Skip Navigation: Avoid going through Home page links and jump straight to content

New Magnitude Prediction for Comet Hyakutake


New Magnitude Prediction for C/1996 B2 (Hyakutake)

(April 22, 1996)

Things just keep getting worse...

Unfortunately, this comet is not living up to its advanced billing as it approaches perihelion. The power-law exponent, which represents the rate of brightening, has decreased as the comet approached perihelion (May 1). Eleven observations by the undersigned during the last two weeks can be represented by the following formula:

m1 = 4.30 + 5 log (delta) + 5 log r.

This formula is used for the preperihelion predictions given below. However, the comet is likely to fade at a greater rate than n=2 during the post-perihelion phase. Thus, the formula

m1 = 5.90 + 5 log (delta) + 7.5 log r

is assumed below for the post-perihelion predictions.

   UT Date      
  (0 hours)      m1
 1996  4 23     2.0
 1996  4 25     1.9
 1996  4 27     1.7
 1996  4 29     1.5
 1996  5  1     1.5
 1996  5  5     2.0
 1996  5 10     3.1
 1996  5 15     4.1
 1996  5 20     4.7
 1996  5 25     5.2
 1996  5 30     5.7

The predictions given above suggest poor post-perihelion prospects for C/1996 B2 (Hyakutake). It may be magnitude 3 or fainter before it is seen in a dark sky.

Because the comet will be close to the horizon in a dark sky or only visible in twilight (or in daytime around perihelion), the comet will look less impressive than these magnitudes suggest. As always, comet brightness can change unexpectedly.

C/1996 B2 (Hyakutake)

1996 Apr. 21.16 UT: m1=2.0, DC=9, Tail: 20 deg. in PA 38 deg...NE....
Charles Morris (Pine Mountain Club, CA) 
[Coma is nearly star like even in the 26cm reflector.]

1996 Apr. 22.16 UT: m1=2.0, DC=9, Tail: ~10 deg...NE....
Charles Morris (Pine Mountain Club, CA) 
[Moon is affecting tail length.]

C/1995 O1 (Hale-Bopp)
1996 Apr. 21.48 UT: m1=7.5, Dia.=7.5', DC=6...10x50 B....
Charles Morris (Pine Mountain Club, CA) 
[In 25cm reflector (156x), fan of material, about 40 deg. wide in PA, 
centered on PA 0 deg.  At 45x, this plume of material can clearly 
be seen being swept back into a tail.  The tail is 30' in PA 270 deg.]

Hale-Bopp is 100+ times fainter, but more interesting than 96 B2 at this point.

Charles Morris

comethome.gif Comet 1996 B2 Hyakutake Home Page