C/1996 B2 (HYAKUTAKE)


Date(UT)   MM Mag Ref Aper Type f  x dia DC taildg tailpa Observer
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960221.17  -   -   -   44.5   L   4.5   111  3x2.5  PA 210 J. Warell & L. Hermansson.
Comments: The comet was sighted at 03.48 UT at 5 degree altitude in 
SSW above a clear but somewhat turbulent horizon at Sandvreten 
Observatory (Uppsala AmatörAstronomer). Magnitude approx. 8.5. The 
coma was moderately condensed with angular size 2.5 arcmin, slightly 
elongated by a short fuzzy tail in PA 210 degrees. No starlike nucleus 
visible (seeing conditions made the complete sample of observed stars 
somewhat smudged at this altitude andmagnification). No qualified 
estimates of magnitude and condensation made due to approaching dawn. 
Site: Sandvreten Observatory of Uppsala AmatörAstronomer. 
Observers: Johan Warell and Lars Hermansson.
Teckning av Johan Warell 05.15 SNT den 21 februari. 18 mm Meade SWA, x111, 0.45-m f/4.5, 
Lumicon Deep Sky filter, synfält 34'.



Date(UT)  MM Mag Ref Aper Type f  x dia DC taildg tailpa Observer
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960301.24    6.5      80   B     20   3' 4   no tail   P.Schlyter
Comments: Site: Nyby, ca 15 km S of Gnesta and 3 km N of Lastringe, 
Sodermanland.  This is ca 70 km SSW of Stockholm, Sweden.


Date(UT)  MM Mag Ref Aper Type f  x dia DC taildg tailpa Observer
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960309.15    S  8.3  S   44.5  L   4.5 63 3' 6  -     -  J. Warell
Comments: Coma round and diffuse, possibly slightly elongated in
PA 200. Mag 9.5 CC, starlike below x200. Total magnitude and
coma diameter significantly reduced due to very light sky and
low altitude (ca 8 degrees), also causing probable
overestimation of DC. Gibbous Moon 10 degrees W. Humid; fog
formed about 10 m above ground at end of observation. 
Fellow observers: Lars Hermansson and Mauritz Andersson. 
Site: Sandvreten Observatory (Uppsala AmatörAstronomer).


Date(UT)  MM Mag Ref Aper Type f  x dia DC Observer
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960314.01    -   -   -   44.5 L  4.5 63  10  6  J.Warell. 
Tails: >0.25 deg PA 130, >0.25 deg  PA 220, >0.3 deg PA 260
Comments: Lumicon Deep-Sky filter used. The comet was ca 7 degrees
above the SE horizon in glow from Arlanda. It was detected
right after rising with 11x80 mm binoculars at about mag. 5.5.
In 44.5 cm L the coma was well condensed, elongated towards W
and edges very slowly diffusing into the sky. The very faint
fan shaped tail between PA 130 and 260 had three lighter rays,
in increasing brightness order: PA 260, 130, 220. The PA 220
ray was most diffuse, the PA 130 most well defined causing the
tail to delineate sharper to the E than to the W. Two
photographs were taken with 140 mm f/3.6 Schmidt-Newton and
Lumicon DSF. Observation made at Sandvreten Observatory of
Uppsala AmatörAstronomer. 
Teckning av Johan Warell 01.15 SNT den 14 mars. 32 mm König, x63, 0.45 m f/4.5, synfält 60'.


Teckning av Johan Warell 02.30 SNT den 18 mars. 32 mm König, x63, 0.45 m f/4.5, synfält 60'.


Date (UT)  MM  Mag Ref Aper Type f  x  dia    DC  taildg  tailpa  Observer
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960319.05  S  2.2!  S   8.0  B   -  20 45-60'  6   5       255    J Danielsson
Comments: Very good and calm weather. Dark sky. Huge, a bit oval coma
with bright, starlike nucleus. Diffuse tail about 1-1.5 degree wide.
The comet was clearly brighter than Beta Libra (2.7 from the SAO-catalogue).
Photografic observation, same date and time as above:
5 min. exp. on 800ASA Fuji Professional colour negative film, 50 mm,
f/2.8 lens, guided exposure.
A long, curved dusttail was recorded. It is 5 degrees at it´s widest 
part and measure 30 degrees as plotted on Sky Atlas 2000.0 (Tirion). It
extends from the coma at PA approx. 255 and then curves in PA 310 on the
middle of the tail. It is suspected that the curved tail is an illusion
created when the comet was recorded as seen in 3D a bit from the side.
5 min exponering med Fuji Super G Press Professional 800 ASA med objektiv 55 mm f/2.8. 
Foto av J. Danielsson 19 mars 0130 SNT.


Date (UT)  MM  Mag Ref Aper Type f  x  dia    DC  taildg  tailpa  Observer
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960319.09  S  2.4!   SC   -    E   -  -   30'   7   2.5   260-280    J. Warell
960319.09  -    -   -   8.0   B   - 11   50'   7   4   260-280    J. Warell
Comments: Clear sky, naked eye limiting mag 5.5. Coma slightly elongated towards PA 270, tail 
wide and straight with many faint narrow streamers visible in 11x80 near the coma. Well condensed 
coma with approx magnitude 9 stellar nucleus in 44.5 cm L, x63,  the nucleus was clearly yellowish 
and surrounded with a fuzzy yellowish-white haze. In the 44.5 cm L the 1 deg FOV was dominated by 
four streamers from the coma reaching more than 0.5 deg from the nucleus. With the naked eye an 
astonishing sight reminiscent of Comet Levy (1990c), but with better tail. Mag. comparison star 
was Beta Lib, mag 2.6. Magnitude corrected for 0.2 mag extinction difference between Hyakutake 
and Beta Lib. Observing site: Sandvreten Observatory of Uppsala AmatörAstronomer.   
Teckning av Johan Warell 00.50 SNT den 19 mars. 9 mm Nagler, x222, inget filter, synfält 25'.


Date(UT)  MM Mag Ref Aper Type f  x dia DC taildg tailpa Observer
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960319.96    3?       60   B     20  20' 5   no tail   P.Schlyter
Comments: Site: Central Stockholm. Light-polluted sky, in addition low transparent stratus clouds, 
thus horrible observing conditions,yet Hyakutake was barely visible to the naked eye!  Of course the
tail was not seen under these conditions.
Note by P. Schlyter regarding his observations: Finally!  All those stratus/stratocumulus 
clouds that had appeared virtually every night disappeared for at least half a night on the 
night of 23-24 March. Earlier I had seen Hyakutake twice, under not-so-good conditions: on 
the early morning of 1 March under a rural sky but only 7 degrees above the horizon in the 
south.  Next time was around local midnight of 19-20 March in central Stockholm. The sky was 
of course severely light-polluted and in addition low stratus/stratocumulus clouds were there 
-- in spite of this Hyakutake was easily seen in binoculars and even barely seen with the naked 
eye. The night of 23-24 March was crystal clear, at least in the beginning.  I observed under a 
dark rural sky.  Hyakutake was seen already around civil twilight.  A few hours later, when the 
sky was dark and Hyakutake was high in the sky, it was impressive: shining as bright as Arcturus 
and having a tail 15 degrees long.  The best instruments were the naked eye and 7x50 binoculars. 
My 20x80 binoculars offered an impressive view of the nucleus but otherwise the magnification 
was just too big.  A star-like but somewhat elongated (in the tail direction) nucleus appeared 
in the center, and the coma was quite condensed and around 1.5 deg in diameter.  The tail 
appeared around 15 deg long, both with the naked eye and in 7x50 binoculars. Clouds appeared 
around 22h local time (21h UT) and disappeared around 23h local time (22h UT).  Around 1h local 
time (24h UT) clouds appeared once more, and this time the sky clouded up for the rest of the night. 
In between the sky was crystal clear.


Image by J. Danielsson taken March 19, 23.00 UT, with 55 mm f/2.8, 3 min on Fuji Super G 
Press Prof 800 ISO. Site: Eriksöre, Öland.
Image by J. Danielsson taken March 19, 23.30 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 March 19, 23.45 UT, with 200 mm f/4.5, 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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960320.92  -    -   -   5.0  B   -  10   >50'  6    ---     ---    A Eklöf
960320.92  E    .3  S     
Comments: Very calm weather. Some haze lit by suburban lighting (mag lim about 4 in that part 
of the sky). Huge coma with a bright, starlike nucleus. Fan shaped structure to the west that 
must have been the beginning of the tail. Due to the bright sky there was no possibility to 
define the outline of the comaor the size of the tail. The comet was slightly brighter than 
Eta Bootis (2.68, but 15 deg higher) The nucleus apperared about an bright as nearby 109 Vir 
(3.7) in 10x50. An intense green aurora bow with a few rays covered the northern sky up to 
about 20 degrees.


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960321.95  E  1.5:  S   -   -   -  -   45-60'  7   10       260    J Danielsson
Comments: Huge, bright coma, long, fan shaped tail formed as broad narrow V. It
was at least 2.5 degrees wide at the faint end. 10 degrees is by the way
a conservative estimate. A small, starlike nucleus, maybe oval, and a wide
well condensed round, grey coma. The nucleus was rather large, say 2.5´
and maybe a bit elongated. 
Very good weather, and the comet was a striking object high on the southeast sky
(the darkest and best sky as seen from Eriksöre south of Färjestaden). It was
also easy to spot on the light polluted skies off Färjestaden. This is the
brightest comet that I've ever observed after Halleys comet from Teneriffe
in April 1986 (mv 2.2) and this is only the beginning. The mag. estimate is
only approximate. I could not defocus the binoculars far enough and had to use
naked eyes. This comet should be seen on even severely light polluted city
skies as a round, diffuse patch with a short tail.
Foto taget 19960321 22.30 UT, 55mm f/2.8, 5 min.exp på 800 ASA Fuji Super G press 
professional negativ färgfilm. Foto: J Danielsson/H Danielsson, Eriksöre.
Negativ delförstoring av föreg. bild, asteroiden Pallas indikerad.


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960322.90  S   1.0 S   8.0   B   4  20  75´   7    10      260   J Danielsson
Comments: Huge, bright coma, long, slender tail formed as a narrow V. 15 degrees 
of tail visible to the naked eye. A rather large nucleus 3´, maybe oval, with a 
starlike glimmering center, a wide well condensed round, white grey coma. Very 
good weather, and the comet was a striking object high on the southeast sky 
(the darkest and best sky as seen from Eriksöre south of Färjestaden).
Foto taget 19960322 22.30 UT, 55mm f/2.8, 12 min.exp på 800 ASA Fuji Super G press 
professional negativ färgfilm. Foto: J Danielsson/H Danielsson, Eriksöre.


Date(UT)  MM Mag Ref Aper Type f  x dia DC taildg tailpa Observer
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960322.91 S 1.3! SC  -    E    -  - 120' 6  20    250  J.Warell
Comments: Very large coma with very faint outer envelope. Well condensed. Tail wide, about 4 
degrees at end point. The brightest part of the tail was straight, rather thin, in the
center of the tail extending 14 degrees. The end part of the tail, seemingly curved slightly 
to the south, expanded to a very wide faint rounded area gradually dimming into the sky.
Comparison stars Eta UMa mag 1.9 and Alpha Leo mag 1.4. In 44.5 cm L f/4.5 at x222 the nucleus 
is very bright surrounded with a yellowish haze, a very long (about 10 arcmin) straight jet
extends towards the tail direction, another fainter jet of 2 arcmin length extends forward and 
diverges from the coma as it curves slightly N. The comet is now an almost unnatural, absurd
sight reminiscent of mideval depictions of bad omen comets. 
Site: Sandvreten Observatory of Uppsala AmatörAstronomer. 


Image taken by Karl-Gustav Andersson, March 22, 2247-2302 UT, with 50 mm f/2.9 and hypered TP 2415.
Negative


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960323.70  E  0.8  S    -   -    -  -   90´    7    20    230   J Danielsson
Comments: Filaments visible in the center of the the plasma tail as observed with
7x35 mm binoculars. The comet was observed on a very dark, country side sky.


Image taken by Roland and Jan Olsson, March 23, 2145 UT, with 85 mm f/1.4, 30 second exp. 
on T-Max 3200 pushed to ISO 6400.
Negative


Date (UT)  MM  Mag Ref Aper Type f  x   dia   DC  taildg  tailpa  Observer
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960323.91  E   0.4  SC   -   -   -  -   150'  7   25       250    J Warell
Comments: Tail straight. A central, well concentrated kernel, was brightest, stretching 15 
degrees from the coma. A fainter envelope of 10-15 degrees opening angle surrounded it and 
gradually disappeared into the sky. In 44.5 cm L x167 the nucleus was less yellowish than 
at the previous observation. A tailward very thin bright jet reached about 10 arcmin from 
the nucleus, to the frontal direction a fainter fan shaped jet with opening angle about 30 
deg, sharpest at the nucleus, was prominent. The coma was blue-green in 11x80 B, thin 
streamers visible to at least 5 degrees from the coma. Mag comparison stars Alpha Boo (0.0) 
and Alpha Leo (1.4). Site: Sandvreten Observatory of Uppsala AmatörAstronomer. 
Observers: J. Warell, M. Andersson, L. Hermansson, P. Sundfors.
Teckning av Johan Warell 22.30 SNT den 23 mars. 9 mm Nagler, x222, 0.45 m f/4.5, synfält 25'.
Image by J. Warell March 23, 22.36-22.41 UT, 135 mm f/4, Fuji Super G ISO 800.
Image by J. Warell March 23, 22.46-22.56 UT, 135 mm f/4, Fuji Super G ISO 800.
Image composite by J. Warell taken March 23, 22.10-22.14 UT and 22.21-22.25 UT with 50 mm f/2.8, 
Fuji Super G ISO 800. Image processing was employed to enhance tail detail, notably the 
disconnection event.


Image taken by Karl-Gustav Andersson, March 23, 2250-2300 UT, with 50 mm f/2.9 and hypered TP 2415.
Negative


Date(UT)  MM Mag Ref Aper Type f  x dia DC taildg tailpa Observer 
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19960323.96  0.1  SC  -  E  -  -  80  8  >34  -  T. Karhula
Comments: Site: Virsbo, Sweden.


Date(UT)  MM Mag Ref Aper Type f  x dia DC taildg tailpa Observer 
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960324.04    0.0      -    E   -  -  90' 6  15    220  P.Schlyter
Comments: Site: Nyby, ca 15 km S of Gnesta and 3 km N of Lastringe,
Sodermanland.  This is ca 70 km SSW of Stockholm, Sweden.
Hyakutake appeared as bright as Arcturus.