SJAA Ephemeris

Comet Comments Don Machholz

Many new faint comets have been discovered in the past few weeks, nearly all by automated equipment designed to find near-earth asteroids and comets. Meanwhile, Comet Lee swings into our morning sky while Comet LINEAR (1998 T1) and Periodic Comet Tempel 2 pass through opposition.

The LINEAR program in New Mexico has found eight more comets, all faint and some with large perihelion distances. Lowell Observatory's LONEOS program found two, one named for Brian Skiff and one for Bill Ferris. The SOHO satellite discovered three sungrazer comets headed into the sun.

COMET HUNTING NOTES: Steve Lee's comet discovery in April was the third accidental find of the past six Southern Hemisphere visual comet discoveries. That is a high percentage considering that there are only two other accidental finds among the 80 discoveries visually found since 1975. What does this mean? Are comet hunters getting lazy?

If the comets were outside typical comet hunting areas, then comet hunters would tend to miss them. For two of the comets this may be true, as the discovery elongations of all three were 72, 103, and 120 degrees from the sun. And if the comets brighten rapidly before discovery, then the usual comet hunting methods may miss them. A third reason for more accidental finds is an increase of activity among non-comet hunters. With the Internet making it easier to report suspicious objects, and the Wilson award motivating the reporting of new comets, it is likely that accidental comet discoveries by amateurs will continue at a brisk rate in the Southern Hemisphere, which is not covered well by the automated search programs.

Ephemerides

C/1999 H1 (Lee)
Date(00UT) R.A.(2000)  Dec	El    Sky	Mag
06-06	08h29.2m	+08d38'	53d	E	  7.4
06-11	08h24.8m	+12d38'	46d	E	  7.3
06-16	08h20.8m	+16d05'	39d	E	  7.1
06-21	08h16.6m	+19d07'	33d	E	  7.0
06-26	08h12.3m	+21d51'	27d	E	  6.9
07-01	08h07.5m	+24d22'	21d	E	  6.7
07-06	08h02.3m	+26d42'	15d	E	  6.7
07-11	07h56.7m	+28d52'	11d	E	  6.7
07-16	07h50.6m	+30d55'	10d	E	  6.7
07-21	07h44.2m	+32d52'	13d	M	  6.9
07-26	07h37.6m	+34d44'	18d	M	  7.0
07-31	07h30.6m	+36d33'	24d	M	  7.2
08-05	07h23.3m	+38d23'	30d	M	  7.4
08-10	07h15.4m	+40d16'	36d	M	  7.6

C/1998 T1 (LINEAR)
Date(00UT) R.A.(2000)  Dec	El    Sky	Mag
06-06	23h16.9m	-12d09'	90d	M	10.8
06-11	23h05.6m	-15d28'	98d	M	10.4
06-16	22h47.9m	-20d06'	108d	M	10.0
06-21	22h18.7m	-26d42'	121d	M	9.6
06-26	21h27.6m	-35d32'	137d	M	9.2
07-01	19h57.8m	-44d36'	153d	M	9.0
07-06	17h54.3m	-47d47'	152d	E	9.0
07-11	16h12.9m	-43d42'	136d	E	8.3
07-16	15h13.5m	-37d47'	121d	E	8.8
07-21	14h40.0m	-32d51'	109d	E	9.2
07-26	14h20.0m	-29d10'	100d	E	9.7
07-31	14h07.5m	-26d28'	91d	E	10.0
08-05	13h59.4m	-24d28'	84d	E	10.4
08-10	13h54.0m	-22d58'	78d	E	10.7

Periodic Comet Tempel 2 (P/55)
Date(00UT) R.A.(2000)  Dec	El    Sky	Mag
06-06	17h23.8m	-04d40'	161d	M	11.5
06-11	17h20.4m	-05d06'	162d	M	11.3
06-16	17h16.7m	-05d42'	162d	E	11.1
06-21	17h12.8m	-06d29'	160d	E	11.0
06-26	17h09.2m	-07d26'	157d	E	10.9
07-01	17h05.8m	-08d33'	153d	E	10.8
07-06	17h03.1m	-09d50'	150d	E	10.7
07-11	17h01.1m	-11d15'	145d	E	10.6
07-16	17h00.2m	-12d46'	141d	E	10.6
07-21	17h00.3m	-14d22'	137d	E	10.5
07-26	17h01.7m	-16d00'	133d	E	10.5
07-31	17h04.3m	-17d40'	129d	E	10.5
08-05	17h08.3m	-19d20'	125d	E	10.5
08-10	17h13.7m	-20d59'	122d	E	10.5

Elements

Object:	Lee
Peri. Date:	1999 07 11.1657
Peri. Dist (AU):	0.708308 AU
Arg/Peri (2000):	040.6689 deg.
Asc. Node (2000):	162.6375 deg.
Incl (2000):	149.3558 deg.
Eccen:	1.00
Orbital Period:	Long Period
Ref:	MPC 34421
Epoch:	1999 07 11
Absol. Mag/"n":	7.0/4.0

Object: LINEAR (T1)
Peri. Date:	1999 06 25.2578
Peri. Dist (AU):	1.468118 AU
Arg/Peri (2000):	226.3361 deg.
Asc. Node (2000):	153.3540 deg.
Incl (2000):	170.1601 deg.
Eccen:	0.99915
Orbital Period:	71,000 years
Ref:	MPC 33451
Epoch:	1999 01 22
Absol. Mag/"n":	8.8/4.0

Object: P/Tempel 2
Peri. Date:	1999 09 08.41663
Peri. Dist (AU):	1.481683 AU
Arg/Peri (2000):	195.02016 deg.
Asc. Node (2000):	118.21147 deg.
Incl (2000):	011.97662 deg.
Eccen:	0.5228125
Orbital Period:	5.47 years
Ref:	NK640
Epoch:	1999 08 10
Absol. Mag/"n":	9.0/5.0