SKYMAP plots with Hale-Bopp

Bjoern Gimle (b_gimle@algonet.se)
Wed, 5 Mar 1997 21:54:21 +0100

Although Hale-Bopp is easy to find, you might want to include it
in SkyMap charts.

One way is to include a pseudo-elset for the comet with your data.

Hale-Bopp pseudo elsets, RMS=3D.0068
1 97000U          97062.00000002  .00000000  00000-0  00000-0 0    14=20
2 97000  45.8766 279.3278 2581797  44.1676   3.7176  0.00305198    12

SkyMap can handle this 330-day period orbit, with SGP or SGP4,
but TrakStar SGP4 cannot:
1997 Mar 03  00:00:00    8=F824'07" N   140=F820'10" E1050302.991   =20
1997 Mar 08  00:00:00    5=F822'20" N   127=F809'47" E 906755.332   =20
1997 Mar 13  00:00:00   24=F849'28" N   177=F812'18" E 964676.917 (50 deg.in=
 5 d.)
1997 Mar 18  00:00:00   18=F831'42" N   145=F804'33" W1113447.727   =20
1997 Mar 23  00:00:00   13=F822'40" N   168=F841'05" W 879925.135   =20

The elset was built by estimating reasonable distances for an Earth orbit
with similar daily motion, converting celestial predictions to Earth
Centered Inertial coordinates and speed vectors with Excel, then
scaling the distances until VEC2TLE produced a reasonable elset.
Then, this was improved with PELCOR. Although far from perfect
(PELCOR often aborts with div-by-0), the errors for Mar-Apr are not
much larger than the diurnal parallax. Intuitively, the argument of
perigee should be closer to 90 degrees ?

Another method is to create a deepsky.txt file with the following lines
(data from Sky&Telescope's web page) (not US/English dates!) :
2000
'Hale-Bopp 27/1-97','Hale-Bopp 27/1-97',19.550,12.33,1
'Hale-Bopp 1/1-97','Hale-Bopp 1/1-97',18.74,4.80,1
'Hale-Bopp 26/2-97','Hale-Bopp 26/2-97',21.105,31.02,1
'Hale-Bopp 3/3-97','Hale-Bopp 3/3-97',21.56,34.80,1
'Hale-Bopp 8/3-97','Hale-Bopp 8/3-97',22.10,38.52,1
'Hale-Bopp 13/3-97','Hale-Bopp 13/3-97',22.72,41.85,1
'Hale-Bopp 18/3-97','Hale-Bopp 18/3-97',23.495,44.38,1
'Hale-Bopp 23/3-97','Hale-Bopp 23/3-97',0.317,45.700,1
'Hale-Bopp 28/3-97','Hale-Bopp 28/3-97',1.155,45.617,1
'Hale-Bopp 2/4-97','Hale-Bopp 2/4-97',1.942,44.167,1
'Hale-Bopp 7/4-97','Hale-Bopp 7/4-97',2.635,41.717,1
'Hale-Bopp 12/4-97','Hale-Bopp 12/4-97',3.220,38.633,1
'Hale-Bopp 17/4-97','Hale-Bopp 17/4-97',3.707,35.267,1
'Hale-Bopp 22/4-97','Hale-Bopp 22/4-97',4.110,31.867,1
'Hale-Bopp 27/4-97','Hale-Bopp 27/4-97',4.448,28.550,1
'Hale-Bopp 2/5-97','Hale-Bopp 2/5-97',4.737,25.383,1

If you run in a directory other than SkyMap's program+data directory,
you can have this as a separate file there. Otherwise, you can append
it to the original file, and use the Deep Sky limit magnitude to
suppress other objects, if you wish.


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