Tue, 02/25/2014 - 05:11
Just a question:
How many members would invest in a spectroscope to be able to submit ongoing spectral data if a suitable database was established???
I'm assuming as a minimum (Lo-res) a Rainbow Optics or Star Analyser 200 grating would be required. Better still would be a Shelyak LISA (Med-res) or the LhiresIII/ Spectra-L200 ( Med to Hi-res). The typical mono CCD used for photometry could be used with available scopes/ mounts.
It would be interesting to get feedback.
Ken
Yes I would submit LISA and potentially L200 spectra when I get it up and running again.
It would depend on the targets though.
Terry
Hi,
I am also thinking of buying an Star Analyser 200 for my filter wheel and would submit spectra as available.
regards,
Josch
Hmmm
Over
Thanks guys!!
Hmmm
Over 100 views and only 2 responses, not sure that's a good starting ratio........
I also want to point out for Ken and others that opinions carry more weight when they come from the voting membership of the AAVSO. I want to encourage the people who are actively asking for the AAVSO to get involved in spectroscopy to take the step of joining the AAVSO.
[quote=uis01]
I also want to point out for Ken and others that opinions carry more weight when they come from the voting membership of the AAVSO. I want to encourage the people who are actively asking for the AAVSO to get involved in spectroscopy to take the step of joining the AAVSO.
[/quote]
Hi John,
I think many "outsiders" who have seen the growth of interest in this area and been involved in developing the capability of amateurs to take research quality spectra are just wondering why AAVSO is not involved, rather than particularly needing AAVSO support. A look at the work already being done currently across a very wide range of targets as showcased in websites like ARAS (which is not a Be star one trick pony as you seem to suggest) and the VdS
http://www.astrosurf.com/aras/
http://spektroskopie.fg-vds.de/index_e.htm
and a comparison of the quality of the discussions in the forums associated with those sites compared with those here suggests that the expertise to allow AAVSO to get up to speed in this area lies outside AAVSO
From my point of view I think there are two useful areas Where AAVSO could be useful in the same way as it is for photometry, namely
1. A centralised database for long term storage of campaign and ad hoc spectra
2. A point of contact between professionals and amateurs (a kind of pro-am "dating agency")
Were AAVSO able to provide this sort of support I would probably become a member. In exchange I believe outsiders can bring real world experience of involvement in Pro-Am campaigns and practical hard won knowledge on how amateurs go about gathering research quality spectroscopic data by people who are actually doing it, which AAVSO lacks currently.
Of course AAVSO and its membership should make up its own mind on this (and probably more fundamentally if spectroscopy is even something they want to be spending time and effort on) but it has been dithering around this subject for a number of years now and to be honest the world has substantially moved on in this area without AAVSO.
Cheers
Robin
Hi John,
That is interesting. I certainly agree with you. I was not aware that the AAVSO would allow non-members to debate policy and direction for the organization. In fact I thought membership was required to participate in these forums. By all means if someone wants to change an orgainzation then they should be a member. Also, a recent post by a non-member should be taken carefully as the person has a financial stake in the Star Analyser and is therefor pushing it. I think, and noone can debate what I think, the use of a Star Analyser in a filter wheel will be very disappointing.
Jeff Hopkins (187283)
Hopkins Phoenix Observatory
[quote=HPO]
Also, a recent post by a non-member should be taken carefully as the person has a financial stake in the Star Analyser and is therefor pushing it. I think, and noone can debate what I think, the use of a Star Analyser in a filter wheel will be very disappointing.
Jeff Hopkins (187283)
Hopkins Phoenix Observatory
[/quote]
Hi Jeff,
I love the way your refer to me obliquely these days ;-)
This is where the scientific method is so powerful. Someone has an idea, someone tests that idea and if it proves false, the idea is modified or abandoned. Real world always trumps theory, even in the face of any imagined fiscal bias ;-)
Here for information are my comparison measurements of a converging beam arrangement using first a 100 l/mm grating at optimum distance, and then 100 l/mm and 200l/mm gratings mounted at a typical filter wheel distance.
It confirms what I recommend. ie that where there is room the 100l/mm grating gives a marginally better result for the same dispersion compared with a 200 l/mm grating mounted closer, but for setups where there is not enough rooom, similar performance can be achieved at half the spacing. This means that many users who might otherwise be reluctant to modify an existing imaging or photometry setup are able to get useful results. This of course also applies to the Rainbow Optics grating and I would urge anyone who already has one to try that first provided it can be fitted in the wheel. ( I specifically designed SA200 to be as widely compatible as possible but filter wheels are getting slimmer and slimmer) I would be interested to see your comparison results and discuss them further with you.
Cheers
Robin
Hello Ken
I was surprised to see so few responses. What does it mean. Possibly nothing. But possibly someting. My take is that a database alone, does not get the juices flowing and the participation. I too have thought of purchasing an SA200, to put in my filter wheel, and could generate spectra as I image other objects. One scope, one camera, just two data reductions. For me, PT is enough to keep me busy. I am still trying to attain the .01 mag accuracy required to have ccd observers line up their data. I would throw a spectra in as a secondary activity.
However, what I think is needed is a campaign leader for spectra. I have asked several folks if they would be interested in doing this. No takers so far. It takes an active amateur leader and an interested professional teamed up to make it happen. They need to be on the forum once or twice a week, pointing out features, and explaining the meaning of things seen in the spectra. They need to point out mistakes as Arne has done with PT. This model of an active amateur leader and a professional leader was used for the PEP and the CCD programs. Howard Landis and John Percy for PEP, and Gary Walker/Aaron Price and Pricilla Bensen for the CCD. The same might work for spectra.
The targets should be very specific and limited in number. It makes no sense to just say "take spectra of any program object". Critical mass is not attained and things will die. Probably just a half dozen designated objects, and of course, a current supernova or two.
I know Arne is working go get funding for a grant to support spectra.
Any spectra leaders want to take this on?
Gary
Hi Gary,
I agree with you. I do not think just a database of spectra would be of much value. Who would look at the spectra? I suspect there would be a great deal of spectra that noone would ever look at more than once if even then. I like your idea of Campaigns or perhaps as Matt likes to say for open ended work, Projects. I think the AAVSO would do well to have projects with project leaders to help and guide users. There could be several levels of projects depending on experience, equipment and interest.
The Star Anaylsers are great for beginning and learning spectroscopy, but I do not think you really want to put one in a filter wheel. Spectroscopy is very different from photometry. There is a lot of adjusting, refining and getting bugs worked out that is entirely different from photometry. With over 30 years of photometry and 8 years of spectroscopy, I know. I have 2 Star Analysers, an ALPY 600 and a Lhires III. The big advantages of the Star Analyser are cost, ease of use and ability to produce low-resolution spectra on faint objects. While this has some utility, little serious data can be gleaned from the low-resolution images. Again, the Star Analyser is great to get started with. Remember, serious spectroscopy of faint objects is the realm of large professional observatories.
For more serious work a mid-resolution spectrograph is needed. These are considerably more money and more complex, but allow excellent spectra to be obtained, The ALPY600 is the least expensive and the LISA while much more is the top end of the mid-resolution. These allow taking of spectra of fairly faint (for spectroscopy) objects of 5th to 8th magnitude. Remember, photons are the key. For more resolution the spectrum is spread out and the available photons to produce the spectrum decrease requiring very long exposures and/or large apertures.
For high-resolution work the Lhires III is by far the best choice. It costs about the same as the LISA (~$5000 sans cameras). The Lhires III can produce professional quality spectra where Dopller Shift (radial velocities) and equivalent widths can be measured. The top end is the eShel, but at around $25,000 that is out of sight for most people, plus if going that route one should consider a larger telescope (meter size). The downside of the Lhires III is it requires bright stars or long exposures or a large telescope.
Mid and high-resolution spectroscopy cannot be done with a telescope that is also set up for photometry. They require dedicated telescopes. While it is possible to automate these equipments, it is much more difficult than with photometry, particularly CCD photometry. Getting the right star on a slit and keeping it there can be a real challenge. Movement that would not be noticed with a CCD image for photometry can move a star out of the slit and essentially shut off the specroscopy.
I look forward to seeing the AAVSO more involved in spectroscopy. I think it is a natural progression from photometry (in addition to).
BTW, for those who did not know, the Society for Astronomical Sciences (SAS) has annual symposiums in California. This year it will be held in Ontario, CA the first week of June. The AAVSO will be having a joint meeting with SAS and there will be much spectroscopy discused, even possibly a free workshop on spectroscopy.
See http://www.socastrosci.org/
Jeff Hopkins (187283)
Hopkins Phoenix Observatory
[quote=HPO]
For more serious work a mid-resolution spectrograph is needed. These are considerably more money and more complex, but allow excellent spectra to be obtained, The ALPY600 is the least expensive and the LISA while much more is the top end of the mid-resolution. These allow taking of spectra of fairly faint (for spectroscopy) objects of 5th to 8th magnitude. Remember, photons are the key. For more resolution the spectrum is spread out and the available photons to produce the spectrum decrease requiring very long exposures and/or large apertures.
[/quote]
Hi Jeff,
These magnitudes are too far out to go unchallenged so lets look at some real world figures.
Firstly the ALPY and LISA spectrographs at ~8-12A resolution are still normally considered low, not mid resolution spectrographs even by amateur definitions. They are capable of going much fainter than 5-8 magnitude though. This is the domain of what amateurs call high (sub angstrom R~5000-20000) resolution but professionals would still call mid range resolution. The tens of thousands of spectra in the BeSS database for example is a good place to verify that this magnitude range is routine at high resolution for amateurs with modest apertures.
At low resolution eg ALPY/LISA/DADOS used at low resolution/LHIRES with 150 grating etc you can add typically at least 4 magnitudes to these though of course the the SNR required has a large bearing on this. (I am assuming >50SNR here) A good recent place to see real world spectra over a wide range of magnitudes and resolutions is the ARAS database of Nove Del 2013 spectra where there are over a thousand spectra taken using a couple of dozen different amateur setups across the globe.
http://www.astrosurf.com/aras/Aras_DataBase/Novae/Nova-Del-2013.htm
And for a current example of "extreme amateur spectroscopy" how about Olivier Garde's high resolution (R~10000) spectrum of SN2014J at mag 11.7 using a C14 and a fibre fed echelle spectrograph, not the most effiecient of spectrograph designs.
http://www.spectro-aras.com/forum/viewtopic.php?f=5&t=766&start=30#p3483
Cheers
Robin
Hi Jeff,
Lots of unsubstansitated dogma to disagree with there Jeff ;-)
In the meantime people elsewhere in the real world are quietly getting on with doing good science. Gianluca Masi for example has a robotic setup doing photometry and has recently added spectroscopy with a Star Analyser mounted in the filter wheel. Already he has 2 novae and 1 supernova confirming spectra to his credit with the corresponding CBETs.
http://www.virtualtelescope.eu/
Cheers
Robin
After over 30
Hi All,
After over 30 years of submitting variable star observations to AAVSO as a member. I jumped in to the spectroscopy ring about 3 years ago. I started with the Lhires II and now also have the Alpy 600. Admittedly the learning curve is a bit steeper than photometry, but with perseverance and the help of many experienced amateur spectroscopists, I now submit spectra (both high and low res) that are acceptable for use in both the amateur and professional communities. Before purchasing any equipment, I wanted to be certain there would be a repository where I could submit my data – just as AAVSO has been my repository for submitting photometric data. I did not want to spend a lot of money on equipment and time learning the ropes of spectroscopy and then have no place to submit data. Whereas AAVSO had no such repository, our friends over in France have done an extremely outstanding and remarkable job of getting the ball rolling so that amateurs could have the equipment, software (free), and data repositories. There are many experienced spectroscopists who are very willing to help newcomers become adept at taking excellent data. I now have sent many spectra to the BeSS and ARAS databases, and I have been involved with campaigns where spectra of specific stars have been requested. All of my needs to be involved with spectroscopy have been met thanks to all of those who have provided the means to do so.
In the mean time, I have been asking for three years if AAVSO has any intention of getting involved with spectroscopy. The answer has always been that it is in the plans and coming soon. The definition of “soon” appears to be as variable as the stars we measure, but there apparently has been little progress in this direction. Perhaps some of us have simply quit asking about when AAVSO will, if ever, enter the realm of spectroscopy. We currently have highly qualified places to send our spectral data. Rest assured, BeSS and ARAS accept only high research quality data. And what make BeSS and ARAS so extra special are the administrators who offer suggestions and help when spectra cannot be accepted because they do not meet the criteria.
With all I have said above, it should be quite obvious that amateur spectroscopy is well on its way, and professionals are accepting data submitted by amateurs to BeSS and ARAS. AAVSO’s reluctance to get involved has put it years behind what already exists. Robin said it best when he said:
“Of course AAVSO and its membership should make up its own mind on this (and probably more fundamentally if spectroscopy is even something they want to be spending time and effort on) but it has been dithering around this subject for a number of years now and to be honest the world has substantially moved on in this area without AAVSO”
Sometimes sitting on your hands simply creates disinterest. Those of us who are serious about our spectroscopy have already found the very highly qualified people and places where we can pursue those interests. If and when AAVSO ever decides to involve itself with spectroscopy, it will have much catching up to do to get on par with what already exists. Perhaps AAVSO should keep on doing what it does best in being a repository for variable star data and leave the spectroscopy to those who have it well underway and who already have the confidence of the professional community.
In answer to the original question if I would send spectral data to the AAVSO DB, I have to say I do not know. I would first have to see what AAVSO has in mind. But AAVSO has to first make the determination that it wants to get involved with spectroscopy, and therein lies the hang-up.
Cheers,
Keith
I think Robin is
Jeff,
I think Robin is experienced and mature enough to be able to contribute to the development of amateur spectroscopy.
We're not just talking about Star Analyser gratings here, I've been using the Rainbow Optics (now only available in the US) and the original Baader 207 l/mm for many years.
If we accept that the gratings can be used as "objective" gratings as well as "in the converging beam" to give repeatable lo-res spectra (just look at some of the world class examples by Torsten Hansen etc), then they can and do make a very cost effective starting point for the novice.
I recommend any beginner to use the gratings as a "Spectroscopy 101" - learn the basics and the limitations as well as understanding the processing techniques.
Kids are not likely to fork out thousands of dollars for an unknown "one trick pony" like a LhiresIII or a Spectra-L200. ( In the interests of full disclosure I should point out that I am the designer and constructor of the Spectra-L200, currently under commercial manufacture by JTW Astronomy in Holland.)
Yes, I would definitely submit spectra to an AAVSO repository, but the choice of targets should be mine, not some small official targets list. I think the first and most important purpose is to provide a permanent place to put spectral data so that it is not lost when the observer is gone.
I my case the spectra would come from an SBIG DSS operating from 4000-9500, R~400 with multipoint wavelength and relative flux calibration. This is data I am generating for spectropolarimetric analysis, which requires high S/N.
If necessary, I would not be opposed to a small fee applied to storing data for targets that are not part of the official targets list. A few dollars to support permanent publication is certainly reasonable, just like a page charge for a journal.
As to the comment that non-campaign work will generate "data no one will ever look at", most of the individual AAVSO data points fall into that category. The stars that will be measured with backyard telescope spectroscopy are going to be relatively bright because spectroscopy requires from 3 to 7 more magnitudes of light than 1% photometry. Bright variable objects are constantly used for research, if just as references for more exotic work.
The great potential power of the AAVSO repository will not be so much in the sophistication of its spectra data (although I think all of us intend to provide the best quality we can achieve), but rather in establishing long time series spectroscopy data sets that support generations of future contributors as well a interested researchers.
Gary Cole, Reno, NV
I'd submit my low-res spectra but depends on requirements. If you want professional-quality data I'm out!
Cheers -
Rob Kaufman
Lots of interesting discussion.
The AAVSO by it's name is interested in "variable stars"
Clearly the recording of the magnitude of variable stars is what is currently done along with support and analysis of what is found.
Taking spectra that vary with time should be an extension of this role. Amateur spectroscopy is certainly improving. I can take a spectra of a 13 mag star with a S/N of >20 and a resolution of 1000 with 1 hr of exposure. This was unheard of until recently. This bring many targets into the realm of amateurs.
So what targets could be submitted and stored by the AAVSO?
My current targets are Be stars plus transients like novas and possibly supernovas. There are other targets that are suitable ie eta car. It would be good to have a central repository for these other targets as BESS currently handles the Be stars and novas etc very well.
I also think that spectra of the standard that I take to calibrate and create instrument responses are also useful to share. Thers are not "variable" but it would be good to see other spectra of calibration standards to check on the accuracy of individual observations.
As I stated in my earlier post I would submit data but would also look at other data submitted to check on my own accuracy.
Terry
I think that Terry makes a good point about the AAVSO keeping its mission in mind with regard to spectroscopy. The mission of the organization has changed and expanded over the last century. But I would expect that whatever initiative the AAVSO takes with spectroscopy will be driven by variable stars.
Photometry is really just really low resolution spectroscopy (or you can look at spectroscopy as really high resolution photometry). I've personally have been pleased to see instrument makers innovating and finding new ways to put this tool in the hands of non-professionals. I think we have to keep in mind that there are trade-offs in this technology and there is not (even professionally) any one spectrograph that works best in every situation. It just isn't possible to maximize both resolution and through-put. And the apperture sizes that non-pros have available put another limit on what is possible.
With this in mind there is not any one cannocial way that spectroscopy has to get done. The observer and the end user have to agree on some things in order for the data to be useful. But most good experiments are tailored to emphasize one aspect of a measurement at the expense of another. I like the arguements over this is better or that is better because both are inevitably better under different situations and the discussion reveals that in interesting ways that everyone learns from. Its good to be passionate. On the other hand I cringe a little over these arguements about a clear absolute right and wrong. Let's remember that we can't see the smiles on each other's faces as we communicate this way. And I do like to imagine each of you smiling as I read your posts.
I'd also like to take this opportunity to appologize if my "AAVSO members" comment offended anyone. We want to continually attract new members. That is one reason why this forum is open and does not disscriminate between members and non-members. I was actually shocked to find out that Robin isn't a member.
But on the other hand, the membership fee is pretty reasonable. Most of us could skip lunch out one day a month and easilly pay for an AAVSO membership from what we save. Or put another way, you couldn't buy a decent eyepiece for your telescope for what it costs to join the AAVSO for a year. If you care enough to hang out here and post, you have already invested in the AAVSO. I'd personally like to count you as a fellow member if you enjoy being here. And the membership fee is a small thing then that benifits the community you are already a part of.
Excellent post Dr. Martin.
I look forward to the 8 March chat.
Jeff Hopkins (187283)
Hopkins Phoenix Obervatory
Hello Robin
I tried to look at some of the spectra at: www.astrosurf.com/aras/Aras_DataBase/Novae/Nova-Del-2013.htm. I see the main page, but when I right click, I get options, but "save file as" or "save as" is not one of them. Should I be able to view these spectra in Maxim--if they are fit files? What am I doing wrong? Using Mozilla as browser.
Thanks
Gary
Hello Gary,
Right click and then "Save" the file on your drive
Then you need a specific software to visualize the spectra
For instance, free softwares from Valérie Desnoux and Christian Buil :
http://www.astrosurf.com/vdesnoux/
http://www.astrosurf.com/buil/isis/isis.htm
Some of the spectra are shown in : http://www.astrosurf.com/aras/novae/Nova2013Del.html
and following pages
Note that in the prototype ARAS data base you have also number of spectra of symbiotics :
http://www.astrosurf.com/aras/Aras_DataBase/Symbiotics.htm
Best regards
François Teyssier
The ARAS databases record the spectral profiles as 1D fit files. These are not your normal 2D image files.
As mentioned, VSpec, ISIS as well as SPCaudAce, and BASS Project will open and display these profiles.
The 1D fit format is the recommended format of archiving spectral data. All the user, target, aquisition and processing information is held in the header.
I do all my Mira type star observations on Rich William's Sierra Stars scope in northern CA. He has installed a 600 line grating on his 24" scope and I am keen to try it out. My mv observations are cheap, so maybe you can join the fun.
Chris Norris NCH
Ken,
I would be very interested in submitting spectral data.
I'm still a rookie though.
John
Yes, I am working with an Alpy 600. As a beginner in this field I would be most comfortable with specific campaigns and known reference stars to guide me in my learning.
Ed
I am having difficulties getting my observatory set up, but once I do (IF I do?), I have a RSPEC "Star Analyser" diffraction grating, with software, with which I could submit spectra.
And I would love to do it!