a couple of noddy questions

[ian_d]

Hi

A couple of questions sprang to my mind when I was out observing last night...grateful for any hints or tips anyone could supply!

1) how do you go about visually estimating the magnitude of a star?

2) are there any variable stars that are good for a beginner to observe (ie ones where you've got a good chance of spotting the variation in magnitude over time - obviously I realise that you can't do this in one session!!)

3) any hints on making reasonable field sketches of what you can see through a telescope / binoculars?

cheers

Ian

[barkis]

Ian, if you are interested in Variable stars, I suggest you get some advice from Astroman, who I know is an expert on that subject, and is a member of the American Variable star Organization. I am sure he will be pleased to answer any questions on the subject.

I am not sure of any aid you can use in Magnitude estimation. The human eye is reckoned to be able to see stars of up to magnitude six with the naked eye. Any star will be progressively dimmer as the number goes higher, so a 1 mag, is brighter than a star of mag2. Usually, where there is no sign, the star is assumed to be positive. Most magnitudes are measured with photoelectric instruments these days, but you can learn to get close to estimating magnitudes with a telescope, by comparing stars of known magnitudes. It is a learning process really. The very bright stars are of minus values, for example -1. The sun is a star, and it's magnitude is -26.

Ron.