Recent content by randa177

I am not sure I understand what you mean, so if these values of U-B and B-V are not fixed then why are they so important in the study of stars and clusters... etc?

By looking at the values of the U-B and B-V that you suggested it seems that there is a corelation between U-B and B-V... for a really red star both values are large and positive, for a very blue star both values are small and negative, and for stars in between theu have smaal positive number...

How can I get a sense of the numbers of (U-B) and (B-V)... if a value of U-B for a star is larger than the other what does it mean? What about B-V... and what about the negative values...

Can you explain this part more please? I didn't really get it.. sorry

But that's what it's used by the RC spectrograph for Blanco 4m telescope: http://www.ctio.noao.edu/spectrographs/filters/blocking/Schott/wg345.gif

It took me a while to reply back, but I am still struggling with this question. The problem si that I don't have the spectra of all stars (I actuall don't have any spectrum of any star in the cluster). Is there another way to do it?

I have a question about the colored filters used for the telescopes. Here I will give an example for the filters of the big telescopes, but I assume that it applies also to the smaller personal telescopes. The range of the visible light goes from about 400nm to about 750 nm. Where the "blue"...

The spectroscopy of star clusters within MC.

What I mean is would I be able to observe it with a 2m telescope or a 1m telescope? How can I figure that out?

Thank you all for your reply, I am mostly interested in studying the Magellanic Clouds star clusters... I know that a 4m telescope would be best, but how would I find out the minimum aperture needed to observe these clusters? Is it just their apparent magnitudes?

Hi, In research, if you want to observe a certain galaxy or cluster, how do you decide to which big telescope to apply (in terms of aperture), how do you know what aperture you need for a certain project? Thanks!

Thank you all for the explanation :) It makes sense now!

But isn't the RA of the object fixed (at least for a certain epoch (i.e: J2000))? One can get the RA from the catalogs (i.e: SIMBAD) so how can it change?

I have a question that I've been thinking about since February! It might be stupid but for some reason I am not getting it! So back in February, I was observing with the 4m telescope in Chile, and each night the night assistant at the telescope would say: you reached the hour angle of (...)...

Does my question make sense?