Frustration at trying to find things

[1 of 5]

I'm sure everyone here not using goto has had this or even still gets it. I was trying to find the sombrero galaxy as it's in the same portion of sky as Saturn and being a total novice Saturn is one of the things I can find with no trouble. With my netbook open showing the region on Stellarium I was instantly hopelessly lost. The reversed image I'm looking at really makes comparing what I'm seeing with the map very difficult. This morning I've just found the bit in stellarium that displays my scopes view. Somewhat belated but better late than never. Can someone please advise what figures to enter for my eyepieces to get the correct view. My scope is a 150 pl 1200mm f8 and eyepieces are 25 and 10mm. Thanks.

[ronin]

Have no idea what stellarium wants, would have thought that you had all the information.

Here are a few extras:

The eyepieces will have a field of view of 50-52 degrees.

The scope being 1200 will give magnifications and aparent field of views of:

25mm eyepiece = 48x, AFoV = 1.08 deg

10mm eyepiece = 120x, AFov = 0.433 deg

A 30mm eyepiece would give 1.3 degree view.

If stellarium needs more there isn't anything else I can think of as relevant.

I would hazard a guess that what stellarium shows is not an exact match to what you actually see. They are just a simulation at the end of the day. So don't expect too much.

[ZEbbEDY]

well i went out with a plan to see 3 messiers and didnt see any of the planned ones.... im pretty sure i saw m57 though it was pretty faint but defo was bigger than a star and in the right area

sky was too dark and too many stars (intense trying to align the finder) its a good problem to have... my technique atm consists of point in the general direction (i know where they are its just getting the scope on target) and slowly sweep the sky until i find something that isnt a star heh

[Carbon Brush]

Hello 1 of 5.

A few general, rather than specific comments that might help.

Was the DSO actually visible in your scope with your dark adaptation and the sky state? I have often found a (say mag 8) DSO using goto, looked through the eyepiece and maybe seen something, maybe not. A DSLR and 30 seconds starts to show something definite. A combination of the sky state and me staring too much at the bright computer are usually the problem. Sometimes I use one eye for the computer and the other for the scope. Last night for example Saturn's moon Rhea was visible with my 'sky' eye. but not my 'computer' eye.

For locating, does your mount have setting circles? You can set these on a nearby bright object, then hop the short distance to the 'faint fuzzy'.

Hope these comments help.

David.

[Steve_meg]

1 of 5 I am also had trouble finding any dso, started with galaxies but no luck so thought some clusters would be a better start but still no luck. my have to try the setting circle if this can be used on a dob.

I also have that problem Davidvalentine especially when I try to use my sky map and turn my touch on. By the time my eyes have focused again I loose where I was.

[onmehedson]

Hi, To anyone who is having bother locating objects with only the finder scope I would strongly suggest getting a telrad finder...

Like you, I had trouble finding stuff, but with the telrad it is possible to keep both eyes open while looking through it so you can see the whole sky with the target transposed upon it...

[Ad Astra]

A couple of things with Stellarium that will help.

1. You can adjust the 'light pollution' number in the sky settings to help match the number and brightness of stars you can see at your location - this makes if much more accurate.

2. Be aware that moonlight, street light, etc. can impact your view. A longer dew shield (even on a Newtonian) can improve contrast, as can installing flocking paper (or black velvet) on the inside of the tube. The idea is to cut out stray light and make sure that only the collimated light from the mirror gets into the field of view. All stray light will lower contrast - and just a little of that can absolutely kill your DSO viewing abilities.

The dark towel over your head is also a great idea. There is a manufacturer here in the states who makes an "astronomer's vest" with lots of pockets for eyepieces and stuff, as well as an oversized "Monk's hood" to block stray light at the eyepiece. The thing won some awards, but it's a bit expensive at $75 - I can make a DIY one for about $15. (Sewing is so a manly art! )

I hope that helps,

Dan

[Viv]

I'm having exactly the same problem.

When Orion was in my view field - then ok - easy, as there are some easy targets to find it.

But I really want to see Sombrero - but no luck so far .....................

[drmillrace]

Another vote for the Telrad especially combined with the "turn left at Orion" book which Gives good instruction and maps oriented to show views through finder and scope

[kniclander]

starhopping is a skill that like anything improves with practice but definitely a telrad or a correct image finder should make it easier along with a good star map or a good guide - my preference is "Guide to astronomical wonders" which has about 1,000 objects each showing the finderscope view and a 1degree circle view. The sombrero will be pretty low in the sky in the uk and it's not very near any bright stars so its a pretty challenging target to begin with. there are lots of easier brighter galaxies in the virgo/coma cluster. don't give up - finding faint and distant galaxies is very rewarding.

[1 of 5]

Thanks chaps. Not giving up. I expected lots of frustration - the universe is very big and my targets very small after all. Stellarium asks for a aFOV which doesn't help me set it correctly for my scope. The telrad idea seems like a good place to start though I'm sure I've seen similar "red dots" with similar reticles for guns for much less. I'll have a trawl of ebay.

[xyz]

Don't forget that you can reverse and invert the Stellarium screen so that it matches the view through your telescope. Configuration > Navigation> check the "Flip" buttons box.

[ronin]

Buy a finder for a scope, not for a rifle.

You stand at the side of a scope not at the butt end of it.

A scope stands on the ground and is not against your shoulder with you looking along it.

[DOBBY]

http://www.12dstring.me.uk/fov.htm try this....

[AstroLuke]

My red dot sight for my M4A1 works alright.

[Digz]

I assume you are referring to the ocular feature within Stellarium?

You should be able to find the aFOV with a google search and add it in.

[1 of 5]

Buy a finder for a scope, not for a rifle.

You stand at the side of a scope not at the butt end of it.

A scope stands on the ground and is not against your shoulder with you looking along it.

Why would that make any difference to a holographic sight? I've used them quite extensively on guns and am very familiar with both their pros and cons so if you can explain why ones for telescopes are different, bar the reticle in the case of the telrad, I'd love to know. They would certainly need to be different to make any difference simply because I'm not shouldering the scope.

[1 of 5]

I assume you are referring to the ocular feature within Stellarium?

You should be able to find the aFOV with a google search and add it in.

Got it now thanks.

[Digz]

Good stuff

[1 of 5]

Don't forget that you can reverse and invert the Stellarium screen so that it matches the view through your telescope. Configuration > Navigation> check the "Flip" buttons box.

Missed that one whilst looking about - thanks.

[Digz]

With the ocular plugin you can tell the scope to be flipped horizontally or vertically, that way you can view Stellarium as normal and when you switch to ocular view the view will be flipped to match what you see through your scope.

[Foton Finder]

Learning to find objects with an alt.-az. mount (such as a Dobsonian) can be tricky, and it does take a lot of practice.

For the brightest DSO's, I suggest starting with good quality binoculars, ideally 50mm or larger, which are going to be even better than the finder, as they give a view that will match the star charts. Then move to the finder, get used to the reversed orientation, and finally the low-power eyepiece. Using Stellarium or other program to reverse the image like the eyepiece view is probably a crutch to be avoided, unless you're trying to spot something really tough, like Pluto.

It is also extremely helpful to figure out the true field of view of the low power eyepiece you use for finding things. That way, you know how far you are moving when slewing "one field of view" in the sky. Instead of using math to calculate, you can use the star drift method. Aim at a bright star that's due south -- say Regulus in Leo. Aim the telescope just west of the star, while looking through the eyepiece. Then, leave the 'scope stationary, and measure how many seconds it takes the star to completely cross the field of view at it widest. Since the Earth turns at 1 degree every 4 minutes, you can figure out the true field of view. (Ex: 5 minutes to cross FOV = 1.25 degrees).

When slewing the DOB, pay less attention to the stars all going the "wrong" way, and thing about which direction the front of the tube is moving. As an example, think "...one field of view to the left, then 1.5 fields "up"..., or similar. Another issue is that when an object is due south, or "near the meridian", moving the front of the instrument up will be north, left will be east, and right will be west. When you observe something rising in the east, or setting in the west, everything will be tilted, so these alt-az directions will not match up with the cardinal directions very well at all. That part takes some practice!

Let's start with the Sombrero Galaxy, or M-104. Late in the evening, this will be in the south. I start with the two bright stars at the top of the constellation Corvus. The one on the left, or east side is a pretty wide pair of stars (a.k.a. Algorab = delta Corvus, and eta Corvus). From here, you can follow a trail of stars to M-104. Start with the naked-eye pair (Delta/Eta), then move slowly to the upper left. You'll see another bright pair, aligned almost vertically, that point back to delta, and in the other direction, line up with a much smaller little line of 3 stars. Let's call the bright pair the "Bridge" stars, and the three tiny ones the "big trio". A little further in the same direction is a smaller, dimmer trio, the "little trio", which is right next to the Sombrero. For measuring purposes, the separation between the two "bridge" stars is almost exactly equal to the distance from the upper one to the big trio, and the separation between the big trio and the little trio. The galaxy is in the same field of view as the little trio.

In 10 x 50 binoculars, M-104 can be spotted from a dark location, but its just barely visible. In an 8 x 50 finder you might spot it, as well. Just find the bridge, the big trio and then the little trio, and the Sombrero will be there!

Good luck and Clear skies,

[1 of 5]

Thanks for that. That's really given me some good courses of action. Appreciated.

[Jiggy 67]

Let's start with the Sombrero Galaxy, or M-104. Late in the evening, this will be in the south. I start with the two bright stars at the top of the constellation Corvus. The one on the left, or east side is a pretty wide pair of stars (a.k.a. Algorab = delta Corvus, and eta Corvus). From here, you can follow a trail of stars to M-104. Start with the naked-eye pair (Delta/Eta), then move slowly to the upper left. You'll see another bright pair, aligned almost vertically, that point back to delta, and in the other direction, line up with a much smaller little line of 3 stars. Let's call the bright pair the "Bridge" stars, and the three tiny ones the "big trio". A little further in the same direction is a smaller, dimmer trio, the "little trio", which is right next to the Sombrero. For measuring purposes, the separation between the two "bridge" stars is almost exactly equal to the distance from the upper one to the big trio, and the separation between the big trio and the little trio. The galaxy is in the same field of view as the little trio.

Wow you make it sound so easy, maybe one day I'll be able to do it that simple....sigh......

[Dave R]

My scope is a 150 pl

With a manual equatorial I find the RA sweep method is much easier than star hopping. There's a good explanation of it here.