2001gy

This supernova was discovered at the time of countryside SCP 2001 thanks to instrument MOSAICII of the CTIO. It was discovered on April 18, then confirmed on April 20.

Its spectral identification and the measurement of its redshift (0.511) was obtained thanks to instrument FORS1 of the VLT (B.17 figure ).

This supernova was discovered before its maximum of luminosity and gained from 4 points from space follow-up in R and I, as well as three points in R and of a point out of I obtained with the instruments of the WHT B.23 ).

**Appear B.17:** In blue, the spectrum of 2001gy. This spectrum was obtained telescope VLT and instrument FORS1 on April 21. The duration is 2400 seconds. The shift towards the red was obtained while measuring on the lines of the galaxy host. In black, the spectrum of the close supernova 1990N observed 7 days before the maximum. To note, the spectrum of 2001gy was smoothed by using a median filter of 5 Å.

B.22 table: Summary of the observations of 2001gy.

Telescope	Instrument	Go back to observationa	filter	Expositionb	seeingc
CTIO	CtioMosaic2	51997.19	I	6300	0.86
CTIO	CtioMosaic2	51998.18	I	7200	1.02
CTIO	CtioMosaic2	52018.20	I	17100	1.13
CTIO	CtioMosaic2	52020.15	I	7200	1.01
NTT	NttSusi	52026.31	I	1800	0.84
CTIO	CtioMosaic2	52382.16 $\dag$	I	7200	1.08
CTIO	CtioMosaic2	52403.15 $\dag$	I	7200	1.21
CTIO	CtioMosaic2	52405.22 $\dag$	I	4500	0.90
NTT	NttSusi	52026.28	R	2400	0.63
WHT	WhtWfc	52080.00	R	5400	0.71
VLT	VltFors1	52374.00 $\dag$	R	2000	0.42

aDate Julienne $\dag$ Images of reference without the supernova.

**Appear B.18:** Supernova 2001gy in band I observed by the Hubble telescope on the right and the CTIO on the left, the magnitudes of some objects of the field are presented in B.24 table .

B.23 table: Summary of the observations with the space telescope Hubble of 2001gy.

Instrument	Go back to observationa	filtreb	Exposure C
HstWfpc2	52047.33	F814W	2400
HstWfpc2	52053.49	F814W	2400
HstWfpc2	52065.59	F814W	4800
HstACS	52478.67 $\dag$	F814W	2200
HstWfpc2	52047.27	F675W	2300
HstWfpc2	52053.42	F675W	2300
HstWfpc2	52065.46	F675W	4700
HstACS	52765.76 $\dag$	F625W	2100

aDate Julienne $-2\, 400\, 000$ corn name corresponds to the average wavelength of the filter in Nm cen second

B.24 table: Magnitudes of some stars of the field of 2001gy.

Stars	I	R
With	21.81 $\pm$ 0.06	-
B	22.68 $\pm$ 0.09	-
C	21.52 $\pm$ 0.03	-
D	19.50 $\pm$ 0.02	-
E	20.04 $\pm$ 0.03	-
F	20.70 $\pm$ 0.04	-
G	21.75 $\pm$ 0.05	-
H	21.81 $\pm$ 0.05	-
I	21.93 $\pm$ 0.04	-

B.25 table: Curve of light of 2001gy in the band R

Phase $\dag$	R $\ddag$
52047.26(0.01)	23.02(0.02)23.02
52053.42(0.01)	23.38(0.02)23.38
52065.46(0.01)	24.26(0.02)24.26

$\ddag$ standard Magnitude in the filter R

B.26 table: Curve of light of 2001gy in band I

Phase $\dag$	I $\ddag$
52047.33(0.01)	22.64(0.02)c
52053.48(0.01)	22.91(0.02)c
52065.59(0.01)	23.46(0.02)c
52026.30(0.01)	22.61(0.12)b
52020.10(0.01)	23.04(0.04)a
52018.20(0.01)	23.31(0.03)a

$\ddag$ standard Magnitude in filter I aObservations with the CTIO bObservations with the NTT OBSERVATIONS with HST

**Appear B.19:** Curves of light of 2001gy in standard magnitudes in the filters R and I
$\begin{figure}\it\begin{center} \epsfig{file=Images/2001gy_LC_R.eps, width=12cm}... ...sfig{file=Images/2001gy_LC_I.eps, width=12cm}\vskip 2cm \end{center}\end{figure}$

**Appear B.20:** Curves of light of 2001gy in standard fluxes in the filters R and I
$\begin{figure}\it\begin{center} \epsfig{file=Images/2001gy_LC_flux_R.eps, width=... ...file=Images/2001gy_LC_flux_I.eps, width=12cm}\vskip 2cm \end{center}\end{figure}$