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Data in WebbObs not accessible to VStar or Light Curve PLotter

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Robert Jenkins
Robert Jenkins's picture
Data in WebbObs not accessible to VStar or Light Curve PLotter

Hi

There appears to be a strange anomaly with data in WebbObs.  Data from YCRA on V0645 Cen that is in the data base is not accessible to Variable Star Plotter nor VStar.  The data does not appear discrepant but neither VSP nor VStar can see it.

Any ideas why?

Robert Jenkins

David Benn
David Benn's picture
LCG vs VSP

I know you meant to say LCG rather than VSP Robert. :)

Indeed, compare https://www.aavso.org/apps/webobs/results/?obscode=YCRA&num_results=25&obs_types=all with what you get for a current plot of V0645 Cen.

Given that both LCG2 and VStar use the same AID web service now but that I suspect WebObs talks to the database server side directly, it may be the web service.

I'm on my way home from work and have not had a chance to look at the web service response directly but it's certainly the case that the data does not appear to load in VStar either.

David

Robert Jenkins
Robert Jenkins's picture
Sorry David you are right; it

Sorry David you are right; it is the Light Curve Generator that is not seeing the YCRB data - sorry about that.

David Benn
David Benn's picture
DIFF not STD

Just looked at the web service response and noticed that the observations in question are being submitted with a MType of DIFF instead of STD, e.g.

https://www.aavso.org/vsx/index.php?view=api.object&ident=000-BCV-333&data=10&fromjd=2457930

vs

https://www.aavso.org/vsx/index.php?view=api.object&ident=000-BCV-333&data=10&fromjd=2457924

so LCG2 and VStar won't display them.

There are ~140 such recent observations in the AID I think.

David

BSJ
BSJ's picture
DIFF not STD

Hi Robert,

David hit the nail on the head. These observations of V645 Cen by YCRA were reported as having differential rather than standardized magnitudes (meaning that the magnitude of the comparison star was not included in the equation). Since this is like plotting apples and oranges, such observations do not belong on the same plot as the ones with regular standardized magnitudes and they are not displayed in VStar or Zapper at all. You actually can see them in the new Light Curve Generator if you select "Differential Magnitude" from the drop-down list in the "Plot another curve" window.

If there is any confusion about the definition of "standardized" versus "differential" magnitudes, please see page 46 (Chapter 5) of the CCD Photometry Guide which explains it.

-Sara

David Benn
David Benn's picture
LCG2 and DIFF

Good to know LCG2 can display them. I suppose that if one wanted to carry out say, period analysis on a set of obs that were of MType DIFF in isolation, there may still be merit in permitting these to be rendered in VStar after all, at some point in the future.

As you say, rendering STD and DIFF on the plot at once makes no sense.

David

Robert Jenkins
Robert Jenkins's picture
Thanks

Thanks David, Sara and Elizabeth for sorting this out.  It would have been a real shame it all of Craig's work got lost in a definition.

Robert

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