Logo
Home=Current Comets | The German group | Tutorials | Archive: C/2011 F1 | Projects, publications | Contact

C/2011 F1 (LINEAR)


An asteroidal object of magnitude 18.5, discovered on March 17, 2011 by the LINEAR project in the constellation Draco, showed cometary activity on detailled observations. Comet C/2011 F1 (LINEAR) showed a strongly condensed 8" coma of total magnitude 18.0, which was slightly elongated towards SW. The comet will not pass perihelion of its orbit until January 2013, when it could reach magnitude 10.0 (IAUC 9202 / MPEC 2011-G58). However, at this time it will be positioned too near the sun in the constellation Sagittarius. Mid-European observers can follow the comet from the beginning of 2012 (15 mag / northern part of Bootes) until the second half of October (10.5 mag / Serpens).

This comet was the only one which was reasonably well observable with medium sized instruments during summer 2012. It was visible until mid-November, when it had reached magnitude 10.2. Until the start of February 2013 it was positioned too near the sun for observations. Thereafter observers in the southern hemisphere should have been able to continue the coverage. According to 14 observations by 4 members of the German Comet Section and 120 international observations the comet brightened continuously before its disappearance. The brightness evolution can be well described by the formula

m = 5.1 mag + 5×log D + 9.6×log r

Thus the comet should have peaked at 9.8 mag around Jan. 20, 2013. However, no further visual observations could be gained. Michael Mattiazzo (Australia) succeeded in catching it via CCD on Feb. 2 at 18:15 UT: the comet was only faintly visible as a 13-14 mag diffuse smudge. Thus the comet must have experienced a major fading - either on its way approaching the sun or immediately thereafter, most probably due to the disintegration of its nucleus.

Total Brightness and Coma Diameter

The coma diameter was estimated to be 1.0' (150.000 km) at the beginning of the apparition. It increased only slightly during the following weeks, measuring still 1.5' (200.000 km) in mid-July. During the following 4 weeks it increased much more rapidly, measuring 3.5' (425.000 km) in mid-September. In November it was estimated to measure 5' (600.000 km)

Until mid-May the coma was well condensed, with a reported degree of condensation of DC 5. During the following 4 weeks it got more diffuse, with the degree of condensation decreasing to DC 3. This value is hold since. No visual tail sightings were reported.

Andreas Kammerer

FGK observations


Back...