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About Merlin66

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    Spectroscopy, Solar observing,- and my wife!
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    St Leonards, Vic, Australia
  1. Jon, can’t say I’ve noticed that....what version of CdC are you using? V4? I’ll have a look later and let you know. ken
  2. Valerio, Well done mate! Good to see you moving along. You've done well to produce your first 1D calibrated profiles. Capella (#1) - Your reference lamp looks a bit out of focus. The calibration is close, but I as I mentioned previously the lack of good reference lines down around 4200A reduces the accuracy. I'd recommend changing the scale to the more common Angstrom ( Chart Settings/ Advanced/ Wavelength unit) When you compare to the reference spectrum you can see the mismatch between features. (look at the region around 5200A) A longer reference lamp exposure and use of the blue lines would help. In the meantime if you want to study a particular region you could "nudge" the calibration. Right click on the target image, Profile Properties/calibration - at the bottom of the window you'll see a box "Lambda offset (nm)" you can enter a suitable number and see the impact on the registration of the two curves (ref spectrum/ target spectrum). Try -0.1 (one angstrom) for starters then try again to improve further. (Note: pressing Apply will show you the impact but will not "lock it in" until you press OK, giving you time to play!) After calibration, normalise the profile to make the numbers easier (!) Select a quiet region in the spectrum (say around 6400, 6400-6410) and set this to 1 ( Image tab/ normalise flux scale) Response Curve: You don't show the response curve you used....The process is detailed in the BASS User Guide (press F1 to open) Section 2.15 gives all the info you need. Labels/ Lines - See Section 2.26 of the Guide. Once you've labelled your spectrum you can save it for future use. I attach some label files which may be useful. Other than the effects of different atmospheric absorption (altitude difference between ref and target spectra), if the same set up is used it should work reasonably close.... I think the calibration of the Aldebaran is sightly out, but obviously the registration between your Capella response and the target is well out! (Look at the bump in the target around 6000A in the target and the bump around 5700A in the corrected version could be an indicator) The last profile shows that your response curve is not working. If you had a good response curve the result would be a spectrum very close to the shape of the ref spectrum (for a K5III). It's always a good sanity check to compare the corrected profile against a reference profile...... You're doing well. Once you've mastered these basics they will be used over and over again on future spectra. Sample TypeF.lbl Sample TypeG.lbl Sample TypeM.lbl Sample TypeB.lbl
  3. Photoshop is used to tweak the image after it has been acquired from the camera and after the pre-processing, flats darks etc. Programs like Astroart can control all your cameras, do the necessary pre-processing and a lot of the post processing you may need. Well worth checking out.
  4. I don’t think it necessary to have a high end mount to do ISS tracking. I ‘m sure the LX200 was used for satellite tracking. It depends on the guide software.
  5. I’ve been using Astroart for the past ten years or so. Fabio has been very responsive to our needs and has regularly issued upgrades based on user feedback. I regularly use Astroart for guiding. Fabio even developed a guiding system for us in spectroscopy. Works very well, I can recommend it.
  6. Greg, OK. It sounds like you have a SS doublet pair, these are usually air spaced. I've used small aluminium foil strips in the past. Onwards and Upwards
  7. I've successfully used a couple of 20Ah gel cell batteries to power my HEQ5 mount for many years. I use a car 12v DC-DC power converter (120w) to give me 15V to the mount. Works well.
  8. I used the 12" LX200 for many years, and found the best "improvement" I made was to change the Dec bearings to needle bearings. Adding dual focusing motors (Zero Shift and mirror knob) as well as the mirror lock also helped.
  9. Did anyone find an ol' brass 1/2" fl Ramsden in the bottom of their box???? I'd really like to relive those days with the 6" f8...........well maybe for a few minutes.....
  10. Photographic negative copies of Ronchi screens were widely used when film cameras were the rage.... Have you tried a piece of fine fly mesh? That's generally my fall back.
  11. Valerio, BASS project has all the tools you'll need. It has a comprehensive collection of star spectra (Pickles and Miles catalogue) built-in and available for comparison. Before adding any more RELCO lamps, just check what exposure you need to bring out the lines down at 4200A. The "best exposure" is the one that gives you the maximum ADU without overexposing - best SNR. Once you have taken some target spectra, you'll get a better feel for the capabilities of your set-up and be able to establish a routine. I've gone for a sub exposure of 300s and depending on the SNR required, may stack 20 or so subs. I use Astroart to control all my cameras and pre-processing. This allows me to quickly do a "profile" along the sub exposure and confirm the maximum ADU. Once you have a good Instrument response curve it can be used for all your spectra. On the proviso that your using exactly the same set up. There will be an atmospheric effect to consider - it's generally accepted that the reference star spectrum (an A type star for convenience) should be taken at/ close to the same altitude as the target spectrum to minimise this effect. To get started, and for practise in the processing, you can use the Pickles/ Miles reference spectrum, then move on to an actual reference star spectrum.
  12. Yes. but it sometimes needs more than one bulb to give sufficient light. I've seen set-up were a ring of four (or more?) bulbs was placed in front of the objective.
  13. Valerio, Ran your data through BASS Project... Pretty good, the resolution is around R=971 in the red. You can see the calibration is limited to the red region - this means the calibration is not so good in the blue. More reference lamp exposure time might pull out the emission lines around 4200A The #1 exposure as you can seen doesn't appear to be over-exposed and the focus is pretty good. The response curve of your camera is obvious, the jump around 5700A is typical! This can easily be corrected by preparing an Instrument response curve and using that to "correct" your spectrum. Comparing with the solar reflected light (G2v) from Mars you've recorded a wealth of lines! Well done. You just need to open and use BASS Project to replicate these results. Onwards and Upwards
  14. Valerio, Good to see your "first light" results! In BASS project it's easy to load all the results and compare the quality of each profile, just hide the "bad ones" and work with the "good". I'll have a look at your results and post my findings.
  15. Many years ago I made a secondary for a Cassegrain conversion of an 12" f5 scope. I was using the Gaviola test method (very straight forward) for testing. https://www.osapublishing.org/josa/abstract.cfm?uri=josa-29-11-480 (It's also re-printed in Allan Mackintosh's "Advanced Telescope Making Techniques", Vol 1, p63)
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