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Request to observe the eclipsing variable TU Lyn

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kki
Request to observe the eclipsing variable TU Lyn

Similar to the case of V610 Cyg in last August  I would like to request the AAVSO community to observe this eclipsing variable. According to Lichtenknecker-database of BAV in Germany, there is no minimum observation of TU Lyn since 1936 untill this year. I investigated this variable, improved its period and calculated the next minimum. It will occur soon on 17 April 2016 21 UT! The duration of eclipse is about 1.56 days. The eclipse will begin about 3 UT 17 April and will end 15 UT 18 April. So it would be very fine, if a part of descending or an ascending part of light curve could be caught, even if the mideclipse could not be observed. Then the period could be verified or could be improved. It would be required that observers also observe some portions of the light curve at maximum so any offsets can be corrected. I hope someone can observe this last chance in this season. Clear sky! KKI

kki
Several information about TU Lyn

The V magnitude of TU Lyn is about 10.5 out of eclipse and about 11.1 at its minimum. The improved period ist 38.944 days and epoch is 2425912.523 from VSX. Please use 88 (000-BBL-419) or 103 (000-BBL-384) on the AAVSO chart as comparison star. Thank you for your collaboration!

 

LMA
LMA's picture
TU LYN

I observed TU LYN last night, no sign of eclipse. Just uploaded my data to the VSX and the graph is attached. Clouds have interfered though, I had to dump many pictures. Tonight is overcast. Will try again tomorrow.

Damien

pva
pva's picture
Eclipse in Progress

I started a run on TU LYN at 3:00 UT April 18th and it is clearly on the rise so it is already past mid-eclipse.  A quick calculation shows it rising at more than 0.05 mags per hour.  I'll watch it for a couple hours and submit my data tomorrow.

Let's try for this one again in the fall.

On another note, I tried searching for TY LYN by epoch in VSX and got zero results.  Since this star has an epoch of October 1929 (2425912.523), I tried searching between January 1st, 1929 (JD 2425612.54237) and January 1st, 1930 (JD 2425977.54237) but get nothing.  Is this a bug or am I doing the search incorrectly?

Clear Skies,
Vance

 

chrismlt
Vance, There was a confusion

Vance,

There was a confusion between TU and TY Lyn ; TU Lyn really is in the VSX when you search for the right epoch as you did mention (JD 2425612.54237 - 2425977.54237). TY is not.

Christophe

pva
pva's picture
Confusion is a Typo

Hi Christophe,

Sorry, the reference to TY LYN is a typo on my part.  I really meant TU LYN which is the star of interest in this thread.  I tried again running a VSX query with only the two JD's in the epoch field and still get no results returned.  I can query TU LYN by name but not by an epoch range so I think this functionality in VSX is broken.  I just wanted to see if anyone else gets the same query results I do.

It would be useful to run a query in VSX looking for stars with epoch's older that say 30 years ago.

Thanks,
Vance

 

 

 

wlp
Epoch search in VSX

Hi Vance,

You are right, this epoch query in VSX actually never worked.  The VSX database contains JD - 2400000, not the full JD.  The query didn't take this into account when using the values from the search form.  I have fixed this, so your query should work now.

One more tip: if you want to query variables without an epoch, put 0 in the upper limit for the epoch.  It also works for periods.

Patrick

pva
pva's picture
Epoch search fixed!

Yay!  Thanks for fixing that, Patrick!  My original query now works and pulls back 16 pages of stars with epochs defined between 1930 and 1940.  There's a lot of newer eclipsing binary stars that don't have epochs defined so using a zero will be helpful in finding project stars to work on.

Thanks again!
Vance

 

WBY
WBY's picture
Epoch Search

Vance and all i just did an Epoch Search for HJD 2425911 to 2425913 with the output order by the default GCVS seq and got the attached results which includes TU Lyn. So the Epoch search does seem to work. You need to bracket the HJD that VSX shows as the base epoch. I suspect, but don't know, that if you make the data range too wide so that there a a huge number of results, It may not work. 

Brad Walter

 

ps. Subsequently, I did a search from 2425900 to 2426000 and got a two-page list of stars including TU Lyn. Patricks's fix works.

pva
pva's picture
Eclipse Data

From my quick plot, it looks like TU LYN rose by 0.10 mags in 90 minutes.  My rough calculations show it would have finished the eclipse around 7:00 UT so I was just catching the last parts of the eclipse. 

Since my photometry was still flat at 6:00 UT yesterday, the duration of this eclipse is 25 hours or less.

Attached is my run from last night.

Vance

 

 

 

pva
pva's picture
TU LYN Eclipse

I ran a time series on TU LYN between 3:30 UT and 6:15 UT April 17th and the variable is steady around 10.5V with no sign of a decline.

I'll try again tomorrow night but in the mean time, hopefully, someone else can look for the start of the eclipse.

 

kki
Thanks for your effort!

Thanks Vance for your effort!  The weather in Japan and Switzerland is not favorable to observation. I hope someone can catch a part of eclipse. The brightness variation of this star will be very very slow. The descending part with the difference of 0.6 mag. in V runs about 18 hours, so the rate of variation will be about 0.033 mag/h.

pva
pva's picture
I've uploaded my data from

I've uploaded my data from last night.  It's flat at the +/- 0.01 mag level.  I'll try again tonight as it will be clear here for the next few days.  A 0.033 mag/hr decline/rise should be easy to detect.

It's not a good time of year to grab this data.  If we don't get it this time around, ping me in October and we'll try again.  I'll be able to run 10+ hours on it then.

chrismlt
All, I'm interested in this

All,

I'm interested in this observation. I just have discovered this thread by chance this morning : it'should have been deserved an AAVSO alert, I think.

Well, the sky is rainy here today. I'll observe, weather permitting, this week, if the eclipse did not occur before.

Christophe, France

kki
Phase plot of TU Lyn

Here is a phase plot of TU Lyn made by me.

 

ATE
Captura de mínimo

Hola a todos:

En una serie desde España del día 2016 Abril 17 desde las 19.50 TU hasta 22.50 TU creo haber capturado el mínimo del eclipse sobre las 20.50 horas TU.

Los datos ya estan mandados a la AAVSO, a la entrada de la estrella TU LYN.

Un cordial saludo.

Teófilo.

pva
pva's picture
Captura de mínimo

Excellent!  Well done, Teófilo!

 

 

kki
Captura de minimo

Hi Teofilo, fantastic! I am eager to see your data of minimum. I have received short observations of descending part in Japan, so we have all three parts, descending, minimum and ascending, of this eclipse. I will make a phase plot of this eclipse, if we have data of Teofilo.

kki
Phase plot of TU Lyn in the near of 0.0

Hi all, I have made a preliminary phase plot with all data of observations in V of the last eclipse on April 16-18 2016 and the survey data. No magnitude shift is applied. It is fantastic! The first minimum observation of TU Lyn since 1936!

The following observers of AAVSO have contributed to this phase plot."ATE"  "FJQ"  "LMA"  "PVA"  "WTHB" Thank you very much for your observations!

Could you observe the variable, if not yet, at the phase out of eclipse, to find zero point of your observations? Thank you.  Kiyoshi

kki
Phase plot of TU Lyn in the near of 0.0 (revised)

I have revised the phase plot of TU Lyn in the near of 0.0. NSVS, KWS survey data are a little shifted, -0.1941 mag. and -0.0113 mag. respectively. Another VSOLJ data set is added. Now the descending part of phase plot looks well.

kki
Phase plot of TU Lyn

Here is the whole phase plot of TU Lyn with obsevations data this April.

kki
Phase plot of TU Lyn in the near of 0.0 (revised)

KRAB has submitted observations about minimum with Planewave 14" CDK and a Canon-500D. His filter is not V but TG. I have added his data without mag. offset to the former phase plot. His data bridge two data sets  by ATE and PVA.Thanks KRAB!

I would like to request ATE, KRAB to observe TU Lyn once again out of eclipse . It doesn't need a long run. We need to find the mag. offset of each observer. Thanks. Kiyoshi

FJQ
FJQ's picture
TU Lyn

I'll reduce/transform my last 19-23Apr16 data on this TU Lyn when I get back home.  Hope I caught a piece of the eclipse that we need to fill in any gaps; did see the eclipse in previously submitted data 15-18Apr16.

James

kki
Thanks for observations out of eclipse

Thanks KRAB, FJQ for your submissions of observations of TU Lyn out of eclipse. I will revise phase plot tomorrow. Kiyoshi

FJQ
FJQ's picture
TU Lyn Eclipse

To:  Kiyoshi,

Please note that because of my location, I could not shoot this any better than about 1.3 air masses.  This is the most light polluted part of the sky facing downtown Los Angeles (8 miles away!).  The only sign of fade out from my own transformed BVI observation is the B channel on UT date18Apr15.

James

kki
Phase plot of TU Lyn (revised)

Thanks James. Yes, I think your B-band data show eclipse at about 18.17  April but V-band data show no eclipse.(As you mentioned it might be because of the light polution.)

I have made new phase plot with data until today. I must adjust now all data applying mag. offset to data sets of each observer.

kki
Phase plot of TU Lyn (revised)

I have adjusted data sets of each observer to APASS mean magnitude and have remade phase plot with adjusted data sets. For clarity I had to omit data with large scatter. Excuse me.

It is very interesting. that old data by WTHB (pink) show ascending tendency to phase 0.5 and descending tendency to 1.0. That means, phase 0.5 is at maximum.

ATE
Ampliación de campaña

Hola a todos:

Me pregunto si podríamos ampliar la campaña de TU LYN al próximo eclipse del día 26 de Mayo.

Yo tendría una ventana de algo más de una hora y como se adelanta una hora y poco, la cogería ascendiendo.

Un cordial saludo.

Teófilio.

FJQ
FJQ's picture
TU Lyn data resubmit

To:  Kiyoshi,

I deleted all my TU Lyn data and will resubmit it to AASVO as aggrigate (sum of 3-5 exposures) to reduce the scatter.  Think this will be my last TU Lyn eclipse data...too far west.

James

kki
Thanks James

Thanks James. I appreciate highly your effort!

kki
Ephemeris for TU Lyn

TOM of TU Lyn on April 17 2016 calculated with data by ATE is 2457496.3713(1) HJD (= April 17 2016 20.91UT) My prediction of TOM was 2457496.3746 (=20.99 UT) so O-C was  -0.0033 d. (4.8 min).  

I have made ephemeris of TU Lyn for May, Oct.,Nov. and Dec. 2016 (I have used the same light elements, which I have used for prediction of eclipse in April 2016. Epoch: 2425912.523, P: 38.94433 d.)

It is also important to observe this variable at phase 0.5. The survey data from NSVS and KWS show no clear eclipse. If there is no sign of elipse, then it is possible that the true period could be the doubled period of 38.9 d. i.e. 77.8 d..

May
date    UT    n
7    8.32    811.5
26    19.66    812

Oct.
date    UT    n
10    2.98    815.5
29    14.31    816

Nov.
date    UT    n
18    1.64    816.5

Dec.
date    UT    n
7    12.97    817
27    0.31    817.5

kki
Eclipse at phase 0.5?

NSVS data of TU Lyn indicates no sign of Min II at the phase 0.5. But it is possible that TU Lyn shows a little eclipse on coming night, May 7 2016 8.32UT. It is very important to observe TU Lyn tonight, whether this varible stays constant or not!

I have improved elements for TU Lyn and have remade its phase plot.

kki
The next eclipse comes!

The next eclipse of TU Lyn comes again. But the observation of this variable is now perhaps difficult.

The eclipse begins about 9.5 UT May 26 2016 and ends about 5.5 UT May 27 2016.

The mid eclipse is about 19.5 UT May 26 2016. The duration of eclipse is about 20 hours.

 

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