Latest image

Comet 21P/Giacobini-Zinner
True color image of periodic comet 21P/Giacobini-Zinner, obtained on 2018 Aug. 23 (2h04-2h38UT) with 15-cm, f/6 Maksutov-Cassegrain and Canon EOS 6D DSLR. Exposure time was 12x120s at ISO3200.
Copyright © 2018 by H. Mikuz, Črni Vrh Observatory.

Welcome to COBS!

Comet Observation database (COBS) saw first light in 2010 and is maintained by Crni Vrh Observatory. It is a free and unique service for comet observers worldwide which allows submission, display and analysis of comet data in a single location.

Amateur astronomers can make valuable contributions to comet science by observing comets and submitting their observations to COBS as professional astronomers typically do not have telescope time required to acquire regular observations. We therefore encourage comet observers worldwide to submit their observations and contribute to the COBS database.

Registered observers may submit observations using a web based form which which stores the observations in an SQL database and stores them in ICQ format. Observations may be queried and plotted in the web site or exported for further processing, analysis and publication. The database currently contains more than 236000 comet observations of more than 1200 different comets and represents the largest available database of comet observations.

The data stored in COBS is freely available to everyone who honors our data usage policy. Please cite COBS as the reference if you use it for comet studies.

Latest lightcurve

Light-curve of 21P/Giacobini-Zinner (Oct 19, 2018).

Type  Comet name  Obs date       Mag   App  T  Pow   Dia   DC  Tail PA  Observer
  V    21         2018 10 19.16   9.7   25.2L   76    3.5  3            HAR11
  V    64         2018 10 19.15  10.3   25.2L   76    2.4  2/           HAR11
  V    38         2018 10 19.14  10.4   25.2L   76    2.7  3            HAR11
  V    46         2018 10 18.74   9.2   10.0B   25   15    2            MAT08
  C      2017T2   2018 10 18.71  15.9   10.6R a180    0.5               RAMaa
  C      2018N2   2018 10 18.71  14.6   10.6R a180    1                 RAMaa
  C    46         2018 10 18.69   9.0   10.6R a180   21                 RAMaa
  C    21         2018 10 18.69   9.2   10.6R a180   12.1      55.0m283 RAMaa
  C    38         2018 10 18.69  10.1   10.6R a180    7.1       4.7m266 RAMaa
  V    64         2018 10 18.13  10.4   25.4T   96    2.8  2/           COLac
  V      2016R2   2018 10 16.18  10.7   20.3T  100    5    2            GON05
  V    21         2018 10 16.17  10.0   20.3T   77    3    3            GON05
  V    38         2018 10 16.16  10.3   25.4L   64    2.9  3            MEY  
  V    64         2018 10 16.11   8.9   20.3T   77    7    3            GON05
  V    38         2018 10 16.08   9.1   20.3T   77    7    2/           GON05

Comet Observing Planner

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Limiting mag:
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Current comet magnitudes and observable region

Comet                               Mag   Trend   Observable          When visible
                                                                  45N              45S
46P/Wirtanen                         9.5  bright  59N to 90S  Best morning     Best morning    
21P/Giacobini-Zinner                10.0  fade    71N to 90S  Early evening    Best morning    
38P/Stephan-Oterma                  10.0  bright  90N to 75S  Best morning     Best morning    
C/2016 M1 (PANSTARRS)               10.5  fade    25N to 90S  Never up         Never up        
64P/Swift-Gehrels                   10.5  bright  90N to 54S  Best morning     Best morning    
29P/Schwassmann-Wachmann            12.0  steady  89N to 90S  Best evening     Best evening    
C/2016 N6 (PANSTARRS)               12.5  steady  90N to 84S  Early evening    Early evening   
C/2016 R2 (PANSTARRS)               12.5  fade    90N to 45S  All night        Never up        
48P/Johnson                         13.0  fade    63N to 90S  Best evening     Best morning    
C/2018 N2 (ASASSN)                  13.5  bright  43N to 90S  Never up         Never up        
C/2017 T3 (ATLAS)                   14.0  fade    63N to 90S  Poor elongation  Poor elongation 
78P/Gehrels                         14.0  steady  81N to 90S  Best evening     Best evening    

The observable region is an approximate indication of the latitude at which the comet may be seen. The period when visible is calculated for latitude 45°N and 45°S.

Top news

Sep. 24, 2018

Observation Alert: Extremely bright mag 12.2 outburst of Comet 29P

A second outburst of 29P/Schwassmann-Wachmann has taken place on 2018 09 23.2 +/-0.1 which has raised its brightness from r mag 13.2 to 12.2. This new outburst occurred 2.6 +/-0.2 days after this first event and its current brightness makes it one of the four most intense outbursts in 8 years.


Latest news

Oct. 03, 2018

Comet landscape

On 30 September 2016, ESA’s Rosetta spacecraft came closer than ever to the target it had studied from afar for more than two years, concluding its mission with a controlled impact onto the surface of Comet 67P/Churyumov-Gerasimenko (67P/C-G).


Sep. 26, 2018

Gaia finds candidates for interstellar ‘Oumuamua’s home

Using data from ESA’s Gaia stellar surveyor, astronomers have identified four stars that are possible places of origin of ‘Oumuamua, an interstellar object spotted during a brief visit to our Solar System in 2017.


Sep. 10, 2018

The Comet Observation Database - Observer tools and case study (EPSC2018-644, Berlin 2018)

This paper introduces the main functionality of the COBS database [1, 2] that is of interest to a comet observer, with application to C/2004 R2 (Machholz).


Sep. 10, 2018

The Comet Observation Database - Structure and content (EPSC 2018-632, Berlin 2018)

The Comet Observation Database (COBS) [1, 2] is a unique web service that enables comet observers to submit, display and analyse comet data in a single location. The service currently represents one of the largest databases of comet observations (containing more than 235,000 observations) and is available to comet observers worldwide.


Sep. 09, 2018

Green comet makes closest approach to earth

On Sept. 10th, Comet 21P/Giacobini-Zinner ("21P" for short) will make its closest approach to Earth in 72 years--only 58 million km from our planet. This small but active comet is easy to see in small telescopes and binoculars as it shines like a 7th magnitude star. Michael Jäger of Weißenkirchen, Austria, sends this photo of 21P passing through the stars of Auriga on Sept. 7th.