Daystar Quantum tuning question

[LTHB]

Yesterday I had an afternoon of clear sky, so I experimented with the settings of my new toy, a used Daystar Quantum 0.5A. (It's been sitting on my shelf for more than half a year, so the bad weather period coming with new gear is over...)

It takes quite a long time to reach working temperature after changing the wavelength setting, so I didn't manage as many test shots as I wanted to, but I got three for the display settings 656.28A, 656.29A and 656.30A:







As many Daystar users report that the Quantum's display settings are not necessarily reliable, I'd like to ask the experts here if one of these test shots looks close to or on band or, if not, how far off they are. (I used the same flat for all three images, which probably accounts in part for the uneven brightness. I normalized the histogram for all three images and applied the same sharpening settings.)

Thanks in advance! Kind regards,

Frank

[christian viladrich]

Hello Frank,
I am happy you finally had some good weather.
The DayStar is actually quite long to reach balance temperature. I have made temperature measurement on my Quantum 0.6A with an IR thermometer. It takes about 25 min to reach the reference temperature (58.3°C) starting from 21°C.
Looking at your three pictures, I would say the first is the closest to Ha. Then, as you go to the red, the spicules become darker and darker, which is the sign you are going away from Ha.
I suggest you try three images :
- first : 6522.8
- second : +0.2 A, allow 20 min stabilisation
- third : -0.2 A, allow 20 min stabilisation.
If the first one is actually on Ha, then the second and third should look the same.

[marktownley]

Number 1 definitely the closest on band - would be worth trying some going down from 656.28, but number 1 looks ok to me.

[LTHB]

Thanks, Christian and Mark!

Christian, that sounds plausible! The air temperature was a little below 0°C yesterday, which probably makes it not easier to reach the reference temperature. So I'll ignore the green light of the LED for the tests and wait at least 20min after each change of the settings. Hopefully I can do some more tests this afternoon.

Thanks for the advice!

Frank

[rsfoto]

Hi Frank,

I never got my DayStar Quantum 0.4Å to work properly and perhaps you read the story.

I agree with Mark, for me comparing with my normal Coronado etalons the first image is the most close or on band.

Congratulations that you got a working DayStar Quantum filter

[LTHB]

Thanks, Rainer! I read the depressing story of your Daystar filter - makes it somewhat hard to recommend Daystar products.

I had in fact not planned to buy a Daystar Quantum, but after some reading here on SC and other forums had decided that SolarSpectrum was clearly the better option. However, my experience is that these are hard to come by, at least in Germany: I tried to order a SolarSpectrum filter from Baader (the local distributor) more than three years ago, but they kept telling me time and again that I have to wait for a few more months. After three years I was kind of tired of that, so when the chance came to purchase a used Daystar filter, I took it. (The seller showed me videos taken with the filter, so I felt the risk of getting a flawed copy was manageable.)

Three more test shots from yesterday, with the display settings Christian recommended, 656.26, 656.28 and 656.30nm, with 20min time for each setting to reach a stable temperature:







I think I can see again that at 656.30nm the spicules are darker, as Christian mentioned. I think they are also a bit darker at 656.26 as compared to 656.28nm - is this also a sign for getting off-band on the blue side?

If weather permits, I'll try smaller steps from 656.28 in the direction of the blue wing.

Kind regards,

Frank

[marktownley]

Looks like the dial is pretty spot on at 656.28, but more exploring is always good

[Bob Yoesle]

I have experienced my Quantum PE filter indicating it is on-band at 6562.8 when in actuality it was significantly off-band high. Therefore, when it is returned from DayStar I will evaluate it using a Hydrogen spectrum tube as described elsewhere on the forum.

The filter will demonstrate a single etalon fringe due to the blocking filter eliminating the off-band etalon peaks. When on-band the single etalon peak will become a dot instead of a ring. This would be the definitive way of establishing a numerical offset differential of the indicated versus actual tuning.

Etalon fringe patterns.jpg (42.62 KiB) Viewed 226 times

Etalon fringes and CWL sm.jpg (223.69 KiB) Viewed 235 times

[DavidP]

You know what would be cool? A group purchase of a Hydrogen spectrum tube power supply. It seems like a quality unit that can power a tube for longer than 30 second intervals can be had for about $300. It could be passed around to those who go in. Tubes are cheap and easily purchased individually. ?!?!

[LTHB]

Thanks for this terrific information, Bob! Actually, I had missed the thread on hydrogen spectum tubes, great idea! It sounds like a project for the next holidays! (Although there is already the SolEx project that Christian posted...)

David, I like the idea of a piece of gear travelling literally all over the world in the SC community! (On second thoughts, however, my recent experiences with the German mail services make me wonder how many stops that power supply would make before its trail disappears somewhere..)

Meanwhile I took three more test shots, this time with settings at 656.26, 656.27 and 656.28nm:







Again, I'm not sure which one is closest to the h-alpha line center, but I would probably guess the second (when the display said 656.27nm).

Comments, as always, much appreciated!

Frank

[rsfoto]

... German mail services make me wonder how many stops that power supply would make before its trail disappears somewhere..)

Do not send it to Mexico. I will surely disappear ...

[christian viladrich]

You know what would be cool? A group purchase of a Hydrogen spectrum tube power supply. It seems like a quality unit that can power a tube for longer than 30 second intervals can be had for about $300. It could be passed around to those who go in. Tubes are cheap and easily purchased individually. ?!?!

Actually, I have fine tuned my DayStar PE 0.6A, SolarSpectrum 0.3 A and SMn-35 0.5 A this way ;-)

Still, you should remember that a small CWL is introduced by the f-ratio used on the telescope. This can be calculated and accounted for easily.

[DavidP]

David, I like the idea of a piece of gear travelling literally all over the world in the SC community! (On second thoughts, however, my recent experiences with the German mail services make me wonder how many stops that power supply would make before its trail disappears somewhere..)

Frank

That is so funny you say that. My daughter lives in Berlin, and I have sent things that have taken weeks. I once sent something that took 4 months. I have sent things that never arrived. But when I order things from Teleskop-Expres via DHL, I receive them in less than a week, never with any problems. Germany seems to run so smoothly in general. Is there something about their postal service, or maybe a secret I don’t know about how to ship there?

[Bob Yoesle]

Actually, I have fine tuned my DayStar PE 0.6A, SolarSpectrum 0.3 A and SMn-35 0.5 A this way ;-)
Still, you should remember that a small CWL is introduced by the f-ratio used on the telescope. This can be calculated and accounted for easily.

Hi Christian,

Do you mean there is a CWL shift introduced by the f-ratio? Can you relate this as a function or proportional to focal ratio?

Or are your referring to the FWHM being widened by a faster f-ratio making a precise CWL more difficult to determine with the telescope versus the etalon tube, which has no f-ratio?

And it would be wonderful to have you participate in the Zoom meeting on February 21 to discuss your findings:

viewtopic.php?f=4&t=30735

[LTHB]

Thanks for the information, Bob! After reading on Christians website and taking some clues from the Zoom meeting I think I'll get a hydrogen discharge tube. This should give me a reliable basis for evaluating the etalon instead of (more or less) educated guesses.

[christian viladrich]

Here is an example of tuning my PE 0.6 A with the Ha lamp. From left to right : Ha, Ha + 0.5 A, Ha + 1.0 A.
We can see the central peak evolving into a small ring as we move away from the center line

http://astrosurf.com/viladrich/astro/in ... lambda.jpg

The wavelength displayed on LCD screen was quite correct in my case.