SN 2000dl

Discovery of SN 2000dl in UGC 1191 from Monte Agliale Astronomical Observatory.

New world record of  distance for supernovae discovered by amateurs

M. M. M. Santangelo, Lucca, Italy,  has discovered with the Monte Agliale 0.51-m reflector, in the course of the Monte Agliale Supernovae 
Search (M.A.S.S.), a supernova in UGC 1191 A, near the center of the galaxy cluster Abell 240. This SN was found at R about 18 on five unfiltered frames taken on Sep. 11.05 UT, and confirmed on nine frames taken on Sep. 17.89 UT and Sep. 19.90 UT; the limiting magnitude of these frames is R about 19.5, (with strong moonlight). All frames were master bias+dark subtracted and master flat fielded. Care has been taken of moving slightly the telescope between each frame, in order to avoid that a point in the sky lies always on the same pixel.
The new object is located at: R.A. = 01h 42m 05s.77, Decl. = +07°39'58".2 (equinox 2000.0), which is about 4" west and 5" north of the host galaxy 
nucleus; CCD astrometry has been performed using various USNO A2.0 stars on three different frames. 
Carefull inspections both on the digitized (both MAST-DSS and ESO-DSS on line) and printed (at Arcetri observatory library) copies of the first (both O and E bands) and second, both B,R,I bands (each on two different sets of plates namely number 684 and 756) Palomar Sky Survey images and of the Palomar Quick V survey, as well as a CCD frame taken with a 0.60 m reflector (BT atlas), reveal nothing at the position of this SN. 
Also the GCVS (variable stars), NLTT and LHS (high proper motion stars) catalogs have been consulted, but the new object does not coincides with known sources.
UGC 1191 A = UGC 1191 NED01 is the brighter (and northern) of a pair of interacting galaxies and is also cross-identified as VV176a = MCG +1-5-23 =  PGC 6272; it is classified as an elliptical galaxy (source: N.E.D. and L.E.D.A. extragalactic databases).
Spectra taken on September 21 by P.Berlind with the Whipple observatory 1.5 m reflector show that SN 2000dl is  type Ia SN about 2 or 3 weeks after maximum; from the same spectra was derived a recession velocity of +18260 km/s for the host galaxy. Assuming a value of 59 km/s/Mpc for the Hubble constant, the distance of UGC 1191 (and SN 2000dl) is 1 milliard of light years.
After a carefull search in the CBAT and Asiago supernovae databases, Santangelo has found that SN 2000dl is the most distant SN discovered by an amateur in the world, in all times.
See the references for the formal discovery claim.

References
IAUC 7494, 22 September 2000

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