Author Topic: What is a good way to star hop ?  (Read 629 times)

ransgesislu

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Re: What is a good way to star hop ?
« Reply #30 on: January 31, 2018, 05:27:08 AM »
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<p class="citation">QuoteI plan to get at least an 8" dob that comes with (I think) a 9 x 50 finderscope. Was thinking of a Z8, but might go with a Sky Watcher to get the discount from being a member of the forum. Anyway, is that finderscope adequate for me for now, or should I plan to go to a Telrad or RACI right away ? I know there are different opinions on this, but I am open to all of them of course.


The 8 inch Skywatcher Tube Dob comes with a straight-through finder and a single speed Crayford focuser. I used straight-through finders for many years but recently switched over to RACI finders.. Straight through finders have some advantages but the rotated image and the more awkward viewing positions are serious disadvantages. Starting out, the comfort and ease of translating between charts and the finder scope make the RACI the better choice.

If you figure an RACI finder costs about $75, and then the Z-8 comes with a 30mm 2 inch finder eyepiece and a nice two speed focuser, I think the Z-8 is a better value, you get more for your money...

Regarding Star hopping:

Charts:

I have been using electronic charts out in the field for about 15 years. These days I use Sky Safari 4 Pro.. (5 for the iOs). Compared to using paper charts, it does seem like cheating.. I get the correct view of the sky for my location and time. The screen can show me what I want, if I want magnitude 5 stars, magnitude 7 DSOs and 25 degree Field of view.. I have it. IF I want magnitude 10 stars, DSOs to 13th magnitude and a 15 degree TFoV, I have it. The databases are far larger than is possible with a paper chart, not only are they much deeper but the information provided for each object is much greater. I can do searches and build observing lists right there in the field. The observing list can circle the objects on the screen..  I have Telrad circles right there on the charts.

Binoculars, Red Dot/Telrads, RACI finders plus a low power wide field eyepiece are all physical parts of the tool kit. They all have their place.. If the skies are dark, I can find most objects with just a Telrad. And that can be with a scope whose field of view is barely larger than the moon..

Jon[/quote]
You make my paper star charts seem primitive. I would dispute the numbers but I seem to have misplaced my abacus.

Randal Samuels

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Re: What is a good way to star hop ?
« Reply #31 on: February 08, 2018, 10:56:19 PM »
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There are many different ways to star hop. (Some will mis-type "star hope" or "star hoping" by ironic accident.) Getting lost along an extended hop can lead one to guessing and hoping and usually requires a restart at the last place that you KNEW was right.

The type of star hop you choose will often be determined by your comfort level with the type of target, its dimness, or the amount of stars bright enough to help you along the way. (When tackling the Virgo Cluster of galaxies, most hoppers have to use brighter galaxies instead of stars.) The amount of light pollution you have to deal with will often determine your choice of optical finder or Telrad-like device, with optical finders being more useful in light polluted viewing.

My number one way to get to targets is to use triangles or other simple shapes. My number one atlas is the Pocket Sky Atlas. Its dimmest stars show up in my 50mm finder. I will stare at the correctly-oriented chart to put an isosceles (or whatever) triangle of a particular sharpness and orientation into my short-term memory. Typically, two stars serve as the anchors at the base of the triangle and the target is at the sharpest vertex. This is one way to find M-101 above the Big Dipper's handle.

When I've successfully found a new target that was a challenge, I will record the star hop method that worked for me.

Good luck.

Lines and triangles are also the primary way that I star-hop ("the galaxy is about 1/3 of the way between naked-eye star X and naked-eye star Y", or "the cluster makes a flat isosceles triangle with X and Y"). This usually is enough to get my target within a 1-degree eyepiece field, if that's what I'm using. Find the field-of-view of your eyepieces by putting their stats (and those of your telescope) into this:

http://www.davidpaulgreen.com/tec.html

I used to use a finder eyepiece with a 1-degree field; I've gotten lazy, though (and a bit better at star-hopping), and use my primary eyepiece for both (112x, 42' field). If my target is small or faint or both, I also use the TriAtlas app for iPhone/iPad to pinpoint the right position; the app has stars down to magnitude 13, and acts as a paper atlas. With this eyepiece and the app, I was able to sweep up all of the NGC globular clusters in the M19/Pipe Nebula region and the planetary nebula NGC 6369 without having to use a Telrad or finder or take my eye away from the eyepiece--it was just a matter of hopping from one globular to the other, using the stars plotted in the app.
Thanks for the link.  I will try it with my current EPs. Is there something similar to TriAtlas for Android ? I don't have SkySafari as many others here do, because they haven't come out with it for Android. Sky Safari 5 anyway.

Tyler Cox

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Re: What is a good way to star hop ?
« Reply #32 on: February 09, 2018, 10:31:09 AM »
These are the two books that I recommend to novices interested in learning how to star-hop.

http://www.amazon.co...t/dp/0933346689

Another one is Star-Hopping: Your Visa to Viewing the Universe by Robert A. Garfinkle.

http://www.amazon.co...e/dp/0521598893

Star-Hopping for Backyard Astronomersby Alan M. MacRobert is my favorite of the three titles.

I mention a number of star-hopping schemes for locating some of the more prominent Messier galaxies in my thread athttp://www.cloudynig...ur-astronomers/

Dave Mitsky