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Are we soon to be ASASSN-ated ?

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lmk's picture
Are we soon to be ASASSN-ated ?

Off and on, we have heard concerns that automated surveys will make many if not most of our individual observations valueless. The usual reply from AAVSO is that it is not much of a concern, and we should continue our observations, as they are all useful.

However, this new all-sky survey ASASSN, appears to have arrived, and may be the "nail in the coffin" for most other observations? They already have been covering a good portion of the sky, and discovered numerous variables, SN and other transients. According to their website, they are planning to expand their system to COVER THE ENTIRE SKY DOWN TO 17th MAGNITUDE ON A DAILY BASIS.

If this plan succeeds, won't they make a large percentage of typical AAVSO observations superflous? Certainly most of mine, as a visual observer, would be. I suppose the realm fainter than 17th magnitude will still be virgin territory, but thats not really practical for visual.

This system really does scare me.

Mike LMK


Herr_Alien's picture
Not that worried

"if there is an object with V-band magnitude between V~10 and V~17 that we might have in our data, send us an e-mail and we will check what we have."

My guess is that estimates for variables brighter than m=10 will still be valuable. I mean it is difficult to obtain (with the same scope) in a single exposure data for stars from m=0 to m=17. Most likely they will set up their exposure time to get data in that interval m10 - m17.

Another thing to keep in mind is the fun factor. Even if there are automatic surveys that track all targets from m=0 to m=20, on all sky, I'll still do visual observations just because it lets me see with my own eyes what's going on up there.


WWJ's picture
"On the Beach at Night, Alone"

Don't be “scared”, Mike. Our pursuit’s for personal interest and amusement. Whatever the all seeing eye of ASASSN offers, we'll still be out there on the drive, in the small hours: a period when there's no other claims on our time or attention. A small loss; the remote possibility of stumbling on something overlooked, to be “famous for fifteen minutes”! Is that what you really regret? Recall the pleasure in designing The Linnoscope, when you might have bought some innovatory instrument. Let's be scared about what actually threatens us, now. List provided, upon request!



HQA's picture

So Mike, you were not scared by 2GSS? smiley

Seriously, all surveys have limits and only cover part of the possible parameter space.  For ASAS-SN, its main constraints are the large pixel size (7.7arcsec; FOV 4.5x4.5 degrees), so it does poorly in the galactic plane (though fine for its main intent of supernova discovery) and the use of a single filter, so no color information about the transients that are found.  I don't know how well they've calibrated their photometry either, or how precise it is, since no ASAS-SN paper has been published yet.  Note also that they need many more stations to reach their desired goal of nightly coverage.  That said, their survey will be very interesting if (a) they continue for a large number of years, like the original ASAS, and (b) they release their data in a public, fast-response manner like ASAS.  If that happens, then some of the nightly monitoring activities of LPVs by the visual observer may be redundant, once sufficient dual coverage is available to see how to transform their V-band to/from visual estimates for continuity.  Many other areas, such as CV outburst monitoring or time series photometry, won't be impacted at all.




lmk's picture
ASASSN limitations


For ASAS-SN, its main constraints are the large pixel size (7.7arcsec; FOV 4.5x4.5 degrees), so it does poorly in the galactic plane (though fine for its main intent of supernova discovery) and the use of a single filter, so no color information about the transients that are found.

 Many other areas, such as CV outburst monitoring or time series photometry, won't be impacted at all.


Thats a good point Arne, the large pixel size in dense star fields will cause it some problems. But they still will detect an outburst even there, though may not precisely resolve it from neighbors.

If they doubled the size of the project they could do B-V on everything, though wink Or, just use what they have and change filters in the case they find something new in "real-time" to get more info on it.

Yes, time series is out of their realm of course, and we won't be affected. But CV and other transient outburst may very well become the sole domain of ASASSN? I don't think many CV, if any at all, get nightly coverage by AAVSO observers, so the ASASSN will definitely catch most of them first, it seems.

Mike LMK

rmu's picture
Time coverage

I think surveys like ASASSN lacks of an inadequate temporal frequency to follow up properly many variable stars or find a nova.

We are all agree in that a visual observer is not as available as an automated survey, he or she has to sleep, nor a computer and goto mount. But this visual observer is much more flexible than survey.

Aldebaran's picture

Hello everyone!

Few thoughts about ASSSN.

Isn't it so, that the survey data might not become totally available for everyone to use? And I think the surveys cannot threaten observing legacy -stars with already long visual observing history. I believe, that visual observers can always contribute to the light curves of the legacy stars, and it will always be valuable! And who knows, for how long are they going to carry out these surveys? 5 years, 10 years or less? Visual observes can carry on for centuries, if we want to!

Best regards,

Juha Ojanperä (OJMA), Finland

HQA's picture
ASAS-SN limitations

Hi Mike,

Perhaps I should rephrase my comment: "early-time notification of CV outbursts" won't be impacted.  There are dozens of times when WZ Sge goes into outburst, or U Sco, or name your favorite star, where our observers with their geographic diversity will see the outburst before the survey would.  That early notification is often essential for professional research, and the visual/amateur community has been very important.  Doubling the number of telescopes to get two colors always sounds feasible, until you consider the cost.  CCD monitoring of the quiescent phase of the CV would still be highly useful, as Kepler has shown many stars having mini-outbursts that fall below the detection limit of ASAS-SN.  Again - every survey has a parameter space.  If a new one with good funding appears, you can change your observing pattern to avoid its parameter space, work with the survey to use its data to your advantage, or even ignore the survey and continue your normal monitoring.  Surveys never hurt; they give us more data to work with.

I look at each new survey as a challenge.  What are they attempting to accomplish?  Will their data be useful to me in my research?  Is there an avenue where I can contribute to their research using my telescope?  Does the survey give me a new idea of research that I can perform?  Are their software/hardware/analysis tools something that I can use?  Will their survey open up new exciting paths, perhaps even including funding?


HNL's picture
individual viewing

 Hi: Don't know if this is the place to mention this.  But, a good friend of mine put me out of business with his sky apps. He just points his phone at a star and it tells him the name.     So, carry  on in your own way. The best is yet to come.


Harry Hilliard
Harry Hilliard's picture
ASASSN = Skynet?


I think that this is the smoking gun...Skynet is about to become self-aware.

Seriously though, I feel your pain Mike.  I have recently started learning how to do astrometry on asteroids, only to find out that pretty much the only data that the Minor Planet Center is interested in are from objects of around 20th magnitude...everything brighter has been covered by robotic telescopes.  Only a few years ago, one could still discover asteroids from their backyard.  Since much of my enjoyment of amateur astronomy comes from being able to contribute scientific data, I'm starting to feel a bit like John Henry.  It seems as if we are the latest segment of society about to be replaced by machines.  The robots are taking over.


switch to photometry of asteroids

It's true that asteroid astrometry is falling out of the realm of small telescopes .... but there's now a new facet of asteroid science which has opened up: asteroid photometry. We know the rotation periods of only a tiny fraction of all asteroids.

Visit the Collaborative Asteroid Lightcurve Link and look around.

PJOC's picture
I've spent virtually every

I've spent virtually every clear night for the last year making BVRI (or some subset) timeseries of novae (V339 Del, V1369 Cen, V5666 Sgr), recurrent novae, CVs, and eclipsing binaries. 

The idea of daily V-band robotic measurements doesnt worry me in the slightest.  Might actually get us onto some novae or previously undetected CVs faster than before.

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