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New Light Curve Generator(LCGv2): Updates, Questions, & Suggestions

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BSJ's picture
API interface to LCGv2

Hi Tim,

The short answer is no. LCGv2 does not have this capability yet. However, I am in communication with Francis about this and hopefully he will be able to implement something along those lines.

Thanks, Sara

BSJ's picture
API Interface to LCGv2

Hi Tim (and anyone else interested in this capability),

Thanks to LCGv2's developer, Francis Hemsher, we now have available a new feature which will allow you to request a specific lightcurve via query string. In other words, by typing the following into the URL address box on your browser: Sct&fromjd=2457201.875086794&tojd=2457931.875086794&delimiter=@@@

... you can get a fully interactive plot of R Sct!

There are also options to request a simple (non-interactive) plot, to specify what bands you would like to display, and to use JD or calendar date along the X-axis of the plot.

Also, you can see both (interactive and static) versions of the URL needed to duplicate a plot you create in the "Preferences" window as shown here:


Just select the link which you can then copy & paste into a webpage, send by email to a friend, or build into your own software programs.

Your feedback is most welcome!


LCGv2 in VSX

VSX now also links out to the new LCG from the detail sheet of an object using this URL.


dks's picture
API Interface to LCGv2

First off, I really like the new LCG. The interactive capabilities are wonderful and very useful. I'm still using the old LCG for some things, however, because the API for the new one still isn't quite as flexible. One thing that would really help would be "Plot previous days" parameter. It's exposed in the interactive form for generating a new light curve, so it seems like it shouldn't be too hard. I'd like to be able to say "show the last 200 days," rather than having to compute the current JD/date and current-200 to pass in the URL.

Shawn (DKS) 

New Feature - URL for Light Curve

We have included a URL link address for the specific light curve you have created in the LCG. This is shown under 'Preferences'. Two URLs are shown: Static and Interactive.

The Static URL provides just the image of the light curve. The Interactive URL provides the image of the light curve with all typical LCG user selections.

Note that the Static URL can be used anytime you want to show an image of your light curve in any application,  journals, reports, emails, etc. It automatically adjusts its size calling environment.

Error bars

I just noticed a nit with error bars.

When looking at a plot, if you turn off 'all contributors' and only select one contributor with error bars enabled it does not remove the error bars for the un-plotted data - it removes the points but leaves the bars.

Bikeman's picture
Observer list incomplete

Try this: Plot LC for star V1454 Cyg for (say) the last 5 days (as of writing this).

Near JD 2458013 you will see a high cadence time series by observer ATE, but this observer is not listed in the box under the plot.


EDIT: After some additional experimentation, I begin to suspect that there is always one observer missing from the box no matter what you input, perhaps the one who's first in alphabetical oder.



Bikeman's picture
Data not refreshing on "fainter than" data points

Looks like another issue:


If you click on a  data point to display the details in the "Observation data" box, and then click on a "fainter than x" data point, not all items in the "Observation data" box refresh to show the data from the new point, instead you get a mix of entries from the currently selected (fainter-than) point and the previously selected point. I just tested this also on a LC of V1454 Cyg.


lmk's picture
Default settings not my preference

One of the annoying "issues" is it doesn't seem to "save" my defaults that I like, when in the select star box. For example, I prefer Calendar day, not Julian day, and I prefer specific bands (V, Vis, CV) rather than all bands, abd a specific number of days backwards in time, but I always have to take the extra steps to reset these, because the defaults provided when I open the box, are the opposite!


spp's picture
LCGv2- No error bars in the Box

When Preferences>Error Bars is checked the error bars appear in the initial plot, but they do not appear inside a zoomed in Box. 

rybi's picture
LCGv2: error - one day shift in calendar date

I think there is an error in showing light curves using calendar date. I've attached an example LC of N2018 Per (V392 Per). It looks like one day shift on calendar scale, for instance instead of "2018/05/05" it should be "2018/05/06" date, and so on ... 

I have date format yyyy-mm-dd in my Win10 settings.


Richard (BRIA)

File upload: 
BSJ's picture
LCGv2: error - one day shift in calendar date

Hi Richard,

Thank you for your post and the screenshot showing the problem you observed with the LCG.

Unfortunately, I am having trouble repeating the problem you reported (see attached screenshot). If you are able to repeat this problem again would you please go through step by step what you did?

For example, did you start out by requesting calendar date from the "Plot another curve" window or did you request the data in JD then switch to Calendar date using the "Preferences"? Did you zoom in to rescale the plot?

Many thanks,


File upload: 
rybi's picture
LCGv2: error - one day shift in calendar date

Hi Sara,

thank you for your tests V392 Per LC generation.

I generate LC of V392 Per from main AAVSO page using option "Plot a light curve" and the next step I change parametres (Julian Day --> Calendar Date, From Date ..., To Date ...) of LC in LCGv2 window. But probably this is not the problem.

When I take 12 days of LC of V392 Per I will get calendar date scaled to 22 UT on each day (this is my current computer time at the moment of the first static LC generation, but it is UT+2h), for instance "2018/05/03 22:00" - see below a static link to LC and attached screen shot 12daysLC.png . 

Static link 12 days LC

When I take 13 days of LC of V392 Per I will get calendar date scaled without time on each day, for instance "2018/05/03" (time=22UT in date "2018/05/03" stays hidden???) - see below a static link to LC and attached screen shot 13daysLC.png.

 Static link 13 days LC



File upload: 
BSJ's picture
LCGv2: error corrected

Hi Richard,

I think that the problem has been fixed. Please check and let me know what you think.

Many thanks to you for finding this and to Francis (LCGv2's developer) for fixing it!


TRE's picture
error bars?

 LCG1 is broken.

How do I get error bars on LCG2?


BSJ's picture
Error Bars

Hi Ray,

To show the error bars using LCGv2 just click "Preferences" then under "Plot Preferences" click "Show Error Bars". If the drop-down box reads "> 0.0" you will see all error bars, but you can limit it to showing only the bigger ones if you want. Because the symbols are so large it can be hard to see the error bars sometimes.

I hope that helps.



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