Bright Comparison Stars

American Association of Variable Star Observers (AAVSO)
Mon, 09/14/2020 - 09:28

As a newbie, I thought I would start with the easy to find bright variables in the tutorial list. Eta Aql for instance (4.3 to 3.49 Mag), but according to the Variable Star Plotter, there are no comparison stars within 900 arcmin of it. 

Similarly I tried Bet Dor. There were some comparison stars within 900 arcmin for binoculars but not standard field, and none were as bright as Bet Dor (4.438 vs 4.08 to 3.49 Mag for Bet Dor). 

So what do we use for very bright comparison stars?



Nucleo de Estudo e Observacao Astronomica - Jose Brazilicio de Souza (Florianopolis, Brazil) (NEOA-JBS)
Hi Carolyn,

Hi Carolyn,

I have a booklet design to newbie with naked eye variable stars charts.

eta Aql is in page 18

beta Dor is in page 10


Or, if you wish, there are two AAVSO sources for these stars with naked eye charts too

American Association of Variable Star Observers (AAVSO)
Bright Sequence Stars & Charts

Newer observers are often confused by the Standard Field chart option.  These are specialized sequences for digital observers so that they can calibrate their filters with high precision. 

Most Observers are better served by selecting the None option for charts; visuial observers who will be observing bright objects can be helped by selecting Binocuilar charts; however, keep in mind that only those targets listed for this prorgram will present charts with comp stars, with this option.

Many other Bright Targets were not initially selected for this program simply because of the absense of suitable bright comps.

The sequence team can only present suitable visual comps for Bright Targets with the cooperation of the Creator (for want of a better term).

New observers so also be aware that they can request suitable comps when those presented are not adequate:

Or request a sequence where none exists:

However, with really bright targets 7V or brighter I suspect it will be an infrequent occurence with espcially smaller fov's that any suitable comps can be located that have not alrady been acomplished.

Also, as pointed out in the previous, the 10 star tutorial charts are another viable option for brighter targets for visual observers.


I weclome you as a new observer.  Be paitient, use the resouces of the AAVSO, including the mentoring program:

Also, feel free to post your questions to a Forum, as you have done herein.

Good Observing & Ad Astra

Tim Crawford, Sequence Team

Royal Astronomical Society of New Zealand, Variable Star Section (RASNZ-VSS)
Bright Comparison Stars

Hi Carolyn,


The two stars you mention, eta Aql and R Dor are a couple of Cepheids - good short periods of a week or so, but the low amplitude is not ideal if you're only just starting.  As you say, they're in sparsely populated sky areas and the comparisons are not close.


Better amplitude stars are Miras, but the periods are long and there are not all that many bright in the overhead sky at this time of year.  Mira itself, omicron Ceti, is near maximum and is worth a look but you will need a larger field than 15 degrees.


If you use a small telescope or binoculars the choices are much wider.


But stick with these two stars as well - they don't get as much attention as they should.



Stan Walker