NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-26 T15:29:27 PDT
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Notes for object SN 1988ac

1 note(s) found in NED.


1. 1998PASP..110..553R
Re:SN 1988ac
5.2.2. SN 1988ac in NGC 3995
As Figure 9 shows, light from a bright star just outside the field of view was
scattered onto the CCD, directly over the location of SN 1988ac. Moreover, NGC
3995 falls near the edge of the chip; a typographical error in the IRAS Bright
Galaxy Catalog (Soifer et al. 1987) lists NGC 3994 in place of the proper
IR-bright galaxy NGC 3995. Throughout the survey, the wrong galaxy was placed at
the center of every image of NGC 3995. However, a majority of images do show
most of the correct galaxy, and the visual search included it. Like SN 1988ab,
this object was not noticed until long after the initial images were taken, and
so there is no spectrum.
The SN appears in four search images, although it is very difficult to separate
from the bright underlying H II region in the last one, and from the scattered
light that appears in all. Each of the images was obtained without a filter, so
a calibrated magnitude cannot be measured. However, treating the unfiltered
detector as roughly equivalent to the V band, one can derive a very approximate
magnitude of about m_V_~16.5 for the initial image on 1988 December 30. Since an
image obtained two weeks earlier shows no sign of the SN, and an image taken two
weeks later shows it to be about 0.3 mag fainter, this value must be near the
peak; given a distance modulus of 33.8 mag to NGC 3995, the peak "V" magnitude
is MV~-17.3, similar to the peak magnitudes for all SNe except Type Ia. Its
location, in the middle of a large H II region, also indicates that it probably
had a massive progenitor. Therefore, we assign a probability of 0.5 that SN
1988ac was of Type Ib/c and a probability of 0.5 that it was of Type II.


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