Cool, I had a go at adding Siding Spring, although it didn't coincide entirely with reality, but I thought it was close enough
Code
Comet "Siding Spring/C-2013 A1"
{
ParentBody "Sol"
CometType "P"
AbsMagn 1
SlopeParam 4
Radius 0.350
Mass 1.681392236e-11 // 2.2e14 kg to Earth mass
RotationPeriod 52.8
Orbit
{
Epoch 2456960.5
SemiMajorAxis 1883.920535902058
Eccentricity 1.00043
Inclination 129.0273411347216
AscendingNode 300.9762794485837
ArgOfPericenter 2.440972538934485
MeanAnomaly -0.003186058483647941
}
CometTail
{
MaxLength 0.5
Bright 1.0
GasColor (0.003 0.009 0.015)
DustColor (0.050 0.050 0.050)
}
}