How to Find Things with a Telescope

Slides are Here

Notes

My Experience and Assumptions

• I am by no means an expert, if you see folks out doing observing and you are curious about how they find things, don't feel bad about asking how they are doing it.
• Going to assume they have learned at least some of the major constellations and bright objects
  • maybe have a list of some of the important ones to learn?
    • Other: North Star, 5 Naked Eye Planets
    • Examples: Pegasus (Great Square), Andromeda, Cassiopeia, Perseus, Auriga, Taurus, Orion, Gemini, Summer Triangle, Sagittarius, Leo
  • Planisphere
• Basically all of my experience is with Dobs and so that is where my info comes from, however I'll try to be generall and note where there are differences between scopes. Apparently you can use the setting circles on eq mounts to find things, but I don't have an eq and it sounds like a delicate process anyway.
• Going to assume you are familiar with your scope, how to set it up, and how to collimate it.

Persistence and Practice

• When trying for the first time, you may need to go back and forth many times between your map and the sky.
• Getting used to finding things in the sky, moving scopes that have backwards fields of view, and what types of objects look like is a long process. Don’t get discouraged

Constellations

• Constellations in astronomy are defined as the regions around the stick figures. This serves as a convenient way to denote where things are located in the sky.

Rule of Pinky

• Sky distances, fingers, palm, hand. Guide from timeanddate.com
  • rule of pinky seems to kinda work, it works best for me toward the horizon

Start with Binoculars

• Binoculars are not my strongest area personally. I'll mention them here and most of the advice for finding things will be similar, but you have a larger FOV so you may not need to resort to some of the telescope techniques.
• Start with binoculars. These match the view in the sky, unlike a telescope, which usually has the view inverted, mirrored, or both. Try to note the star magnitudes.
  • what types of inversions with what types of telescopes, image orientations from orion
    • this is a big adjustment you don't have to deal with when looking through binoculars
• I'm going to be talking about field of view a fair bit, sometimes binoculars have fields of view in 'distance at 1000m' instead of angular field of view. There are converters for this. astronomy.tools has one.

Determine Target

• Observing Programs
• Books
• What's Up Doc? (from AL)
• other resources on the planning side
  • sky and telescope: this week's sky at a glance (newsletter will send this to email)
  • RASC handbook
  • books dedicated to specific things like binoculars, Messier, binaries, variables
• Planning won't seem like that big of a deal at the very start, because everything is new. So, if you decide to ignore the advice about planning your observing, keep this in mind: you may soon find that every night you go out you look at the same 4 or 5 things, if that's the case, it's time to start planning your sessions. Unless you are perfetly fine with looking at those things, I don't blame you.
• If you are using a dob, stuff at zenith is a pain to get. Maybe plan on things a little below. It's not impossible though, and you will have better seeing the higher up you look. show example with starblast? you should bring the starblast and the telrad for demo purposes. Might be a pain to bring though

Maps

• Use a map of some sort to determine where it should be. Make sure it's turned to match the sky's orientation
• Stellarium
  • what parts are premium on mobile?
    • night mode works in free version, also free version shows FOV middle-bottom (FOV is based on smaller screen dimension)
    • parts that are premium: fields of view menu (doesn't even appear), advanced options for grids&lines and landscapes and atmosphere and so on, observing tools (fov sim and telescope control), calendar (doesn't really matter)
• try sky safari
  • I like Stellarium better
  • doesn't have telescope feature
  • the search is a little better, it has a section for messier
• sky atlases
  • Sky and tel pocket atlas that I own
  • "observer's sky at" new book (to me) with lower mag

Field of View

• Even more importantly for telescopes is knowing your FOVs
• show the tables I made for mine
  • 2X barlow does mag*2 and FOV/2
• astrotools website for fov
• what is fov of binoculars
• how to calculate if you are a glutton for punishement
  • Formula: Eyepiece FOV / (Telescope Focal Length / Eyepiece Focal Length)
    • according to astronomy.tools
    • It's probably good enough for our purposes in depth FOV guide
• fov rings for star maps / entering telescope for stellarium
• Lowest power eyepiece to start. This is why

Finder Scopes

• Telescope pointers, Red Dot, Reflex Type (telrad, rigel), Finder scope
  • Rigel only has inner 2 rings compared to telrad, they are the same angular size
• how to align, from scratch and if you are pretty sure it's right
  • day / night options
• I always verify that my finder is on at the beginning of the night
• look through with both eyes

Find a Starting Point

• Find a logical starting point. Any good landmarks?
  • ie: constellations, bright stars, planets, triangles
• do cardinal directions (NESW) or relative directions (in the direction of lyra) work better for you or both
  • or below/above when close to the horizon
• if you are really struggling, make sure you are in the right part of the sky.
  • tell my crab nebula story

Finally Time to Look in the Eyepiece

Methods

• frequently I will use escalating techniques as I look and still don't see things
• point right at it - ex: albireo, orion nebula, planets, moon
  • can you see it with the naked eye? if so, point right at it
• point and scan aka star hopping: vol1 - ex: andromeda
  • thinking about moving where the telescope is pointing instead of moving the fov
    • I also tend to do this when tracking an object
• Imaginary Lines - ex: m13 and double cluster and a bunch of others
  • "it's about halfway between X and Y and about that distance off"
  • then scan
• Imaginary Triangles - ex: m13 and double cluster and a bunch of others
  • This is the method Small Optics proposes
  • One big benefit of his is that it requires you do to prep, which is a good thing to get in the practice of.
  • make triangle, hold up the one you drew, verify, then scan that area if you aren't right on
• Star Hopping: vol2 - ex: crab
  • thinking about moving the FOV
  • star hopping in the telescope
  • why I'm trying star charts that go a ways past 6th or 7th magnitude
    • this you could also draw / print beforehand
• FOV can help you
  • 2 stars in, then zoom - ex: ring nebula
  • M32 and M110: knowing what is what, getting them both in one FOV
• Telrad/Rigel specific - ex: crab
  • place naked eye object on ring at angle. I think this is what folks on cloudynights are referring to as the geometric method.

Am I looking at it?

• Things are not like hubble images, they are frequently more like fuzzy patches
  • averted vision
  • Stellarium and other apps can fail you here since they have astrophotography images ex: andromeda
• things being fuzzy means that sometimes it is hard to tell if you are looking at the right thing
  • verifying using surrounding stars - ex: crab or ring

Concrete Examples

• the orion nebula
• alberio
• andromeda
• M13
• the double cluster
• crab nebula
• ring nebula (star wide, go small)
• M52 (knowing how big the object is can be really important) I couldn't tell it was there without higher mag. not sure if m52 is right or if it was something else

Again, It's About Practice

• Once you find the target (and have enjoyed looking at it) move the binos/telescope away and try to find it again. This improves your skill. Doesn't always work though. Before you move it away, look through your finder scope to see the approximate position in the sky.
  • Practice, Practice, Practice
• Frustrations you will have.
  • Looking at the completely wrong part of the sky and/or getting turned around and confused
  • Not being sure if you are looking at the right thing.
  • Weather

Some Good Resources

• This YouTube playlist on finding things by Small Optics

Questions?

Contact Me

To Do:

• More examples?
• What other guides have people made? What did they have to say?
  • https://www.youtube.com/watch?v=reGkLPsm7Ds/
• Magnification and FOV table for LCT
• Lots of pretty pictures
• Pictures through scope of aligning finder first time
• averted vision
  • BBC Sky at Night
  • Folks from Cloudy Nights

How to Find Things with a Telescope by Jake Meinershagen is licensed under CC BY 4.0