It may be useful to have a number-color code for comets. It is only a suggestion. If you do
not like it, do not use it. However classifying and labeling objects and events, is part of the
scientific method. There are some precedents with color codes:
1) In the Olympics they use Gold, Silver and Bronce.
2) For asteroids we have the Torino Scale:
3) The military have a DEFense-CONdition code that goes from 5 (lowest, blue) to 1 (highest, White) levels:
4) And the USGS Volcanic Activity Alert-Notification System goes from level green (low) to red (high):
We need something simmilar for comets. For example we could have:
- Grey comet. A comet that will not be brighter than magnitude 15. Thus is remains faint and uneventful.
Examples: C/2013 VB17, C/2013 PJ44, C/2013 CM77.
The American Association of Variable Stars Observers, AAVSO, has defined the “inner sanctum” as magnitudes
below 15th. Very few observers visit the inner sanctum, and we could have something simmilar for comets.
Thus grey comets could be defined as those that stay all the time in the inner sanctum.
- Green comet. A comet that exhibits a green coma. If a comet is producing CN (blue) and
C2 (yellow) in about equal proportions, then the resulting color will be green. A green comet represents a
healthy, robust comet.
Examples: C/2007 N3 Lulin, C/2013 R1 Lovejoy.
- Golden comet. Comparing with the Olympics, a golden comet is one that deserves a gold
medal for its performance. No doubt comets C/1995 O1 Hale-Bopp and C/1996 B2 Hyakutake belong
to this category.
- Yellow comet. Yellow is the color of the Sun, so a yellow comet code might be reserved for Sun
Example: the Kreutz group, C/1965 Ikeya-Seki.
- Observational Priority 2-Orange. An OP 2-Orange comet is one that deserves our attention
for some reason. For example comets that have outburst should be observed more regularly than other
comets. Also comets that have fragmented.
a- Comets that have had outburst: 29P/SW1, 17P7Holmes.
b- Comets that have fragmented: 73P/SW, 101P/Chernykh
c- Comets that have tail disconnection events: C/1908 Humason.
d- Comets for which we are going to cross the orbital Plane and the emitted particle distribution will be
visible: C/1956 Arend-Roland.
e- Comets for which we need to confirm activity at the same place in the orbit: Confirmation of
Photometric Anomaly of comet 67P/Churyumov – Gerasimenko. Or confirmation of reactivation of
Asteroidal Belt Comet 133P/Elst-Pizarro on the same place in the orbit.
- Observational Priority 1-Red. An OP 1-Red comet is a comet that definitely deserves
our attention at every opportunity that is available. This may be due to the fact that the comet
may disintegrate, or because it may pose a threat to our planet. Interestingly comet 1P/Halley
belongs to this category. In 1910 our planet went through the tail of this comet and there were
widespread fears that our atmosphere could be contaminated with the poisonous CN gas that is
present in comets. In that case there was no real danger. However the situation could have been
very different if the comet had been expelling large particles, or if the comet could impact
Earth. Examples: It has been predicted that comet 109P/Swift-Tuttle may impact our planet on
August 14, 2126. Other examples: Comet C/2012 S1 ISON.
a- Comets that are predicted to disintegrate; C/2012 S1 ISON.
b- Comets that may collide with planet Earth; 109P/Swift-Tuttle.
c- Comets for which planet Earth may cross the tail; 1P/Halley.
Anybody can issue an Alert: Observational Priority 1-Red or Observational Priority
2-Orange. In fact if you discover an outburst you should issue an OP-2 Alert.
This classification is not intended for the media or the public. It is intended for the observers.
For example a grey comet is obviously difficult to observe, while a golden comet must be
amazing to see. And OP 1-red comet must be under survey all the time.
The disintegration of C/1997 N1 Tabur was not recorded. That of comet C/2008 J4 McNaught
also went unobserved. The disintegration of C/2009 R1 McNaught was not observed either.
The disintegration of comet C/2012 T5 Bressi took place on February of 2013 in front of our
own eyes, but there are only 5 images by Rob Kaufman of Australia, when there should have
been hundreds. Why? Because no alert was given.
Also consider this: I have 48 visual observations of comet K1 and 3
observations of comet
V5, in spite of the fact that the disintegration probability of the first one is 21% and of the second
93%. The present elongation angle of V5 is 111 degrees, easy to see. Don´t you think that we
need to raise the alert of the observers concerning V5?
I believe one of the reason we are in this forum is because we want to conduct our business
scientifically and professionally. I hope so. And that means issuing alerts when they are
needed, with a number, color or symbol code. You can issue an alert.
A cometary observer would do well in placing OP 1-red comets at the top of his observing
list, then OP 2-orange comets next, and then the rest.
Ignacio Ferrin, Ph. D.,
Group of Computational Physics and Astrophysics, FACOM,
Institute of Physics,
Faculty of Exact and Natural Sciences,
University of Antioquia, Medellin, Colombia
You can reach me at the University of Antioquia, Faculty of Exact
and Natural Sciences, Institute of Physics, Medellin, Colombia 0500-1000.
You can write to me at firstname.lastname@example.org
You can call me at my office 0057-4- 219 5661 from UT 15 h to 22h.