[AAVSO-DIS] New Chart ID Description

[Aaron Price]

  Today we changed how the Chart ID is written on charts. For a while now (~2000ish) we've 
stamped a date in the upper righthand corner of the chart in the format of YYMMDD. Beginning 
today the Chart ID is now a four digit number followed by some letters. Examples:

1005a
1005z
1005aa
1005az
1006a

  The four-digit number indicates the version of the Variable Star Database that was used to 
plot the comparison stars on the chart. The letters are a base-26 index of the number of 
charts plotted since that version of the database was released. The combination of the two 
will allow for a unique chart ID for every single chart ever plotted. You should never see the 
same ID twice. 

  In your observation reports, please report whatever Chart ID you find in the upper righthand 
corner of the chart. New charts will use the new format. If you are using old charts with the 
YYMMDD Chart ID on them, then continue to report the YYMMDD Chart ID until you replace the 
chart. You do NOT need to update your charts just to get a new Chart ID. 

  The advantage of the new system is that researchers (and other observers) will be able to 
see the exact chart that you used when you made your observation. They will be able to take 
the Chart ID that you submitted with your observation and enter it into VSP. VSP will then 
give them a chart that looks identical to the one you used to make the observation. It will 
have the same comp stars, the same field of view, same orientation, etc. I hope to have this 
tool completed in a couple of weeks and will post a message when it is ready for use.


-- 

Aaron Price
Technical Assistant, Technology
American Association of Variable Star Observers
www.aavso.org