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Date and Time of the Query: 2019-07-23 T23:55:58 PDT
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Notes for object SN 1991T

2 note(s) found in NED.


1. 1998PASP..110..553R
Re:SN 1991T
5.2.5. SN 1991T in NGC 4527
Four visual observers independently discovered the bright SN1991T (see Fig. 12)
in the Virgo cluster galaxy NGC 4527. Although its spectrum was at first rather
featureless, after several weeks it began to show the characteristics of a Type
Ia event (Filippenko et al. 1992; Phillips et al. 1992). Its light curve was a
bit peculiar as well, having a peak somewhat broader and brighter than usual
(Phillips et al. 1992).
We note that three of the five SNe were noticed, unaided, by one of the
comparators. The other two were discovered (and announced) during the interval
between one observing run and the next, but they were obvious and we would have
noticed them independently (indeed, AVF "rediscovered" SN 1991T while observing
NGC 4527 on 1991 June 12). In no case was a SN missed during the comparison
process and later brought to light; therefore, we believe that the search method
was an effective one. It is possible that one or more SNe occurred in the sample
galaxies and were not detected by anyone, so the set of five SNe provide a lower
limit to the actual number that may have occurred.
Although all five SNe were considerably brighter than the detection limit at the
time of discovery, this is not surprising given the nature of our survey. We
observed nearby galaxies in which most SNe are expected to have peak
brightnesses well above the limiting magnitude. Specifically, an unextinguished
SN in a galaxy at the median distance modulus of our sample would appear 3.1,
1.6, 0.5, 1.2, or 1.7 mag above the limit of our charts, for SNe of Types Ia,
Ib/c, II-L, II-P bright, and II-P faint, respectively. Recall that the images
themselves clearly showed objects nearly 1 mag fainter than our
charts. Moreover, with at least 2 weeks (and more typically 4 or 6 weeks)
between consecutive observations, we were unlikely to find SNe on the rise,
slightly brighter than the detection limit. Finally, the distribution of
detection magnitudes must reflect small-number statistics to some degree.

2. 1997MNRAS.290..663B
Re:SN 1991T
2.2 SN 1991T
The photospheric-phase behaviour of SN 1991T was atypical. At peak it was
exceptionally luminous. It also exhibited strong iron-group lines in its
pre-maximum spectra, plus weaker-than-normal intermediate-mass spectral
features. NIR spectra of SN 1991T and their analysis have been presented in
Meikle et al. (1996) (day ~0), Spyromilio et al. (1994) (day 60) and Spyromilio
et al. (1992) (day 338). The spectra for days 60 and 338 are included in Figs 1
and 2 respectively. An optical spectrum at about the same phase as the day-60
NIR spectrum was obtained in AAT service time, and is shown in Fig. 3. Also
shown is an AAT service spectrum taken on day 403.


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