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I seem to recall giving imPPG a quick try…(?)
As far as I know, these tools all use the standard Lucy-Richardson (LR) deconvolution algorithm. The Xterminator suite of tools in Pixinsight only became available last year and uses a deep neural net (so-called ‘AI’ or machine learning) approach. My understanding is that the nets have been trained to recover Hubble images from deliberately corrupted versions therein, and are therefore sensitive to galactic and nebula-like features. These new tools were a game-changer in deep sky imaging; suddenly we could extract astounding levels of detail from our data.
While not tuned for solar work, they appear to work better (in my opnion) than standard LR. Unfortunately they are only availaibe in Pixinsight – which is not free. Maybe there is an opening for someone to repeat the AI approach for solar and planetary… 🙂Hi Peter,
If you are new to Pixinsight then – well done! It’s a bit of a learning curve but well worth it – especially for deep sky.
A good way in is with Warren Kellers book ‘Inside Pixinsight, otherwise info is scattered over the web. The early stages of calibration and stacking are well treated in videos by Adam Block (in fact all of his videos are good).I haven’t been around teh forum for while so just seen Robin’s post…
I also took some hi res spectra of b Per but, similarly, missed the eclipse as such. Mine are shown as a phase plot and include some ‘historical’ data from 2018, through 2020 (but inlude Decmber last year and Jan this year). I used longer exposures (1 hr) and used the Ha line and water absorption features to determine the shifts. As mine are over an extended period I also subtracted any long period orbital velocity with the wide companion.
Attachments:
Well, it wasn’t in the Ha I took immediatley after…
But good idea to try small shift next time (which might be a while as I have switched to Alpy for a bit 🙂
Cheers
Kevin
so looking at one sub just now – its gone!
I looked back at the flats from last time and no obvious dust… I also did a ‘binning’ at the same level as the spectrum and no obvious defect in the resulting plot
Kevin
Hi Robin
Thanks for tip… I’ll have a look later.
Its clear outside so running another session. Repeating the gam cas HeI…
I’ll let you know if it spontaneously dispapears – or persists
[BTW I am using a 460EX too]
Snap!
I took this at about the same time (been away for a few days so only processing now…)
Reassuring to see close similarity.
I have some accompanying photometry so aim for flux calibration soon…
Kevin
Hi all,I just thought I would let you know what I concluded after much experimentation with the Lhires on various reference stars and with/without filtersI bought a Baader orange filter (as per Robin’s suggestion) with a view to eliminating any higher order contamination and it worked well. Compared to the no-filter option, things at least seemed more consistent. But the prior inconsistency was, I thought, a clue in itself.My backyard is subject to quite a lot of stray light, what with street lights, my drive lights on a motion sensor (the dog has to come outside occasionally !)I looked at some of the raw spectra in Pixinsight and used the various stretching tools to examine luminance gradients across the entire image. There was some evidence these were larger without the filter.I then looked again at my efforts to seal the joints between the plate components with tape and there were still some possible entry points for light. In particular, there was a gap around the rear end where the grating sits. (I am talking <= 1mm of course). I used a plastic box, sprayed with matt black paint there. Then at the front there was a seam that I had left for some reason – I taped it up.The result was that, without the filter, the ‘up tick’ at the red end was much reduced, although IRs were not quite as consistent as using the filter as well. I conclude that there probably was some light ingress and that this was reduced by the sealing at joints, and possibly further by using the filter (it’s near the sensor).
Kevin
Hi Robin
The Atik460EX has a bigger chip than the 314 and sees up to 6628A (and down to 6472A). I’ll set up a dropbox folder and let you know how to access
Cheers
Kevin
Hi Andy
The airmass for Regulus was around 1.35, that for Castor 1.15…
They were taken on the same night.
I am using a C11, and bright stars inevitably straddle the slit (already the slightly wider one at 35mu).
I might try an experiment with moving the collimator axis a little.. you know, the screw on the bottom of the Lhires.
Keep safe
Kevin
Greetings to all in these strange and difficult times… I hope you are keeping safe.
Anyway, I am looking again at the instrument response in my Lhires data. I have a ‘hockey stick’ response with an uptick at the extreme red end (centred on Ha). In the raw spectrum there is a spreading of the line here but, of itself, I dont see that it implies a greater binned amplitude.
As Robin suggested earlier in this thread, I looked at using the UVES stars for reference. I attach a couple of plots showing results for castor and regulus. Each plot shows (i) the non-IR corrected spectrum; (ii) the use of the star’s own IR obtained using the reference in the ISIS database; (iii) the IR from the other star of the pair.
On the one hand, the ‘uptick’ in response at the extreme red end is removed somewhat, in both IR-corrected cases. On the other hand, the corrceted responses differ considerably. Reassuringly, the IR for each star is fairly independent of camera binning (1×1 and 2×2 give good agreemenet for each star) so I think the IRs have been processed OK.
On balance therefore, I am inclined to agree with Andrew, that using IRs in these high-res spectra may introduce other artefacts in an unrelaible way.
Robin, I also note that, in some of your Lhires examples, you crop at around 6612A. I have started to so this too, so the worst of the uptick is discarded.
I would have thought that, as long as it’s clear what you do (I uncheck the IR box on the dbase entry, and insert appropriate comments in the header) its OK to use an uncorrected spectrum?
Keep safe
Kevin
I used a Pi 4 in a recent project and found it was getting very hot. I fitted a small fan… Things seem OK now but I was disappointed to see this issue in the Pi lineup. I’ll use a 3 (or 3B) in subsequent projects!
Kevin
The ‘systemic velocity’ is included in the orbital component in the model so, theoretically, I have already subtracted it. I was happy just to get something that was roughly sinusoidal and not too bady offset from zero!
Kevin
Hi Robin
Thanks for reminding me about this talk – I may have been in the audience!
I’ll have a look at the ‘lamp in front of the scope’ possibility… Is it readily available?
Kevin
Hi Andy
OK, I’ll go with CV for this one… (V-filter to follow 🙂
Tomorrow night should be clear here and I am keen to try a comparison on the same target with a mono (cooled) CMOS camera. I’ll stick with Lum filter on this experiment for a better comparison.
Kevin
Thanks …
I have done regular processing with darks and flats, so I think I’ll leave the (semi)-automated processing for now [The cosmetic file is usually generated using a threshold on the dark image, looking for outliers]
I liked AstroImageJ as it had a simple preview facility which allows you to scroll through the images
