V711 Tau - a RS CVn star

V711 Tauri is a RS CVn star. It is a binary system with a late evolved chromospherically active star and a main-sequence or sub-giant companion. With a magnitude V=5.64, it is fairly bright and within reach of 0.28m telescope with the echelle instrument. The binary period is 2.8 days.

A key article on this system and why to observe it is there:
https://arxiv.org/abs/astro-ph/0303154

telescope inside the dome with optical fibers

On the night of october 9th, I woke up around 1am to check the sky and it cleared up from cloudy evening. I started acquisition of 10 min exposures, signal seemed ok.

 first spectrum of the serie, quickly reduced in ISIS

The signal went up at the beginning as the star was rsing high in the sky but after few hours I noticed the signal was getting poor - a quick check outisde confirmed that clouds were coming back. Oh well, I got 20 spectra covering around 4 hours of time.

observatory control computer screen shot at the end of the acquisitions

I reduced the 20 spectra together to obtain a high signal-to-noise spectrum but I also looked at the individual spectra over time around Halpha, no significant change nor shift seems to appear (maybe a small shift, to be confirmed).

merged spectrum (over the visual domain)

Halpha (order 34) 

spectrogram over 4 hours (Y axis is time, X axis is wavelength); bright line is H alpha

Olivier Garde observed it on october 3rd and I was able to observe it again night of october 11th.

PRISM control screen at the end of the observing run on V711 Tau on october 11th

with Gemini hand controler & telescope camera also visible

Here is a comparison of those three observations, there are some radial velocities involved due to the binarity of this system (Doppler effect):

and the code in MAtLab using my scripts to obtain this graph (modified for the Y legend & title full text):

otz_plot -600 800 0 1 '_v711tau_20161003_966_34.fit' -f '_v711tau_20161009_987_34.fits' -f '_v711tau_20161011_950_34.fits' -y p 1 2451142.943 2.83774 -w Ha -s 6549 6550 -x RVH -t s 'V711 Tauri (RS CVn star) - Halpha - Olivier Garde & Olivier Thizy' -l Doi -p png

Here is the spectrogram obtained in ISIS with the one from october 9th (on top) as a comparison:

On can see that Halpha emission (but not only) is actually shifting toward the blue during the approximatly 5 hours total exposure. A graph showing the first and last exposure show a shift of about 40km/s in about 5 hours:

This is promising for the future and more observations are required!...

Jour de la Nuit - Le Versoud with GAG

October 8th, 2016 was a national day to switch back the stars. Around 700 event were organized in France. One occured in Grenoble and one in a small city close by - Le Versoud. It was organized by the GAG - Groupement Astronomique du Grésivaudan: https://groupeastronomiegresivaudan.fr/

I went to help them and after a talk done by the president of the association, wer were lucky enough to see the Moon between clouds. Around 30 people were there, with lof ot small children.

441 days later...

Hello,


I have my observatory up and running for 441 days now. I looked at my notes and I have observed 60 nights - so around 14% of the nights or an average of more than 4 nights per month.

Total observing hours is around 300h (so 5h in average per night... but winter nights are coming back!). I also have a strong increase after I left Shelyak with 32 nights and 179 hours observing since that time - I am wondering why... :-)

I recorded 230 spectra/targets (around 4 per night) for a total exposure time of 153h (6.4 days!) so an average of 40min total exposure time per target.

My exposure/observing ratio is 51% (in other word, I have around 49% 'overhead' time). This could be just time to start & open the observatory, visual observation with other people (they are included in), time to point a target, maintenance time, etc... There is room for improvement there as 49% is too high. Several issue with guiding and GoTo accuracy due to motor stalled or motor lag is the primary root cause and I'm working to improve it.


I have put my spectra in a personal database, similar to what I use for ARAS spectra I am responsible for. The list of spectra with a thumbnail:
http://www.astrosurf.com/thizy/obe/db/index.htm

And the last one only with some details for each spectra:
http://www.astrosurf.com/thizy/obe/db/last_index.htm

Titan mount adjustments & Number of exposures calculation using SNR

OK, I made some finetuning of the mount few days ago and acquisition are much easier now. I still have few "motor stalled" so I need to work on this again but now the pointing model is great and I can point my targets within the field of the guiding camera. If I resync on a target and go to another one close by, usually it points very close to the fiber hole!

Tonight's session is done remotely from the house. It works great and I can watch Star Trek Into Darkness on TV tonight! :-)


I have also improved my procedure by measuring the SNR of the first spectrum (or using the first two spectra, dividing them and calculating single exposure SNR = measured SNR / 1.4). I then use the single exposure SNR to calculate the number of exposure to reach 100 of signal to noise ratio:

Nb Exp = (100/[single exposure SNR])^2

My first exposure time is set so I reach maximum ADU around 40000. This means that once I know the number of exposure, I can reuse the same number for all my acquisition of the same target no matter what sky conditions are, I just adjust the exposure time to reach 40000 max ADU...

Constellation 738 - Savoie/Isère meeting with clubs

Some time ago, I initiated some public outreach observing evening in Revel with several people and clubs from the area. Some people - specially from the GAD (Groupe d'Astronomie du Dauphiné) club - have picked up from there and organized some discussions between clubs & isolated astronomers to group together and organise combined events.

On october 1/2, in chamrousse, an 'Inter Club' was organised and a name (Constellation 738: 73 for Savoie area & 38 for Isère area) was proposed. Goal is to help in communicating events, work together if/when the Planetarium of Grenoble/Claix is build, organize big event together...

Here are some pictures from GAD during this event where I did a talk on introduction to spectroscopy...

GAD web site is: http://www.astrosurf.com/gad/