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February 2018 b Per observing campaign - Spectroscopy

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weo
weo's picture
February 2018 b Per observing campaign - Spectroscopy

AAVSO Alert Notice 610 announces an observing campaign on the bright (V~4.57) triple star b Per to cover the interval before, during, and after an eclipse predicted for mid-February 2018. Please see the notice for details and observing instructions.

For this campaign, spectroscopy is covered in this forum thread, and general discussion and recommendations and photometry are covered in the Campaigns and Observation Reports forum thread "February 2018 b Per observing campaign".

Many thanks, and good observing,

Elizabeth Waagen, AAVSO HQ

perdiguero
perdiguero's picture
About spectroscopy...

Thank you very much for the observational alert. I participated in the last three photometric campaigns and I will enrol again into the incoming one. We will stay in touch!

Just only a request about spectroscopy.  I could take spectra with a Baader slit spectrograph, able to give resolutions of 800 (covering almost all visible spectrum) and 5000 (covering a window of 700 A wide), but the friends of Aras Spectroscopy could take spectra with échelle-spectrographs and resolutions of 10.000 or more. More details about the requirements of resolution, window coverage or most important bands, etc... would be apreciated.

Greetings,
Fran

perdiguero
perdiguero's picture
First spectrum

Hello,

here is a first spectroscopy approach to b Per. The resolution is not very good (I have to focus better) but I hope it will be of some interest. I choosed a window where Ca II bands could be visible.

Taken with a RC 14" and a Baader DADOS slit spectrograph (1200 l/mm, slit 25 um, R=4194, 0.1228 A/px). 7x200" integration.

Greetings,

Fran

a_mirosh
a_mirosh's picture
Spectroscopy of b Per in North Carolina

Hello b Per observers,

Our team of two professional and one amateur astronomers has been observing b Per at two locations in North Carolina since October 2016. We use a 81-cm and a 60-cm telescope equipped with Sheyak's Eshel spectrographs and cover a spectral region from ~4100 to 7900 A with a resolving power of ~12,000. Over 100 spectra were taken in the 2016/2017 observing season and nearly 40 since September 2017.

In order to reach the goal of constraining the spectroscopic orbit of the internal binary in this triple system, a spectral resolving power of at least 10,000 to precisely measure the radial velocity is needed. At the same time, lower resolution spectra, especially beyond the above mentioned range, would be very helpful for searching for signs of the third component. The most important period for the spectroscopic observations is the time around the expected eclipse. However, observations before and after the eclipse are also important to provide comparison with the data taken during the eclipse. The signal-to-noise ratio in the continuum has to be high (at least 100), as the third companion is supposed to be much fainter than the stars of the internal binary.

We are planning to keep observing the system every clear night until the end of the season in April/May 2018.

Anatoly Miroshnichenko

psomogyi76
Feb.11: no obvious change (H8 - CaII H region)

I've just finished with a spectrum serie (till cloud), by features (Si II, H8, Ti II 3913, CaII 3933, nothing new) there is no change to my previous weeks (see: http://www.spectro-aras.com/forum/viewtopic.php?f=5&t=1952). Evaluating velocities later. Hope somebody continues, forecast got bad here for the next few days.

- Peter

FJQ
FJQ's picture
Spectroscopy of b Per

I've taken Ha, Hb, & CaK spectra (LhiresIII with a 2400 l/mm grating) of this star on 4,7,8,9,10, & 12Feb18 while taking simultaneous RVB photometry with an ST-8xe and 400mm mirror lens system ontop of my spectra taking telescope.  I still need to upload some M67 data to derrive my transform coefficients with this system.  Should have some results by tomorrow....hope it clears for one more run at b Per!

James

p.s.  Got another CaK and photometry run yesterday (13Feb18) just before clouls closed up.....thats probably it until Thurs nite (16Feb18UT).

FJQ
FJQ's picture
Spectroscopy of b Per

I'm pretty new to analyzing spectra, but here is a comparison of velocity corrected H-Alpha spectra taken with a LhiresIII (2400 l/mm grating) on 4 and 14 Feb 2018:

Here is a link to a larger version of the .png image:

http://astroimage.info/spectra/b%20PER%2004&14Feb18%20VC%20corrected.png

The difference between them in 1.8A.  I have Hb and CaK for these and other dates I'm about to analyze as well.

James

Robin Leadbeater
Heliocentric corrected ?

Hi James,

Have these been heliocentric corrected ? (The tellurics lining up suggests they may not be)

Cheers

Robin

psomogyi76
aftermath on the CaII region

James,

You spectra seem to be the closest by time to the eclipse, despite my long series from "other" times...

Such RV shifts turn to be well expected (outweighting the heliocentric differences in a few days). Let me show here my period-RV diagram I've experimentally processed so far:

bPer_20180211_state_RVs.png

(Details: http://www.spectro-aras.com/forum/viewtopic.php?f=5&t=1952#p10225 )

However, such a curve seems to be known (see SB9 database), though I'm rather curious why mine is not perfectly sinusoidal.
It would be nice to see professional evaluations gathered so far, to put our results in context.

Cheers,

Peter

FJQ
FJQ's picture
Heliocentric corrected ?

To:  Robin,

I used Bass V1.98 under the Tools, Calculate Velocity correction.  The results box that comes up after I input my Lat/Long/Elev and b PER's decimal RA & Dec says "Barycetric Correction (km/sec)."  I'm going to have to take some time to learn how to do the Heliocentric correction in Isis.

James

Robin Leadbeater
Heliocentric correction

Hi James,

The correction is very easy in ISIS. You can either just tick the box when doing the data reduction or use the calculator under the "misc" tab which calculates both barycentric and heliocentric values (though the difference only a few m/s so only really needed for exoplanet work)

ISIS knows your location from the setup. The date of observation and name of the target come from the fits header and the target coordinates are brought from SIMBAD automatically provided you are connected to the internet.

Cheers

Robin

FJQ
FJQ's picture
Heliocentric correction

To:  Robin,

Thanks for the feedback.   I usual stick very clear of any IS function besides (MaximDL) renaming, flats, and image calibration; spent literally 100 hrs on study of IS to get used to spectral functions and ignore all the French still showing in the menu;  purely monolingual without google translate!

I'm going to my high altitude dark sky site to shoot LhiresIII and LISA spectrum at a dark sky site.   Will work on Heliocentric correction in IS when I get back....maybe can figure it out by March hopefully!

James

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