Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 03/26/2018 - 01:59
In renewing my transforms using M67 I note a bunch of NSV variables that appear in the VSX. Will single night observations of these variables serve any good purpose? I took estimates of several using an ensemble of M67 standard stars, but am not sure if the shotgun approach (many variables of probably different types measured with a single generic check and ensemble) is productive. Uncertainties look OK, data transformed. However, I am wondering if a nightly program of "shotgun" measuring would be productive. Or perhaps time series? Of taking each indivudually with more attention to check and ensemble?
Ed
ps - most of the others are eclipsing binaries (i.e., E_ and H_ Cnc), obviously one needs next ToMs of these to be productive.
NSV variables are an heterogeneous bunch.
While many might be actual variable stars, some might be bogus.
Since they are suspects, you approach might be okay to show if they are apparent variables.
Once you find that out, you can follow them up later.
I see that most of them do not even have a range published so cleaning up that mess might be worth doing.
However, some objects do not have an AUID. Is it useful that you submit data on several stars that will end up being constant?
Our policy is to avoid assigning AUIDs to these objects because then people start observing them when there is no need to.
What I would do is to collect data and keep them until you can detect variability.
If you find proof of variability, we can assign an AUID.
If not, we won't. That doesn't necessarily mean they are not variable, they might be EA-type eclipsing binaries, you may be measuring them at maximum. So it might be a long-term project. Or you may just revise the obvious ones. That is up to you.
Once you find variability, knowing the star colors (e.g. from 2MASS and APASS) will help making an educated guess about its type and that will determine how often they have to be observed.
To make things easier, if the stars are not too close together (no bright companion in a 17" radius), you can check their ASAS-SN light curves. That will give you some years of data that will be conclusive in most cases. So if they are not crowded, this should probably the first step. This way you wouldn't need to observe them or submit data.
ASAS-SN light curves can be seen using the ASAS-SN external links in the VSX star's detail sheet.
Entre 2500 in the "Enter number of days to go back" box to be sure you'll get all the data. Be patient, queries may take several minutes to be completed.
So I would check ASAS-SN data if the stars are relatively isolated and for those who are not I would observe them to find signs of variability.
Using ASAS-SN you may comfirm some are variables and in most cases there wouldn't even be a need to observe them, analyzing ASAS-SN data would be enough to solve them.
Some small amplitude variables might require better photometric quality so for stars fainter than 14 your data would be important to rule out this kind of variability.
As you see, there is no simple answer to your question but you have several options or approachs and whatever you choose may give interesting results and help us clean up the NSV catalogue vagaries in VSX.
Cheers,
Sebastian
Thanks Sebastian,
I will contact you off-forum for some addition information.
Ed