Comet 1996 B2 (Hyakutake)

Photographic observations of Comet 1996 B2 (Hyakutake)

Jure Atanackov - naked eye, 7x50 B, 11.5cm L at 25x,125x

March 18/19 - Jure Atanackov - Magnitude: +2.2; Coma diameter: 15'; Tail Length: 5 degrees
This was my first observation of the comet. I observed in the evening, starting at 23:30 local. I immediately spotted the comet as a featurless nebulous blob in Bootes. 7x50 binoculars revealed a 15' coma with a faint 5 degree tail. The coma diameter and tail length would've been higher had I been able to observe from a dark sky location.

March 19/20 - Jure Atanackov - Magnitude: +1.7; Coma diameter: 30'; Tail Length: 10 degrees
My second observation proved much more successfull. The sky was much more transparent than the previous evening. I started at 22:30 local. The coma was much larger and had a distinct bluish hue. The central condensation was shining at around 3.5 magnitude. The tail was also much longer, at least 10 degrees. The difference was probably made by the much better sky the second night.
When I packed up, I had a final look at the comet and it's surroundings. I was positively awe-struck at the way the comet was easily visible and not only that, it was already a very obvious object among the stars!

March 20/21 - Jure Atanackov - Magnitude: +1.2; Coma diameter: 1 deg; Tail Lenght: 20 degrees
I observed the comet around local midnight, starting at 23:45. A very bright object to the naked eye with a huge 1 degree coma and a 20 degree tail. In binoculars the blue-greenish hue was now very striking. Central condensation now at 3. magnitude. The tail was twice as long as the night before, obviously very rapid development.

March 23/24 - Jure Atanackov - Magnitude: -0.2; Coma diameter: 1.5 deg; Tail Length: 50 degrees
I managed to get a short observation of the comet in the evening hours from my backyard. I immediately spotted the huge head of the comet. The central condensation was shining at around 2. magnitude, eveloped in a soft 1.5 degree greenish glow. The tail could be traced some 50 degrees into Bootes. In 7x50 binoculars streamers flowing from the central condensation tailward were spotted on both sides of the tail. I began to set up the telescope but the sky clouded over again and that was it.
The comet was really big this evening, quite exciting was the fact that the 50 degree tail lenght exceeded that of the famous Comet West of 1976. This was really becoming a Great Comet!!

March 24/25 - Jure Atanackov - Magnitude: -0.5; Coma diameter: 2 deg; Tail Length: 75 deg
This time I persuaded my mom to drive me to a site 30 km away, Radmirje. I set up my gear at around 00:30 and began waiting. After several minutes I glimpsed a portion of the tail through a hole in the clouds, no less than 50 degrees from the head. The sky then cleared. The following observation was crammed into 25 minutes of completely clear sky - first I observed with the naked eye, the coma was a ghostly 2 degree greenish glow with a distinc central condensation. The tail was a sight to behold - it went all the way from the head in Ursa Major to Virgo, a full 75 degrees! A truly awe-inspiring sight. Through 7x50 binoculars the coma was a soft greenish glow with a golden yellow central condensation and tailward spike going some 2 degrees. The coma contained a parabolic hood some 10' sunward of the nuclear condensation. Multiple streamers were visible extending from the head on each side of the tail, some 3 degrees out. Multiple streamers were also visible in the first 10 degrees or so of the tail. A major surprise was a distinct knot, some 20 degrees down the tail.
Through the telescope the nuclear condensation was resolved into a point like source with a 120 degree fountain extending sunward of the nucleus and the tailward spike already seen in the binoculars. After only several minutes of telescopic observations, I obandoned the telescope and resumed naked eye observations, just to take in the proportions of this monolithic comet.

March 28/29 - Jure Atanackov - Magnitude: +1.0; Coma diameter: 1 deg; Tail Length: 25 degrees
I was again in Radmirje this evening. This time my observing friend David Zagorc came along. The sky was extremely transparent, but the Moon at first quarter phase had become a serious hinderance for observing the comet. Nonetheless the comet was a very spectacular sight even with the Moon up. It was located in the northwest above the snow covered mountains. The observing location was also covered in 30 cm of snow, the result of several nights snowing.
With the naked eye the tail was at least 25 degrees long and the head had become much more condensed than the last time I saw it.
I also observed with 7x50 binoculars. The huge coma had shrunk to only half its maximum diameter and gained in surface brightness. The condensation had become somewhat more elongated tailwards. Also the greenish hue was not so readily apparent, probably due to the Moon.
The comet had also faded by a large amount. Perhaps the great difference was caused by the Moon washing out the fainter outer parts of the coma.
At 20:30 local, while watching the comet with naked eye I was surprised by the apperance of a very bright sporadic fireball. It was estimated at -10 magnitude. It covered 120 degrees of the sky in 6 seconds, green in color, fragmenting twice. We also heard a multiple sonic boom 4 minutes after the fireball's apperance.

March 29/30 - Jure Atanackov - Magnitude: +1.3; Coma diameter: 0.8 deg; Tail Lenght: 17 degrees
The weather remained fine and so I observed the comet the next evening as well. This time from my backyard again, right at the end of astronomical twilight, when the comet was highest in the sky. The apperance had not much changed since the previous observation.
The coma had shrunk a bit and gained surface brightness, shining at +1.3 magnitude. The tail was somewhat shorter at 17 degrees, probably a combined effect of the comet receeding from Earth and increasing interference from the Moon. Nonetheless, still a very specatcular comet!

March 30/31 - Jure Atanackov - Magnitude: +1.5; Coma diameter: 40'; Tail Length: 15 degrees
Again I observed from my backyard immediately after twilight's end. The comet was now shining at +1.5 magnitude with a 15 degree tail. Again the coma had become somewhat more condensed. Still a very nice comet to the naked eye.

April 5/6 - Jure Atanackov - Magnitude: +2.1; Coma diameter: 20'; Tail Length: 15 degrees
After almost a week of bad weather the sky cleared again and I could observe the comet. I observed it in early evening hours, it had proceeded further into the western sky (Perseus) since the last time I saw it. I observed with the naked eye and 7x50 B. The coma had shrunk to only 20' but gained in surface brightness tremendously. The large halo was gone, now the coma was parabolic with a uniform brightness gradient towards the nuclear condensation. The head no longer exhibits any green hue, it has become white. The tail is still 15 degrees in length, it is also more narrow and condensed, especially the first 4 or 5 degrees have a rather high surface brightnes with a uniform drop-off towards the end of the tail.
Overall, the comet is still very apparent in the western sky, still spectacular to an astronomer but probably lost some glamour in the eyes of public.

April 6/7 - Jure Atanackov - Magnitude: +2.4; Coma diameter: 17'; Tail Lenght: 16 degrees
Comet quite obviously faded in a single day. Coma diameter slightly smaller. With the naked eye, the tail can be followed for 16 degrees. Comet's head very condensed with the naked eye. In binoculars the tail is still 16 degrees long. The tail section immedtiately behind the head lost some surface brightness.
Also observed the comet with the telescope. A bright central condensation was visible, the sunward fountain less distinct and the tailward spike had disapeared. No streamers visible. Still spectacular in the telescope.

April 7/8 - Jure Atanackov - Magnitude: +2.6; Coma diameter: 15'; Tail Lenght: 20 degrees
Comet further faded. Observed with the naked eye and binoculars. Observations immediately after astronomical twilight. Comet now +2.6 magnitude, but the tail length increased. Tail now faintly visible to 20 degrees.

April 8/9 - Jure Atanackov - Magnitude: +2.8; Coma diameter: 15'; Tail Length: 15 degrees
Comet now almost 3rd magnitude. Tail length decreased to 15 degrees. Observed in early evening with naked eye and binoculars. Despite the fading, the comet is still a splendid sight in binoculars and with naked eye as well.

April 12/13 - Jure Atanackov - Magnitude: +2.6; Coma diameter: 8'; Tail Lenght: 18 degrees
After a long spell of bad weather and fog, the comet was observed again after 4 days. Visibility relatively poor due to high humidity. Observed in early evening with naked eye and binoculars.
The coma has further shrunk, now only 8' in diameter, but very high surface brightness. The tail is longer again at 18 degrees with the naked eye, would've been even longer in better conditions.

April 15/16 - Jure Atanackov - Magnitude: +2.4; Coma diameter: 7'; Tail Lenght: 15 degrees
Comet now getting low in the west. Apparently some brightening in the last week. Coma diameter small, but with very hig surface brightness. Tail now 15 degrees with binoculars. Low clouds forced end to the observation. Valley really stinks.

April 17/18 - Jure Atanackov - Magnitude: +2.5; Coma diameter: 7'; Tail Lenght: 14 degrees
Observed from Radmirje immediately after astronomical twilight. Despite the low elevation, the transparency was good and comet was a splendid sight with the naked eye and the binoculars. Small very condensed coma, with the tail now 14 degrees long. First 5 degrees high surface brightness. First visible at the start of nautical twilight.

April 19/20 - Jure Atanackov - Magnitude: +2.3*; Coma diameter: 5'; Tail Lenght: 12 degrees
Comet seen very low in the west. With binoculars the head was very condensed and small (5'). In binuculars the tail extended 12 degrees. This was the final sighting of the comet.
* - corrected for atmospheric extinction.

Back to
MBK Team homepage