C/1996 B2 (HYAKUTAKE)


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960325.00  E   0.2  SC   -   -   -  -   150'  7   50      230    J Warell
Comments: The tail length had increased dramatically since last night, but coma diameter was 
similar, and total magnitude only 0.2 brighter. Tail straight the first 35 degrees, then making 
an angle of about 10 degrees to the W, i.e. PA 240. The faint end of the tail was at an elevation 
of about 35 degrees, where the sky was lighter than at the zenith due to haze. In 44.5 cm L x63 
the central coma and jets were similar to last night, but the sunward fan was wider, about 120 
deg opening angle. Darker (shadowed?) areas alongside each side of tailward jet, behind the 
sunward fan, most contrasty just opposite. The nucleus and its haze very pale yellowish, as last 
night. In 11x80 B, streamers and light areas in tail visible for at least 10 degrees. Mag 
comparison star Alpha Boo (0.0). Site: Sandvreten Observatory of Uppsala AmatörAstronomer. 
Observers: J. Warell, M. Andersson, L. Hermansson, P. Sundfors.
Teckning av Mauritz Andersson 00.00 SNT den 25 mars. 18 mm Meade SWA, x111, 0.45 m f/4.5, 
synfält 25'.


Image by J. Warell March 24, 22.29-22.39 UT, Celestron Comet Catcher 140 mm Schmidt-Newton f/3.6, 
Fuji Super G ISO 800.
Image by J. Warell March 24, 23.15-23.19 UT, 50 mm f/2.8, Fuji Super G ISO 800.
Image by J. Warell March 24, 23.41-23.52 UT, 135 mm f/2.8, Fuji Super G ISO 800.


Image composite by J. Warell, from images taken March 25, 00.35-00.37 UT, 00.55-00.58 UT, 
01.04-01.07 UT with 50 mm f/2.0, Fuji Super G ISO 800. Image processing has been applied 
to enhance tail.
Svart/vit version


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960325.11  E  -0.2  SC   -   -   -  -  66x54'  8   >48     -    T Karhula
Comments: A truly amazing sight! Brightest object in
the morning sky. False nucleus as bright as Eta UMa (+1.9 mag). A straight
tail reaching Alpha Com seen with naked eye and direct vision (41 deg),
to Epsilon Vir with averted vision (48 deg) and suspected down to Gamma Vir
(62 deg!). At Epsilon Vir it was ~6 deg wide. The tail seemed to twinkle
or fluctuate (seeing effects?). The W border of the tail was sharper than
the E part. In 44 cm L (100x) the false nucleus was yellow and ~10" in size.
A bright, narrow and straight "spike" stretched several deg from it along
with the broader part of the tail. A fan of bright material, "bow shock",
emerged from the sunward side of the false nucleus, reaching a few arc
minutes NE. The comet's motion with respect to background stars was evident
in 10 seconds. The magnitude of the coma was estimated quite easily without
glasses since I'm nearsighted. Magnitude refers to coma only. Slightly
brighter than Arcturus and Vega. The coma was situated a few deg from zenith.
Very transparent weather. NE lim mag = +7.0. Temperature -11 C. A night
worth staying up for! Site: Virsbo, Sweden.


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960325.85  E  -0.4  SC   -   -   -  -  60':  7.5   >34     -    T Karhula
Comments: Observed from Akesta observatory,
outskirts of Vasteras (120k people), first quarter moon, NE lim mag ~+5.0.
Tail reaching Alpha CVn. Coma distinctly bluish and clearly brighter than
Capella. There was a line of 300-500 people + Television team eager to
watch with our 15 cm R.


Image taken by Margareta Westlund March 25, 01.36-01.41 UT, with 52 mm f/1.8, hypered TP 2415.


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960326.80  E  -0.1  SC   -   -   -  -  50':  7.5   >40     -    T Karhula
Comments: Observed from Akesta observatory,
first quarter moon, NE lim mag ~+5.5. The coma had faded somewhat since
yesterday but tail was longer due to clearer sky. The tail pointed almost
exactly away from the Pole star and it appeared like a clock's hour hand
when it rotated during the evening. Again a crowd of ~200 people arrived
to observatory. This was my eighth clear night in a row (most of them
moonless) when I could observe Hyakutake and it must be extraordinarily
fortunate being March!


Image taken by Karl-Gustav Andersson, March 26, 2125-2130 UT, with Celestron C90 
Maksutov-Cassegrain + telecompressor for 500 mm f/5.5, hypered TP 2415. Note a very 
interesting patch of nucleus ejecta material in the tail direction.


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960327.08  E   0.7  SC   -   -   -  -   100'  7   65      210    J Warell
Comments: Tail longer than ever, straight, thin. Its opening angle seemed smaller than 
earlier dates. Color of coma distinctly blue-green visually, as customary. Mag comparison 
stars Alpha Cyg (1.3) and Alpha Lyr (0.0). In several instruments (44.5 cm L, 14 cm 
Schmidt-Newton, 20 cm Schmidt-Cass.) the sunward pointing fan and tailward spike very 
prominent. Site: Sandvreten Observatory of Uppsala AmatörAstronomer.
Image by J. Warell March 27, 02.05-02.35 UT, Celestron Comet Catcher 140 mm Schmidt-Newton f/3.6, 
Fuji Super G Press Prof ISO 800. Site: Sandvreten Observatory.
Image by J. Warell March 27, 02.39-02.43 UT, 50 mm f/2, Fuji Super G Press Prof ISO 800. 
Site: Sandvreten Observatory.


Image by Åke Lysell taken March 27, 00.30 UT, with 28 mm f/2.8, 3 min on Kodak 1000 ISO (colour). 


Date (UT) MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960327.91 -    -   -  25.4  L   5.6  x45,145  -  -  -  -  J. Danielsson
Comments: Two drawings showing structure around CC. Note the bar shaped structure perpendicular 
to the tailward ray. Sunward fan. Nucleus very small, white. Site: Färjestaden.
Teckning, x145
Teckning, x45
Image taken March 27, 21.00 UT, with 35 mm f/2.8 and Fuji Super G Prof 800 ISO.
Negative


Drawing (x145) by J. Danielsson March 31, 22.30 UT, with a 25 cm L f/5.6 under a very hazy sky. 
The nucleus looked stellar, surrounded by a greyish condensation of approx. 1 arcmin size. 
Site: Färjestaden, Öland


Image by J. Danielsson taken April 2, 20.00 UT, with 35 mm f/2.8, 20 sec on Fuji Super G Press 
Prof 800 ISO. Hazy and very bright sky due to moonlight. Site: Eriksöre, Öland.
Delförstoring, 800dpi


Image by J. Danielsson taken April 3, 20.30 UT, with 55 mm f/2.8, 60 sec on Fuji Super G Press 
Prof 800 ISO. Site: Eriksöre, Öland.
Image by J. Danielsson taken April 3, 23.30 UT, with 55 mm f/2.8, 2 min on Fuji Super G Press 
Prof 800 ISO during total lunar eclipse. Site: Eriksöre, Öland.


Date (UT) MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960404.01  S  2.2  SC  -    E   -  -   20'   7.5  14      320    J. Warell
Comments: Straight tail, well condensed coma, more so than previously. In 11x80 B a very small 
nucleus and a bright elongated patch in the tail, 7-10 degrees distant from the coma 
(disconnection event?), thin slender in central part of the near-coma tail. Magnitude ref. stars 
Alpha Per (1.8) and Delta Per (3.0). Altitude 17 degrees above N horizon at 00.10 UT during total 
lunar eclipse. Limiting mag. 6.6. Observers: J.Warell and L. Hermansson. 
Site: Sandvreten Observatory of Uppsala AmatörAstronomer.
Image by J. Warell April 4, 00.03-00.16 UT, Celestron Comet Catcher 140 mm Schmidt-Newton f/3.6, 
Fuji Super G Press Prof ISO 800. Site: Sandvreten Observatory.
Image by J. Warell April 4, 00.33-00.56 UT, 50 mm f/2, Fuji Super G Press Prof ISO 800. 
Site: Sandvreten Observatory.


Image by J. Danielsson taken April 4, 20.00 UT, with 55 mm f/2.8, 1 min on Fuji Super G Press 
Prof 800 ISO (Moonlight interfered). Site: Eriksöre, Öland.


Date (UT) MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960405.84  S  2.2  SC  -    E   -  -   20'   7.5  20      320    J. Warell
Comments: The possible disconnection event from April 4.08 was not visible. Tail straight. 
Mag comparison stars Alpha Per (1.8) and Delta Per (3.0). Lim. mag. 6.5. In 11x80 B the 
coma was bluish, tail very faintly yellow. Site: Ulricehamn.


Image by J. Danielsson taken April 6, 20.00 UT, with 55 mm f/2.8, 5 min on Fuji Super G Press 
Prof 800 ISO. Site: Eriksöre, Öland.
Image by J. Danielsson taken April 6, 20.30 UT, with 135 mm f/3.5, 5 min on Fuji Super G Press 
Prof 800 ISO. Site: Eriksöre, Öland.


Image by K.G. Andersson taken April 6, 20.53-21.05 UT, with 135 mm f/3.5, on hyp TP 2415, D19 8 min.


Image by J. Danielsson taken April 7, 20.30 UT, with 135 mm f/3.5, 5 min on Fuji Super G Press 
Prof 800 ISO (subimage of negative). Site: Eriksöre, Öland.
Image by J. Danielsson taken April 7, 20.30 UT, with 200 mm f/4.5, 10 min on Fuji Super G Press 
Prof 800 ISO (subimage of negative). Site: Eriksöre, Öland.


Image by K.G. Andersson taken April 7, 21.13-21.28 UT, with 135 mm f/3.5, on hyp TP 2415, D19 8 min.


Date (UT) MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960408.95  S  2.5  SC  -    E   -  -   -     -   >10     -       J. Warell
Comments: Streaks of cirrus covered parts of sky, but not at the position of Hyakutake. Hazy sky. 
Comparison stars Alpha Per (1.8), Epsilon Per (2.9) and Beta And (2.9). Site: Ulricehamn.


Image by J. Danielsson taken April 9, 20.30 UT, with 55 mm f/2.8, 5 min on Fuji Super G Press 
Prof 800 ISO. Site: Eriksöre, Öland.
Image by J. Danielsson taken April 9, 21.00 UT, with 200 mm f/4, 10 min on Fuji Super G Press 
Prof 800 ISO. Site: Eriksöre, Öland.


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960410.83  S   2.6  SC   -   E   -  -    7'   8   15      050    T Karhula
Comments: Small coma yet with high surface
brightness in 7x50, a straight tail from S of Beta Per up to near Lambda
Per. The first 10 deg was conspicious. Ref stars Beta Per (not in
eclipse) and Zeta Per. Deep twilight. NE lim mag ~+5.5. Site: Västerås.


Image by K.G. Andersson taken April 13, 21.30-21.40 UT, with 135 mm f/3.5, on hyp TP 2415, 
D19 8 min. 


Image by J. Danielsson taken April 14, 20.00 UT, with 200 mm f/4.5, 3 min on Fuji Super G Press 
Prof 800 ISO. Site: Eriksöre, Öland.
Image by J. Danielsson taken April 14, 20.30 UT, with 135 mm f/3.5, 10 min on Fuji Super G Press 
Prof 800 ISO and Lumicon Deep Sky Filter. Site: Eriksöre, Öland.


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960426.85  S   1.1:  AsA   80   B   4  20   2'   9   0.4      -    T Karhula
Comments: Almost stellar coma, bright background drowned most of the tail which must have been 
much longer, coma fainter than Mercury (+0.8), comet not seen with naked eye (Virsbo, Sweden). 
Ref = ICE:s mag for Mercury (AsA=Astronomical Almanac).