SN1989B in M66

ABSTRACT

The file SN1989B.gif is presented to display data associated with monitoring a SN event by amateur SN observers. The data was weaned from the observations of various individuals who were involved in the project of discovering and monitoring SNe (SUNSEARCH [1985-1991]). In the light curve depicting their observations, definite trends are noted, here is a "thumb-nail" analysis of the the magnitude estimations of the bright SN (1989B) in the galaxy NGC 3627 (M66).

When the event was discovered information involving a standardized set of photometrically sequenced comparison stars was sent to each participant, weaned from "The Type II SN 1973-R in NGC 3627", (A&A.,_56_,1977, F. Ciatti and L. Rosino, (1977). There is uncertainty at this time (or in the past) wheather v (visual) to V (V-band) conversions or color corrections were applied by any of the participants. The observations were inserted against the V magnitude templete of (BL)= Leibundgut AJ., 105, Jan., (1991), and CCD photometric data, (Wells et.al, (1994) and a color trend (B-V) histogram of the mean type Ia SN (BL).

DATA

At maximum light the observations are in pretty good agreement with the templete. At later times (~15 days onward) some of the estimates seem to break away from the V-band in the direction of the blue-band (B)(fainter magnitude)(Note: there is a gap in observations to this point in the event [~day 5-17]), while others follow the V-band in good agreement with epoch decay. Notice also the color curve (B-V) breaks away from the V curve at about the 4 day (from maximum) mark and follows its trend of progression throughout the event. It is only conjecture at this time wheather any of the estimates allowed for any color or transformation corrections (the photometrically sequenced comparison stars used in the cited paper had very little color diversity in their values) thus, personal equation (see J. Isles- Webb Society Deep Sky Observers Handbook, Vol. 8 "Variable Stars" (pg. 40)(1990) regarding visual magnitude pitfalls) seems to have had an effect on at least some of estimates, which appear to be a direct result of the color trend of the type Ia event. Perhaps in the future some method to alliviate these scatter points and align these values can be addressed....

(Note: the two solitary points before maximum light represent this authors' pre-discovery magnitude estimate (IAUC# 4735) and R.Evan's discovery estimate).

Steve H. Lucas 8/10/96

References:

1.) B. Liebundgut et.al: A&A,Suppl. Ser_89_, 537-579(1991)

2.) L.Wells et. al: AJ.,_108_,(6) December (1994)

SUPERNOVA OBSERVING FORM


EVENT:    SN 1989B
PARTICIPANT: Sunsearch
DATE: Discovery to 135 days past maximum
LOCATION: Various Locations
TELESCOPE: Various
MAGNIFICATION:
ANGLE OF OBJECT IN DEGREES FROM HORIZON (AIRMASS): Not noted
COMPARISON STARS: Article: The Type II SN 1973-R in NGC 3627 by F.Ciatti,
and L. Rosino

                 V-MAGNITUDE      B-V VALUE     COORDINATES [2000])

STAR A: 14.40           0.61
STAR B: 14.70           0.79
STAR C:         14.86           0.62
STAR D:         15.31           0.68
STAR E: 15.53           0.87
***************************************************************************
*****
MAGNITUDE ESTIMATES 

DATE     MAGNITUDE     COMPARISON     EPOCH OF  CORRECTED MAGNITUDE  
(1989)          (raw)            STAR USED         EVENT?              
(observer)
***************************************************************************
*****

1/28    13.5                                    -12                        
s
1/30    13.0                                    -10                        
e
2/9     12.0                    n/c             0                          
m
2/10    12.3                                    1                          
J
2/10    12.0                                    1                          
m
2/11    12.0(*)                                 2                          
z
2/11    12.1                                    2                          
p
2/12    12.1                                    3                          
p
2/12    12.2(*)                                 3                          
lc
2/19    [12.13 +/-0.05 CCD Mag.]                        10                 
(IAUC # 4742)
2/25    13.3                                    16                         
j
2/27    13.5(*)                                 18                         
lc
2/28    13.8                                    19                         
p
3/1     13.2                                    20                         
w
3/2     13.5                                    21                         
a
3/4     13.8                                    23                         
p
3/6     13.3                                    25                         
c
3/7     13.3                                    26                         
c
3/8     14.1                                    27                         
m
3/8     13.3                                    27                         
r
3/9     13.4                                    28                         
c
3/9     14.1                                    28                         
m
3/10    13.6                                    29                         
j
3/10    14.0                                    29                         
a
3/11    13.6                                    30                         
c
3/11    13.5                                    30                         
r
3/11    13.7                                    30                         
s
3/13    [13.69 CCD Mag.]                                32                 
(IAUC # 4761)
3/14    14.2                                    33                         
p
3/25    [13.99 CCD Mag.]                                44                 
(IAUC # 4780)
3/26    14.0                                    45                         
c
3/26    14.1                                    45                         
w
3/26    14.4                                    45                         
p
3/27    14.1                                    46                         
c
3/28    14.2                                    47                         
c
3/29    14.2                                    48                         
c
3/29    14.4                                    48                         
p
4/1     14.3                                    51                         
c
4/5     15.3                                    55                         
m
4/7     15.2                                    57                         
e
4/8     14.6 (*)                                        58                 
        lc
4/9     14.6                                    59                         
p
4/11    15.4                                    61                         
m
4/22    15.4                                    72                         
e
4/24    15.6                                    74                         
m
5/6     15.6                    E               86                         
e
5/6     15.7                    E               86                         
s
5/8     15.7                                    88                         
m
6/25    16.3(**)                                        135                
        skf
***************************************************************************
*****
LEGEND:

p=Dana Patchick
m=Tom Martinez
j=Gus Johnson
z=Kim Zussman
lc=Lynn Carroll
w=Jenny Worsnopp
a=Jay Albert
c=Dennis Casper
s=Steve Lucas
r=Rich Marcisz
e=Robert Bunge
skf=Brian Skiff
(*)=Photographic aperture photometry
(**) Not included in SN 1989B.gif

By Steve H. Lucas (updated 8/10/96)(Internet: 76620.1721@compuserve.com)