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>  comets or asteroids ?  <
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- Index:
- Comet C/2013 US10 Catalina did not disintegrate. Why?
Comet C/2014 AA52 has the longest standstill ever
The Secular Light Curve of C/2013 A1 Siding Spring
Comet C/2014 Q1 may have left the standstill
- Call to observers: Strive to the limit
- A definition of "Secular Light Curve"
- Secular Light Curves of Comets On Line

- Will Comet C/2013 UQ4 Catalina Disintegrate?
- Updated SLC of Comet C/2013 V5 Oukaimeden
- Final Visual Secular Light Curve of Comet ISON
- Updated SLC of Comet C/2012 K1 + Observers Tally

- Comet 67P/Churyumov-Gerasimenko, Photometric Anomaly
- Comet C/2012 K1 Panstarrs, Disintegration
- Comet C/2012 V5 Oukaimeden, Disintegration
Medellin Scale: A Number-Color Code for Comets
- ISON's file
- Temperature of a Comet
- Did comet Kohoutek "fizzled"?
- Scientist's 10 Commandments
- Quotations
- Atlas of Secular Light Curves of Comets, V.2009
- A New Physics Paradox: The Seeing Paradox
- Observational Priority List

- Other Important Documents:
- 140511 Quantized Beyer's Method to Measure Magnitudes

140511 Infinite Aperture Magnitudes

- 140309 Link to Arxiv.org manuscript
- 140307 Three Predictions


1. A Prediction on Comet 67P/Churyumov-Gerasimenko

Resume.  We present evidence to conclude that the Secular Light Curve (SLC) of this comet exhibits a photometric anomaly in magnitude that is present in 1982, 1996, 2002 and 2009.  We interprete this anomaly as a topographic feature on the surface of the nucleus.  Thus we predict that the images that will be taken from spacecraft Rosetta on August of this year, will show a region morphologically different from the rest of the nucleus, at one of the poles of the comet.

- The Secular Light Curve of comets 1P/Halley and
    67P/Churyumov - Gerasimenko

          For some years I have been developing the concept of Secular Light Curves (see references 1-11),  a scientific way to show the brightness history of a comet.   The light curves are presented  in two depictions: the reduced magnitude vs log of the Sun’s distance, R, and the reduced magnitude vs time.  Reduced means that the comet-Earth distance has been removed and only the dependence on the distance to the Sun (R) remains.  As  an example in Figure 1 we show the SLC of the famous comet 1P/Halley.


Figure 1.  The Secular Light Curve of comet 1P/Halley, log plot.  The vertical axis is the reduced magnitude.  The horizontal axis is the log of the solar distance.  The central vertical line marks the perihelion of the comet. 
Time runs from left to right but not linearly.(Reference 7).

                Time goes from left to right but not linearly.  The line at the bottom in the form of a pyramid is the bare inactive nucleus.

                We have drawn the red lines above the data and not through the data.  Why?                

          Because there are many physical effects that affect cometary observations like twilight, moon light, haze, cirrus clouds, dirty optics, lack of dark adaptation, excess magnification, and in the case of CCDs, sky background too bright, insufficient time exposure, insufficient CCD aperture error, and too large a scale.  All these effects diminish the captured photons coming from the comet, and the observer makes an error downward, toward fainter magnitudes.  There are no corresponding physical effects that could increase the perceived brightness of a comet.  Thus the envelope is the correct interpretation of the data.   

            The envelope represents an ideal observer, with an ideal telescope and detector, in an ideal atmosphere.  

    We learn a lot from this plot.  For example, the plot is descrived by about ~30 parameters, of which about  20 are new and measured from the plots.   Also we learn that comets turn on and turn off.   In this case the comet turned on at R= -17.3 AU and turned off at R= +33.9 AU from the Sun.   We also learn that some comets exhibit a Slope Discontinuity Event before perihelion, that slows down the brightness rate to a more relaxed pace.    For comet 1P/Halley this took place at R= -1.70 AU.  We also notice that after the Event the comet continued increasing in brightness steadily. 

This is a typical SLC exhibited by many other comets.   And this is a healthy robust comet.   

We had to go into this previous introduction,  to  be  able  to   understand the photometric behavior of comets. Now let us look at the SLC log plot of comet 67P/Churyumov-Gerasimenko.

Secular LIght Curve of comet 67P/Churyumov-Gerasimenko

Figure 2.  The SLC of comet 67P/Churyumov-Gerasimenko.  It exhibits a photometric anomaly pre-perihelion that is present in 1996, 1982, 2002 and 2009.   

            In this plot time flows non-linearly from left to right.   We also learn a lot from this plot.   The comet exhibits a rounded shaped light curve characteristic of water dominated comets.  However a dip shaped feature is seen before perihelion. 

        In Figure 3 we have subtracted the envelope of the comet to show the anomaly more clearly.  

 Photometric Anomaly of Comet 67P/Churyumov-Gerasimenko

Figure 3. The envelope of the light curve has been substrated and now the light curve is flat.  The photometric anomaly is clearly seen and repeats in four apparitions, 1982, 1996, 2002 and 2009.  Thus it must be a real feature. The question is: what does it mean?. 

    In this plot the anomaly is more clearly seen.   We are interpreting the photometric anomaly as a topografic feature on the surface of the nucleus.  For example, consider the case is which the pole of the comet is pointing to the Sun about 56 days before perihelion.   Then the brightness decrease by a factor of 5.3 may imply that there is field of debris, a region of pure dust or an island of only rocks, but in any case this region is depleted in volatiles.

    Spacecraft Rosetta will reach the comet in August of this year, and will take high resoltion images of the surface.  

    Thus we predict that there will be a region at one pole morphologically different from the rest of the nucleus.  

        26 other Secular Light Curves can be found in Reference 7, the “ATLAS OF SECULAR LIGHT CURVES OF COMETS”, Version I.    

2 A Prediction on Comet C/2012 K1 Panstarrs

       Figure 3 already shows something remarkable.  The light curve does not resemble that of the famous comet Halley.   The comet does not look healthy and does not look robust.  It shows a kink, a Slope Discontinuity Event + a photmetric dip.  This SDE took place at - 5.35 AU from the Sun, slightly above the orbit of Jupiter.

This is the same type of signature exhibited by the famous comet C/2012 S1 ISON, a comet that we predicted would disintegrate and in fact disintegrated.  

Thus there are reasons to belive that this comet may also disintegrate as comet ISON did.   However, since the perihelion distance of this comet is q = 1.05 AU, the comet does not reach to the critical distance R(critical) = - 0.62 AU at which many comets have disintegrated in the past.

    Thus we predict that there is a 21% chance that this comet may disintegrate.

The observational circumstances are somewhat complicated.  The comet reaches perihelion on August 27th.  What follows is the Elongation angle Sun-Earth-Comet. 

Date 2014   E (º)   Date 2014   E (º)     Date 2014   E (º)

     March 15   107      June  1     78        August 27   20 Perihelion

     April 1    119      June  15    60        Sep    1    24

     April 15   123      July  1     42        Sep    15   40

     May   1    115      July  15    27        Oct     1   59

     May   15    99      August 1    9.3       Oct    15   78

                         August 10   0.3 *     Nov    1    100

*From August 6th to August 14th, the comet will be within reach of Sun observing spacecrafts like SOHO and STEREO.  


Secular Light Curve of comet C/2013 V5 Oukaimeden

Figure 5.  The SLC of comet C/2013 V5 Oukaimeden exhibits the same Slope Discontinuity Event + dip signature exhibited by the famous comet C/2012 S1 that disintegrated. 

    This comet exhibits a Slope Discontinuity Event + a photmetric dip.  This SDE took place at - 4.03 AU from the Sun, slightly below the orbit of Jupiter.

This is the same type of signature exhibited by the famous comet C/2012 S1 ISON, a comet that we predicted would disintegrate in this same web page and in fact disintegrated.  

Thus there are reasons to belive that this comet may also disintegrate as comet ISON did.   However, the perihelion distance of this comet is q = 0.62 AU < R(critical) = - 0.63 AU, a distance at which many comets have disintegrated in the past

Thus we conclude by predicting that there is a 93% probability that this comet will disintegrate.

Unfortunatelly the observational circumstances of this comet are difficult.   It will remain most of the apparition below elongation angles E < 40º.  Thus verifying that the comet disintegrated will be challenging.  The comet reaches perihelion on September 28th, and it is expected to disintegrate before that date.  What follows is the Elongation angle Sun-Earth-Comet. 



It is the policy of this site to give credit for any contribution used.

     You may use the information given in this page, provided that the source is acknowledged, in accord with good scientific practices. Proper referencing of this work:

Ferrín, I., 2014. "Three Predictions: Comet 67P/Churyumov-Gerasimenko, Comet 

                               C/2012 K1 Panstarrs, Comet C/2013 V5 Oukaimeden",


It is unfortunate that non-scientific, non-ethical behavior can still be found in Astronomy. 





1. Ferrín, I., 2005a.  Variable Aperture Correction Method in 

        Cometary Photometry,  ICQ 27, p. 249-255.

2. Ferrín, I., 2005b.   "Secular Light Curve of Comet 28P/Neujmin 1, 

        and of  Comets Targets of Spacecraft, 1P/Halley, 9P/Tempel 1,

        19P/Borrelly,  21P/Grigg Skejellerup, 26P/Giacobinni-Zinner, 

        67P/Chruyumov-Gersimenko, 81P/Wild 2".  Icarus 178,  493-516.

3. Ferrín, I., 2006. "Secular Light Curve of Comets:   

        133P/Elst-Pizarro".  Icarus, 185, 523-543.

4. Ferrín, I., 2007.  "Secular Light Curve of Comet  9P/Tempel 1".  Icarus, 187, 326-331.

5. Ferrín, I., 2008.  "Secular Light Curve of Comet  2P/Encke, 

        a comet active at  aphelion".  Icarus,  197, 169-182.


6. Ferrín, I., 2009. "Secular Light Curve of Comet  103P/Hatley 2, 

        the next target of the Deep Impact EPOXI Mission". PSS, 58, 1868-1879. 


7. Ferrín, I., 2010.  "Atlas of Secular Light Curves of Comets".   PSS, 58, 365-391. 


8. Ferrín, I., Hamanowa, H., , Hamanowa, H., Hernández, J., 

        Sira, E., Sánchez, A.,  Zhao, H., Miles, R.,  2012. 

        "The 2009 apparition of methuselah comet  107P/Wilson-Harrington:  A case of comet

          rejuvenation?".              PSS, 70, 59-72.


9. Ferrín, I., Zuluaga, J., Cuartas, P., 2013.  "The location of 

        Asteroidal  Belt Comets on a Comets’ evolutionary diagram: 

        The Lazarus Comets".  MNRAS, 434, 1821-1837.


10. Ferrín, I. 2013.  "The secular light curves of comets C/2011 

        L4 and  C/2012 S1 compared to that of comet 1P/Halley".


11. Ferrín, I. "The Location of Oort Cloud Comets C/2011 L4 

        Panstarrs and C/2012 S1 ISON on a Comets' Evolutionary Diagram".  


12. Sekanina, Z. 2002. ICQ, 24, 223-236

13. Minor Planet Center repository for astrometric observations


14.  The spanish group measure magnitudes with several CCD apertures.  


        It is managed by Julio Castellanos, Esteban Reina and Ramon Naves. 



Hi !

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  ferrin@fisica.udea.edu.co
You can call me at my office 0057-4- 219 5661 from UT 15 h to 22 h .

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