# Tag Info

14

The easiest way to determine the magnitude of a given star is probably to use the Pogson relation. The idea is to determine the magnitude of a star knowing the magnitude of a reference star; it is thus quite easy, using a well-known reference as Vega or Sirius. The Pogson relation is given by: $$m_1-m_2=-2.5\ log\ \left({\frac{E_1}{E_2}}\right)$$ where ...

8

This is a very common question, yet very hard to answer if you prefer a clear, concise, uncontroversial answer that applies to all situations. So I'm not going to do that. Instead, I'm going to describe your main options, and let you choose. Be aware that you'll make the choice while still not knowing much about optics. So, in a sense, it will be just the ...

7

Squinting works the same way as a pinhole camera. Ideally, light from a single point source entering your eye anywhere on your pupil will be focused on a single spot on your retina. But this works perfectly only if you have perfect vision; otherwise light entering near the top of your pupil may be directed to a slightly different spot on your retina than ...

6

The Failures of High Magnification Higher magnification doesn't help you observe deep sky objects better. Deep sky objects unlike stars are extended objects. They subtend a finite solid angle on you. This ensures that the surface brightness(brightness per unit solid angle) of extended objects remains constant. Hence, a higher magnification would not make it ...

5

As for projecting the Sun onto a screen at a low cost, I would recommend starting with a ~50-200\$ sunspotter box, which is basically a lens mounted on a wooden box, that projects the sun onto a white piece of card. The advantage of using a telescope is that it can be programmed to track the Sun, so that if you want to trace sunspots, for instance, you can do ...

4

The aperture of your 4.5" telescope is one thing, it's also important what focal length you have. Is it a f/5 or rather a f/8? The f/8 would be suitable for viewing the Moon, Jupiter, Saturn, maybe even Mars and Venus. You can also buy a good solar filter, attach it in the front of the optical tube assembly, and view the sun. But be careful with that, and ...

3

It depends. The Barlow is usually a cheap shortcut for avoiding to buy an expensive short focal length eyepiece. Also you need Barlows and high magnification usually only for small objects. For example the ring nebula (M57) is pretty tiny, and might benefit. Your telescope is still rather wide field, so getting high magnifications might be neccessary to ...

1

Try the moon first. If you see nothing but black, assuming that you don't have a lens cap on or something, then most likely, you are zoomed in on, well, relative blackness. The star you were viewing is probably off to the side now. Or, you may just be looking through the eye-piece at the wrong angle or something. The moon is too big a target to miss, and ...

1

You have to set your equatorial axis to tilt to match your latitude eg if you were at 5 degrees North then the axis needs to tilt to 5 degrees. Then you need to find an object of known RA and declination (at my latitude I always used Polaris as it didn't move) and then set the setting circles (the dials) to those, then direct the telescope to the RA and ...

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