One of the toughest issues for the beginning amateur astronomer is finding the deep-sky object that you want to observe. If you are using a GOTO telescope or one equipped with digital setting circles, the telescope will help with that. But, if you are using a low-tech Dobsonian style reflector or a small alt-az mounted refractor, or even just binoculars, then you will need to learn how to Star Hop. Star Hopping is simple, inexpensive, and can be a fun way to learn the night sky! You don't need to be an advanced astronomer to find deep-sky objects. All you need to Star Hop is a few equipment related items, star charts, and a little practice. Listed below are 4 steps to help you in learning the techniques of Star Hopping. These steps are general, use them as a guide and follow them as you like. It all depends on the object, your equipment, and sky conditions. Go with whatever works for you.....
#1 Necessary Equipment: - Obtain a star-finder/wheel (or use a monthly astronomy magazine sky chart). - Purchase a star atlas that has individual charts detailed enough to show stars of at least 8th magnitude. (Can also purchase a planetarium program for your laptop or smart-phone) - Purchase an observing guide-book for deep-sky objects. - Get a red-dot finder, Telrad, or other bulls-eye finder. Mount on your telescope. - To go with your telescope, you will need a good short-focal length (f3 to f6) wide-field Finder-Scope. At least a 50mm refractor, but preferably an 80mm that uses standard 1.25" eyepieces. Find one that has a correct-image diagonal, also called an Amici Prism. This will allow for a comfortable observing position with a right-side up view that will match the actual sky and your star charts. - Use a small folding table beside your telescope to hold your charts, books and notes. - A red-light that you can stand or clip on the table to illuminate your charts, etc. - A low-power, wide-field eyepiece, (30 - 40mm) in the main telescope. - Good alignment between the Finder-Scope and main telescope so that an object will be centered in both.
#2 Advanced Preparation: - Make a list of objects that you want to observe and the constellations that they are located in. - Use your star-finder/wheel to determine when the constellation will be above the horizon while dark. - With your star atlas, (or planetarium program), lookup the constellation and find the object on the star chart. - Find a bright naked-eye star near the object. This will be your starting 'Jump-Star'. - With a pencil and ruler, use the stars on the chart (or printed page from your planetarium program) that form a pattern: triangle, square, line, that leads toward the object from the jump-star and 'connect' the stars using the pencil. - Utilize your observing guidebook or planetarium program to find a description, photo, or sketch of the object. Get a feel of how difficult the object will be to see in your telescope. Small and faint? Large and bright? Is it beyond your telescope aperature size or level of darkness of your observing site? (you may need to save this object for a trip to a dark-sky location or viewing thru a friends larger telescope)
#3 Practice and Execution: - Start with easy to find objects on your observing list. - Find the constellation in the sky using the star-finder/wheel. Is it in good position for observing? - Open the star-charts to the constellation and find the object on the chart. - Review the star-patterns that you previously penciled in. - From the chart, find your naked-eye jump-star in the sky and center using the red-dot and Finder-Scope. - Verify that the star is visible in the main telescope's wide-field, low-power eyepiece. - Using the star-patterns that you traced on your chart, begin using your Finder-Scope to 'Hop', or move the telescope to the first star-pattern. After verifying the telescope view to the chart, continue hopping. - If you get lost, return to the naked-eye jump-star and start over. - Depending on your Finder-Scope and if the object is bright and visible in the finder, you may be able to hop right to the object and have it centered in the main telescope using only the finder. - If not, then using the star-patterns, center the finder in the general location of the object and then begin sweeping using your main telescope's low power eyepiece. Start by moving the telescope one field diameter in each direction. - If not successful, use the finder to re-center the general location, and begin sweeping three fields per direction. - If still not successful, return to the jump-star and repeat using the star-patterns to verify that you are in the correct general location of the object. If your advanced preparation from reading the guidebook indicates that the object is small or faint, try switching the main telescope's eyepiece to a higher power and repeat sweeping. - Once you've successfully found the object, make note of the equipment used, (telescope, eyepiece), sky conditions, observing location, and a brief description of what features you were able to observe of the object. - If unsuccessful, record the same above information, but with a note to make another attempt on a different night.
#4 Patience and Perseverance: - As with any hobby, the more you put into it, the more you will get out of it, and the better you will become at it. It takes time to develop your Star-Hopping abilities. - If you stick with it, eventually, you will be able to find objects quicker and easier. - Along the way, you will find that you have become a better observer. - Now that you're able to find the deep-sky object that you are interested in observing, why not take your observing to the next level and try your hand at sketching! How to Sketch:
Hope you enjoyed the visit. Come again soon!
Larry McHenry, Pittsburgh, PA. USA