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Hi Derek,
Thanks, Having tried film based spectroscopy for some 15 years I know the difficulties. I never captured a single one!
I was glad to help, it has been an interesting challenge. It always feels good when you finally see it come together and you actually understand what you’re looking at!
Great fun,
Cheers,
Bill.
PS. Will you be attending the BAA weekend in September at Armagh, or perhaps the IMC again, in Germany this year. Looking forward to catching up with you at some point.
Hi,
I was sent Henry Soper’s remaining original material a while back but I’ve never seen any of Harold’s. It’s quite fascinating to see the differences between the film results and current video systems.
cheers,
Bill.
PS, Had to check. Yes, one of Harold’s photographs is in Neil Bones’ book. I knew I had seen one recently. Do you know what happened to his originals?
I have scanned the ones from Henry, ultimately I’ll send them to the BAA for archiving.
Hi,
Since I may well have done the same thing, (but realised what was going on and am sticking to that story), I’m keeping it a secret to save their blushes… ;-))
cheers,
Bill.
Hi,
Well, as I said, all things being equal…
You can see the curvature on the image and if it was this small discrepancy then that’s more lazy than I am! As long as there is no point of inflection along the dispersion then the spectrum can be corrected on the fly provided a few bright lines can be identified.
I’ve tried the method that C. Buil described using images of grids for distortion correction but it’s frankly not worth the trouble at your average meteor spectrum resolution.
Cheers,
Bill.
Following on from the other thread about astronomy magazines, it is a sad end to a venerable journal.
Maybe some other publisher will take it on and revive it’s standing.
…”small number statistics…” I agree!, mmm, lies, damned lies and statistics.
Quite fascinating though…
I can’t remember where but it was a claimed correlation between large meteor showers and rainfall, I don’t think that one stood the test of time.
Cheers,
Bill.
Hi,
I still use a quite elderly Epson 3170 Photo. This is a general purpose flat bed scanner but it has a built in light source in the top panel and came with a set of film holders (for 35mm mounted/unmounted and 6×6 format). I really like mine.
You can pick them up second hand (ebay etc) quite cheaply now. I’d check the driver software is still available from Epson before you consider buying one, just in case…
Cheers,
Bill.
Hi All,
I’ve re-fitted three of my cameras with the plastic film grating and re-aligned the various cameras so I get overlapping FOV’s. This, ostensibly, is so I can compare the spectroscopy characteristics of the various camera/lens/grating combinations.
Unfortunately no spectra from last night but the the testing of the ZWO camera continues nonetheless.
Captured a nice bright meteor on one of the WATEC 901HX/RC camera’s
and the same meteor on the ZWO 174MM.
I’ve half sized the ZWO image to try and visually make the images comparable. On screen the ZWO images look very dark but when stretched even just a little they reveal all the data that is really there! The global shutter and slower frame rate/longer exposure give a nice “chopped” image. The glow from trail can even be seen to infill the gaps.
Also the higher native bit depth of the ZWO means the pixels are less likely to saturate. Using the slice function in IRIS a lightcurve can be extracted easily.
…shows the terminal flare nicely.
Cheers,
Bill.
That’s a great result, excellent teamwork! I was pretty sure it was strongly foreshortened, not quite right at me but pretty close. (Also good to know where to point my other spectrum systems!)
I’ve found another small bit of the plastic grating film and I’m now intrigued… I have many spectra with nice lines long-ward of 500nm. I would have thought there would have been some blue lines with the brightness of the meteors but there are none. Ed Majden over in Canada contacted me about some spectra he had that showed the same thing.
I think I’ll change the lens on one of my systems to an 8.5mm and stick some plastic grating on that, see how it goes. Tried this before but clearly need to run it a bit longer!
Cheers,
Bill.
Hi,
Outstanding! I hope a few stations got it. To get it to work I had to use USB2 (rather than USB3) then tweak the camera interface until it talked to UFO HD. At 17.1fps (camera setting) and 25fps on UFO HD it runs fine. Oddly if I set UFO HD to the camera rate it was not happy. Lots of dropped frames with USB3 at high frame rates.
Definitely some comms/driver issues so I’ve no idea how this would roll up into the data UFO HD would produce for orbit/analyser but I’ll leave that to the NEMETODER’s… ;-))
To get a decent limiting mag I’m using a 50mS exposure as the pixel pitch is 5.6um. Sensor is 1936 x 1216 pixels.
It’s got potential!
cheers,
Bill.
PS- quick edit, I meant to add there was a hint of the 557.7nm line so I’m betting this’ll be a fast one….
Ahh -ha! great minds think alike….
BUT I’m afraid not, well not at the moment. This is one of those UFO HD/driver problems. If the camera is set to it’s 2×2 binning (the performance is exceptional) however UFO HD throws up a media mismatch error. I can’t get it to work at the binned frame size at all. HandyAVI will run it fine at 2×2 but that’s not got such a good user interface.
The small pixel size certainly reduces the mag limit but even so, at full res, I can still see +8 stellar on the frames without the grating in the way. So it’s still pretty good and the point is to get as high a resolution as possible. A few more results will show whether it’s a viable instrument comparable to the venerable watec’s.
Bill.
Hi,
Thanks, I’m planning to leave the plastic grating in place to see how it compare’s to the other gratings. I’ll need to make up a little cardboard holder to make it a bit more secure though.
An interesting little side experiment!
Cheers,
Bill.
After a bit of processing…
What I think is remarkable is the performance of the cheap plastic grating film. I have had this stuff for decades and cut little bits from the sheet as various projects have come and gone. Might need to invest in some more and do some additional observations.
Some of the more expensive gratings are not so good at the blue end so either this meteor was VERY blue or the plastic grating is better than the glass gratings under some circumstances…
Anyway I’m pleased as I’m now at less than .5nm dispersion on the sensor. Which is pretty good for general meteor observations.
The colourised version illustrates the neutral Mg and H+K Ca lines in the UV resolved. The last little UV bump is an iron line at 374.9nm, that’s not too bad.
Onward’s we stumble…
Now there’s a question!, and there’s probably a near infinite number of opinions as to which is best… 😉
PS. …but apart from JBAA of course, The Astronomer…
Hi,
I often wonder about the progression to grumpy old man status….
This is an excellent example, I subscribed to S+T for decades then I too let it slide a number of years ago. It’s gone from a quite superior magazine with technically interesting articles (some even had formula!) to positive mediocrity. I decided to buy a CD compilation of all the past editions and the difference decade to decade is clear (I think so anyway).
Oh well, I suppose that’s what called progress….
Cheers,
Bill.
Hi,
Yes (ish)… Full tracking is way beyond my progamming skills but I think using a rotating mirror system one could build something that would at least “slow” them down along one axis. That would certainly help but then there is still the coverage issue.
Probably my only regret leaving the university is not having access to an optical lab and workshop where I can experiment anymore.
cheers,
Bill.
Hi,
HROfft was written in the 90’s as part of a much longer Japanese meteor project, the Radio Meteor Observations. It is fully automatic so perhaps not as “flexible” as spectrum lab but that’s the very reason I like it. I first used it in 1998 but as today, it’s excellent bad weather insurance!
Once you get it set up and talking to Colorgramme it’s a case of leaving it alone. The only time I check the computer is if I see any odd results on the RMOB page!
The one downside is that because it’s designed to be left alone the thresholds are set quite high. It means that it’ll only record the strongest echoes. You can see this in the radiograms. 27 may be the count but there’s probably double that in actual echoes. Also it doesn’t have any way to discriminate against interference so the results can completely misleading if you have a noisy environment.
This is the main site run by Hiroshi : http://www.amro-net.jp/radio.htm
cheers,
Bill.
Hi,
Great result. I always find the moonbounce remarkable to hear/see! (Grant, moonbounce is the term given to radio emissions that are emitted from the earth and reflected back from the moon. The Graves radar is so strong that when the moon passes through it’s beam the signal gets reflected back. If you’re running a meteor monitoring system you can see the echoes as a trace on the display. These reflections also changes frequency vary slowly over time, that is doppler shift, showing the motion of the moon about the Earth!)
It was solid clouds here also. The very high pressure may have settled the weather but the stratocumulus associated with such weather never broke up.
Ive attached a couple of traces from the peak showing the many reflections I got.
Very active for several hours.
Cheers,
Bill.
