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Fantastic spectra Robin!
It is an intriguing method for learning about other planetary systems.
Andy
Robin, that is an interesting analysis of the AAVSO data.
I’ve taken a brief look at a couple of the papers and there is mention of different durations of totality. For the 1997-98 Graczyk et al (1999) found totality lasted 450d in U-B and 477d in B-V. While for the 1976-78 Saito et al (1980) found totality lasted just 300d, and Saito note this is “shorter than those estimated during earlier eclipses“.
I’ve not read them in detail, though I wonder if this is a clue to what is happening..
The duration Hugh found is closer to 300d than 450d, at 332d using H-beta. This appears similar to the AAVSO data analysed by Robin, where by eye it looks to be just over 300d.
Cheers,
Andy
Indeed an excellent paper by Hugh. Great to see spectra from multiple observers contributing to Hugh’s research on VV Cep.
The shift in central eclipse timing without an apparent long term change in period is a puzzle. It would be interesting to know how accurate the various central timings were over the past hundred years. I wondered whether there was any possibility that different spectral features were used to estimate the central eclipse in early work compared to modern work of the 1990’s and onwards, resulting in a systematic shift in observed in the central time.
Cheers,
Andy
Hi Tor,
The detail of the theory explains both of these problems. Indeed I believe that the Earth and Moon have similar surface compositions is one of the key lines of evidence for the theory.
First, this happened during the formation of the solar system, when there may have been more planets than we find in the solar system today. The proto-Earth and its impactor, another protoplanet probably of similar size to Mars, would have been in similar orbits. The planets would interact gravitationally which could shift them into different orbits, eject one of the protoplanets out of the solar system, or as in this theory the protoplanets collided. The merged planet and moon would follow a similar orbit around the Sun to the original protoplanets. It is worth noting this orbit isn’t necessarily exactly where the Earth and Moon are found today as gravitational interactions between the planets were common in the early solar system, before the planets settled into the orbits we find today.
In the massive impact, the outer surface of the proto-Earth and the impactor would get mixed together. Some of this material would be ejected into space, settle into an orbit around the Earth and coalesce to form the Moon. Hence the surface of the Earth and Moon are similar compositions, a blend of the proto-Earth’s surface and the impactor. You can get a better idea from this video.
https://www.youtube.com/watch?v=BoU9OA92trA
Best wishes,
Andy
I had a secondary mirror recoated by them about 3 years ago. They did a good job of it, though of course this was much simpler than a heavy curved mirror.
Andy
Hi John,
Glad to help.
I’ve cleared the formatting data from your post. There hidden text formatting present in word processors such as Word. I copied and pasted it into a pure text editor to remove the formatting. On Windows I use Notepad, and I forget the name of the standard one on Macs as I use Sublime Text.
Cheers,
Andy
Hi John,
Thanks for pointing out those missing Journals. I’ve added Volume 110, Numbers 1 – 3. There are changes in the pipeline so it isn’t worth doing a check of all Journals at this time. Though if any are missing that anyone needs access to sooner rather than later, let me know and I’ll get them added.
Best wishes,
Andy
Hi John,
Brief update as I’m having internet problems.
I now understand different the Journals may have been created with different security permissions. So the one you are attempting to print must have the printing option prevented.
Am I correct in thinking you have already found a work around, but this is a pain? Are you wishing to print lots of Journals/Articles or have you printed what you need.
Best wishes,
Andy
Hi John,
All of the Journals are also available in pdf format on the BAA website. You could try printing these instead.
You need to be logged in, and then you can access them at one of the following locations.
The older Journals are accessible via Publications -> Downloads -> Journal Archive.
https://britastro.org/downloads/3844
The newer Journals can be accessed via Publications -> Journals.
I was able to print pages from the August 2007 Journal without a password. This was using Acrobate DC on Windows 10.
Best wishes,
Andy
Hi Alla,
Hopefully someone with specific knowledge of your setup will respond, but I thought I’d give a few general pointers.
You’ve not mentioned whether you have been able to polar align your mount. With that type of telescope mounting the first step is to get the polar axis aligned. From the look of it, that mounting has a polar scope to help get good alignment.
Then you typically go through a one or two star alignment, where you need to know a few bright stars.
I’ve found even with aligned GoTo telscopes, they won’t always get your selected object in the eyepiece. Sometimes they are spot on, but otherwise they’ll get it close and you then need to look around a bit, usually with the help of the finderscope.
If you don’t find someone to visit, then you may have a local astronomy society who can help. Looking on our page of Local Societies affiliated to the BAA, I see there is a North Essex Society.
https://britastro.org/links_affiliated
https://www.northessexastro.co.uk
I’m not sure how far they are from you. During normal times, some local societies hold telescope workshops or star parties, where you could get some help.
Best wishes,
Andy
Hi Stan,
I have just sent you an email about changing your name on the website.
Best wishes,
Andy (BAA Systems Administrator)
There are also the Celestron Starsense and Meade Starlock. The drawback is that I think these only work with their products, but sound a lot like what you describe.
A few years ago I got the equivalent 50mm guide scope and camera, currently selling for £235 on this page. I think it was more expensive when I bought it and prices have come down. They do various options, including the telescope guider body with a non-rotating helical focuser on which you could put your own camera of choice for £109.
https://www.altairastro.com/guide-scopes-97-c.asp
Of course the main purpose of this setup is as a guide camera rather than a digital finder, but I found it worked perfectly for my purpose. A GoTo mount that wasn’t quite good enough to always put the target in the small field of view of the guide camera on a spectrograph.
Best wishes,
Andy
I’ve now merged V1405 Cas and Nova Cas 2021 into a single object. Either id can be used to upload data, and they will both show in the V1405 Cas light curve.
Cheers,
Andy (BAA Photometry Database Manager)
Another couple of thoughts. Fundamentally, even with a “perfect” telescope a star is a disc due to diffraction in the optics, and you rarely see performance at the diffraction limit as atmospheric turbulence blurs this disc.
Cheers,
Andy
Hi Lars,
I’m afraid there is nothing in the BAA Spectroscopy Database. It is on the faint side for most spectroscopists at around 14th magnitude, but there are some who can go that faint.
Best wishes,
Andy
Hi Mike,
Hopefully one of our current AIP4Win users will jump in. If not then I can offer you some help by reviewing your spreadsheet results. I have a little knowledge of AIP4in though I’ve not used it in many years. I manage the BAA VSS/Photometry database and did a lot of the work to create the spreadsheet. I’ll also be the person to set you up with a login.
You can contact me via my official BAA email address photdbm@britastro.org.
As you’ve already got AIP4Win and the spreadsheet working, you are well on the way to submitting observations!
Best wishes,
Andy
Hi Lars,
Rspec is designed to be easy to use but has limited functionality.
BASS is the next level up. It has a lot more functionality and is a lot easier to use than say ISIS. ISIS is pretty much the gold standard in spectral processing, but is the hardest to use.
I suggest starting out with BASS as it is free, and see how you get on.
I also suggest starting simple. The A-type star is used to response correct the spectrum. This is to remove the bulk effect of the Earth’s atmosphere, and to adjust the bulk profile of the spectrum for the telescope and camera sensitivity. Note this doesn’t remove any spectral lines, just large scale features that affect the shape of the continuum. While this is important for getting a correct continuum, I wouldn’t bother with your first few spectra unless you really want to. I took spectra for 3 to 6 months before attempting a response correction.
When you are ready to do a response correction, then you will need to choose an A-type star at about the same altitude and on the night of your observation. The altitude of the star will affect the response correction as when you look lower down you are looking through more atmosphere. Also, atmospheric conditions can affect the response, so a response taken on one night may not work on another night.
Most important of all is to keep it fun! Don’t worry about getting things exactly right at the start.
Best wishes,
Andy
If anyone is interested then I would not let age hold you back.
I am fortunate enough to have returned to university in my late forties to do a PhD in astronomy. While I have seen more years than most of my fellow PhD students, I’ve met plenty older than me who only started once they retired.
Andy
I’ve been in contact with the BAA Office and they have confirmed there has been a bit of a delay to the Journal this month. They should be arriving with people any day now, noting the BAA Office haven’t yet received their box of copies, to their home addresses as they are of course working from home at present.
Paul & David, I was sorry to hear you had problems with your Journal deliveries. I’ve done a little investigation with the BAA Office to check there is no ongoing problem.
David’s appeared to be some kind of delivery problem. He’s had no changes to his address and his address was in the list sent to the printers in August.
There was a minor problem with Paul’s address that we didn’t spot. Basically an issue around the country not matching a known Royal Mail Zone causing it to fail. We discovered this after the December Journal print run and have implemented some changes to avoid this problem in future. The Office are now able to produce a list of any problem addresses before doing the Journal run, so they can fix them prior to generating the mailing list to the Journal printers. It only affected a handful of members, I think less than 6, who were sent their Journals separately by the Office. We should have spotted and fixed this sooner, so our apologies.
Best wishes
Andy (with my BAA Systems Administrator hat on)
