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Date: Thu, 8 Apr 93 10:41:31 EDT
From: David Kratz <kratz@aquila.larc.nasa.gov>
Hitoshi:
Here is the synopsis of my observations to date of SN1993J. It seems
that my magnitude estimate from 4/4 is significantly brighter than others have
reported. I can not explain this; however, a friend of mine estimated SN1993J
to be about 10.5 that same night (This was relayed to me after I reported my
observations). In any case, I will endeavor to supply unbiased observations
for as long as I can still see SN1993J.
Dave
Date Time (UT) Telescope Eyepiece comparison *'s mag estimate
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4/2 1:00 8"/f3.5 TVP 10.5+paracorr a = d > b > c > SN > e 10.6
4/4 2:00 8"/f3.5 TVP 10.5+paracorr a = d > b > c > e > SN 10.8
4/8 0:45 8"/f3.5 TVP 10.5+paracorr a > e > SN > f > h 11.5
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Additional comments:
The 8"/f3.5 in combination with the 10.5 millimeter TeleVue Plossl & the
paracorr coma corrector yields 79 power.
4/2: SN1993J is fainter than comparison stars (a), (d), (b), (c), and brighter
than comparison star (e).
Strong interference from moonlight (magnitude limit 13.0--13.5).
AAVSO magnitude designation: 1c/SN/1e or 3a/SN/1e <---This means that
the difference in magnitude between comparison star (c) and SN1993J, and
the between SN1993J and comparison star (e) are equal; and that the
difference in magnitude between comparison star (a) and SN1993J is 3
times the difference between SN1993J and comparison star (e).
Observation made from the Yorktown Battlefield, Virginia, U.S.A.
4/4: SN1993J appears to be fainter than comparison star (e) by the same
magnitude that comparison star (g) is fainter than comparison star (f).
Very strong interference from moonlight (mag limit about 13.0).
AAVSO magnitude designation: 4a/1e/SN
Observation made from the Yorktown Battlefield, Virginia, U.S.A.
4/8: SN1993J appears to be brighter than comparison star (f) by half the
magnitude that comparison star (f) is brighter than comparison star (h).
AAVSO magnitude designation: SN/1f/2h
SN1993J also appears to be fainter than comparison star (e) by twice the
magnitude that comparison star (e) is fainter than comparison star (a).
AAVSO magnitude designation: 1a/2e/SN
Both of these comparisons lead to a magnitude estimate of 11.5.
Limiting magnitude 14.0 (magnitude 14.0 foreground star 30" SW of SN1993J
is just visible).
Observation made from the Yorktown Battlefield, Virginia, U.S.A.
Comparison stars:
star mag. position from center of M81 on supernova chart by Thompson & Bryan
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a) 10.3 11.8' West 0.3' South
b) 10.4 3.3' West 7.2' South
c) 10.5 3.7' West 7.2' South
d) 10.3 12.4' East 7.5' South
e) 10.7 4.5' West 9.7' North
f) 11.8 4.2' West 2.0' North
g) 11.9 0.3' East 3.5' South
h) 12.4 5.5' West 2.1' South
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