The aim of this service is to provide charts (using Guide 9.0) and suitable comparison stars
for relatively bright comets,
i.e. brighter than magnitude 10-11, to aid observers in making brightness estimates.
To avoid confusion with Flamsteed numbers we have underlined the magnitudes of all comparison stars.
Stars with B-V<1.0 were selected where possible; those with B-V>1.0 are given in italics, and should only
be used when no suitable alternatives are available.
The source of the comparison stars on these standard charts is primarily the Tycho-2 catalog, of which only VT-magnitudes
are used. When reporting data to the ICQ (International Comet Quarterly) the source code thus should be given as TK,
unless indicated otherwise.
We plan to issue new charts on a regular basis, if possible not later than 2 days before the date of first observation.
Occasionally we also issue special charts for fainter comets that are of particular interest.
Below magnitude 10-11 comparison stars usually are taken from a different source (such as APASS with ICQ code AQ,
ASAS-3 with ICQ code AU and TASS4 with ICQ code TA), because Tycho-2 is becoming very unreliable here.
It should be noted also that the ICQ advises against the use of Tycho-2 for comets fainter than magnitude 10.5.
So be sure to always check the proper code(s) given on the top right corner of the chart.
If you wish to be informed about the issue of new charts you can
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Currently we have charts available for:
Chart 1 21P/Giacobini-Zinnerperiod 14 July - 19 July 2018
Chart 2 21P/Giacobini-Zinner period 19 July - 24 July 2018
Chart 3 21P/Giacobini-Zinner period 24 July - 31 July 2018
Chart 4 21P/Giacobini-Zinner period 31 July - 6 August 2018
Chart 5 21P/Giacobini-Zinner period 6 August - 13 August 2018
Chart 6 21P/Giacobini-Zinner period 13 August - 19 August 2018
Chart 7 21P/Giacobini-Zinner period 19 August - 25 August 2018
Chart 8 21P/Giacobini-Zinner period 25 August - 31 August 2018
Chart 9 21P/Giacobini-Zinner period 31 August - 5 September 2018
Chart 10 21P/Giacobini-Zinner period 5 September - 10 September 2018
Chart 11 21P/Giacobini-Zinner period 10 September - 15 September 2018
Chart 12 21P/Giacobini-Zinner period 15 September - 20 September 2018
Chart 13 21P/Giacobini-Zinner period 20 September - 25 September 2018
Chart 14 21P/Giacobini-Zinner period 1 October - 5 October 2018
Chart 15 21P/Giacobini-Zinner period 5 October - 10 October 2018
Chart 16 21P/Giacobini-Zinner period 10 October - 16 October 2018
Chart 17 21P/Giacobini-Zinner period 16 October - 21 October 2018