Chart ID Numbers

Listed here are posts to the AAVSO Discussion group that describe the Chart ID numbers.

Discussion group message posted April 2009:

Stephen Hovell wrote:
> Greetings to you all.
> 
> Please can someone explain the system used in naming charts generated by 
> VSP. I am referring to the chart label in the top right hand corner.
> 
> Some times different stars have the same numbers eg X Normae (FOV: 210', 
> mag 115) and combined EI-IU TrA (FOV: 210', mag 115) both have the 
> number 1108 but the letters differ.

"1108" refers to the current version number of the comparison star database. The suffixed letters are a running index of the charts generated from when that compstar database was updated. Together they give us sufficient information to regenerate the same, exact chart as you did, with the same compstar information (even if a subsequent update changed the comparison star magnitudes). That is why there is a fill-in area at the bottom of the VSP form where you can enter a chart identifier to retrieve a previous chart.

—Arne

New Chart ID Description Announcement posted in July 2008

ChartID Lookup/Plotting Tool posted in July 2008