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Peter, I tested the 20mm glass filter and you are correct, it does block IR. I’ve lost my UV LED so can’t see if it blocking UV too or not.
But as you say, still seems odd for this to sit behind the etalons.
The glass filter is now at least clean so at least I can use it even if I can’t source a new one.
Thanks.
James
Peter,
Thank you very much.
I think that is my confusion. If only 656nm gets through the etalon, why is there a UV/IR blocking filter behind it, as the etalon will have filtered out those wavelengths already.
James
It has been purposefully painted to look like a glass cylinder; the white paint strategically placed to show it reflecting light coming from the left, and to give the appearance of glass. So I don’t think this represents an unfinished telescope. I would be skeptical that it is a telescope as I’m not aware of glass refractors, or why you’d want one. The end cap of the glass tube is different to the ends of the telescope near it on a mount.
We need an expert in glass artefacts of the C17th to indicate what a glass cylinder might have been used for. I was wondering what other material it could be; plastics weren’t known, rock crystal seems unlikely, ice again seems unlikely. So I would have thought it does represent glass.
Interesting story.
Personally, I think if a society pays for affiliated status it shows a certain amount of commitment. I would have kept paid affiliated status which only entitles the society to a paper journal and the handbook, no access to online stuff other than membership stuff. Unless affiliated societies pay up, and maybe the cost should be related to the number of members like the FAS, there is nothing special about affiliated membership, and all those societies who have been paying and supporting the BAA for years will now just get the same as everyone else jumping on the free-bandwagon.
James
Nottingham Astronomical Society (affiliated to the BAA)Well you’ve done your bit and raised the issue on this forum for all to see, and to show how passionate you are about the matter. It is up to Council to decide if it is worthy of their time to discuss it further and/or take action.
Steve, the obvious answer is for you to join the Council, debate the matter, and convince everyone else to vote a different way.
I can see you are annoyed by this, but I suspect it is VERY low down anyone else’s priority list.
James
A great day of talks and catching up with people, and a great venue too. Well done to the organisers and speakers!
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This is the purpose of the survey, to ascertain what you want. Do you want more pages in the Journal? If you do, what do you want on those pages? More of the same, or something else?
The survey has been designed to be as open to ideas as possible.
James
Mike, it is a massive undertaking to record one meeting, let alone three days’ worth of meetings. And that is just the recording of audio and video, putting microphones on speakers, along with capturing the slides, let alone the subsequent editing, matching of sound and video, labeling, electronically adjusting lighting and sound, and then uploading, plus checking nothing infringes copyright and seeking speaker permissions. It really is a massive job, and not an enjoyable one for a volunteer.
I’ve resolved the streaking comet. Now I have streaking stars when they are not meant to be. An overly stretched image shows the subtle streaking. I’ve posted this question on SGL too, but I do wonder if this is somehow related to my flats or darks, or maybe because I had the ISO too high (3200 for Canon 6D). More work in progress. It is just a case of finding the time to sit down and change the myriad of variables, stack and see if things have improved. I am SLOWLY getting there.
https://stargazerslounge.com/topic/407703-streaky-stars-in-dss-comet-stack/
James
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Thanks Peter. I think I may have discovered the issue. I hadn’t appreciated it was possible to use roller ball on my mouse to zoom right into the comet to get a better placement of the purple ring, and also I hadn’t been pressing the save icon on the right, under the comet icon. I’m still not sure if I am meant to press the save icon on EVERY sub, or just at the end of marking the comet on all the subs. Anyway, the first stack I’ve done since implementing these changes seems to be OK, now I’m trying to keep the stars and comet static so it taking my poor laptop even longer!
I will report back with results.
Thanks for replying.
James
I agree that there should be very clear comments on what has been done to manipulate ANY image. For planetary this will usually be along the lines of “best 50% of 10,000 frames stacked, sharpened with wavelets and brightness, contrast and RGB adjusted”. The difficulty arises when dealing with images like this lunar occultation of Mars. I have seen several images of this occultation online where the processing comments should read along these lines:
1. Best 50% of 10,000 frames of Mars stacked (taken 60 minutes prior to lunar occultation). Derotated in Winjupos. Wavelets and RGB adjustments.
2. Best 50% of 10,000 frames of the lunar limb stacked (taken 60 minutes prior to the occultation of Mars). Wavelets and RGB adjustments.
3. Capture of lunar occultation taken during the event to show apparent spatial interaction between the Moon and Mars and to collect timing points.
4. Photoshop editing of two separate images (Mars and lunar limb) to merge into spatially correct apparent lunar occultation of Mars.Using a bit of lunar limb and a full-face Mars from Richard’s original data (https://britastro.org/observations/observation.php?id=20221211_181703_df51689fca6965b0) as shown below, it is possible to construct the attached animated gif, which is totally made up, but just a rough representation of what was observed in time-lapse. But this face of Mars wasn’t the one that got occulted by the Moon, it is just the same full face of Mars slipping behind a layer in Photoshop. The issue then is neither the actual lunar limb, nor the actual face of Mars are correct; if the Mars image was taken 60 minutes before the Martian features will be in the wrong place, and the illumination of the lunar limb will be subtly wrong too.
But this all boils down to what is the purpose of the image? If it is for scientific scrutiny then this made-up composite has little value. If it is for maximal visual impact of a lay audience then this method is likely the one to follow.
James
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Thanks all for the comments.
I’ve made contact with Robert Mackenzie and he is happy for me to scan the publication.
Another job to add to the list… 🙂
I will share once scanned.
James
Ok, I think we have a plan for people who want a copy.
Either post a cheque for £20 to Alan and he’ll post the book out. Or if you want to send me £20 electronically along with your address and whether you want him to write anything in the front of the book, and I’ll write Alan out a cheque for the money and print out the address and give it him a print out once a week or so.
I spoke to him on the telephone just, and he thinks we may need more copies…
I’ve also listed the book on Amazon, but they take £6 per item, so to cover costs of the book and postage and the Amazon fees, it is listed at £25.
I’ll message everyone who has shown interest in the book this same message. Contact me for Alan’s address if you don’t already have it.
James
