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VStar needs a plug-in for TESS light curves

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schaefer
schaefer's picture
VStar needs a plug-in for TESS light curves

I would like to ask for a VStar plug-in that pulls out light curves from the TESS database.  This is an obvious new need and additional data source, for the wonderful variable star light curves just starting to pour in from TESS.  Unfortunately, there is now no way that the public can access the TESS data, even through MAST, so this is perfect for AAVSO, while VStar would have this as one of many appropriate plug-ins.

 

        In particular, the TESS data is easily available on the basic MAST website, for example at https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html      .  Clicking on the graph icon for the TESS data (there can be many lines and icons for each TESS sector), and we get an OK graph showing the data.  But I need special analysis for each light curve, so I have to get it into a text form such that I can browse it and write my own algorithms.  Unfortunately, the TESS light curve at MAST is there only in FITS format for the light curve, with no CSV or ASCII light curve available.  So I want the VStar plug-in to enter the MAST FITS files and simply make a light curve listing (a header plus many lines of BJD, Flux, and SigmaFlux) that I can browse and put into an ASCII file or into an EXCEL file.

 

         In Honlulu, I asked both Ricker and Vanderspek how to get a simple listing of TESS light curves, and they only knew to go onto MAST.  Calling the MAST help desk, they said my only option was to (1) install Python, (2) learn how to use and program in Python, (3) install to selected Python routines that MAST would provide, (4) write my own short Python program, and (5) then getting a simple listing of the light curve from the FITS file on MAST is easy and fast.  Honest, that is what the 'Help' Desk told me.  Well, there really must be some simple and fast way to get a simple listing (a way that does not require a man-month of preparation).  A VStar plug-in for TESS data is a natural addition that will help many AAVSOers avoid a man-month of work each.  Please help on this plug-in task.

clkotnik
clkotnik's picture
TESS Plugin Beta

Please take a look at the attached revised documentation for the Kepler VStar plugin.  This adds the capability for TESS to the Kepler and K2 functionality already there.  In addition, the documentation describes the MAST portal as the data source.

I this looks like what you could use and you would like to try the beta version of the software, just let me know.

best regards

Cliff

schaefer
schaefer's picture
VStar plug-in for TESS works, but the JDs are all screwed up

Perfect, you had indeed already thought of TESS for a plug-in, and got it working as part of the Kelpler and MAST plug-in.  (Checking with Sara yesterday morning, she did not recall a TESS solution, and recommended that I pass the need along to this forum.)  Your solution is indeed easy and produces exactly what I want.

 

BUT, in the one example I tried, the reported JDs are all screwed up.  For V Sge, the plot I get out on VStar shows the real TESS light curve as displayed by MAST, so I am really pulling across the V Sge data.  But the plot and the listing give calendar dates (and corresponding Julian dates) of 13 Aug 2013 at the start.  Now, TESS was not up then, so the JDs coming out of VStar must have errors, big errors.  Could you get this working for the correct dates?  (And, please tell whether the listed "Julian Date" is JD, HJD, or BJD?)

 

I chose V Sge as the example to try because it is my one case of ground truth where I got the MAST Help Desk to send along a CSV file.  This shows the same plot shape as does VStar and MAST, so it is the same data.  (Well, the MAST Help Desk file had brightness in Flux, instead of magnitudes, but this is trivial.)  The first data point in the MAST Help Desk file has BJD = 2458683.35265 (18 July 2019) and an SAP flux of 4301.83 +- 10.71.  This is appropriate for Sector 14 of TESS starting on that date and covering the V Sge position.  Further, my fitted eclipse times fit closely with my century-long O-C curve, so the TESS BJDs are correct in this file.  So this is just to confirm that the VStar 13 Aug 2013 is wrong.  The deal with the MAST Help Desk person was that he'd pass along the CSV light curve for just one target, and if I needed anything more, then I'd have to find an alternative method.  Well, soon after this, I realized that TESS was a perfect match to add to the Harvard and AAVSO data, with TESS providing eclipse times from 2019 to add to the eclipse times from 1890--1989 from Harvard and from the last several decades from AAVSO.  (My science is to generate awesome O-C diagrams with >100 years for many CVs, CNs, LMXBs, and HMXBs.)  So that is why I was asking around at HQ a couple of days ago, trying to find a general solution for getting a simple CSV version of the TESS light curves.  So I am very happy that you do indeed have a simple and general solution.

clkotnik
clkotnik's picture
VStar Kepler/TESS Plugin Beta

I guess I was not clear.  The current "live" Kepler plugin does not handle TESS dates properly.  However, I have a beta version that does.  It also reports the date as BJD instead of JD which is more accurate.

So I would be grateful if you gave it a test.  I have sent a message to you via the AAVSO contact system with instructions.  You should have that now in your email.  Please let me know how it goes.

Cliff

David Benn
David Benn's picture
VStar Kepler/TESS Plugin Beta

Thank you Cliff for this work!

David

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