours we can cover 30x0.22 = 6.6 sq.deg.. In a typical night of 8 hours, we are able to cover ~26 sq.deg.. The available sky south of -30deg. in declination in any night is ~5000sq.deg.; in a month we will be able to cover a tiny fraction on the order of 300 sq.deg..
The requested grant will be used to acquire a larger and more sensitive CCD. We plan to buy a Finger Lake Instruments IMG camera with a Marconi CCD. The chip is thin an back-illuminated (Marconi 42-40) of 2048x2048 pixels of 13.5x13.5 micron. The peak QE is 80%. The field of view would become 75'x75" (1.57 sq. deg.). i.e. 7 times larger than with the ST9. In a typical night of 8 hours, we would be able to cover ~150 sq.deg., and in a month close to ~1800 sq. deg. This is more than one third of the available sky. Furthermore, we would be able to reach fainter magnitudes due a higher QE. A new CCD could then greatly improve our efficiency and our contribution to achieve the NASA's goal.
The existing ST9 would then be used in the original destination (the 35 cm telescope) with the filter wheel. It will be used for follow-up and light curve observations. It could also be shared, as well as the CCD ST7 that we already have, in the new installed telescope that belongs to the national amateur association (Asociacion de Aficionados de Astronomia del Uruguay). They have built a 38cm telescope that is also located in the OALM. They are willing to use the telescope for follow-up and photometric observations of NEOs.
The OALM has a strong commitment in outreach activities. More than 10.000 persons visit the Observatory every year, most of them are primary and secondary students. Almost hundred people visit us in our monthly open-house. Several amateur groups have their instruments in the Observatory campus. The press frequently requests us information about astronomical events. Since the Centurion survey telescope has the capability to be controlled with the Astronomers Control Program-ACP through the Web, we plan to offer the telescope to the public. The days around full moon are not useful for our survey due to the sky brightness. We plan to let students and amateur groups control the telescope during these days. For this purpose we are translating the ACP web interface into Spanish ... [link to home site of project for more in depth information]