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Date and Time of the Query: 2019-05-26 T17:44:04 PDT
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Notes for object SN 2001du

2 note(s) found in NED.


1. 2003PASP..115....1V
Re:SN 2001du
3.14. SN 2001du in NGC 1365
SN 2001du was visually discovered by Evans (2001), about
90" west and 10" south of the nucleus of the nearby barred
spiral galaxy NGC 1365. The SN was classified as Type II-P by
Wang et al. (2001). We have independently measured the
position from three different SN images available on the
Internet: an image by G. Bock, a deeper image by T. Dobosz,
and an image obtained with the YALO 1 m at CTIO. We derive
three slightly different positions, respectively:
{alpha} = 3h33m29.15, {delta} = -36deg08'32.0;
{alpha} = 3h33m29.14, {delta} = -36deg08'32.0; and
{alpha} = 3h33m29.15, {delta} = -36deg08'31.5.
(Uncertainties in each are ~0.7", ~0.5", and ~0.3",
respectively.) Together, these measurements differ from each
other by ~0.7". The measurements all differ by >~0.5" from
that measured by Jacques (2001). We adopt the position
measured from the YALO image, with the smallest error. This
adopted position is ~0.7" from the position we initially
quoted in Van Dyk et al. (2001); the difference is likely
due to the improved astrometric solution, but is consistent
with the overall uncertainties discussed here. Given the
uncertainty in the measured positions, and the relative
disagreement with previously measured positions, we adopt
a total positional uncertainty of +/-0.8".
The SN site is in 100 s F336W, F555W, and F814W
exposures obtained by GTO-5222 on 1995 January 15.
(Unfortunately, the Cepheid Key Project
[Silbermann et al. 1999] very deep images are of the
opposite arm of NGC 1365.) We could apply the 2MASS
astrometric grid using only three relatively bright stars
on the F555W mosaic. We estimate the uncertainty in this
application, based on one other object on the mosaic, and
find +/-0.4", which leads to a grand total uncertainty
of +/-0.9". Figure 21 shows the SN site on the F555W WF3
chip. Three objects, AC, are detected within the error
circle (a source that looks somewhat extended is toward
the center of the circle, but it is undetected by
HSTphot). Object A, to the south, is blue, with
m_F555W_ = 24.30 +/- 0.21 mag and no detection at F814W;
object B, to the west, is also blue, with
m_F555W_ = 25.02 +/- 0.32 mag and no F814W counterpart;
and object C, to the east, is relatively red, with
V = 24.44 +/- 0.23 and V-I = 1.03 +/- 0.30 mag. (The
F336W exposures are of insufficient S/N to show any
object at the SN site.) Since SN 2001du is of Type II-P,
we assume that of the three detected candidates, this
red eastern star is the most plausible progenitor
(but still unlikely; see below).
The Galactic extinction toward the host is
A_V_ = 0.07 mag, but we possibly can use the color
information from the F555W and F814W images to estimate
the extinction local to the SN, as well as study the
properties of the SN's stellar environment. Figure 22
shows the (V-I, V) color-magnitude diagram for the
environment. The reddish progenitor candidate, star C,
is indicated. It is interesting that no red (M-type)
supergiant stars, the presumed SN II progenitors, with
V-I >~ 1.8 and V >~ 25 mag, are detected in the
environment, likely because of the low S/N of these
images. It is also notable that many of the detected
stars, including star C, have V ~ 24.7 and V-I ~ 1.1 mag.
These presumably K-type supergiants either all have
ages ~12-16 Myr and are in the blue loop core He-burning
phase, or they are intrinsically far bluer and younger
supergiants experiencing similar, larger amounts of
extinction, A_V_ ~ 2.5 mag.

2. 2003PASP..115....1V
Re:SN 2001du
3.14. SN 2001du in NGC 1365
Given the distance modulus {mu} = 31.3 mag to
NGC 1365 determined from HST observations of Cepheids
(Silbermann et al. 1999) and only the Galactic extinction,
if star C is the progenitor it has M_V_^0^ ~ -6.9 and
(V-I)^0^ ~ 1.0 mag. With possibly higher local extinction,
A_V_ ~ 2.5 mag, this becomes M_V_^0^ ~ -9.4 and
(V-I)^0^ ~ 0.0 mag. We consider it more likely that the
relevant archival data were just not sensitive enough to
detect the true progenitor of SN 2001du. Assuming only
Galactic extinction, the progenitor had M_V_^0^ >~ -6.3
and (V-I)^0^ <~ 1.5 mag. Program GO-9041 has imaged
SN 2001du in several bands with WFPC2, and these data
will be public in late November 2002. At that time, or
possibly earlier, we will know the exact location of the
SN and potentially learn more about the nature of the
progenitor.


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