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Hi Peter,
It looks like you are off to a good start. The hydrogen Balmer lines are clearly visible so everything must be working. I note there is a bit of a wiggle in the spectrum from about 5300 to 5900 Angstroms. From the regularity in the spacing I wonder if this might be an interference effect that I have heard of with some cameras. There could be a hint of it at other wavelengths too.
Cheers,
Andy
Hi Dave,
I can give some insight into the variable star observations and spectra, as I manage those BAA databases.
BAA Variable Star Section Database: http://britastro.org/vssdb/
BAA Spectroscopy Database: http://britastro.org/specdb/
It used to be that amateurs and professionals would request this type of data by contacting the Section Director, and this still sometimes happens. However, it is now far more common for them to simply download the observations from the website. We have notes on the database websites asking researchers to acknowledge the use of the data.
We also send a copy of all our variable star observations to the AAVSO once per quarter. While researchers will often come to the BAA databases, some researchers may only look at the AAVSO website, in which case sharing our observations makes them more widely available and useful. The AAVSO acts as a bit of a central hub for variable star observations, receiving observations from a number of global organisations. The AAVSO acknowledge the individual organisations as well as the observer in the data. It is important to note that the AAVSO database does not store all of the information that is held by the BAA Variable Star Section database. In particular we additionally record the chart and comparison stars, so that light curves can be updated when more reliable comparison star magnitudes become available. Something which has happened many times over the decades, and otherwise causes unreal bumps and dips in the light curves.
The BAA Spectroscopy Database is relatively speaking quite new, though I already see it referred to amongst the spectroscopy community. With time it will become better known, as observers refer to it in their communications, and interested researchers are pointed to it. There has been an example of this in the past month with a Pro/Am project looking for a place to archive historic spectra, so they can be made available to researchers for download.
There are also a good number of dedicated campaigns to observe particular targets. Though I primarily make variable star and spectroscopy observations, I see these going on for solar system targets as well. Those involved in these campaigns will usually have an understanding of how their data is being used.
Best wishes,
Andy
Hi Tony,
That is a nice looking spectrograph, and at least being orange you are less likely to bump your head on it in the dark. It sounds like things are progressing well and I’ll be interested to see the results once it is operational.
Best wishes,
Andy
Hi again Jeremy,
The BAA does hold meetings in Wales, but I don’t think there are any coming up in the near future. Anyone please correct me if I have missed any! I am not sure they are particularly frequent but I’ve been to at least 3 meetings in Cardiff.
Not in Wales, but just across the Bristol Channel is a Back to Basics Workshop at Bristol on 10th March.
https://britastro.org/Bristol2018
Best wishes,
Andy
Welcome to the BAA Jeremy!
The Sky-Watcher ESPRIT are good scopes so there is plenty of interesting observing available to you. Though I am sure you are aware of that from your prior time in the hobby. Joining Observing Sections is a great way to become involved and meet fellow enthusiasts. That is certainly the area that I find most rewarding.
Best wishes,
Andy
Hi Tim,
Thanks for the suggestion. The Website Operations Team will take a look at the feasibility, so I won’t say a yes or no at this stage. I can see the benefits.
Best wishes,
Andy
Hi Jack,
I use an ecoair DD122 Classic Mk5. I got it a few years ago from an online retailer but I cannot remember who. As Peter says it is import to get desiccant based dehumidifier so it will work in cold temperatures. Here are a couple of pictures.
I also run a 60W tube heater near my computer to avoid condensation causing problems with it.
Best wishes,
Andy
Hi Nick,
I have a dehumidifier that I run in my observatory for a couple of hours after each observing session. I find this does a good job of removing the moisture that builds up on surfaces in the observatory. Important to note that you would need a low temperature dehumidifier as there are some which only work at room temperature.
Andy
That is a nice spectrum of Alioth on your member page, showing the hydrogen absorption lines.
Stacking is useful for fainter targets to increase the signal. However, you need good tracking for it to work well with a star analyser, to avoid any drift of the star. If there is even a slight drift then this can blur the spectrum, which might be what you were seeing. One way to reduce the problem is to align the wavelength axis of the spectrum North South, on the assumption that any drift will be East West. This could even help by spreading the spectrum over a few pixels, but requires that you have no drift in the North South direction.
Sharpening should normally be avoided. The algorithms can introduce artefacts and change the line profiles. I have heard of it occasionally being used to bring out faint lines, but it is very risky and will invalidate most of the scientific data contained within the spectrum.
Cheers
Andy
Hi Jack,
I’m not sure of the make of my flip mirror as I bought it a few years ago and it is a generic one without a company logo.
There won’t be any side to side adjustments with flip mirrors, or up and down for that matter. They are designed so the light either goes straight through or is diverted up at a right angle. If you are using this in a finder setup then you would normally mount it within finder rings with screws to hold and adjust the finder scope position.
Flip mirrors aren’t usually used in finders. Instead you use them in the light path of your main scope so you can view with an eyepiece or another camera without have to detach your main equipment. Nothing wrong with using them in a finder, but there may not be any benefit to doing so.
Best wishes,
Andy
Hi David,
You have already received some great advice for getting started with the links posted by Andrew and Robin. I started out by reading books on the subject, but there is no one book that I would recommend as the best starting point. I can always recommend a few, but you may be able to get all you need from the internet to get going without having to spend money on books.
Starting off with a nice easy target like Vega is definitely the right way to go. I found it took me a few months to learn how to use my setup and get comfortable with the processing, but I was still able to get some pleasing results right from the start. The star analyser is an excellent way to learn. As well as being simple it will also allow you to go fainter than with higher resolution spectrographs, so there are a whole range of targets you can observe.
Good luck and please keep us posted on how you get on.
Andy
Hi Alun,
Sounds great. It would be very nice to have it fully remotely controllable. Good luck with your modifications.
Andy
Hi Andrew,
Thanks for posting your results. You have the same camera as me, so it is interesting to see your results.
It is a while since I ran my test, and I don’t think I removed the hot pixels, so it is possible they are the cause of what I saw. I really wanted to measure the median pixel value, but the software I was using did not calculate that statistic. So I measured the max, min and average pixel values. Leaving the camera be, and then running a series of bias and dark frames. I must redo it sometime, this time removing the hot pixels.
Here are my results for reference.
Test Run 1
Test Run 2
Cheers,
Andy
That is an interesting test Andrew, a great demonstration of just how small the dark current is with these modern CCDs. Can you remind me which camera you use?
Also, have you also looked to see if there is any bias drift? That is the one thing that surprised and horrified me when I ran some tests on my camera last year.
Cheers,
Andy
Hi Alun,
That is a nice bit of remote control for your neon and flat field lamps. I did give it a bit of consideration, but found I don’t really need it at present. I am at the telescope when I change target, and everything is sufficiently solid that nothing moves when I flick the switches on the spectrograph. This would be great for remote observing!
Andy
Hi Denis,
Here is a summary of the results for the successful candidates in 2017.
President: Callum Potter 290
Treasurer: Geoff King 285
Business Secretary: Bill Tarver 280
Papers Secretary: Jeremy Shears 285
Meetings Secretary: Hazel Collett 283
Trustees:
- A Lorrain 228
- D Arditti 209
- J McClean 184
- R McKim 182
- J Chuter 159
Council:
- P Bosley 135
- S Bosley 119
- P Abel 230
- P Carson 162
- R Sargent 158
Total Votes Counted: 320
Null/Void votes:13
Votes not Counted as not renewed or not members: 29
Best wishes,
Andy
Hi Denis,
The results will appear in the report of the AGM in the February Journal. I am seeing if I can get hold of a copy to add to this forum thread.
Thanks for pointing out the ‘Who’s who’ Peter.
Best wishes,
Andy
Hi Ron,
I also own a 10″ Altair Astro (GSO) RC. I understand that Altair made some kind of modification to the GSO RCs before selling them. I think it was something to do with the mirror cell but I don’t know exactly what. They have stopped selling them now.
I’ve done collimation once and it was a bit of an ordeal. I expect it is one of those things that once you have done it a few times then it gets much easier. I’ve found it to be very stable and appears to hold collimation well. Though as I am also using it for spectroscopy, I don’t worry too much about having the collimation absolutely spot on as this won’t affect the spectrograph resolution, just the throughput and so SNR.
I also upgraded to the Feathertouch Focuser and found it to be rock solid. I’ve not bothered with a motorised focus as I am in the observatory and I can tweak the focus if needed. Though I find the whole telescope and focuser to be extremely stable and so I rarely need to adjust it, except due to seasonal temperature changes.
If you get a 16″ then I’ll be very interested to hear how you get on with it. I wonder about one day upgrading to a larger GSO RC. Though for me the choice was also about a compromise between matching the focal ratio with my LHIRES III spectrograph, and keeping the focal length short so that I have a reasonable field of view in the guide camera.
Best wishes,
Andy
Hi Colin,
The shop has now been updated so you can order 2016 and 2017 Journals.
Apologies for the delay.
Andy
Hi Colin,
I am very sorry that no-one has contacted you. Normally someone would respond within a few days at the most and so for some reason I don’t think your message could have been received. If everything works as it should then you should automatically receive a confirmation email from the website.
I will check the stock availability of the Journals and then get the shop selection updated. I’ll let you know when this is done.
It is also worth knowing that when you are logged in you have online access to the entire Journal archive. Journals from recent years can be viewed from the Publications -> Journals menu. The full archive of all Journals in pdf form can be access from Publications -> Downloads -> Journals Archive.
Best wishes,
Andy Wilson
BAA Systems Administrator and Web Content Editor
