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American Association of Variable Star Observers (AAVSO)
Sun, 02/13/2022 - 00:31
When getting the photometry on my target star, I often find other GCVS variables in the field. Since the data is there, is there any reason not to go ahead and submit an observation of these fortuitous stars?
This is a frequent question that elicits a wide range of opinions! IMHO, the quick answer is no, go ahead and report the other variables. However, understand that if you report one variable magnitude to the AAVSO Database and never again, that single data-point will serve little/no purpose. The better option is for you to take responsibility for gathering sufficient data for this additional target(s) so that you could provide additional astrophysical information and help confirm its properties. Are you up for that? Don't just consider GCVS variables. Have you noticed all the VSX variables in your field?
A more interesting question is whether amateurs could report magnitudes (instrumental or standard?) of all stars in their images, submit and archive the results (not the images, too big?) in a database that could be data-mined in the same way that professional surveys are being archived and researched? Possible, practical, cost effective, worth it?? AAVSONet Epoch Database already does that.
Are there thoughts to modifying VPhot and WebObs to allow those full-field reports?? Sounds like a good idea.
To the original question: I submit data on all variables with an AUID in my reports. I'm not doing one-off data collection, but reporting on "my" variables almost every clear night.
And to keep track of all stars I observe, I maintain a spreadsheet of target variables and surepititiously observed variables. So far qty 10 targets and qty 27 others.
I'd really love to see the AAVSO have a way of including all-star photometry of amateur images in the Epoch database. I've got a huge number of data images saved from years of photometry that will be lost when I'm gone. I do fear that the practicality of the AAVSO doing this and serving as the repository for the data for someone's future use is impractical. I presume the compute cycles for passing large numbers of images through VPhot for this would also be expensive. Then their is the issue of the quality of the data. The current AAVSO Epoch database is from images that have had some level of AAVSO quality control and management. Opening this up to other amateur images would mean not being able to say much about the quality of that data.
I'd sure love for my concerns to be easily dealt with though. Seeing how valuable the Harvard plates have become, it's easy to believe that there is value in the photometry that could be generated from amateur images.
I agree with some of the opinions expressed in this thread.
One big concern though is that "all variables in a field" includes stars that may not actually be variable (e.g. spurious NSV stars) or stars that only have millimagnitude variations (e.g. lots of Kepler variables).
Thus, even when the project (that is, observing all VSX variables) sounds good, there are some caveats.
Stars added to VSX from surveys lists, or in the batch mode (not individual submissions), have no AUIDs and thus observations can not be submitted for them. We chose to do it this way because we couldn't be sure that those objects were worth observing, even some might be duplicates.
We decided that requesting AUIDs for specific targets when people wanted to submit data was going to be the best approach. So we added the "Request AUID" button to VSX.
However, right now, and given that the "observe them all" approach is taking over, the number of AUID requests is becoming overwhelming.
Those requests are including objects with amplitudes below 0.01 mag.
We are going to have a discussion at HQ to address this issue and see if we need to change the way we handle these requests.
But for now, and also for the future, one thing has to be kept in mind:
*you need to check what stars you are going to submit data to. It doesn't make sense to submit observations with a 0.02 mag. error for a star that only varies by 0.002 mag. We do not want to add noise to the database.
Since VSX includes millimagnitude variables for completeness, the "observe them all" approach, without any further checking, is not feasible. There has to be some filter. You need to confirm (e.g. through consistent light curves showing the star variations, not single points, as Ken correctly mentioned) that you are capable to detect the reported variations if you are going to submit data on small amplitude variables.
AUID requests have to be addressed individually, so keep in mind that whenever you submit one, it is not that a robot will be approving them. In the current state of things, we need to check every request to see if the star is actually variable (besides the spurious NSV objects we have some survey entries that turn out to be artifacts, e.g. among ASAS-SN variables) or if its amplitude makes it worth observing.
Generally speaking, I wouldn't request AUIDs for objects with amplitudes <0.02 mag., unless you are completely sure that 1) you can detect those variations easily, and 2) you are going to dedicate some time to observe the star, and it's not going to be just an isolate datapoint.
Thanks for keeping these things in mind.
We'll let you know if our AUID request policies change.
There are many very good survey systems, all having good optics, good technique, good skies, good data processing. It seems largely pointless for observers not having all of those conditions to clutter databases with noise.
My AUID requests are taylored to my observing capabilities. My system capabilities and seeing limits are different for mag 9 versus mag 17.
I would not request an AUID for a 17th magnitude star having 50 mmag variability. You can try to observe those dim stars before requesting an AUID, just to see how it goes. If you can't see the variability that the surveys and VSX report, then there isn't much reason to request the AUID.
If the reported variability is seen clearly, then feel confident to request the AUID.
Once stars are selected for AUID requests, I observe them for at least a season.
New information ranges from confirmation of already known SPPs to new information on LPVs and irregulars. Occasionally, comps that are variable are found and reported. I also keep checking for changes in data quality. My data is often the only detailed long-term data available so I cannot compare my new data to data from other observers.
The caveat is that there are occasions at the margins where I wish I could retract the AUID request. I may not reliably see the variability that the surveys reported. ( just like Sebastian says ). I simply don't submit data for that star anymore.
Bill:
This is a frequent question that elicits a wide range of opinions! IMHO, the quick answer is no, go ahead and report the other variables. However, understand that if you report one variable magnitude to the AAVSO Database and never again, that single data-point will serve little/no purpose. The better option is for you to take responsibility for gathering sufficient data for this additional target(s) so that you could provide additional astrophysical information and help confirm its properties. Are you up for that? Don't just consider GCVS variables. Have you noticed all the VSX variables in your field?
A more interesting question is whether amateurs could report magnitudes (instrumental or standard?) of all stars in their images, submit and archive the results (not the images, too big?) in a database that could be data-mined in the same way that professional surveys are being archived and researched? Possible, practical, cost effective, worth it?? AAVSONet Epoch Database already does that.
Ken
Are there thoughts to modifying VPhot and WebObs to allow those full-field reports?? Sounds like a good idea.
To the original question: I submit data on all variables with an AUID in my reports. I'm not doing one-off data collection, but reporting on "my" variables almost every clear night.
And to keep track of all stars I observe, I maintain a spreadsheet of target variables and surepititiously observed variables. So far qty 10 targets and qty 27 others.
Peter
BPEC
Years ago VPhot actually did extract full image photometry of each image. It did this in aid of a "Variable Search" function.
Because the feature was rarely used and added 30s+ to the processing of each image the feature was deactivated.
Maybe there should be a discussion about this again?
One thought is that a full frame photometry would be submitted to the Epoch database.
George
George,
I'd really love to see the AAVSO have a way of including all-star photometry of amateur images in the Epoch database. I've got a huge number of data images saved from years of photometry that will be lost when I'm gone. I do fear that the practicality of the AAVSO doing this and serving as the repository for the data for someone's future use is impractical. I presume the compute cycles for passing large numbers of images through VPhot for this would also be expensive. Then their is the issue of the quality of the data. The current AAVSO Epoch database is from images that have had some level of AAVSO quality control and management. Opening this up to other amateur images would mean not being able to say much about the quality of that data.
I'd sure love for my concerns to be easily dealt with though. Seeing how valuable the Harvard plates have become, it's easy to believe that there is value in the photometry that could be generated from amateur images.
Clearest skies,
Walt
I agree with some of the opinions expressed in this thread.
One big concern though is that "all variables in a field" includes stars that may not actually be variable (e.g. spurious NSV stars) or stars that only have millimagnitude variations (e.g. lots of Kepler variables).
Thus, even when the project (that is, observing all VSX variables) sounds good, there are some caveats.
Stars added to VSX from surveys lists, or in the batch mode (not individual submissions), have no AUIDs and thus observations can not be submitted for them. We chose to do it this way because we couldn't be sure that those objects were worth observing, even some might be duplicates.
We decided that requesting AUIDs for specific targets when people wanted to submit data was going to be the best approach. So we added the "Request AUID" button to VSX.
However, right now, and given that the "observe them all" approach is taking over, the number of AUID requests is becoming overwhelming.
Those requests are including objects with amplitudes below 0.01 mag.
We are going to have a discussion at HQ to address this issue and see if we need to change the way we handle these requests.
But for now, and also for the future, one thing has to be kept in mind:
*you need to check what stars you are going to submit data to. It doesn't make sense to submit observations with a 0.02 mag. error for a star that only varies by 0.002 mag. We do not want to add noise to the database.
Since VSX includes millimagnitude variables for completeness, the "observe them all" approach, without any further checking, is not feasible. There has to be some filter. You need to confirm (e.g. through consistent light curves showing the star variations, not single points, as Ken correctly mentioned) that you are capable to detect the reported variations if you are going to submit data on small amplitude variables.
AUID requests have to be addressed individually, so keep in mind that whenever you submit one, it is not that a robot will be approving them. In the current state of things, we need to check every request to see if the star is actually variable (besides the spurious NSV objects we have some survey entries that turn out to be artifacts, e.g. among ASAS-SN variables) or if its amplitude makes it worth observing.
Generally speaking, I wouldn't request AUIDs for objects with amplitudes <0.02 mag., unless you are completely sure that 1) you can detect those variations easily, and 2) you are going to dedicate some time to observe the star, and it's not going to be just an isolate datapoint.
Thanks for keeping these things in mind.
We'll let you know if our AUID request policies change.
Best wishes,
Sebastian
There are many very good survey systems, all having good optics, good technique, good skies, good data processing. It seems largely pointless for observers not having all of those conditions to clutter databases with noise.
My AUID requests are taylored to my observing capabilities. My system capabilities and seeing limits are different for mag 9 versus mag 17.
I would not request an AUID for a 17th magnitude star having 50 mmag variability. You can try to observe those dim stars before requesting an AUID, just to see how it goes. If you can't see the variability that the surveys and VSX report, then there isn't much reason to request the AUID.
If the reported variability is seen clearly, then feel confident to request the AUID.
Once stars are selected for AUID requests, I observe them for at least a season.
New information ranges from confirmation of already known SPPs to new information on LPVs and irregulars. Occasionally, comps that are variable are found and reported. I also keep checking for changes in data quality. My data is often the only detailed long-term data available so I cannot compare my new data to data from other observers.
The caveat is that there are occasions at the margins where I wish I could retract the AUID request. I may not reliably see the variability that the surveys reported. ( just like Sebastian says ). I simply don't submit data for that star anymore.
Ray