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Excellent, Jack, good idea.
Perhaps you can also upload spectra to the Spectroscopy Database…….
Kind regards,
Marc.
Hi Robin,
Many thanks for your concern and experienced viewpoints. much appreciated !
To clarify something first: With ” incident light intensity” I did not ment throughput. It concerns the light bundle falling in on the grating of the spectrograph coming directly from the slit. Hence: Intensity depends on the energy and is proportional to the square of the Amplitude, which is sinusoidal and proportional to the slit width. Two effects are multiplicated here : increasing slit width increases the spatial fraction or area of the light bundle and besides that the spectral fraction. It is a common way to express the theoretical behaviour in analytical spectroscopy like absorption/emission/fluorescence type.
Throughput is the final result of the “Spectrograph train” and is proportional to the Bandpass/slit width.
Excellent Idea to compare the two set ups. I already used the CAOS calculator to see the preliminary difference, thanks Robin.
Anyway I’m certainly interested in the “set up result” comparison with Jack. As soon as he has uploaded his spectrum to the database we will start comparing fluxes. Also the excellent work input from Ernst, who always gives an evaluation of the recorded spectrum is very valuable. Last evaluation indicated a perfect and reliable match of the EW for the V and the R component on the baseline so far, so this is excellent news for this short exposure. We’ll see how it evolves…
Photometric slit recording tests are already foreseen, I hope Jack has also such a slit, so we can compare those also. Very interesting and scientifically important experiments.
Have a nice day,
Kind regards,
Marc.
Hi Jack,
Of course a different slit width influences the spectral recording behaviour. Indeed to better compare the two spectra I recommend converting the X-axis scale to Å and dito cropping between 6520 – 6620Å. However the spectral information of both spectra is very similar, taking in account the different moment of observation.
Increasing the slit width increases the incident light intensity and amplitude, but in this case slightly decreasing the Resolving Power. The incident light intensity increases proportional to the square of the slit width, so a compromise must be made to end up with a nice PSF,a good spectral baseline and SNR. In case of the newest CMOS camera’s impressive reduction of exposure times can be reached by optimal gain settings, cooling to -20 C° and appropriate dew/condense control.
Kind regards,
Marc.
Hi Jack, the same here, no major changes, baseline indicates slow decline.
Last days unfavourable weather, forecast for coming week unfortunately not good in our region.
Kind regards,
Marc.
Many thanks, Jack ! Much appreciated!
Indeed, you are absolutely right about the input of time and all efforts needed, but it was worth it.
Now we have again more free time to do observations and simultaneously record spectra. 😉
Kind regards,
Marc.
Hi Robin, Paul and Andrew.
Many thanks for your interest in our books, also on behalf of Richard.
Concerning the content of book2 a more detailed overview of the different chapters is available following this link:
Therein you can see the detailed table of contents to compare with former online documents.
For all people who have already downloaded the former online documents “Analysis and Interpretation of Astronomical Spectra” and “Practical Aspects of Astronomical Spectroscopy” those documents were in fact reworked and adapted to the new table of contents of book2. Therein I introduced a more detailed background on the chemistry and physics of astronomical interest for spectroscopy. Furthermore book 2 operates also as a companion for the Spectral Atlas containing additional astrophysical information running parallel to the plates in the Atlas. Therefore when I was reviewing the Atlas in detail I proposed another sequence of the chapters in contrast to the former online version.
This way the Twin book project is also a nice tool for lecturers within spectroscopy courses. The purpose of our works is to make a contribution to the knowledge of the growing group of amateur astronomers stepping into spectroscopy, even less “scientifically skilled” people, who are also interested in this relatively new field offered by their astronomy club or observatory.
For the more advanced amateur astronomer the books are a vademecum in the step up process in working together with professional environment.
To give an idea how the two books are synchronised you can find a presentation I gave last year following this link:
http://www.armandpien.be/slides/slide/twin-book-project-door-marc-trypsteen-8
and some excerpts presented at the optics study day at the UGent University on March 17th 2017 following this link:
https://www.docdroid.net/8uKTb9N/optdag2017tryponline.pdf
Kind regards,
Marc.
Great ! Many thanks for your interest Andy.
I’m very pleased to see on the “Astronomical Spectroscopy for Amateurs” forum that a “specialist” like Robin Leadbeater already is enthusiastic about the books.
It was great working with an editor like Cambridge University Press !
Kind regards,
Marc.
Indeed, thanks for this alert Ernst,
Besides your message: “it is not exlude that the eclipse could begin some days before the calculated date August 4th”
it could also be later. According to the work of Leedjärv et.al. (A&A 1999) it seems the orbital period has a tendency of increasing between the eclipses due to a possible mass transfer or mass ejection. (Approximately 1% per two former eclipses).
http://adsabs.harvard.edu/full/1999A%26A…349..511L
Anyway we hope the weather conditions will be favourable at the very moment of the (calculated) beginning of the eclipse.
Usefull weather info with “observation location” input possibility:
http://www.meteoblue.com or http://www.meteovista.com/international/4220/0
Kind regards,
Marc.
Hi Ernst,
Congratulations, nice presentation, reads smoothly! Important “to the point” scientific information for the amateur!
Your article on page 24 concerning P Cygni is a nice example of how the VV Cep campaign philosophy can evolve especially for the correction of the H-alpha line fluxes in respect to the M star continuum. Therefore we need of course photometry data of an eligible standard star.
Keep up this excellent magazine!
Will it stay free downloadable in the future?
Success!
Kind regards,
Marc.
P.S. Suggestion on the article on page 8: fig.3 instead of “erlaubte” simply “Energieübergänge” to avoid misinterpretations.
Hi Robin,
Nice work on AZ Cas. indeed difficult area, perhaps also something for my ‘poorman” 😉 debayered DSLR, which has a reasonable QE in the blue area.
Concerning the LHiRES dispersion the native is of course approx. 0.06 Å/px as you can see in the attachment and in a 3x binning absent environment. 😉
Kind regards,
Marc.
Hi Robin,
I’ll ask Ernst if a Pro-Am is foreseen or will be activated on VV Cephei.
Concerning the info links: strange those links do not work. Hope these attachments can help you.
Concerning the dispersion (the graph is a screenshot of BASS version 1.9.7) it was indicated within the BASS project software. Measurements by BASS gave for example in the red region: R= 11949@6571 Å, which was sufficient enough.
Initially without the 2x binning/zooming function the dispersion was in fact 0.17 Å/px which gives a more realistic dispersion for a LHIRES III 2400 L/mm with a slit of 35 µm and a 15 MP Canon Debayered DSLR with pixel pitch 4.69 microns.
So the original dispersion is 0.17 Å/px and the 2x zoom/binning 0.33 Å/px.
Kind regards,
Marc.
Indeed, Robin with a good background subtraction VV Cep will be quite doable for the H-alpha.
BTW do you intend also to register the high resolution spectra of the Fe II lines at 4233 Å ?
For that we need subtraction of a nearby M type stellar spectrum.
Kind regards,
Marc.
Hi Robin,
Oh sorry, AM/PM error.
Correct 24h notation implemented now. Thanks! 😉
Kind regards,
Marc.
Hi Ernst,
I’m glad you mention a possible “quenching” of the V component. This was also my very first impression when I saw my first spectra. I did not have time to check the spectra I registered yesterday (27.05) to confirm this trend. Perhaps it could also be an effect of momentary pulsations which could be the precursors of the coming eclipse?
In the beginning of next week I will certainly email you my spectra. As the weather here is changing to mainly cloudy and rainy with thunderstorms I hope to register next spectra in the second half of next week as the weather will be good again. Anyway I will contribute to this project on a regular basis.
Kind regards,
Marc.
Hi Robin,
I’m observing from a location next to the “Beisbroek” forest in Bruges, Belgium, so local time here is UT+2h. Last days we had very clear nights with excellent seeing, but now the weather is changing on cloudy and rainy with thunderstorms coming over. Perhaps the second half of next week will be the next opportunity to observe. Unfortunately until mid July we must undergo the annual period of the so called “gray nights” or twilight nights. Fortunately the beginning of August will give enough dark nights to register the start of the VVCep eclipse!
Kind regards,
Marc.
No problem, James, if the pieces are too small to rub you can follow an alternative procedure: pulverize some pieces to obtain approx. 1 or 2 grams of powder, put it in a glass test-tube or anything similar. Add slowly the acid solution (Nitric acid or Hydrochloric acid 1% aq. solution) to solve the powder. Then add ammonium hydroxide solution (10%) to make alcaline. In case Iron is present you will see a brown-yellowish precipitate which is mainly composed of Iron hydroxide. After filtering add some droplets of a DMG solution (1%in alcohol) to the filtrate: if meteorite material is present you will see a reddish colored precipitate.
Kind regards,
Marc.
Hi James,
To check if your “Gutter collection” contains possible meteorites you can try following tests:
1. Native Iron test: a magnet is attracted. This test was apparently positive.
2. Streak test: Therefore you scratch the rough side of ceramic material ( such as an old bathroom tile). If negative, this means if no streak (colored or not) is visible, it is a vote for a meteorite.
3. DMG test or Nickel test. This can be done qualitatively bij etching a part of the material with an acid solution (Nitric acid or Hydrochloric acid 1% solution in water). Afterwards you rub the stone with a solution containing 1% DMG (Dimethylglyoxime) in alcohol with 10% ammoniumhydroxide. (available at local pharmacies or on line shops). If positive means a red color is appearing. You may then go to a specified lab to do a quantitative test to determine the % Nickel.
4. Estimate the density of the rock: first weigh it on an analytical balance (ask local pharmacist), then put it in a measuring cilinder filled with water, put the rock in it and calculate the difference of the water level. Calculate density which is mass divided by volume. Depending on the type of meteorite this gives 3.5 to 4.5.
If all tests are positive go to a university lab for detailed analysis!
Success,
Kind regards,
Marc.
Hi David,
Many thanks for this friendly welcome. Encouraging enthusiastic people in the exciting world of spectroscopy is my mission and passion.
Concerning the LR spectral possibilities in case of VV Cep:
Because measurements of Radial velocities, Equivalent Widths and V/R component behavior require real R values >10000 those measurements are not possible with a low or medium resolution spectrograph.
Nevertheless LR recordings are certainly welcome for other purposes. Here come two doublets to the scene: Sodium Na I at 5889.95-5895.92 Å and Potassium K I at 7665 – 7699 Å . Their behavior (IP) and broadening is interesting to study general behavior, observe effects such as reddening, which is important to estimate temperatures & distances. Also the fact that with LR a broader spectral range is visible, which can give insight in the overall behavior of interstellar mass transfer around the primary eclipse period. So LR spectral recordings are certainly welcome and I encourage interested people to participate! Exposure times for Alpy and LISA between 180 and 300 s will be sufficient, depending on telescope size.
Of course we must keep in mind that spectrographs like the Alpy and LISA are in fact designed especially for the study of faint astronomical objects.
So LR spectra can be uploaded to the database, so we can compare them individually.
Success !
Kind regards,
Marc.
Many thanks, Ernst, highly interesting !
Indeed developing a model for V/R variability in case of VV Cep needs more measurements. Therefore the upcoming campaign for VV Cep is very important. Additionally,in case of other eclipsing binaries possible ideas applicable to the VV Cep system can be transferred. Most recent concerns a 3D modelling of the accretion disc in an eclipsing binary, here V1239 Her :
https://arxiv.org/pdf/1702.00587.pdf
I wondered also if VV Cep has already been subject of asteroseismologic studies/recordings, as spectroscopy is limited to the line of sight observation.
Kind regards,
Marc.
