Possible campaign to do observations nearly simultaneously between AAVSO and Swift

Thu, 07/21/2022 - 20:40

I and some of the other board members, staff members and section leaders have been discussing a possible big project for AAVSO.  The goal would be to get AAVSO data nearly simultaneously with data from NASA's Neil Gehrels Swift Observatory for a class of objects.  We think the class that poses the fewest risks is active galactic nuclei, because a lot of the AGN targets that Swift will observe will be known in advance, and will vary slowly enough that data a few hours apart, or even a day apart, can still be useful. If the program is highly successful, we might consider something more ambitious in the future.  There are typically about 10 AGN observations per day, scattered over the sky.  Swift already has an ultraviolet/optical telescope on board that generally gets U band observations, and sometimes gets B&V data, but it does not do anything redder than V band.  We'd like to apply to the Swift proposal's program for funding "correlative observations" to help suppport AAVSO's administrative efforts for organizing this.  A few of the objects will be very bright in optical, but most will require the ability to reach something like 17th magnitude.  We want to get a sense of whether this is exciting to the people who have this capability before proposing to do it, in order to ensure that we can deliver results.

The goals of a program like this would be to use the time delays in variations in emission in different wavelengths to map out where the emission is coming from.  We know it has to be coming from somewhere close to the supermassive black hole, but it's still not fully understood just how much emission comes from different parts of the region.  So, there is an exciting goal to all of this.  If you're interested, you can comment below, or write me at thomas.maccarone@ttu.edu.



American Association of Variable Star Observers (AAVSO)
AAVSOnet can play a part

The AAVSOnet team is investigating how to use VOEvents to set targets in a timely fashion. The VOEvents are also being used by some other AAVSOers.

I believe that in the past the AAVSO issued VOEvents for GRB's; we can dust of the software they used.

Sounds like an exciting project!


Interesting idea, and I hope…

Interesting idea, and I hope we can be of help.

A) If we knew the targets ahead of time, one or more people could just submit projects to AAVSONet to follow them on every clear night. I'd be happy to help. At first blush, I don't see any administrative costs involved with this, but I do not manage the network!

B) While I presently only observe one AGN, I have noticed that it seems different observers use different apertures in their observations, leading to data that cannot be compared observer-to-observer. I would think that some organization among observers would need to be implemented and enforced. In the case of NSV6690, if someone uses a very small aperture to try and isolate the AGN from the rest of the galaxy and someone else averages over the entire galaxy the difference may be a few tenths of a mag, possibly swamping the true AGN variability. Not trying to be negative, just pointing out  a pitfall we may need to consider and overcome.



Swift/AAVSO campaign

This sounds like a great idea, Tom!  In addition, it can bring in at least some limited funding for the AAVSO.

George, this doesn't require VOEvent, but just continued monitoring.

I'm assuming that, to support the Swift effort, you'd want to use Johnson/Cousins filters so that there would be overlap in the B&V bands?  As mentioned, providing measurement apertures and selected comparison stars would be important to match the photometry across multiple observers.

As Peter mentioned, AAVSOnet is one path for those with small telescopes, without red filters, or who wish to monitor objects in an opposite celestial hemisphere.


American Association of Variable Star Observers (AAVSO)
Actvie galaxies observing

     This sort of thing sounds great, but it would a good idea to be sure there's not too much overlap with on-going work elsewhere.  Obvious things include the ZTF and ASAS-SN surveys, where there's northern or all-sky coverage at few-days cadence in two filters.  There is continued long-term monitoring of active galaxies in Italy, Bulgaria, Russia, and elsewhere, usually in BVRI.  It is nevertheless seems difficult to find out who's doing what.  Massimo Villata and/or Claudia Raiteri in Italy would be good contacts to ask about this; Tom Balonek is another good person active in this area.

     In re comparison stars, the obvious thing for most cases would be to simply adopt the Pan-STARRS 'refcat2' Sloan gri photometry of field stars (fainter than about mag 13.5 in any color), transforming as necessary.  There are BVRI sequences already in the literature for many of the most-observed objects.  (Again, digging them out from journals can be problematic, though I have done a bunch of it.)  I recently revisited about a dozen of these in UBV in hopes of getting somewhat tighter link with the Landolt system.