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Behind the Scenes at AAVSO: Charts and Sequences

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SXN's picture
Behind the Scenes at AAVSO: Charts and Sequences

May 21, 2014 was a red-letter day for the charts and sequences team. At 19:56UT Tim Crawford sent me an email, informing me we had received our 800th official request for a new sequence through the channel.

Of those 800 requests we have been able to fulfill all but 53 appeals, a 93% return rate. Most of those requests were filled within 48 hours, often much sooner. Satisfying those requests is only part of what the charts and sequences team does, but it is one of the most rewarding tasks, especially when we can deliver same day service to our observers.

We also create hundreds of new sequences for objects that come to our attention via other avenues, such as CBA and VSNET targets of interest, novae, supernovae and other transient objects, and upcoming AAVSO observing campaigns.

We have been actively addressing reported errors and issues, and requests for sequence revision and additions via CHET, the chart error-tracking tool, which allows observers to report and track the progress of chart issues. CHET can be accessed on the website at: Of the 659 reports currently residing in CHET only 62 remain unresolved as of May 27, 2014.

We refer to VSP as an “Automated Chart Plotter, but there is a ton of work that goes on behind the scenes to make these ‘automated’ charts available. There are people who work tirelessly day after day, selecting the stars for sequences, documenting the work that is done, updating the lists of new and revised sequences, and checking off the requests for new sequences as they are completed.

The charts and sequences team is made up of volunteers and staff who work countless hours each month revising old sequences and creating new sequences. The current members of the charts and sequences team are Sara Beck, Thom Bretl, Tim Crawford, Robert Fidrich, Keith Graham, Jim Jones, Mati Morel, Sebastian Otero and Mike Simonsen.

Tom Bretl, Tim Crawford, and Jim Jones account for about 90% of the work. Tom continuously works on chart issues reported to CHET. Tim works on filling requests for new sequences, and Jim tends to the needs of observers chasing after cataclysmic variables for CBA and VSNET campaigns. Sebastian Otero provides invaluable insight into bright star catalogs and photometry and southern hemisphere sequences. He also adds new stars and transient objects to VSX in a timely fashion and advises us on various other topics.

I’ve been an AAVSO observer long enough to remember the ‘bad ole days’, when AAVSO charts existed for a thousand or fifteen hundred stars, but the number of really good charts with excellent sequences could be counted in the hundreds. If you needed a chart for a nova that was just discovered in Scorpius yesterday, you might have to wait for weeks or months to lay your hands on one. If you wanted to follow a star no one else was observing you usually had to make up your own chart and sequence. If you needed reliable photometry that went fainter than 12th magnitude, you were out of luck.

Now we have charts and sequences available for thousands of stars in an unlimited combination of chart orientations, fields of view and limiting magnitudes at the click of a mouse. New sequences for transient objects are available almost as soon as the objects are announced and if you need a sequence for a star no one else is observing, all you have to do is send an email and your wish will be fulfilled in a matter of days or hours.

This didn’t happen because we invented some automated program that assigned comp stars to sequences at the push of a button. This happened because a small group of volunteers and staff had a vision and a dream, and were given the chance to innovate and solve one of the AAVSO’s biggest challenges in its 100-year history.

When the next 100-year history of the AAVSO is written, this solution to an age-old problem will be featured big time. We have done more in eight years than all the chart committees in the history of the AAVSO. Since 2009, the team has created over 3100 revised and new sequences, and there is no sign of progress slowing down any time soon.

On behalf of the charts and sequences team, we are proud and happy to be able to serve AAVSO observers in this capacity.

Mike Simonsen (SXN)


Harry Hilliard
Harry Hilliard's picture
Your charts are great. I use

Your charts are great. I use them for everything. Thank you for all your hard work, it makes things much easier for the rest of us. My hat is off to all of you at AAVSO. Sincerely, Harry

hhu's picture
Congratulations to the chart

Congratulations to the chart team and their big effort!  yes

pukemaru's picture
Congratulations to the Chart Team

I'd like to add my thanks. I have made extensive use of the services of the Team, and have really appreciated the quality and speed of repsonse. 

Kindest regards
Stephen [HSP]

BPO's picture
Congratulations to the Chart Team

Yes, I'd like to echo these congrats.

A truly massive undertaking, many thanks to the charts and sequence team for their hard work and quick responses to comp requests.



The sequence team is to be highly commended for their valuable work in providing observers with sequences for their favourite stars.  And APASS is of course a wonderful asset.  There is a downside to this however.  Do all these stars get observed well enough so that their characteristics can be adequately described?  Also, does this not draw observers away too much from the legacy stars?  They have been thoroughly observed for decades but are now often seeing large gaps in their lightcurves.  Maybe some more guidance is needed here?


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