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.
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Currently we have charts available for:
P/2020 M3 (ATLAS)
C/2020 S3 (Erasmus)
P2020 M3 (ATLAS)
Chart 1 P/2020 M3 (ATLAS) period 13 October -13 October 2020
Chart 2 P/2020 M3 (ATLAS) period 13 October - 19 October 2020
Chart 3 P/2020 M3 (ATLAS) period 19 October - 24 October 2020
Chart 4 P/2020 M3 (ATLAS) period 24 October - 28 October 2020
Chart 5 P/2020 M3 (ATLAS) period 5 November - 10 November 2020
Chart 6 P/2020 M3 (ATLAS) period 10 November - 15 November 2020
Chart 7 P/2020 M3 (ATLAS) period 15 November - 20 November 2020
Chart 8 P/2020 M3 (ATLAS) period 20 November - 25 November 2020
Chart 9 P/2020 M3 (ATLAS) period 2 December - 7 December 2020
Chart 10 P/2020 M3 (ATLAS) period 7 December - 14 December 2020
C/2020 S3 (Erasmus)
Chart 1 P/2020 S3 (Erasmus) period 12 November - 17 November 2020
Chart 2 P/2020 S3 (Erasmus) period 17 November - 21 November 2020
Chart 3 P/2020 S3 (Erasmus) period 21 November - 26 November 2020
Chart 4 P/2020 S3 (Erasmus) period 26 November - 1 December 2020
Chart 5 P/2020 S3 (Erasmus) period 1 December - 7 December 2020