Fountain Valley, California 12/24/2008 9:31:26 AM
GRAS proudly announces a historical discovery of a supernova SN2008ig by Italian Amateur astronomer Alessandro Dimai
Amateur astronomer makes outstanding discovery from across the globe
Amateur astronomer makes outstanding discovery
In December 2008 a supernova has been discovered, for the first time, from Europe throughout a remote controlled telescope positioned on the other side of the world, in Australia.
The discoverer is Alessandro Dimai, a member of the astronomical association of Cortina d’Ampezzo (Italy) (see web page www.cortinastelle.it ) and of the CROSS (Col drusciè Remote Observatory Supernovae Search) program: on 15 December 2008 he observed, with the 12’’ GRAS15 telescope, a piece of sky in the southern constellation of Centaurus, in which the little galaxy ESO269-020 resides. Dimai suddenly noted, within the spiral arms of such a galaxy, a small star not visible in archive images. The new discovery has been submitted to the CBAT (Central Bureau for Astronomical Telegrams) of Baltimora (USA) which made it official giving the new star the name “SN2008ig”.
The peculiarity is that the telescope which allowed this discovery is not located in Italy, but in a village in the southern part of Australia, more than 15.000 km far from Cortina d’Ampezzo. SN2008ig has been anticipated, some days before, by another CROSS discovery performed using the Australian telescope GRAS15, but this latest supernova, called SN2008ib, is still waiting for spectral analysis to be confirmed.
Col drusciè Remote Observatory Supernovae Search (CROSS) program
Three observatories, fifteen amateurs astronomers, 800 images every night and 27 official supernovae: this is the CROSS program, the major Italian program of searching for extragalactic supernovae. The CROSS was born in November 1999 from wishes and work of a couple of amateur astronomers of Cortina d’Ampezzo, one of the main winter tourist resorts of the Alps and of the world, which hosted Winter Olympic Games in 1956.
Since 1999, more than 120.000 galaxy images have been taken with the automated and remote controlled telescope of Col Drsuciè Observatory (1800m above sea level), allowing the discoveries of 27 official supernovae, 2 novae in the Andromeda Galaxy and a minor planet called Cortina d’Ampezzo.
The main instrument of Col Drusciè Observatory “Helmut Hullrich” is a 20’’ Newton-Cassegrain reflector telescope, used in Newtonian configuration (f/5) for searching for supernovae. A CCD camera Hi-Sis 43 is connected to the Newtonian focus, providing images with limiting magnitude +18.5 taken whit 40 seconds exposure (visual limiting magnitude +6.5).
In a second dome there is an 11’’ Schmit-Cassegrain reflector, totally automated and equipped with a CCD camera SBIG ST8 XME. This telescope is used for outreach purposes, solar and planetary observations and, if required, also for searching for supernovae.
In order to be competitive internationally, it has became fundamental to create collaborations with other groups of amateurs astronomers, with the aim to perform extensive surveys of the galaxies of northern hemisphere. Thus at the beginning of year 2008 the CROSS enlarged, signing up new researchers. Now it can rely upon about fifteen members coming from many Italian cities and three astronomical observatories where take the images.
The CROSS, managed by Alessandro Dimai, Giulia Iafrate and Marco Migliardi (all belonging to the astronomical association of Cortina) has created a catalog with more than 2500 galaxies, selected between the northern hemisphere more massive elliptical and spiral ones. Every clear night the coordinators prepare a list of galaxies and share the list to the observatories assigned to take the images. The next morning these images (two for each galaxy) are distributed to the members of the collaboration in order to be controlled. By the evening the coordinators receive the check results, verify possible doubts, figure out which galaxies need more verification images, update the catalog and prepare a new list for the incoming night.
The convenience of be able to employ the telescope of Col Drusciè from one's home pc provides a non-stop time continuity of the galaxy sampling, shut off only by bad weather conditions. Due to this new technique it is possible to monitor 300 to 400 galaxies every observational session. Adding the images taken by the collaborators at Mandi (Udine, Italy) and Santa Maria a Monte (Pisa, Italy) observatories, the CROSS takes more than 800-900 images (400-450 galaxies) every clear night.
A few CROSS members were not completely satisfied to monitor only the 2500 galaxies in the northern hemisphere, so they had the idea to try to discover supernovae also in the other hemisphere. This choice because of the competition between supernovae searchers is less severe in the austral hemisphere. In spring 2007 Alessandro Dimai and Marco Migliardi started this adventure, renting observational time at the telescope network GRAS (Global Rent a Scope). After the first growing pains, mainly due to the learning of the fairly complex remote control system - always solved online by the GRAS society chief, kind Mr. Arnie Rosner, which is available 24h per day via Skype - the searching went on without problems and in a few months have been performed thousands of observations.
The sample of galaxies of “CROSS South” program comprises about 1000 galaxies with declination between -25° and celestial South Pole, imaged with GRAS15 telescope. Now, after one year and an half of work, at last the first supernovae of the southern hemisphere arrived!
The CROSS program, with its 27 supernovae, puts itself in the framework of the main amateur research programs in the world, and third in Europe, behind the English Tom Boles and Mark Armstrong.
The most prestigious supernovae upon the 27 discovered so far, are SN1999gn, (http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=11555in ) NGC4303, the first official discovery and also the first in the world discovered by an amateur astronomer group using a remote controlled telescope, and SN2006X in NGC4321, that has allowed accurate magnitude measurements of supernovae Ia, contributing to compute distances in the Universe. Both NGC4303 and NGC4321 are Messier objects (M61 e M100); in the sky have been discovered more than 5000 supernovae, upon which only 50 exploded in galaxies belonging to Messier catalog, about 1%! This is an extremely rare event and it is easy to image that, within the history of a research group, to discover a supernova in a Messier galaxy could never happen. Discarding to any statistics, the CROSS has to be accounted as an exception to the rule!
Here is the list of the CROSS discoveries http://www.cortinastelle.it/cross/scoperte.htm
Translation by Giulia Iafrate
Many members of GRAS and the RAS Observatory routinely perform the following research activities: Astrometry, Photometry, CCD Imaging, Remote Astronomy, Robotic Astronomy, Supernova, Variable stars, doubles star research, binary star research, eclipsing variables, comet research, asteroid hunting, Astrophotography, Galaxies, Nebula, Planet, Space, Minor planets, deep space, Gamma Ray Bursters, Astroimaging, astroimager, photography
They use the following equipment to perform their activities: CCD cameras, scientific filters, technical experience, research, telescope mounts, optical systems, Paramount, Takahashi, SBIG, FLI, Astrophysics, CCD camera,
