Forum Replies Created
-
Posts
-
Hi Bill,
That makes sense, in as much as something odd at the blue end in the reference spectra gives you trouble correcting the continuum. Do you know what the rough continuum shape should be for meteors? Any speculation on my part would more than likely be wrong.
I’m not sure if this will help, but sometimes I use BASS to process my spectra. This creates the response correction in a slightly different way. You still use your spectrum and a reference spectrum, but once you’ve done the division you use your mouse to select specific points on the divided spectrum. BASS then joins the dots to create a smooth response curve. I’m not sure if that would give you a way to create a response curve avoiding the dips or peaks.
Instrument and atmospheric correction is a tricky area. I’ve been struggling with it myself for the better part of this year, but I think I’m about there with my latest spectra.
Fascinating work you are doing. Like you say you can get lots of useful information even without the continuum correction.
Best wishes,
Andy
Hi Bill,
I’m glad you had a successful night with the weather cooperating! That is a nice spectrum you have captured.
I’m not sure if there is any reason why you could not apply this to meteor spectroscopy, but when I am correcting for the instrument and atmospheric response I use an A type star. Ideally one with an easily available professionally corrected spectrum. The temperature of the star is not the important thing, it does not need to match the target. The instrument response will be calculated from my spectrum compared to the professional spectrum across all wavelengths. What matters is that A stars have very simple spectra so it is easy to smooth the response as there will just be a few blips for the hydrogen lines.
Best wishes,
Andy
An interesting point Robin. I had thought that this would be better suited to a lower resolution setup than my own, and I should use my low resolution grating. However, since I know the spectral line I’m interested in, then high resolution should not be a problem and as you point out the increase in contrast will be a benefit.
Cheers,
Andy
Hi Robin,
Thanks, that is good to know. Taking a daylight spectrum sounds like a useful and interesting test anyway. It would be handy to see how well my flat correction works across the slit. With stellar spectroscopy I always aim to put the star in about the same position on the slit, but there will be times like this when I’ll want to use more of the slit height.
Best wishes,
Andy
Robin & Richard,
Thank you for your replies. It is good to hear it is not a crazy idea, though one that might only give negative results.
I had been thinking that one exposure might be sufficient with the slit appropriately aligned. Though it is a good point that 2 positions might be needed due to the contrast between day side and night side of Venus.
Robin, I have one of the newer LHIRES IIIs, do you think the flat field calibration lamp is sufficiently good?
If aurora were the cause, then I would hope there would be an “obvious” green line due to oxygen at 5577 Angstroms, or at least strong enough to be above the noise.
The other issue would be knowing when to look, as ideally this would be when CME has been ejected in the direction of Venus.
I’ll try it out with an early morning in September when Venus is better placed. See how feasible it is to get good data.
Thanks,
Andy
Dominic, Nick and Callum,
Some interesting ideas.
I’ve decided to opt for a middle of the road powered USB hub. If it doesn’t work then I’ve only spent £25. The computer is in the observatory at the moment, but I think 5m cables is just over the limit for stable usb camera connections. I’ll give some of the other suggestions a go if this doesn’t work.
I actually had 2 cat5 cables laid from the observatory to the house when I had the original observatory built. That gives me internet in the observatory, and also gives me the option to remotely control everything in future if I want to. However, they only go to the wall of the observatory, not to the pier.
Thanks,
Andy
Roy, Dominic and Martin,
Thank you for your responses. I hadn’t realised you get get powered cables, which gives me another option.
Martin, the Cat 5 to usb solution is also interesting. Like you say probably overkill for what I need, but worth looking at in more detail if I can’t solve the problem with simple extenders or hubs.
Thanks,
Andy
Hi Cameron,
Those are wonderful images. Great to be able to make the most of an opportunity to take images from a more Southerly location.
Best wishes,
Andy
Hi Mike,
It doesn’t look as though the spectroscopy meeting will be recorded. Hopefully the presentations will be made available after the event, as often happens.
Glad to hear you are already learning Visual Spec. Spectroscopy is a fascinating area that has really taken off in recent years. Variable stars make ideal targets for spectroscopy.
Best wishes,
Andy
Hi Mike,
Those are great looking spectra and an interesting comparison. Nice to see the BAA collection being put to good use.
If you fancy taking things to the next level then there is a wealth of free spectroscopy processing software now available. I’ve used BASS and ISIS, but there is also RSpec, Vspec and I think maybe a few others. These can produce a graph of a spectrum and help you to identify elements, along with various other functions.
I’m still a bit of a beginner in spectroscopy myself, starting out in September last year, but if you want pointers to any of the software then please let me know.
Do you know about the BAA spectroscopy workshop on 10th October at the Norman Lockyer observatory? It is being organised by the Variable Star Section noting it is more about an introduction to spectroscopy rather than variable stars.
Andy
Hi Donald,
May I also welcome you to the BAA. I became seriously interested in astronomy at around the same time as you, just over 30 years ago when I was 11. Jeremy has given you some excellent advice which I completely agree with. I find being involved with observing sections to be the most rewarding part of my BAA membership. You certainly don’t need to be an expert and there are plenty of people in the sections willing to offer help and advice.
As a variable star observer myself I concur with Jeremy that your equipment is ideally suited to making variable star observations. Although much useful work is done with CCDs and DSLRs, variable star observations made by eye are still of immense importance and value. Indeed the Variable Star Section has more active visual observers than CCD/DSLR observers.
Using binoculars or a small telescope to observe variable stars is a great way to use and improve your knowledge of the sky. I have a few variables that I follow with binoculars when I don’t have the time to do imaging or just want a relaxing observing session looking at the stars.
I’m sure any other section would welcome you too. The Comet and Deep Sky Section spring to mind with your equipment.
It is worth pointing out that next Saturday, 27th June, is the Exhibition meeting in Cardiff. If you are able to attend then it is a great place to see the work of the different observing sections and discuss how best to start contributing observations. That is how I started out in variable star observing, when I attend an exhibition meeting at Cambridge back in 2001, if my memory serves..
Best wishes,
Andy
I’d have to say that it looks a lot like an aeroplane vapour trail being illuminated by the setting Sun. A nice picture of one but in my opinion it is not a meteor or other astronomical phenomenom. Others have posted similar thoughts on the Bristol Post website.
Cheers,
Andy
Robin,
Stunning results. To obtain spectra of supernova down to mag 17.5 is really very impressive. Especially as you cannot directly see the target for guiding but have to work out the offset from a visible star.
Best wishes,
Andy
I too was at Longyearbyen in Svalbard for a fantastic eclipse. The corona was particularly impressive though my photo does not do it justice. I also saw the shadow bands both before and after totality.
By the end of totality my toes had gone numb with the cold and I had to do some jogging around to return the circulation!
Here is an image I took with a Canon EOS 450D and a 50mm lens.
We also saw a sun dog as totality approached. In this picture you can also just make out a balloon that took off at around first contact. This image was taken with a handheld Canon IXUS 220 HS.
Andy
Hi Dave,
Welcome back to the BAA! I’m the VSS database secretary so I’m sure we have a lot of interests in common. I too got seriously interested in astronomy when I was 11, all of 30 years ago now! That must have been around the same year..
Although we have programme stars, we welcome observations of any variable star. The VSS has a new online submission system for variable star observations which went live in February this year, and that will accept observations regardless of whether or not they are on the VSS programme. I know Tony has been uploading a lot of the SPA observations onto the database.
Good to make contact and I look forward to meeting you sometime.
Andy
