The discovery of SN 1995al in NGC 3021

On the evening of October 31st Piero Mazza and myself, along with other amateurs of the Circolo Astrofili di Milano, headed for Passo San Marco, a mountain pass l00km north of Milan, at an altitude of 1850m a.s.l. These mountains, situated in the province of Bergamo, are the usual observing sites for amateurs in Milan, being easy to reach even in winter.

Although the first quater moon hadn't yet set we began our search in Pegasus, Aries and selected galaxies in Pisces. We observe with 35 to 50cm Dobsonians, depending on nights, usually with the smallest exit pupil allowed by seeing. This means usually from 1.5mm to 2mm.

After the moon had set, we shifted our search in the north west as Ursa Major, Lynx, the Leos were rising. NGC 3021 is part of our usual observing program. It is a spiral galaxy in Leo Minor (type SBe), some 2' wide, and apparent magn. 12.5. It is an easy target even in a 20cm, yet it is compact and must be analysed at high powers.

We found the suspect star with the 35cm, an home-made Dobsonian, with porthole glass mirror "home-ground". The long f/ratio (6.4) allows a very small obstruction, thus stellar images are usually smaller and suffer less from seeing than larger Newtonians.

The star was not seen on our chart. We use Thompson's charts (but they cover only 1/3 of the galaxies in our program, and NGC 3021 is not included) and charts we have drawn from Palomar Sky Survey plates. When we began using our charts, we made sure that no stars were missed due to over-exposure of the galaxy on original plates; they should be "safe" for visual search with our instruments.

We estimated the star brightness (an educated guess having no sequence), its position from the nucleus. and waited an hour to see if it was an asteroid (the galaxy is not far away from the ecliptic). We decided to get back home for further checks (various reference sources).

Confirmation was possible thanks to the help of Mirko Villi, (who e-mailed enquires to various amateurs and astronomers) and Guy Hurst and the TA network. Photographic confirmation came 24 hours later from Mark Amstrong (CCD image) and Christian Pollas, on a plate taken with the OCA Schmidt. The discovery circular was issued about 12 hours later.

Piero and myself are part of a dedicated group of Italian amatuers who regularly hunt for Sne. Since 1991 the group has managed some 100,000 observations of the closest 800 galaxies. Other successful hunters include Mirko Villi and Giancarlo Cortini (2 each, codiscovers in 1991 and 1994) and Alessandro Gabrijelcic (I in 1995).

We would like to thank also Bob Evans: we consider him our "spiritual Maestro" in the art of super-nova hunting.

Clear nights to all,

Piero Mazza and Stefano Pesci (e-mail: peste@micronet.it)