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Seven Ways To Find Things In The Sky - Are there others?

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#51 Hesiod

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Posted 31 August 2020 - 07:08 AM

I would start by asking myself what the hell is ngc6946, as usually identify objects by names.
So, once figued out am going for the Fireworks galaxy, I would drawn a triangle from Alderamin, eta Cep and the galaxy, the distance between Alderamin and eta Cep being twice as much as between eta Cep and the Fireworks.
Now I move the telescope to have the Telrad 8°circle to touch eta Cep and the 0.5° to be along a line from Alkurah and Alderamin.
At such point start to star hop (if am not "landed" directly upon the galaxy): since my fov is around 2/3 of a degree I can not frame both the galaxy and the nearby cluster so, if are at a light polluted site, go for the cluster and then move southward by a full field of view and westward by half fov.
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#52 Jim4321

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Posted 31 August 2020 - 08:50 AM

I dunno if this will qualify, but Celestron has added a new method, sort of, the StarSense Explorer.  It uses your cell phone's camera, their app, and a special phone mount & mirror on 4 models of their beginners' telescopes to create a guided push-to system.  

 

 

https://www.wired.co...orer-telescope/

 

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#53 Keith Rivich

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Posted 31 August 2020 - 11:04 AM

I have learned of seven ways to find specific targets in the sky with my telescope and was wondering if there are others that I have not come across.
 
Visual

  • What you can see with your eyes alone when you look up 
  • Star Hopping – Naked eye and optically assisted but still visual

Computer Assisted

  • PushTo - encoders
  • GoTo - encoders
  • Plate Solving - camera based

Setting Circles

  • Equatorial Alignment - Right Ascension/Declination
    Altitude Azimuth Alignment

Each has its advantages and its challenges, so I have learned to use 5 of them.
 
I have not tried RA/DEC setting circles because I don't have an equatorial mount but I could polar align my ETX scopes.   And I have not used plate solving because I am not using a camera at this time.
 
But are there others?   Another approach?
 
What's your favorite?
 
Edit:  I was not thinking of scanning for discovery, but I guess that would apply.  It just isn't a way to find specific targets.

A hybrid style I use on my 25", and at times my 18", that kinda fits across a couple of your categories is to use my binoculars to look through the Telrad and easily move the scope to the DSO. I can clearly see the slightly out of focus inner two rings of the Telrad along with the in focus wide field of the binocs. Its pretty cool looking, the rings seem to float among the stars.


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#54 brentknight

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Posted 31 August 2020 - 11:30 AM

And what would you do if you still failed to find NGC 6946? That seems like a very likely outcome, given that it is a face-on spiral with fairly low surface brightness, and you are observing from light-polluted skies. Would you then:

 

Conclude you were in the wrong place, and try over using the same technique?

Conclude that NGC 6946 is invisible from your location?

Try again using the same technique but higher magnification?

Try again using a completely different technique?

 

The great virtue of star-hopping in the narrow sense of the word is that you know that it lands you on precisely the correct spot. So if the object remains invisible at all magnifications, you know that you really can't see it (at least then and there) instead of wondering if you were in the wrong place.

This scenario involved angle gauges, but it really points out the same issue with Go2.  Unless you have really good Go2's, the object will only be in the field of a low power eyepiece.  An object on the threshold of visibility is not going to jump out at you and you will need to star-hop within the field to identify it...



#55 tommm

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Posted 31 August 2020 - 12:12 PM

But my experience was that you many times can't do that because there are no visible stars close by, so you hop to where you think it should be, but it isn't there, then you have to search, and many times I didn't find it, even after trying several nights.

 

That's why I added GOTO to the last Dob I made.  I use OnStep and it usually puts objects within the 0.85 deg fov at 118x, and many times within the 0.55 deg fov at 147x - it always will if I first GOTO a nearby visible star, do a "sync" and then GOTO the object - so that is the eyepiece I many times start with. It also has a spiral search feature, so if the object is near the fov, selecting that will find it.

 

I find that I have actually come to know the sky much better using GOTO and SkySafari, because I have explored many more objects and areas with them than I did star hopping years ago. In the past I would hunt, fail to find some new object, then go back to just viewing the same old couple dozen objects.  Or not even try for new ones, just look at some of those two dozen and call it a night.  I didn't learn the location of many objects.  Now it is much later at night than I thought when I finally decide to quit because I was so engrossed with observing one object after another, looking at the SkySafari map to get my bearings as to where I am looking and what's there.

 

I know some folks do very well star hopping. I didn't do as well, and I would rather spend the bulk of the time observing rather than hunting in frustration.  Folks like Jon don't need to defend star hopping to me. I know they do well with it. I didn't.

 

It reminds me of a time I was on top of a local mountain peak and struck up a conversation with a couple guys there.  They said they were looking for deer. About that time one of them says "There's one laying under that tree" as he points down the hill about 1/4 mile away to some Mountain Mahogany.  The other guy and I strain to see, but nothing. He keeps saying "It's right there, obvious as can be!"  We can't see it. The other guy says "He has always been like this, I hardly ever see them."

 

Edit: But you don't need GOTO to do the above. It can easily be done with SkySafari and setting circles, or Az setting circle and Alt inclinometer, etc.


Edited by tommm, 31 August 2020 - 12:20 PM.

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#56 brentknight

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Posted 31 August 2020 - 12:17 PM

But my experience was that you many times can't do that because there are no visible stars close by, so you hop to where you think it should be, but it isn't there, then you have to search, and many times I didn't find it, even after trying several nights.

 

That's why I added GOTO to the last Dob I made.  I use OnStep and it usually puts objects within the 0.85 deg fov at 118x, and many times within the 0.55 deg fov at 147x - it always will if I first GOTO a nearby visible star, do a "sync" and then GOTO the object - so that is the eyepiece I many times start with. 

 

I find that I have actually come to know the sky much better using GOTO and SkySafari, because I have explored many more objects and areas with them than I did star hopping years ago. In the past I would hunt, fail to find some new object, then go back to just fewing the same old couple dozen objects.  Or not even try for new ones, just look at some of those two dozen and call it a night.  I didn't learn the location of many objects.  Now it is much later at night than I thought when I finally decide to quit because I was so engrossed with observing one object after another, looking at the SkySafari map to get my bearings as to where I am looking and what's there.

 

I know some folks do very well star hopping. I didn't do as well, and I would rather spend the bulk of the time observing rather than hunting in frustration.  Folks like Jon don't need to defend star hopping to me. I know they do well with it. I didn't.

 

It reminds me of a time I was on top of a local mountain peak and struck up a conversation with a couple guys there.  They said they were looking for deer. About that time one of them says "There's one laying under that tree" as he points down the hill about 1/4 mile away to some Mountain Mahogany.  The other guy and I strain to see, but nothing. He keeps saying "It's right there, obvious as can be!"  We can't see it. The other guy says "He has always been like this, I hardly ever see them."

That's a good idea.  I'll try that next (or if) there is a dark night.  I still think a little star-hop (or pattern recognition) is required if the object is pretty faint.


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#57 aeajr

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Posted 31 August 2020 - 12:19 PM

Note that when I posted the comment below I had intended to quote this post so I could respond to it.   Edited to add it so that it makes more sense.
 

And what would you do if you still failed to find NGC 6946? That seems like a very likely outcome, given that it is a face-on spiral with fairly low surface brightness, and you are observing from light-polluted skies. Would you then:
 
Conclude you were in the wrong place, and try over using the same technique?
Conclude that NGC 6946 is invisible from your location?
Try again using the same technique but higher magnification?
Try again using a completely different technique?
 
The great virtue of star-hopping in the narrow sense of the word is that you know that it lands you on precisely the correct spot. So if the object remains invisible at all magnifications, you know that you really can't see it (at least then and there) instead of wondering if you were in the wrong place.

 
 The great value of ALTAZ method is that you know you are in the right place.

You can confirm by surrounding stars if you wish. If you can't see it you can't see it. No different than any other DSO.  You will always be limited by your aperture, the atmosphere and light pollution.

 

The question about finding that target was about process.


Edited by aeajr, 31 August 2020 - 04:26 PM.


#58 brentknight

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Posted 31 August 2020 - 01:28 PM

I'm just wondering if the process of finding things is more of a 2-phase thing.  Ed has pointed out the seven ways to locate the object.  If the object shows up for you after one or more of these ways, your done trying to find it.  If the object is something like a very small planetary nebula that looks just like a star, or maybe a faint galaxy in the Virgo Cluster, you might need to try additional different ways to find the object at the smaller scales.

 

Angle gauges and Go2 won't help here at all.  Actually, most of these methods probably won't work.  Some of the methods I might use to find this small planetary:

 

  • Drift method: From a known object in the field, let the telescope drift in RA the appropriate amount (probably only workable with an EQ mount).
  • Star-hopping within the field: Star hopping with just your eye from a known object in the field.
  • Pattern recognition: Looking for shapes and patterns that match your references that can help pin down the object.
  • Use higher or lower magnification.  Definitely use averted vision.
  • Use filters.
  • Create a more detailed finder chart.

I realize that once you get beyond the really nice WOW objects, your deep into faint, faint fuzzies.  They may not look like much, but I still think they are fun to track down...


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#59 Tony Flanders

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Posted 31 August 2020 - 03:46 PM

The great value of ALTAZ method is that you know you are in the right place.


To what degree of accuracy? Do you usually land within one degree of your target? Two degrees? A half degree?
 

You can confirm by surrounding stars if you wish. If you can't see it you can't see it. No different than any other DSO.


Interesting. The statement "if you can't see it, you can't see it" is very alien to my way of thinking. My immediate reaction when I can't see a DSO is that I need to try harder, or in a different way. Typically the very first thing I would try would be to raise the magnification. And that is only a reasonable course of action if I'm sure the object will be within the reduced field of view.

 

Also, when looking for faint galaxies in particular, the chance that there will be some other faint galaxy very nearby is quite high, since galaxies tend to come in clusters. So either way, my next step would indeed by to identify the surrounding stars, so that I know where my telescope is pointed with accuracy significantly better than one degree.

 

I keep thinking that I should try homemade digital setting circles myself. Sadly, my two biggest scopes have square bases, and there isn't any easy and obvious way to make an accurate azimuth scale for a scope with square groundboard and square rockerbox. But I suppose I could do it for my Z130.


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#60 brentknight

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Posted 31 August 2020 - 04:05 PM

To what degree of accuracy? Do you usually land within one degree of your target? Two degrees? A half degree?
 


Interesting. The statement "if you can't see it, you can't see it" is very alien to my way of thinking. My immediate reaction when I can't see a DSO is that I need to try harder, or in a different way. Typically the very first thing I would try would be to raise the magnification. And that is only a reasonable course of action if I'm sure the object will be within the reduced field of view.

 

Also, when looking for faint galaxies in particular, the chance that there will be some other faint galaxy very nearby is quite high, since galaxies tend to come in clusters. So either way, my next step would indeed by to identify the surrounding stars, so that I know where my telescope is pointed with accuracy significantly better than one degree.

 

I keep thinking that I should try homemade digital setting circles myself. Sadly, my two biggest scopes have square bases, and there isn't any easy and obvious way to make an accurate azimuth scale for a scope with square groundboard and square rockerbox. But I suppose I could do it for my Z130.

You just need to make the circle a little bigger than the base.  Sadly, after going through the effort, I'm not using the circle much - but I need to try harder in the future since I know many find it very useful...

 

Complete-Small.jpg

 

Pointer.jpg

 

 


Edited by brentknight, 31 August 2020 - 04:15 PM.

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#61 aeajr

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Posted 31 August 2020 - 04:14 PM

I dunno if this will qualify, but Celestron has added a new method, sort of, the StarSense Explorer.  It uses your cell phone's camera, their app, and a special phone mount & mirror on 4 models of their beginners' telescopes to create a guided push-to system.  

 

 

https://www.wired.co...orer-telescope/

 

Jim H.

That is a plate solving solution.  That is what they call it when the computer/phone takes pictures of the sky and matches it to stored star charts.  It is the only one I know of at the moment.    Celestron also had Starsense for their GoTo scopes but it only does the alignment. They are still using encoders to find the targts.



#62 aeajr

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Posted 31 August 2020 - 04:17 PM

I would start by asking myself what the hell is ngc6946, as usually identify objects by names.
So, once figued out am going for the Fireworks galaxy, I would drawn a triangle from Alderamin, eta Cep and the galaxy, the distance between Alderamin and eta Cep being twice as much as between eta Cep and the Fireworks.
Now I move the telescope to have the Telrad 8°circle to touch eta Cep and the 0.5° to be along a line from Alkurah and Alderamin.
At such point start to star hop (if am not "landed" directly upon the galaxy): since my fov is around 2/3 of a degree I can not frame both the galaxy and the nearby cluster so, if are at a light polluted site, go for the cluster and then move southward by a full field of view and westward by half fov.

Looks good!



#63 aeajr

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Posted 31 August 2020 - 04:20 PM

I'm just wondering if the process of finding things is more of a 2-phase thing.  Ed has pointed out the seven ways to locate the object.  If the object shows up for you after one or more of these ways, your done trying to find it.  If the object is something like a very small planetary nebula that looks just like a star, or maybe a faint galaxy in the Virgo Cluster, you might need to try additional different ways to find the object at the smaller scales.

 

Angle gauges and Go2 won't help here at all.  Actually, most of these methods probably won't work.  Some of the methods I might use to find this small planetary:

 

  • Drift method: From a known object in the field, let the telescope drift in RA the appropriate amount (probably only workable with an EQ mount).
  • Star-hopping within the field: Star hopping with just your eye from a known object in the field.
  • Pattern recognition: Looking for shapes and patterns that match your references that can help pin down the object.
  • Use higher or lower magnification.  Definitely use averted vision.
  • Use filters.
  • Create a more detailed finder chart.

I realize that once you get beyond the really nice WOW objects, your deep into faint, faint fuzzies.  They may not look like much, but I still think they are fun to track down...

Regardless of what method you use, you will always be limited by the aperture of your scope, the atmospheric conditions and the light pollution levels.   So they really have nothing to do with methods to find things.  



#64 aeajr

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Posted 31 August 2020 - 05:07 PM

To what degree of accuracy? Do you usually land within one degree of your target? Two degrees? A half degree?

Just like any alignment based process, the degree of accuracy is affected by the accuracy of your alignment.  I align zero on my AZ scale on Polaris at the start of the night.   And, as with any solution that uses setting circles or gauges, the resolution of your scales will impact accuracy. 
 
The AZ scale on my Dob is 24 inches in diameter.  The AZ scale on my ES Twilight 1 is only 6 inches.  My AZ hits are better on the Dob than on the EST1.

 

My digital angle gauges provide .01 degree resolution.  The analog circular angle gauge has a resolution of maybe .25 degrees. 

 

If I am missing it is almost always in the AZ not in Alt. If I were not quite precise with my AZ alignment at the start of the night I would recognize the error and adjust for it as as it would always be the same.  
 
Last night I was doing a comparison of my 5" Mak vs. my 12" Dob to see how the views differed under the light of a nearly full moon.   Seeing and transparency were very good. 
 
I had my 5" Mak F15 on a ES Twilight 1 mount. with a 6" AZ circle.  Finder was a 5X25 RACI and a 32 mm Plossl yielding 59X and .8 degree FOV. 

 

With the Mak I went to M10 and M12, globular clusters.  I hit one nicely in the FOV of the eyepiece.  The other was just outside the eyepiece FOV to the left.   Anything I missed with that scope last night was just to the left.  The GCs were so washed out under that nearly full Moon that I could barely see them. Switching from the 32 Plossl to a Celestron 8-24 zoom, I walked up the mag.  Couldn't resolve any stars in M10 or 12.  Tried my 14 MM and 8.8 mm ES82, but no help. 
 
For comparison I used my 12" Dob, AltAz coordinates, to find the same two GC.  My alignment was very good list night so I was doing my hunting with my BH Zoom at 24 mm rather than my 38/70 or 20/82 eyepieces.  In that scope the 24 mm zoom setting gives me 63X and .75 degree FOV.   

 

The goal for the evening was to see how aperture affected the view of planets and DSOs under these light polluted conditions. 
 
In the 12" I hit both in the FOV.  Naturally they were much more visible and as I cranked up the mag, using the zoom, I could resolve individual stars.  Ain't aperture wonderful?
 
So, in general, if I have been accurate on my alignment of the AZ scale I usually hit the target or am within about 1/2 degree.  The digital angle gauge is normally right on the money as far as altitude goes.  There is no dependency on the mount being perfectly level as the angle gauge reads the absolute angle of the tube, not the angle relative to the mount. 
 
I was hitting targets within 1/2 a degree AZ on both scopes all night long.  Alt is always on the money.   
 
At the end of the night, around 11:00, using the 12" Dob I pegged Uranus at 8 degrees altitude above the horizon right on the money.  Same with Neptune.   
 
In the case of these star like targets I set the scope, then moved up the mag with the zoom till they resolved into disks.  That eyepiece takes me from 63 to 190X and everything in between. 
 
 I can always go to my low power wide view if I am not hitting quite as precisely as I would like. But last night I was spot on all night. 

 

Interesting. The statement "if you can't see it, you can't see it" is very alien to my way of thinking. My immediate reaction when I can't see a DSO is that I need to try harder, or in a different way. Typically the very first thing I would try would be to raise the magnification. And that is only a reasonable course of action if I'm sure the object will be within the reduced field of view.
 
Also, when looking for faint galaxies in particular, the chance that there will be some other faint galaxy very nearby is quite high, since galaxies tend to come in clusters. So either way, my next step would indeed by to identify the surrounding stars, so that I know where my telescope is pointed with accuracy significantly better than one degree.
 
I keep thinking that I should try homemade digital setting circles myself. Sadly, my two biggest scopes have square bases, and there isn't any easy and obvious way to make an accurate azimuth scale for a scope with square groundboard and square rockerbox. But I suppose I could do it for my Z130.

Not alien to me at all. 

 

At my home location, Bortle 8 sky and tons of ground light pollution, there is a lot I can't see with my 80 mm refractors.  When I first started I went after the North America Nebula with that GoTo scope so many times. 4 degree FOV.  I could tell by the star pattern that I was on it but I could not see it.   If you can't see it you can't see it.   

 

I picked up an OIII and a Nebular filter. Still could not see it. 

 

If I had used star hopping, AltAz or chanting to the astronomy gods, it would have made no difference.  What I can see has nothing to do with the method I use to get the scope to the right spot.

 

If you want to give this method a try without an AZ scale, here is how you do it.  I did this for months with great success before I added the AZ scale on my XT8i.

  • Find a star near your target and use that has a way to estimate your AZ position.
  • Or use a compass, but don't forget to adjust for the local variation between Polaris and magnetic north
  • Using the angle gauge, set the altitude
  • Scan over to where you estimate the target to be.

You'll hit it.   Use your low power wide view to give you the best opportunity.

 

My friend, having learned this method, now uses the angle gauge to help in polar aligning his EQ mount. Don't ask me how as I don't have an EQ mount.  But last night he told me this was making his alignment easier. 

 

 

If you take a look at this discussion you will see pictures of how people have added AZ scales to their scopes.  You may pick up an idea that will work for you.

 

Using an angle gauge to help find targets – AltAz coordinates
https://www.cloudyni...y/#entry8120838

 

Printable Setting circles
https://www.cloudyni...ntable circles

 

Making an adjustable AZ gauge on a Dob.
https://www.cloudyni...e/#entry9433327


Edited by aeajr, 31 August 2020 - 05:34 PM.


#65 Jon Isaacs

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Posted 31 August 2020 - 05:22 PM

Note that when I posted the comment below I had intended to quote this post so I could respond to it.   Edited to add it so that it makes more sense.
 

 
 The great value of ALTAZ method is that you know you are in the right place.

You can confirm by surrounding stars if you wish. If you can't see it you can't see it. No different than any other DSO.  You will always be limited by your aperture, the atmosphere and light pollution.

 

The question about finding that target was about process.

 

With GOTO, with DSCs, with manual setting circles, there are a number of possible problems. Improper setup, equipment failure, wrong information from the computer/ tablet for a number of reasons. 

 

I've seen people looking 90 degrees from the target because something slipped, the wrong time, location, it's not at all definitive.

 

Star hopping, you're depending on your skills star hopping and it's possible to make an error, I do sometimes. But it becomes apparent quite quickly if I've made an error because the star fields are wrong.

 

Jon


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#66 aeajr

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Posted 31 August 2020 - 05:29 PM

With GOTO, with DSCs, with manual setting circles, there are a number of possible problems. Improper setup, equipment failure, wrong information from the computer/ tablet for a number of reasons. 

 

I've seen people looking 90 degrees from the target because something slipped, the wrong time, location, it's not at all definitive.

 

Star hopping, you're depending on your skills star hopping and it's possible to make an effort, I do sometimes. But it becomes apparent quite quickly if I've made an error because the star fields are wrong.

 

Jon

Quite true.

 

With my GoTo and PushTo mounts, if I am having problems I target a known star. If I didn't hit it I redo te alignment.  In fact, a standard test for me, after aligning the second star is to GoTo the first alignment star.  If that doesn't work, nothing will. 

 

A smart man once told me, "Son, you have to inspect what you expect!"

 

I essentially do the same thing with the AltAz method.   Once I have the AZ scale aligned I target a known star.  I should hit it it with no problems.  If I don't, I know to make adjustments.  In fact I can make the adjustments while on the target star.

 

By any of these methods, you know pretty fast if something is wrong.  More often than not, it is human error, a factor that also comes into play in star hopping. wink.gif


Edited by aeajr, 31 August 2020 - 05:29 PM.


#67 Jon Isaacs

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Posted 31 August 2020 - 05:52 PM

Regardless of what method you use, you will always be limited by the aperture of your scope, the atmospheric conditions and the light pollution levels.   So they really have nothing to do with methods to find things.  

My biggest limitation is not my equipment, not my scopes, not the light pollution, it's my skills as an observer.  As Tony said, when he can't see something,  he tries harder. 

 

For me, that doesn't mean just knowing that the object is somewhere in the field of view, it means knowing exactly where it is in the star field so I can "point my averted vision" in exactly the right location.  This means figuring out the star field and exactly where the object is relative to stars visible in the main eyepiece.  It might take 15 minutes, it might take 30 minutes to finally see a difficult object but that is what it takes sometimes. 

 

This is one of the virtues of star hopping, understanding the field of view in the main eyepiece.  Knowing exactly where that object is.  

 

I essentially do the same thing with the AltAz method.   Once I have the AZ scale aligned I target a known star.  I should hit it it with no problems.  If I don't, I know to make adjustments.  In fact I can make the adjustments while on the target star.

 

That's good but you are still limited by the inherent accuracy of the system.  At some point, star hopping in the main eyepiece as described above becomes an important tool.  

 

It's also a good way to identify multiple galaxies/objects in the same high power field.  

 

Jon


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#68 brentknight

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Posted 31 August 2020 - 05:53 PM

Regardless of what method you use, you will always be limited by the aperture of your scope, the atmospheric conditions and the light pollution levels.   So they really have nothing to do with methods to find things.  

I think you might be misunderstanding me.  I know (because I have seen them) that I can see right up to about 12 mag galaxies from my Bortle 5.5 front yard.  I don't even try for anything fainter than that.  Those galaxies are pretty darn challenging to see though - they never pop right out of the field.  But if I know exactly where to look, I have a much better chance of finding them.  My post was attempting to describe some of the methods that could be used to go that little extra distance to confirm an object.  In my mind they have everything to do with finding faint things or small things.

 

Go2 and angle gauges work great for getting to the general area (and it sounds like possibly within a degree or less - I'll have to work on that).  But if you have to use AV or higher powers just to detect the target, I think you need a couple more ways...


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#69 hcf

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Posted 31 August 2020 - 07:33 PM

My biggest limitation is not my equipment, not my scopes, not the light pollution, it's my skills as an observer.  As Tony said, when he can't see something,  he tries harder. 

 

For me, that doesn't mean just knowing that the object is somewhere in the field of view, it means knowing exactly where it is in the star field so I can "point my averted vision" in exactly the right location.  This means figuring out the star field and exactly where the object is relative to stars visible in the main eyepiece.  It might take 15 minutes, it might take 30 minutes to finally see a difficult object but that is what it takes sometimes. 

 

This is one of the virtues of star hopping, understanding the field of view in the main eyepiece.  Knowing exactly where that object is.  

 

This is where platesolving is very useful. With the PSWAI, if I take the time to align the piggybacked camera with the scope very accurately, I can match the view in Sky Safari with that in my ES 82 18 degree EP on my 8" Dob about a 1.2 degree FOV. Not exactly centered but close enough to match the stars. Once I think I am at the right spot, a platesolve confirms it on Sky Safari which shows me where to look for the DSO. So a mixture of platesolving and star hopping is very powerful. It also helps if the DSO drifts away a little and you can't find it again in the EP.



#70 aeajr

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Posted 31 August 2020 - 11:54 PM

I think you might be misunderstanding me.  I know (because I have seen them) that I can see right up to about 12 mag galaxies from my Bortle 5.5 front yard.  I don't even try for anything fainter than that.  Those galaxies are pretty darn challenging to see though - they never pop right out of the field.  But if I know exactly where to look, I have a much better chance of finding them.  My post was attempting to describe some of the methods that could be used to go that little extra distance to confirm an object.  In my mind they have everything to do with finding faint things or small things.

 

Go2 and angle gauges work great for getting to the general area (and it sounds like possibly within a degree or less - I'll have to work on that).  But if you have to use AV or higher powers just to detect the target, I think you need a couple more ways...

Let's not confuse getting the scope to the right spot with knowing what the target looks like or whether it will be observable with this scope under these conditions.   Those are different skills requiring different preparations and different knowledge.

 

When I say 7 ways to find things in the sky I am talking about knowing where to point the scope.  Whether you use visual cues, computerized mounts or setting circles, the goal is to get the scope pointed to the right spot.

 

Now that you are there, would you recognize it if you saw it?   Ahhh, that is another matter entirely.   If you wouldn't recognize it while star hopping, you won't recognize it with a GoTo, PushTo, Plate Solving or setting circles. 

 

All these navigation tools do is get you to the right spot so you can see it, if you can see it, if you can recognize it.  

 

Like using the GPS in your car, once you have arrived at your destination, you still need to recognize the destination.  But it should be there in front of you. 


Edited by aeajr, 01 September 2020 - 07:40 AM.


#71 Mitrovarr

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Posted 01 September 2020 - 01:48 AM

It's all going to come down to a matter of definition. For instance, I would regard plate solving as just a way you calibrate goto, not another method.

 

My list would be:

 

Manual unassisted:

Visual finding: Pointing the telescope at a visible object.

Point and scan: Figuring out the position of an object you can't see, point the telescope at that position, and scan around in the eyepiece to find the object.

Star hopping: Use a sequence of star hops to find objects.

 

Manual assisted:

Equatorial setting circles

Alt-azimuth setting circles (combined with an updated computer chart with current alt-az position) - rare

Digital setting circles

 

Motorized:

Alt-azimuth goto

Equatorial goto


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#72 Tony Flanders

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Posted 01 September 2020 - 05:27 AM

Let's not confuse getting the scope to the right spot with knowing what the target looks like or whether it will be observable with this scope under these conditions.   Those are different skills requiring different preparations and different skills.

I do not agree. For me, they are all different aspects of a single skill, and it isn't really meaningful to separate them, either in theory or in practice.

My ultimate objective is to see my target object through my telescope. Knowing that my telescope is pointing kinda sorta in the right direction is useless unless I can actually see the object -- or confirm that it is invisible.

To illustrate, let me explain how I would likely look for NGC 6946 through my telescope. As it happens, this is an object I am familiar with -- though not under the name Fireworks Galaxy. What a dumb name; nobody calls it that! But let's imagine this was my first time viewing it.

The very first thing I would do is note that it is an extremely large face-on spiral, much like M101. And like M101, I would expect it to have fairly low surface brightness. I would expect it to be likely visible through a 50-mm finderscope under dark skies, and almost certainly visible through the main eyepiece, even at low power. So under dark skies, I would include in my bag of tricks for this particular galaxy techniques such as sweeping across a broad swath of sky, which rely on the foreknowledge that the object will be readily visible.

 

Given that this galaxy forms one vertex of a right-angle isoceles triangle with Eta Cephei at the right angle and Theta Cephei at the other vertex, and that it is just 2 degrees from Eta, I would simply point my scope at the right point with respect to those two stars, and it would almost certainly be sitting there near the middle of a low-power eyepiece view, and readily visible. This is a rather unusual case, because the galaxy is very close indeed to one seriously bright star and fairly close to a second. If it were farther from the reference stars, I might use a different technique.

At the opposite extreme, if I were observing from Cambridge, MA, I would start with the assumption that my quest for the galaxy will fail. In general, face-on spirals are hard to see from urban locations, and Messier already snapped up most of the exceptions to that rule.

 

In particular, it's very unlikely that this object would be visible at low power. If I can see it at all, I would expect to be using perhaps 10X or 15X per inch of aperture, requiring me to pinpoint the location before I start observing. So I would start at Eta Cep and then hop from there over to the location of NGC 6946 -- either through the main scope at low power or through my finderscope. I would likely start by triangulating the location with respect to the two 7th-magnitude stars that lie less than a half degree from the galaxy. I would then note two 10th-magnitude stars that are charted right on the galaxy's edge, which would allow me to pinpoint the location of the nucleus, the most likely place to start looking.

 

After scanning my low-power eyepiece's field of view carefully many times with averted vision, I would then raise the magnification to a 2-mm exit pupil and try all over again. After that I would raise the magnification yet again and try all over again.

 

Note that in the unlikely event that I succeeded in seeing NGC 6946 from Cambridge, the initial work of getting to the correct location would be a trivial fraction of the total time spent looking for it. That's why I would start with star-hopping -- allowing me to know where I am at all times with accuracy much better than 0.1 degree -- rather than with a less accurate method.

From my astronomy club's observing field in Westford, MA, I would start with the assumption that this galaxy is going to be visible, but I am going to have to work really hard to find it. I would not use techniques like the low-power sweep, because NGC 6946 would be unlikely to catch my eye at low magnification. But I would likely start by pointing my scope at the right spot w.r.t. Eta and Theta, which ought to be accurate much better than 0.5 degree with stars so close to my target. If I can see NGC 6946 directly at low power, then I'm done except for the detailed viewing. Otherwise, I would revert to proper star-hopping, either from that location or (if I was having trouble identifying the field stars) from Eta Cep.


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#73 Jon Isaacs

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Posted 01 September 2020 - 06:16 AM

Let's not confuse getting the scope to the right spot with knowing what the target looks like or whether it will be observable with this scope under these conditions.   Those are different skills requiring different preparations and different skills.

 

When I say 7 ways to find things in the sky I am talking about knowing where to point the scope.  Whether you use visual cues, computerized mounts or setting circles, the goal is to get the scope pointed to the right spot.

 

Now that you are there, would you recognize it if you saw it?   Ahhh, that is another matter entirely.   If you wouldn't recognize it while star hopping, you won't recognize it with a GoTo, PushTo, Plate Solving or setting circles. 

 

All these navigation tools do is get you to the right spot so you can see it, if you can see it, if you can recognize it.  

 

Like using the GPS in your car, once you have arrived at your destination, you still need to recognize the destination.  But it should be there in front of you. 

I am talking about knowing exactly where the scope is pointing. 

 

I say this: If you didn't recognize it using GOTO, PUSH TO, Plate Solving or with Setting Circles, there is still a reasonable chance that you will be able to see it star hopping.  This is because when you star hop, with a good enough chart and enough effort you know visually exactly where that object is in the star field. 

 

This is the next step if you didn't see it just pointing the scope in what is supposed to be right spot. 

 

Your ALT-AZ circles get you relatively close but you just know it is somewhere in the field of view, you don't know exactly where it is. It doesn't get you to the exact right spot.  Using the GPS analogy, it gets you to the neighborhood but not to the front door of the house.  And the houses have no numbers on them. 

 

Jon


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#74 clearwaterdave

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Posted 01 September 2020 - 07:22 AM

Adding to what Jon is saying.,For me the last hop is the most important one.,It should center your target.,But how can you center something you can't see?.,By studying what I call the nest.,this is the stars that surround the target.,that will also be in the fov.,my last hop will go something like this.,"If I put that star in the 6 oclock position my target will be centered.,and those 2 very faint stars are just above to the right".,knowing exactly where the target is in relation to the stars in the nest is key to "seeing" it.,I have found fuzzies I would have NEVER seen if I was just scanning the area.,even if I knew it was there somewhere in the vacinity.,

  This has not only proven to be much more accurate but also the most rewarding way to see stuff for me.,cheers.,


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#75 aeajr

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Posted 01 September 2020 - 08:30 AM

These are great posts guys and I think people who are reading them will gain so much from your comments. 

 

So let me add mine.   

 

Getting to the right spot vs. recognizing your target when you get there.

 

Regardless of how you arrive at the proper spot in the sky you still have to recognize the target.  Well how do you do that?

  • Understand the class of target - planet, star, open cluster, globular cluster, galaxy, nebula, ???
  • Understand the characteristics of the target
  • Understand its magnitude - is this a bright object or a dim object
  • Get a feel for its surface brightness in comparison to your local light pollution
  • Have a feel for size - Some things will exceed your field of view and some will be very small
  • What is around the target that can either help you identify it or zero in on it
  • What are the effects of atmosphere on what you see; transparency and seeing

Experience

 

When I first started with naked eye and binoculars I learned to find things visually and by their relationship to things I could see.  With the help of others, a planisphere, charts and apps I learned to split mizar and alcor, find the coathanger and other things in the sky through star hopping methods. It lead me to write a quick start guide targeted on binocular users.  That guide is published here on CN.

 

I then purchased an ETX 80, an 80 mm GoTo.  One of the things I wanted to see was the Andromeda Galaxy.  I knew it was in the sky and about where it was. I had read it was a visual target from some locations and that it could be seen in binoculars.  

 

I identified the path from the Great Square to follow the stars with my binoculars.  No luck

I worked the path from Cassiopeia with my binoculars.  No luck

I set the GoTo on the proper spot a dozen times.  No luck

 

I declared that M31, the Andromeda Galaxy, could not be seen from my home location in my Bortle 8 sky with tons of ground light pollution. 

 

I couple of months later I got an 8" Orion XT8 Intelliscope.   Still no luck while using the Intelliscope PushTo or star hopping.   :(

 

First trip to a darker location, Bortle 6, I found it with the help of the Intelliscope PushTo system. I asked one of the experienced people to confrm that I had it.  Really?  Is that what it looks like?  Oh!  :(

 

 

I pulled out my binoculars.  Oh, now I see what it looks like in binoculars.   In fact, if I used averted vision,  could see it naked eye, barely.   OK!

 

Got home the same night and pulled out the binoculars.  Oh, that smudge is M31?  I have seen that lots of times but that is not what I had expected to see.

 

Put the 80 mm ETX 80 on it and sure enough, I could see it, this faint, sort of off white smudge in the sky.   

 

Still could not see it with my naked eye and even with the 8" Dob it was still just an off white smudge.  The smudge was just a bit brighter in the Dob.

 

I had used multiple methods to try and find the Andromeda Galaxy.   

  • Naked eye
  • Star hopping with binoculars, an 80 mm refractor and an 8" Dob 
  • GoTo with an 80 mm refractor
  • PushTo with an 8" Dob

Each method got me to the right location.  In each case, other than naked eye visual, I had found it.   I just didn't recognize it.

 

All the triangulating based on star patterns, using a variety of methods to find the target could not overcome my lack of experience in observing and my miss set expectation as to what it would look like when I found it.  As my time at the eyepiece built up I had this same experience over and over with the North America Nebula, galaxies and other low surface brightness objects.  I learned about surface brightness and not to pursue these from my home location.  

 

Over the last 5 years I have used 5 of the 7 methods listed n the first post to find things.   I have had success with eachmethod and I have failed with each method.  Confirming I have the right object by multiple methods has given me a much better understanding of what I can see and what things look like when I am on them.

 

This is why I separate the method of getting to the right spot from actually recognizing the object when you are there.  My experience tells me that these are two different things, two different skill sets that have to be learned.  There is finding the target and then there is recognizing you found it. 

 

I have experience this many times.  I have had someone tell you he has some faint object in the eyepiece, but look as I may I can't see or or can't recognize it.   Others see and recognize it, but I don't.  Lesser eyesight or lack of understanding kept me from recognizing what was there to be seen.  In this case there was no finding method, someone else had done that. 

 

So I separate the method of finding from recognizing and seeing because in my experience they are two different things.  

 

Naturally, your experience, your understanding, your approach will vary from mine.  




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