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AAVSO Target Tool - a new tool for our community

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stellakafka's picture
AAVSO Target Tool - a new tool for our community


For the last year, we have been working with a group of very talented developers to create a new online tool that would give information of targets that need observing, to those observers who want recommendations on what to observe each night. After multiple integrations, discussions, improvements, tests, more tests and more improvements, I am delighted to introduce our AAVSO Target Tool. It provides lists of stars that are in need of observing, and that are visible from the location of your observatory. The recommended lists of objects were selected by our observing section leaders; a star’s recommended cadence of observations was determined based on individual star characteristics and completeness in our database. You can select targets based on their specific types (CVs, LPVs, eclipsing etc) and/or simply what can be observed from your observing site. Targets that are part of our alerts are marked as “high priority”.


You can find this tool at:


For more information on how you can use the tool’s functionalities, please go to the relevant help page at:


Many thanks to Prof. Keivan Stassun, Dan Burger and their team members, Chandler Barnes, and Kenneth Li, from Vanderbilt University who worked hard to build this tool for the AAVSO. It was a pleasure to work with our observing section leaders, John Percy, Gary Billings, Dennis Conti, Andrew Pearce, Michael Poxon Gerry Samolyk and Frank Schorr, on target selection, discussing the idiosyncrasies of various targets. Credit also goes to our past president Jeno Sokoloski who secured funding for this tool through the Research Corporation for Science Advancement foundation, and Sara Beck from HQ who helped coordinate all this process.


We hope you enjoy it. Comments are welcome, as we try to improve the tool’s functionality. Happy target selection!

Best wishes – clear skies,


Bikeman's picture
"Last observed" entry


Excellent tool!

One remark/bug report:

If an alert calls for observations in many bands, there will be several lines genareted for that target, e.g. V1687Cyg (WR 140) has separate entries  for U, B, V, R, I and Visual. I think this makes sense, but the "last observed" column that states how old the most recent observation is should then be specific for the band in question. However this seems to list when the most recent observation in any band was made for that target. Example: Even the "R" filter entry for V1687Cyg currently has a "2 days ago" marker, even tho the last observation of V1687 Cgy in that band is several weeks old. If this field was band-specific, it would IMHO be more useful, otherwise you could just as well list all the requested bands (e..g "UBVRI+Vis") on a single line in the output list .



David Benn
David Benn's picture
Invalid Date error

This looks like a great tool, thanks! However, I'm seeing an Invalid Date error wherever a date/time should appear, as per the attached screenshot.

I've created an account, set obs lat/long and my location (Adelaide, South Australia). The latter is a UTC+9.5h.








HTY's picture
Invalid Date error

Same here David.  I reported this on the feedback link on the first day.


David Benn
David Benn's picture
Reporting errors

I missed the Feedback link on the tool's page Tim.

I guess that raises the question of whether we should report bugs/comments here or on the Feedback page?

I'm thinking that in the early stages it makes sense to post here for others to see; may avoid some duplication.



BSJ's picture
Please continue to post your

Please continue to post your comments and bug reports here on this forum. Don't worry Tim, we are also seeing what has been sent via the feedback form and private emails, but I think its better to keep everything in one place from now on so people can see what has already been reported.

Many thanks,

BSJ's picture
AAVSO Target Tool bugs

Thank you HB and David for reporting those bugs.

They are now on the fix list.


Filter by brightness, period, etc.

It's currently a little difficult to select e.g. bright targets when sorting by Min Mag., as the tool lists all the targets with no specified value first. The same occurs for for Max Mag., although there are only a very few objects where that occurs. Would it be possible to make this easier, perhaps by changing how the sort works (e.g. objects with no value in a sorted column are always placed at the bottom of any sort, either ascending or descending)?

It may also be useful to allow multiple sorts/filters, allowing a user to e.g. select targets brighter than 10th mag. that are High Priority. Of course, that may be quite a bit of work, depending on how the system works behind the scenes!

Finally, is it possible to add Ephemeris Info links to suitable targets other than exoplanets, e.g. EBs? I'm not sure if there would be a way to do that without manually finding the correct VSX link for each target.


BSJ's picture
Ephemeris info links

Hi Daniel,

I just finished adding ephemeris information (where it exists) to stars on the EB list. As you suspected it was a manual process so there is always the possibility I made a mistake with a URL. If you see any mis-connections or other problems along those lines, please let me know.

Your ideas about sorting are good ones and I will add them to the wish list.

Many thanks,

clkotnik's picture
EB/EP Time of Min

Thanks for the new tool.  

I'd like to clarify what it means for an EB or EP to show up on my list of targets.  Does that mean that the object is visible from my location or that it is both visible and has an eclipse that night?



BSJ's picture
EB/EP Time of Minimum

Hi Cliff,

When a star shows up on your list of targets, it simply means that it should be visible from your location and has nothing to do with whether it is expected to eclipse.

As you probably noticed, I have attached a link to the ephemeris from VSX (where available) in the "Notes" field of EB & EP targets in an effort to make things a little more convenient for you.


PYG's picture

Maybe I've got this wrong, but many CV's listed here have absurdly long cadence times.  I'm seeing lots of 5d for UG stars for example.


pox's picture
Hi Gary,

Hi Gary,

I think this must be due to the period being taken from another source (probably VSX or CGVS) where 'period' there refers to the orbital period and not the average outburst period. Classic example of 'garbage in, garbage out'!

dokeeffe's picture
Will this replace the current program-stars-need-observation csv

This looks great, good work. I have 2 questions.

1: Is the program stars in need of observation data still ok to use? > 

2: Are there any plans to add an API feature to the new tool? The reason I ask is that I currently use the csv file from the program-stars-in-need-of-observation to create a schedule for my observatory using astropy astroplanner. A REST api to this new tool would make this easier to do.



BSJ's picture

Hi Derek,

To answer your questions...

1) The "Program Stars in Need of Observation" tool is still OK to use and we have no plans to take it off the website for now although it isn't being maintained.

2) That is a great idea about adding an API to the Target Tool. I discussed this with the programmer and it is now on his "To Do" list.


LKR's picture
Thanks everyone!

Thanks to those who

1) created this

2) are using it!

3) are reporting problems!!

Great feedback loop! I hope people will use this often once all the bugs are worked out (and you can't fix bugs you don't know exist so keep 'em coming!)



Great Target Tool

This looks to be a great tool that I am sure will only get better with time.  It is great because it shows some of the forgotten or new target that I was not aware of.  I will use this to add extra targets for observation runs.

John R

nmi's picture
Thanks for tool - How do we find RV Tau stars?

Thanks for tool - How do we find RV Tau stars?


danburger's picture
AAVSO Target Tool update

Hi everyone,

I am the lead developer on the AAVSO Target Tool. The following problems have now been fixed:

- Times showing up as "Invalid Date" in Microsoft Edge and Internet Explorer

- Conversion of telescope DMS coordinates to DD

Meanwhile, I found a problem with the last observed time on targets where a particular band is mentioned. Currently the last observed time shown is for all bands for that target instead of that particular band. We hope to have it fixed soon. Thank you for your patience! 


David Benn
David Benn's picture
Invalid Date fix and column headings

Hi Dan

Great stuff. Thanks for the Invalid Date bug fix. Looks good now.

I just noticed that column headings don't line up with the columns of values themselves, at least not with my version of Safari (9.13). I'm still running Mavericks on my several years old Mac. It's getting closer to death everyday but not quite there yet. My teenage kids spend all my money. ;)

Let me know if you want a screenshot.


danburger's picture
Hi David, I just tried it on

Hi David, I just tried it on Safari for iPad and got the same problems. I will take a look...

Excellent tool...

Excellent tool...

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