The Lowspec spectrometer

[Thalestris24]

4 minutes ago, Merlin66 said:

I don't have any first hand knowledge of the LowSpec, so I have to assume that Paul designed it correctly.

In my Littrow, with an 1800 l/mm grating which gives a limited wavelength coverage, I have to refocus at every micro setting.....the focus can vary up to 1.8mm across the visible spectrum.

It was 42 deg C yesterday and they're saying tomorrow could be even hotter!!!

 

If you're interested the Lowspec 3d files are here with the assembly guide pdf at the bottom of the file list.

My old eyes find it hard to judge focus - I must see if I can get my cataracts done. I'll ask my GP to refer me but I expect waiting times are long.

I was thinking about incorporating a calibration light source(s) - worth it?

I'm always complaining about the cold here this time of the year - there was a hard frost this morning. It never gets very hot in the summer - mid to high 20's at best, on a few days of the summer. I couldn't cope with Oz high temperatures!

Thanks

Louise

[Merlin66]

I’ll contact Paul....

yes, a reference lamp ( neon or Richard Walker’s fluoro starter bulb) is mandatory for successful slit spectroscopy.

Ken

 

[Thalestris24]

18 hours ago, Merlin66 said:

I’ll contact Paul....

yes, a reference lamp ( neon or Richard Walker’s fluoro starter bulb) is mandatory for successful slit spectroscopy.

Ken

 

Hi Ken

Well I have some basic neon bulbs but they are only good for the red end of the spectrum. I did some research and found postings about using a glow starter like you mention. TBH I'd never heard of them before! Of course, I know about fluorescent tube starters - but 'glow starters', um, no! The original RELCO ones that people mention don't seem to be available any longer. There are other makes of 'glow starters'. They are very cheap so I ordered a pack. Will have to wait and see if they operate the same as the RELCO one. Fingers crossed! I'd thought about a high pressure sodium bulb. You can get clear SON bulbs quite cheap but they run at around 90V and I think they need a ballast to operate. Still might be a possible if the glow starters are a, er, non-starter! I also thought about laser pens but I gather their nominal wavelengths are +/- 100A but could possibly be themselves calibrated against a cfl. One can go round and round in circles when it comes to calibrating anything... 

Louise

[Merlin66]

Louise,

On the Astronomical Spectroscopy IO group there's some info (I think in the files area) on alternative Relco type lamps. The Telluric absorption lines/ bands make a good double check.

I use the Habitat FILLY decorative lamps - "Blue Cross" for calibration in short wavelengths (unfortunately now unavailable) , and Neon in the Red.

Most of the ProAm requests are for specific wavelengths, so calibration is important.

Ken

 

 

[Thalestris24]

2 hours ago, Merlin66 said:

Louise,

On the Astronomical Spectroscopy IO group there's some info (I think in the files area) on alternative Relco type lamps. The Telluric absorption lines/ bands make a good double check.

I use the Habitat FILLY decorative lamps - "Blue Cross" for calibration in short wavelengths (unfortunately now unavailable) , and Neon in the Red.

Most of the ProAm requests are for specific wavelengths, so calibration is important.

Ken

 

 

Hi Ken

Sorry, only just picked up your reply. Well, having ordered the starters off Ebay, I'll see what they are like when I get them. I keep meaning to browse the spectroscopy groups... What sort of lamp/bulb is the Habitat one you mention? Did you have spectral data for it? What about using a cfl - I presume they are not good enough for calibration?

Not sure what you mean by "ProAm requests" but any spectra I may acquire are not likely to go further than the spectroscopy forum on here and then only if I think they're good enough (which they probably won't be!). For me, it's all about the journey!  

Louise

[Merlin66]

The Filly lamps were decorative lamps sold a few years ago. Buil did a review and they proved to be popular. Yes, the spectral data for the FILLY lamps is available.

ProAm is a collaboration between the proffesionals and amateur "data collectors"

  

[Thalestris24]

16 minutes ago, Merlin66 said:

The Filly lamps were decorative lamps sold a few years ago. Buil did a review and they proved to be popular. Yes, the spectral data for the FILLY lamps is available.

ProAm is a collaboration between the proffesionals and amateur "data collectors"

  

Hi

I was wondering what sort of lamp/bulb they used - maybe can still get something similar? I presume they were some sort of fluorescent or other kind of discharge tube/bulb?

Thanks

Louise

ps Ok - I've some references to it. Doesn't sound like anything similar will be easy to find  

Edited December 20, 2019 by Thalestris24

[Merlin66]

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

 

[Thalestris24]

2 minutes ago, Merlin66 said:

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

 

Yeah, I found that now. I've come across some old adverts for some of the blue ones but nothing current, unfortunately

[Merlin66]

Start with the fluoro and the neon......

relax and spend some time playing with BASS Project.

[Thalestris24]

13 minutes ago, Merlin66 said:

Start with the fluoro and the neon......

relax and spend some time playing with BASS Project.

He he - I'm overthinking it, I know! Still... hid xenon headlights might be good, though not especially cheap. Xenon has so many lines right across the spectrum - maybe too many!

Louise

[andrew s]

7 hours ago, Thalestris24 said:

He he - I'm overthinking it, I know! Still... hid xenon headlights might be good, though not especially cheap. Xenon has so many lines right across the spectrum - maybe too many!

Louise

They tend to be high pressure and the line are very broad and washed out. Not ideal in my view.

Regards Andrew 

[ejp1684]

As I mentioned in my previous post on Lowspec I used a Philips S10 starter bulb which works quite well. There's more info in my other post.

Paul has said he hopes to develop Lowspec to include a calibration unit, although I haven't heard any more on this. He also seems to be designing other improvements to the grating holder and changing gratings. 

Eric.

[Gasman]

8 hours ago, Thalestris24 said:

He he - I'm overthinking it, I know! Still... hid xenon headlights might be good, though not especially cheap. Xenon has so many lines right across the spectrum - maybe too many!

Louise

Hi louise

Just realised I ordered some Relco starters quite a while back I'd be happy to send you a few if you like?

Steve

[ejp1684]

Here's a calibration image from the Philips S10 bulb. The lower end of the spectrum is the most difficult and needs more exposure, once above 450nm it's straightforward.

Eric.

[Thalestris24]

1 hour ago, andrew s said:

They tend to be high pressure and the line are very broad and washed out. Not ideal in my view.

Regards Andrew 

Yeah, I found out late last night, after I'd posted, that the xenon part of the bulbs' description is a bit of a misnomer as it's only used to start things off and the discharge is really from metal halides. Pity, really.

Thanks

Louise

[Thalestris24]

20 minutes ago, Gasman said:

Hi louise

Just realised I ordered some Relco starters quite a while back I'd be happy to send you a few if you like?

Steve

Thanks for the offer, Steve. Hang on to them, please! I'll see what the ones I ordered are like first.

Cheers

Louise

[Thalestris24]

18 minutes ago, ejp1684 said:

Here's a calibration image from the Philips S10 bulb. The lower end of the spectrum is the most difficult and needs more exposure, once above 450nm it's straightforward.

Eric.

Hi Eric

Thanks for that - I'm afraid I'd completely forgotten you'd mentioned the S10 (my memory capacity is dropping by the week ). I'm a bit in the dark as to how one identifies the wavelengths in these starter bulbs? As I say, I'll see what the ones I ordered are like but the s10 looks like it will be good for the blue end of the spectrum.

Thanks

Louise

[ejp1684]

6 minutes ago, Thalestris24 said:

I'm a bit in the dark as to how one identifies the wavelengths in these starter bulbs?

I'll see if I can locate the web address for the info, if not I can attach the files I have.

Eric.

[Thalestris24]

26 minutes ago, ejp1684 said:

I'll see if I can locate the web address for the info, if not I can attach the files I have.

Eric.

Oh ok, thanks I just read your previous post and how you found the data on a French web site. I take it it's the one branded as S10 'Ecoclick Starter'?

Louise

ps: oh well, just ordered x10 of the S10s off Amazon for less than a fiver and free postage - can't be bad! (What's the worst that could happen?)

Edited December 20, 2019 by Thalestris24

[ejp1684]

Finally found out where the S10 info came from. The link to it was 'yimg.com' which means it was one of the now defunct Yahoo groups, now the Astronomical Spectroscopy group at 'groups.io'. I think the BASS project is now there as well. The Astronomical Spectroscopy group is worth joining if you haven't already done so, lots of useful info and great advice when you need it. But I've attached the pdf file anyway.

Eric.

SpectraPhilipsS10Starter.pdf

 

[Thalestris24]

2 minutes ago, ejp1684 said:

Finally found out where the S10 info came from. The link to it was 'yimg.com' which means it was one of the now defunct Yahoo groups, now the Astronomical Spectroscopy group at 'groups.io'. I think the BASS project is now there as well. The Astronomical Spectroscopy group is worth joining if you haven't already done so, lots of useful info and great advice when you need it. But I've attached the pdf file anyway.

Eric.

SpectraPhilipsS10Starter.pdf 743.09 kB · 2 downloads

 

That's great, thankyou so much! Lots of lines, lol. It will be interesting to compare to the S10 to the 'Vernons' brand I ordered. Yeah, I joined both the groups a while back but I've just been completely focused on learning 3d printing and building the Lowspec! It's taken up all of my astro energy!! I will sit and run BASS and try and learn how to use it. Something to do over Christmas Off to Tesco now  

Cheers

Louise

[Gasman]

One interesting thing I found out regarding the starter bulbs.

While Shelyak were developing the Alpy 600 software 'Demetra' I sent a few spectra I had taken to François which threw up a discrepancy with no Hydrogen lines showing in the reference spectrum. It turned out that the Hydrogen in my Relco bulb had all but disappeared maybe with use or leakage??? Which reminds me I need to change it!

Steve

Edited December 20, 2019 by Gasman

[Thalestris24]

I had a tentative go with BASS on a cfl spectrum. I need to spend time reading the BASS documentation... Anyway, managed to get this based on a 1 point mercury calibration and the Simspec theoretical dispersion of 1.02A/pix.:

It compares to this annotated CFL spectrum:

But doesn't line up exactly. I used one of the mercury lines which BASS said was 435.833nm but the annotated figure says 436.6nm. From my calibration the large peak on the right is at 620.8nm whereas the annotated one is 611.6nm. Obviously a single point calibration relies on knowing the precise dispersion. I just used the Simspec calculated value of 1.02A/pix. So may not be accurate enough. Otoh, maybe it's just a variation between CFL bulbs. I couldn't figure out how to do multiple points of the CFL. I'll have to read some more . Annoying that BASS doesn't appear to have an undo button... Still, early days! It doesn't look like I'll get any of the starters before Christmas but I might have a go with a pure neon bulb as neon is an element option in the BASS calibration procedure. Will get my soldering iron out tomorrow .

Louise

 

[Merlin66]

Louise,

Well done! I see you using BASS Project....

Use the earlier fluoro reference, it's more reliable. Put it down to different CFL lamps.

You could also image a solar spectrum by pointing the LowSpec to a bright sky...

The profile you show is very promising, you'll get a better result using multi-point calibration..

The scaling of your result ----not quite correct. I think you may have used a setting which would apply to a target spectrum, not a reference spectrum.

I would also change the wavelength units to Angstroms...more widely used in astronomy.