Strange light curves for Tyc 3603-1124-1

Tue, 09/19/2023 - 00:44

I've taken over 1400 B- and V-filter CCD photometric measurements of Tyc 3603-1124-1 beginning in September, 2021 and continuing within the last month.  The results look very strange to me.  VSX lists the star as a HADS variable, but the rise to brightness is slower than the fall.  PTD analysis yields a period, P=0.1359594542 d, very close to the value listed in VSX, P = 0.1359594542 d.  Fourier analysis results show only a fundamental frequency, F1 = 7.353743 per day, and one harmonic frequency, F2 = 14.7146561 per day.  Phased plots comparing the LCs from 2021 and 2023 show a different shape between the earlier and more recent measurements, with the change being different for the B and V filters.  Most interestingly, the B-V color index shows a clear change in temperature over the last two years.  I've made some plots as jpg files, but have not been able to upload them with this message.  Hopefully, the Dropbox links below will allow viewing.  I'm really scratching my head on this one.  Has anyone seen anything like this before? 

American Association of Variable Star Observers (AAVSO)
It has an UID

Why not put those 1400 observations in the database?

Variable Stars South (VSS)
TESS has nice light curves …

TESS has nice light curves (two sets of TESS-SPOC data) with a cadence of 200 sec from July and August this year.

There are also datasets from December 2020, but at a cadence of 1800 sec the light curve does not display clearly without phasing.


Variable Stars South (VSS)
MAST Portal procedure for TESS light curves


Go to the Mast Portal at

If you know most of the following, sorry for posting un-necessary detail.

The "Select a collection..." seach box can be left at default (MAST Observation by Object Name or RA/Dec).

In the "and enter target:" box type "TYC 3603-1124-1, r=4s" (omitting the quotation marks) (r=4s means search radius of 4 arc sec) and click Search.

A table with 24 rows is displayed. In the Provenance Name column, rows 19 to 22 are labelled TESS-SPOC (Science Processing Operations Centre). Scroll to the right to see the column headed Exposure Length (checking the boxes for the relevant rows in the far left column highlights the rows to make identification after scrolling easier).

Rows 19 and 20 show 1800 (sec), 21 and 22 show 200. These numbers are the cadences of the time series. Click the disk icon for row 21 in the Actions column (to the left). A zipped folder will be downloaded. Open the folder, then drill down through the subfolders until you come to the files. The one ending in _lc.fits (its always the top file in my experience) is the one you want.

In VStar choose File > New star from Kepler/TESS FITS file v2.2...

Repeat the download for the data in row 22.