whether to post non-SN classification report spectra to TNS

[Hamish Barker]

To clarify for fellow ARAS forum contributors who might also collect spectra of TNS Alert targets, and particularly to ensure not to be making problems at the TNS end (apart from my posting a spectrum of an incorrect star - show of hands for those here who have never done that? ), I asked the TNS, Gaia alerts and Asassn survey if it was appropriate to upload spectra and classification reports for non-SN objects.

I received the following responses:

From Ofer Yaron of the TNS team:
"Hi Hamish
Thanks for your message.

If you're obtaining spectra for reported ATs, you should certainly report the classifications to the TNS (assuming you're secure with the classification).
Many of the ATs indeed turn out not to be extragalactic transients, and it is very important to be aware of the actual classifications.

The guideline for trying to avoid reporting on variable stars and as such refers to the submission of the AT (discovery) reports, not to the classifications.

Once an AT is on the TNS, and a spectrum of it is obtained, it is certainly valuable for everyone that the classification is reported and updated on the TNS.

Best, Ofer"

From Simon Hodgkin of the Cambridge Astronomical Survey Unit (managing the Gaia Alerts system):
"Dear Hamish,

Many thanks for your question and your work in classifying Gaia Alerts. TNS support our Alert stream, and accept our alerts in their current form. There has been some discussion with TNS concerning our significant fraction of Galactic transients, because TNS prefer to "focus on as-secure-as-possible extragalactic transients” (not only Supernovae). As Ofer Yaron (at TNS) puts it - this all falls in a “grey area”.

I think that GSA does not dominate their data rate - and so it’s not a big issue. Also they have a keyword ‘AT_Type’ which helps the user distinguish between New Sources, and transients with historic data. If some level of pre-classification/filtering is required by TNS, then we will look at it (assuming sufficient resources).

For GSA, it would be great to have access to your classification spectra, and your best estimate of classification. And TNS seems the best option to me, given that the transients are published there. And honestly I don’t see a better alternative right now. But to cover yourself, and avoid any possible conflict, you may prefer to check with the TNS team that they would be happy with this.

Either way, please let me know. We do have a Marshall for posting and discussing classifications (though no method for ingesting the spectra themselves). There is also a Black Hole TOM for transients (currently in ‘beta’) which may be considering handling of spectroscopy as well as photometry. I’m copying in Lukasz Wyrzykowski who is managing that system.

Hope that helps!

Simon"


and finally the following from Krzysztof Stanek (PI of the Asassn survey):
" Dear Hamish,

if somebody (including us) posted an alert on TNS, then a spectrum of that alert should also be posted on TNS, even if it is not a supernova.

You could also post them to BAA spectroscopy database, I don't see a problem here.

So, in my not very humble opinion, what you are doing is perfectly fine.

Best,
Kris"

Wishing everyone here at the ARAS forum clear skies, good seeing and exciting discoveries,
Hamish

[Robin Leadbeater]

Yes but it important that the spectrum is good enough to make a useful and accurate classification, taking everything into account, not just the spectrum. Many objects cannot be identified just from a noisy low resolution spectrum. The problem with TNS is that it was set up specifically to replace the supernova confirmation system which is based on a spectrum and there is no option to post a spectrum without a classification. A classification "other" specifically means it is not any of the listed types.

For example you have just classified AT2022cxx. How do you know it is not a CV? Actually this appears likely to be the already known mag 13 emission line star SS 175 so the spectrum and classification does not really tell us anything new. It could though also be mag 12 TYC 6558-1893-1 which is shown in SIMBAD with coordinates only ~2 arcsec away and not resolved in the DSS image for example so your spectrum would likely be a blend. (It is also possible that these are actually the same star, there is no sign of elongation of the star image in DSS, we would need a higher resolution unsaturated image to be sure).

Gaia have proposed it might be a gravitational lensing event (certainly a possibility given its location in the crowded region of the milky way.) A single spectrum cannot prove this but multiple spectra showing variability could disprove it. The light curve together with an unchanging spectrum would be needed to prove it though. What is the light curve doing? I expect the groups who study lensing events are already looking at this.

The other Gaia suggestion is a Be star. This would at least need a high resolution spectrum though to determine the H alpha line profile which will be tough for us at mag 12. To be honest I am not even sure though that there is actually much interest in this from the professional community. For example as far as I know there was no professional follow up of the stars we found in this Be star candidate survey
http://www.astrosurf.com/aras/be_candid ... idate.html
and Coralie has not replied yet to our work on HD58859

Cheers
Robin

Cheers
Robin

[Robin Leadbeater]

The key words are from Ofer at TNS

"you should certainly report the classifications to the TNS (assuming you're secure with the classification)"

It is worthwhile giving a bit of history behind my relationship with TNS. I joined TNS when it first started up as the only amateur. Before that Dan Green at IAU used to personally check every supernova spectrum and classification. (Only from professionals. He did not believe that this was something that amateurs would ever be able to do) He become overloaded though as the surveys came on line. TNS was the solution to this but it became very clear early on that the quality of classification people (except for me, all professionals) were making dropped significantly. Ofer then put out a warning that people must sanity check their classifications making sure that their spectra support the classification and show the features specific to that classification. (This is doubly difficult for us as amateurs as our spectra are generally noisier and lower resolution and we do not have the astrophysics knowledge.) I decided however that it was possible for me to do this in one very specific area, namely classifying certain types of supernova, based on the system proposed by ZTF using very low resolution spectra. I built the ALPY200 specifically to duplicate what ZTF were planning to do and actually started up before they did. When they started up, they then effectively took over, classifying hundreds a month and I do not do many classifications now as there are enough professionals to cover this area. amateur Claudio Balcon is still doing this sort of work on a regular basis though using a home built spectrograph similar to the ALPY200.

Cheers
Robin

[Tom Love]

Please ignore me if this is too far off topic, but I think this discussion raises some wider points for amateur astronomers who want to participate actively in doing science. Some people enjoy the craft of taking useful observations, but don't want to participate further. Some want an active role in planning, analysing and publishing observations - essentially working in a manner similar to a graduate student or an academic researcher. But, today, very few professional astronomers work in isolation. Modern scientific research roles will nearly always be part of a research group with a high degree of collegial support, and ideas and data are pretty constantly tested with colleagues before anything is done with them.

For an amateur astronomer, this is tricky. It's difficult to set up an arrangement with a number of colleagues so you can work in a research team, like a professional researcher, with the benefits of peer support and scrutiny. This means that there is a risk of doing work that is a poor fit (or even just wrong) without being aware of it. It also makes it hard to develop your scientific knowledge and experience. I've heard Peter Velez make the comment that amateur spectroscopy can be a lonely business, and I agree.

That said, amateur spectroscopy has some pretty strong elements of community - we're on this ARAS forum, after all - but that isn't quite the same as having colleagues on a research project. Some of us in Australia and New Zealand (including Hamish) have a periodic zoom meeting where we discuss our various activities and sometimes look at and debate our observations. This is a good thing, but still has limitations. Personally, I do radial velocity work on eclipsing binaries, working in a little group that includes two retired professional researchers from that field, which is great and gives me the kind of support and opportunity for scientific development that I need. Robin's TNS example is a good one of developing a relationship with a professional or group that enables you to do some good science. Another good example would be the relationship that I think some groups have developed with Steve Shore. But developing those kinds of contacts and relationships isn't necessarily easy, and can take time and effort to do. And we don't have some kind of right to expect professional researchers to spend time on our interests. Working in modern day academia can be very pressured and stressful, and it's important to respect that when people generously give you their time.

So, my reflection is that those of us who want to engage more actively with doing good science somehow need to find mechanisms for peer support both so we can develop as scientists, and so that we do good, relevant work. Given the recently distributed IAU survey on professional and amateur collaboration this is probably something we should be raising in that forum.

[Robin Leadbeater]

There is also a Black Hole TOM for transients (currently in ‘beta’) which may be considering handling of spectroscopy as well as photometry. I’m copying in Lukasz Wyrzykowski who is managing that system.

I hope you have more success than I did with this if you try it. It is for posting photometry and spectra of microlensing events. I was pointed to it by the BAA assistant director for exoplanets but I tried and failed to get it to accept my spectra and I have been waiting for months for them to work out why it failed despite several follow ups.

Robin

[Hamish Barker]

thanks for your posts Robin and Tom.

Regarding the BHTom system, it was a little fussy and doesn't accept fits spectra. I had to download an example spectrum that was on the system to work out what it wanted. Then take the DAT text spectrum file from isis, open it in excel then add the words "wavelength flux" at the top, and save with the columns separated by a tab (or might have been a space).
https://bh-tom.astrolabs.pl/bhlist/33405/

https://bh-tom.astrolabs.pl/bhtom/stati ... sample.csv

my spectra were only relative intensity (not absolute flux calibrated) but then their system seems to rescale them, presumably according to the flux in the recorded light curve of the time when the spectra were taken.

[Robin Leadbeater]

Regarding the BHTom system, it was a little fussy and doesn't accept fits spectra. I had to download an example spectrum that was on the system to work out what it wanted.

I tried that too but it still failed. It was passed on to someone else to look at. This was some months ago so perhaps they have fixed something and not told me. It should just work the same system as TNS for example which happily accepts fits and simple dat files and plots them without difficulty. To me BHTOM has a bit of the feel of a student project where they are "re-inventing the wheel"

Cheers
Robin