American Association of Variable Star Observers (AAVSO)
Mon, 04/23/2012 - 20:08

Unfair or uneven as it may seem, not all outbursts are created equal. An outburst of the dwarf nova AB Draconis is not going to be heralded as the next most exciting thing in astronomy. After all, it does this three or four times a month. We've seen it before.

SS Cygni still holds a place in our collective heart, even though it goes into outburst every couple weeks also. It's bright and easy to follow throughout its entire cycle with a small telescope, and its antics are fun to watch. But its the long-term, continuous coverage that makes continued observations scientifically valuable.

There are over 1500 known dwarf novae, and more are going to be discovered every year. How are you supposed to know which ones are "important enough to sound the alarm" and which ones are more common occurrences?

Well, you've come to the right place. Help has arrived.

The basic premise we are going to use to compile these lists is that astronomers will generally be much more interested in outbursts that happen very infrequently, or occur in systems that are poorly understood, in some cases- downright mysterious.

So the first logical place to start is a list of all the CVs that only erupt every 10 to 50 or more years or so. Catching one of these in action could be a once in a lifetime event, like seeing Halley's Comet. There are two groups that automatically qualify based on this criteria- Recurrent Novae, like U Scorpii, and WZ Sagittae type stars, like WZ Sge, VY Aqr, PQ And, etc.

Attached to this note are two files. Recurrent Novae and WZ Sge type stars listed in VSX, sorted by their maximum magnitude in outburst. After all, you shouldn't bother monitoring a system if it never gets bright enough to see in your telescope, so this will help you to whittle down the list.

There is another list you can find in the BAAVSS website, called the Recurrent Objects Programme. It contains UGSU, UGWZ, old novae, nova-like stars, and frankly, a lot of poorly understood objects that if they ever do go pop in the night, it will be big news to those of us who care about this sort of thing. (I've also added a file containing these stars for your convenience.)

So there is one way to start building an observing program around some stars that are definitely worth following, even (or especially) for visual observers!

Add some of these stars to your observing regime, and if you ever see one in outburst notify AAVSO headquarters and me immediately.


These aren't the only stars you should observe by any means. For one thing, they rarely, if ever do anything. Most of the time they will be extremely faint or extremely boring. You need to observe some other CVs you can actually make observations of also. Think about adding a bunch of the Legacy CVs to your program. These tend to be bright and active, so you won't have to wait five years to see your first outburst!

In the coming months, I hope to add some other suggestions to the mix. For now, better get busy plotting some charts.


Fantastic information &

Fantastic information & resources Mike, thanks.  I'll go through them and see what else I could or should keep and eye on.  The ROP list from BAAVSS contains mostly northern objects (naturally!) and it would be great to have a whole-sky list.  Just when you've got a spare year or two LOL!!


American Association of Variable Star Observers (AAVSO)
Old Novae

Had a look at the ROP a few weeks ago as I was interested in adding a few more old novae and other "stellar freaks" to my program. Particularly interested in old novae that have bottomed-out within range of my telescope: 16th mag or brighter; not all that interested in making a whole bunch of <fainter than estimates -- although I do have a few of those too. Thanks for the info, Mike. Keep up the good work.




Sorry to jump in late on this thread guys, but I want to say thanks for all the information you have posted here! I have spent all day updating my charts from old novae, and the excel and pdf files hit the spot. I wonder are there many observers looking at 'old' novae for evidence of recurrence?

Here's to the dark nights ahead!


Svensk Amator Astronomisk Forening, variabelsektionen (Sweden) (SAAF)
Yes, fascinating! I've

Yes, fascinating! I've learned a lot from this thread, have started to keep an eye on WZ Sge (in addition to T CrB, an older acquaintance), and read parts of the interesting PhD dissertation by Ashley Pagnotta.

/Gustav Holmberg, HGUA