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How to Point Weak Celestial Objects with Manual Pointing Telescopes


Pointing weak celestial objects using the technique of "Star Hopping," which involves using reference stars to locate faint objects.

Often, beginners struggle to point out faint objects, whether with binoculars or manual pointing telescopes, because these objects are not visible to the naked eye and sometimes even in the finder scope.


The simplest method to locate them involves using well-visible reference stars with the naked eye or visible in the finder scope to reach the position of the desired faint object, which will then become visible in the telescope eyepiece, equipped with sufficient optical power to reveal the object.


This method is called "Star Hopping."


This method, which requires minimal knowledge of the sky, involves consulting a detailed sky map (such as the Sky Atlas 2000.0 or Uranometria by W. Tirion, or printed maps from software like Starry Night, The Sky, or the free planetarium software Cartes du Ciel) that allows us to locate the position of the object of interest and nearby stars.

The key to this method is using stars near the object we want to point out because they guide us in the directions to follow, hopping from one star to another, to reach the desired object. This method is widely used by enthusiasts of visual deep-sky observations.

The Ideal Equipment

To point out these reference stars, we use the finder scope. It is advisable to use a reasonably powerful optical finder, such as a 7x50mm finder, equipped with a well-visible (preferably illuminated) reticle against the sky's background. To facilitate Star Hopping, it is recommended to use a low magnification eyepiece with a wide field of view, such as an eyepiece that frames at least a half-degree field, equivalent to the diameter of the Full Moon. However, if the sought-after object has a very small angular diameter, it is not advisable to use excessively low magnifications, as there is a risk of not being able to see it. In this regard, UltraWideAngle (UWA) eyepieces come to the rescue, as they can offer high magnification and simultaneously provide a very wide field of view.


Here are a few examples:

Manual pointing of M57 in the constellation Lyra. This is one of the easiest faint objects to point manually because it is located almost precisely on the imaginary line connecting the stars Beta and Gamma of the constellation Lyra. In practice, you aim the finder at Beta or Gamma Lyr, locate, still in the finder, the midpoint of the imaginary line connecting the two stars (which are about 2 degrees apart, i.e., less than half the field of view of a finder), and at approximately the midpoint (slightly closer to Beta), you will find the M57 nebula. It is very small (less than 1 arcminute) and completely invisible in the finder, requiring at least 30-40x magnification to be recognized among the stars.

Manual pointing of M51 in the constellation Canes Venatici. This beautiful spiral galaxy is quite large (size: 11'x7') and relatively bright, but not easy to point out because it does not have many bright stars nearby. It is located below the so-called handle of the Big Dipper (Ursa Major), about four degrees from the last star of the handle, eta UMa. To point it out, center the star eta UMa in the finder, and at the edge of the field, you will notice, more or less in the West-Southwest direction


Credit: The Telescope Doctor – Plinio Camaiti, Auriga (www.auriga.it)




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