Picking a Reference star

[EdWiley]

I understand that when participating in a Pro-Am program I can expect to be given a reference star so that all observers are computing their efficiency on a common baseline. Right now I am just training myself on various stars, but I want to go through the entire process with my new Alpy600. There are lots of A-class stars around. So, in my training, rather than trying to find a combination of a MILES standard close to a target star, I assume that I can pick any convenient "hot star" (close to the target) and use the match from the Pickles catalog. For example, if I want to try a G0V and there is a nice A0V close to it but not on the MILES catalog, can I use the Pickles catalog and use the A0V profile to determine efficiency.

Is this a correct assumption?

Thanks, Ed

[Christian Buil]

Ed, definitively yes. The Pickles is an excellent backup solution for quick calibration
if Miles stars are not available (and well adapted to Alpy resolution). But check the
interstellar redening of your AxV reference star if possible (you Francois Tessier data base of hot stars ?).

Christian

[Robin Leadbeater]

Hi Ed,

It would be a nice project to extend the Miles database of actual spectra to include more stars suitable as references. I think this could be done using an Alpy for example from a good site on photometric nights, correcting for instrument response and atmospheric extinction using the existing Miles standards. I suggested this recently to the team at AAVSO who are looking to get more involved in spectroscopy. It is very similar to the work that AAVSO are already doing, measuring reliable comparison star brightnesses for variable star work.

Cheers
Robin

[Christian Buil]

Robin, this is one of my projects (one of the reasons for the photometric slit for Alpy / Lisa, really necessary to establish such a catalog). I agree, photometric night are necessary, also a protocol. A project for a long time and for many observers!

But my experience shows me regularly that it is not the quality of the reference star which limits often the accuracy for estimating the instrumental response. In many situation for the moment...

For "young" spectroscopic observers (but alosi experimrented), my suggestion is to find the instrumental response
with a Miles star, then make the spectrum of another close Miles star in a standard way (with the computed RI),
then compare with the true profile of the second star. It is really informative and the basic.

The error observed is often much large of the Pickles approximation.

Christian