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TYC 3657-1980-1 is "tuning fork"

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KTU
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Joined: 2011-02-20

I got tired of HT Cas, and move on MT Cas. MT Cas is not much observed..

In VSP there is no ref stars in photometry table to MT Cas, so I pick out near by TYC 3657-1980-1 to be as ref star ( 12.58 V-mag ).

On the basis of single 8 hous run , 867 measurement, TYC 3657-1980-1 seems changes quite rapidly, according to Peranso analysis 1.636 h. "Singin" like uning fork!

I used 30cmF4 Newton, MX716 ccd , V-filter (Baader) and 25sek exposure time.

As a bonus, in minima of MT Cas lightcurve, is shown little bump, real or not? 

Both are very interesting stars! 

How and where  I can find is TYC 3657-1980-1 ( Epoch: 2000.0 RA: 00h14m38.334s DE:+54?40'29.66") classified as a variable?

Cheers,

Timppa

And attachmets were??
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KTU
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And attachmets were??

TYC 3657-1980-1, a new variable star
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Sebastian Otero
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It looks like a DSCT with a period close to 0.035 d.

>>> How and where  I can find is TYC 3657-1980-1 ( Epoch: 2000.0 RA: 00h14m38.334s DE:+54?40'29.66") classified as a variable?

You should check VSX and make a search by position
http://www.aavso.org/vsx/index.php?view=search.top&ql=1

It is not in VSX.

It has J-K= 0.19 and B-V= 0.35 which is perfectly consistent with a DSCT.

APASS V data range between 12.384 and 12.426.
Your plot shows a range 12.57 - 12.60 or so but the plot with the two variables shows it at 12.43 - 12.46. Why the difference? Where did you get that values from?
In any case, you should use APASS Vmags for any comparison star you choose. These values are available through the UCAC4 entry in VizieR and you can also search for other information (spectra, colors, cross-identifiers, position).

Consider submitting it to VSX.
Create a VSX account and use the New Star Wizard to do it. It is a step by step process with useful examples.
Submit a magnitude range for it based on those APASS V comp star values. Use UCAC4 position for the submission. Add some cross-identifiers like those from GSC and 2MASS (the TYC identifier for the Primary name is okay). Determine the star's period, an epoch of maximum light and attach a phase plot as a supporting document. Use your epoch as phase 0 in the submitted phase plot, which should show more than one variability cycle for clarity (phases 0 to 1.5 or 0 to 2 for pulsators).

If you can get data on other nights, that would be great because the period based on only a couple of hours will be very rough. Also it looks like the star has a changing amplitude so it is likely multiperiodic. Increasing the time baseline of the observations always helps.

Congratulations for your discovery!

Cheers,
Sebastian
-----------------------
Sebastian Otero
VSX Team
American Association of Variable Star Observers


 

"APASS V data range between
KTU's picture
KTU
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"APASS V data range between 12.384 and 12.426.

Your plot shows a range 12.57 - 12.60 or so but the plot with the two variables shows it at 12.43 - 12.46. Why the difference? Where did you get that values from?"

I rushed with my observation. Checked out what went wrong.  Plot with the two variables was done with raw images which had not been calibrated! I had to learn to slow down and be more careful and  accurate. Sorry my misrepresentation.

Attached lightcurve done with calibrated images.

I noticed today that only 1.8" to east of TYC 3657-1980-1 (12.58mag) my Cartes Du Ciel show 11.8mag star UNA 1425-00348181. My lghtcurve contains both stars, and which star is real variable?

TYC 3657-1980-1             Mean J2000 RA: 00h14m38.334s DE:+54?40'29.66"

UNA 1425-00348181        Mean J2000 RA: 00h14m38.540s DE:+54?40'29.47"

USNO-A2.0 1425-00348181 = TYC 3657-1980-1
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Sebastian Otero
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UNA 1425-00348181 is not another star, it is just the USNO-A2.0 designation for the same star with a position somewhat off (BTW the correct format is USNO-A2.0 1425-00348181).
If your software has more than one catalogue loaded it may be displaying duplicate stars (that's why some programs have an option to avoid displaying one catalogue when another is active).

This kind of problem can be avoided if you search the star in VizieR instead of trusting software. There you would have seen that there is only one star in the area.
You can also check Aladin images to see what the field looks like.
Anyway, the USNO-A2.0 position was fairly off and that contributed to the confussion.

The question of how you calibrated your images still remains because your star shows V= 12.58 when it has V= 12.40

Cheers,
Sebastian

" The question of how you
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KTU
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" The question of how you calibrated your images still remains because your star shows V= 12.58 when it has V= 12.40"

Thanks for your effort with my data! 

Camera is Starlight MX716 ccd. Maxim DL 4 is software which perform the calibration. Master flat contains 23 images, Master Dark 15 images, Offset some 200 images. Calib images I used for this run is in attachment + 1 raw + 1 calibrated image. Flat images are (clear)sky flats. Filter I used is 1¼" Baader UBVRI - V-Filter.

Ref stars are (shown  pic in previous post - MT Cas Rfe and Chk stars.jpg):

Ref1: TYC 3657-1245-1 Visual magnitude: 11.58

Ref2: TYC 3657-1914-1 Visual magnitude: 11.42

Ref3: TYC 3657-1637-1 Visual magnitude: 11.46

No other corrections made.

Please tell me where it gone wrong, I'm trying to learn.

Cheers,

Timppa

Magnitude sources
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Sebastian Otero
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The problem is that you are not using proper magnitudes. Those are Vt magnitudes from Tycho-2. 1) They are not transformed to V and 2) they are not good for faint stars.

Ref1: TYC 3657-1245-1 Visual magnitude: 11.58 = 11.337 V (B-V= 0.18)
Ref2: TYC 3657-1914-1 Visual magnitude: 11.42 = 11.250 V (B-V= 1.53)
Ref3: TYC 3657-1637-1 Visual magnitude: 11.46 = 11.406 V (B-V= 0.09)

Ref2 is a red star, B-V is 1.53. It's better not to use red stars as comp stars because they could be variable. use stars with similar colors so there will be no differences caused by lack of transformation.
Since your variable is a DSCT it will be white-yellowish.
All this information can be found in APASS and is available through the UCAC4 entry in VizieR. That's why I had recommended to use those values for your comparison stars.

Once the values are changed the result will be okay (don't use the red star though).

Cheers,
Sebastian
 


 

For stars fainter than 10.5 don't use Tycho-2 data
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Just one addition to Sebastian's recommentations:

The Tycho-2 photometry below 10.5 mag has quite large error, this is why it is recommended to use APASS photometry data for stars fainter than 10.5V.

Apart from accessing UCAC4 Catalogue via Vizier or Aladin you can find APASS photometry on the APASS website,  or via Seplot.

Clear skies,

Robert

Tycho-2 and SeqPlot
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Just be aware that Tycho-2 magnitudes ARE transformed to the Johnson Cousins (standard UBVRIc) system in SeqPlot. Don't transform them again. 

Brad Walter

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484