Forum der Vereinigung der Sternfreunde

Th-Ar lamps come with a price tag I don't like. They need an expensive power supply unit.

However, I found on ebay two Argon bulbs for a flashlight. It is a 8.63V 0.5A bulb. It should arrive next week. These are "Phillips PR20 Argon Torche Lamp 8.63V 0.50A P13,5s"..
I am curious to see the their spetrum.. They seem to be powered by DC current.
Admitting that this sounds like a promising lamp for calibration, can I power it simply, or do I need some really stable current, or some other expensive care like the ThAr lamps?

It uses an odd voltage, 8.63V.. Judging from the flashlight, it seems it was meant to be powered by 4 1.5V C-type cell batteries.
Is it somehow likely that differences in current will cause shifts in Argon lines, or some artifact that can spoil calibration at the high dispersions a LhiresIII can reach with the 2400 l/mm grating ?

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Fil.

Big Wooops!

It seems these are argon-filled filament lamps.. So I think I just spent 5€ unnecessarily.. This should give me a nice black-body spectrum, instead of emission lines from argon discharges..
This brings me to my despair-question: Would molecular Argon have any usable absorption lines ?
I should have known when I noticed it uses continuous current, and not alternate current...

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Fil.

Hi Filipe,

I haven't got a clue, really but from the link below it seems that an Argon filament lamp can work quite well:

http://astrosurf.com/buil/calibration/lamp1.htm

Cheers,
Sander

Hello Sander, Filipe
These are discharge lamps not filament lamps, but they do work well for calibration. Unfortunately the Argon model cannot be found in Habitat in the UK any more but perhaps still in Germany?

Robin

Hello Filipe,

I have to disappoint you, Ar in its ground state as is contained in an filament lamp absorbs only in the UV, around 1000A. See the energy level diagram below. From:
http://physics.nist.gov/PhysRefData/ASD/lines_form.html
The emission lines can be seen only in a glow discharge or otherwise excited Ar. This is what happens in these Filly lamps.

Regards, Martin

Hello together,

I searched this kind of lamp some months ago on german webpages, but without succes.

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Herzliche Grüße / best regards

Lothar

https://lotharschanne.wordpress.com/

Hello all,
I think the Ar Filly lamp (3 blue arrows) is not available any more but there is some interesting news from Christian Buil on other new Filly designs.
The dots design has Ne and Ar and Xe and the rose design has Xe.
http://astrosurf.com/buil/isis/He_calib ... filly2.jpg

Robin

Thanks Robin,

we have it here:
http://www.habitat.de/pws/ProductDetail ... irect=true

Just ordered

Sander

Christian Buil has just confirmed that both designs (rose and dot) have the same spectrum (Ne, Ar and Xe)

Robin

Thank you everyone!

If I was to burn out the filament on one of the Argon-filled incandescent bulbs, the only current that could go through the lamp would have to run through the gas inside it, thus causing a gas-discharge! What prevents me from applying such high current that would cause a discharge on the available Argon inside the lamp? (crazy idea) Why would this not work ? Would I be melting something that I shouldn't ?

On a different note, and not trying to compete against the Filly lamp price, but there are cars with Xenon headlights.. Would these probably be of any use? Has anyone bought or rented a recent car and pointed a Lhires at it's headlights ? I would like to see the spetrum of a Mercedes!

I also remember neon lamps used in car tuning.. I supposed those would be somewhat ready for connecting to 12V power, however, I am skeptical that these lamps would produce a nice narrow emission spectrum.. I have a feeling that lamps that are coated on the inside tend to have distracting wider features in the spectra, like fluorescence bulbs...

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Fil.

Hi Filipe,

the incandescent Xe bulbs would not ignite when filament is broken because pressure is not correct, unless you apply several 1000 V. Fo Xe headlights see here:
http://en.wikipedia.org/wiki/Headlamp#H ... ht_sources
or more detailed:
http://de.wikipedia.org/wiki/Xenonlicht
for spectroscopy they are not useful because they operate at high pressure, giving broad lines, similar to sodium high pressure street lights

Regards, Martin

Martin, thank you!
I'm learning so much about lamps, recently!

Yesterday, I found on ebay a shop selling a variety of gas-discharge tubes with a variety of gases inside.
http://www.socalnevadausa.com/servlet/t ... Categories

Looks interesting but still requires some electrical adaptation before it can be used reliably in the field, without anyone getting an electrical shock..

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Fil.

Fil,

Did you see these on the same site?
http://www.socalnevadausa.com/servlet/t ... Categories

They look like the Filly lamps but for 110V which would be even safer than 250V

Robin

Yes I recognized the rose one.. I also recall the two-color flower from somewhere.. But I was not certain about them, as the pictures are a bit dark. I can't be certain if the lamp is exactly the same.. If so, perhaps there is some electrical adaptation inside the lamp-holder.
Or perhaps the lamp works with either 110V or 220V.. I would expect one version to be dimmer than the other, no?

How would the two-color version work? What can be colouring the light? glass pigment, or different gas combinations? How do the famous advertising Neon lamps work regarding different colours?

Another question about Filly lamps: In my understanding a current travels through a gas from an anode to a cathode, but the lamp appears to be made of a single "wire".. Is that "wire" really a glass tube in the shape of a rose? If so, how come it is so cheap ?

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Fil.

Hello Fil,

My Filly lamp has now arrived so I can answer the questions.

Neon lamps have a resistor in series to limit the current. The resistor is larger for 250V compared with 110V. The brightness can still be the same. The glass of the filly lamp is cold of course but the base is quite hot. The resistor must be in the base.

There are three electrodes in the filly lamp. Two are are close together and are connected to the electrical supply. These produce an orange glow when the electricity flows through the gas between them. The third electode is coated with a phosphor chemical which glows green when the uv light from the glowing gas excites it. It is not connected to the electricity. The green light from this electrode is not useful for calibration because it is a broad continuum.

The lamps are not expensive because they are quite simple and are made in China in large quantities.

I have attached a quick badly focussed spectrum taken with my hand held spectroscope showing the wide range of lines (Ne is strongest but the other lines in the blue and green from Ar and Xe are also useful)

Cheers
Robin

Thank you for a nice description, Robin!

It would seem the best way to use such lamp would be to wide the green image behind the neon electrodes..

Still, I am curious to find out what is the longest exposure that one can make of this lamp (varying with spectral region) before a line saturates.. I figure this will be important if one decides to hang a bulb in front of the telescope while catching object photons on faint objects..

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Fil.

Hello,

I think a better way is the use of HCL's. They have sharp emission lines and when the filling gas is Ar then they have also a lot of lines in the short wavelength area.

Lo

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Herzliche Grüße / best regards

Lothar

https://lotharschanne.wordpress.com/

Hi Fil,
The answer will be to reduce the time the lamp is switched on. We have some work to do first identifying all the lines and measuring their strength then we can decide on exposures.

Lothar,

The lines from the Filly lamp are also very narrow. I have found two Kr lines near KI 7699A for example. With the lamp mounted in front of the telescope in line with the slit, they are narrower than the LHIRES internal neon lines and the telluric lines measured on the star.

With Ne Ar Xe and Kr in the gas there should be many lines to chose from. Not as good as Th Ar of course but much cheaper at only 4 euro

Cheers
Robin

I can confirm what Robin said, the Filly bulb lines are very narrow, and not very intense. Attached is a recent 200A wide simultaneous exposure of del Sco in the HeII (4686A) region with the Filly (argon only) bulb in front of my C11 corrector plate. The total exposure is one hour and the argon lines are still narrow and there is certainly no sign of saturation.

Bernard Heathcote

My Filly lamp has arrived and I was a bit disappointed that the intensity is so low.
It is just a glow around the electrodes. Can be used for direct illumination, but not with a diffuser (to get homogeneous slit illumination).
As a workaround one may move the lamp over the aperture during the long exposure, to get some sort of complete slit filling.
For me this is not critical, since I'm slitless on stars, but for accurate radial velocity determination this may be an issue.

Attached some pics from the echellette prototype spectrograph to illustrate what I measured. I used 2x3 binning (so sharpness cannot be judged) to keep integration times lower.
From top to bottom:
- 60s neon fluorescence tube (car tuning part )
- 60s filly lamp
- 300s filly lamp, 5x contrast enhanced (factor 25 w.r.t. 60s image)
As comparison for the wavelengths:
- Sky light (unbinned) 2nd order from bottom shows H-alpha and O2-B, 4th order from bottom H-beta at left and MgI triplet at right, upper order has at left the G-band and H-gamma

Sander

Hello Sander,
There is no need to move it around the aperture, just mount it in line with the slit. (see a attached. My slit is orientated in the Dec direction) My checks compared with Tellurics show Kr lines near 7699A it to be correct within the measurement error (1km/s)
You can even leave it in place during the exposure. The loss of light is only about 0.1 mag on a 280mm aperture. See also Buil's tests here.
http://astrosurf.com/buil/isis/He_calib ... method.htm


Cheers
Robin

Hi All!

I tried to order the lamp at www.habitat.de
But the first problem is, they deliver only to germany, and the payment is only via credit card possible. I am from Austria, and i have no private credit card (and i need no).
Is there any other possibility to order the lamp at a other dealer?

Regards
Richard

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Sternwarte Gaisberg / IAU Observatory B21
www.observatorium.at

Hallo Robin,
In several shops I tried to get such a lamp socket without succes. Do you know the producer or any name of the item?

regards
Christian

Hallo Christian, The socket is standard E27 ("large" fitting), for 220V as in any household bulb.

Sander

Hello Sander,
thank you for this information. But that's not what I really mean. The socket on Robin's telescope has a hinge which enables him to position the lamp off the rays of a star or in front of the corrector plate. I am not able to find such a socket.

Regards
Christian

Hello Christian I bought it off eBay. It is a photgraphic light. There are many different suppliers but this is the one I bought.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0833503232
They are also available in France
http://cgi.ebay.fr/280698319176
Perhaps you can find them on ebay.de too

Cheers
Robin

Thank you Robin,
it was no problem to buy such a socket. For the German readers: it is a proxistar Lampenfassung E27 mit Reflexschirmhalter (ohne Reflexschirm!).
It would be nice when you place your 2D-spectrum obtained with this configuration in this forum.
Regards
Christian

Hello Christian,
I have already made some comparisons of the accuracy of the Ne lines near H alpha and Kr lines near 7699A with the telluric lines. The lamp lines agree with the telluric lines to better than 0.03A (1.5km/s)

Attached is the result for epsilon Aurigae at 7699A (the range is 7670-7720A at 0.3A resolution) the two lines are Kr from the Filly lamp. The exposure is 6 x 600 sec. There is also a double Ne line just to the right of the field which could be used by moving the wavelength a bit.

Cheers
Robin

Here is a comparison of the accuracy of the LHIRES internal neon, telluric line (twilight sky) and filly lamp near H alpha.

The calibration was made with the internal neon amd the filly lamp and telluric lines were compared with this. The differences are small but in this case the telluric line wavelength would have been closer to the publiahsed value if the filly lamp had been used instead of the internal neon.

Robin

After a big help from Robin, I now have a Filly bulb (Fil with a Filly)! I think the best way to put it in front of the aperture is with the electrodes facing sideways. This reduces the green glow and appears to increase the intensity of the interesting discharge color. I believe Robin has it set up this way in the picture.

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Fil.

Hello Robin,
I am interested in learning how you process your spectral files. I took some spectra of my filly lamp, processed it with Visual Spec and saved the results as bmp-files. My problem is to mark and comment the lines because of the limited graphic capabilities of VisualSpec.

Christian

Hello Christian,
The line centre labels were made using Vspec but as you say it is not very flexible so I normally save the Vspec graph as a bitmap image using the "file" "export bmp" function and do the labelling in a separate graphics program (Paintshop Pro in this case)

It is also possible to use gnuplot which Vspec can connect to directly ("tools" "run gnuplot") but I have not tried this.

Cheers
robin

Hallo,
hier ist das Spektrum der Filly-Lampe. Leider konnte ich nicht alle Linien zuordnen. Ich bin mir auch nicht sicher, ob meine Angaben immer richtig sind. Insbesondere bei den Ionen Xe II und Xe III bin ich mir unsicher, da besonders letztere bei Glimmentladungen nur sehr selten vorkommen dürften. Vielleicht kann mir jemand von Euch weiterhelfen. Die mm-Angaben im Dateinamen beziehen sich auf die Einstellung der Mikrometerschraube. Verwendet wurde ein Lhires III mit 600 L/mm. Kalibriert habe nur mit zwei Linien, daher können zwischen der Skala auf der x-Achse und den Wellenlängen der einzelnen Linien leichte Unterschiede auftreten.
Viele Grüße