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Easy EAA target for July

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#1 ChrisFC

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Posted 01 July 2016 - 09:09 PM

I know its late but how about a nice field like Star Cluster NGC 6520 and Dark Cloud Barnard 86 Space.

Sorry, not deep space savvy enough to suggest something difficult


Edited by ChrisFC, 01 July 2016 - 09:10 PM.


#2 Relativist

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Posted 02 July 2016 - 11:02 AM

I'll check later today, and if there are no better suggestions, I'll make the two threads. I think that combining the 'easy' deep sky object NGC 4725 and the challenge solar system object Makemake is a great opportunity. Also having Pluto as the 'easy' solar system object with guidance from a mag 2 star rounds out the minor planet theme.



#3 nytecam

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Posted 02 July 2016 - 11:37 AM

Is Makemake a KBO?  Anyway its out the chainsaw again on my neighbour's trees for some lowly southern sky - hehe

 

Nytecam



#4 cnoct

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Posted 02 July 2016 - 11:44 AM

I second ChrisFC's suggestion of NGC 6520 and Barnard 86.



#5 Relativist

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Posted 03 July 2016 - 06:18 PM

So far we have in one field:

 

Easy deep sky object

Challenge solar system object

Challenge deep sky object

 

I think we may have a winner, we can combine them into one thread too. I'll make the thread later today.



#6 MartinMeredith

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Posted 04 July 2016 - 08:52 AM

Yes, do take a look in the dark! We're lucky here that blinds are ubiquitous so I can simulate night at any point. The screen gamma setting makes a huge difference too. When I drag the image from my laptop to my auxiliary monitor the tail disappears (even on the DSS image).

 

I've just checked the classification of Arp 159 and it is "Disturbed with interior absorption" (same class as Centaurus A) -- so no mention of the tail. It isn't very obvious in the Arp catalogue photo but is very clear on the DSS image below, and it is telling that I spotted something while observing without knowing there was anything to spot.  I tend not to look at the Arp images before observing as it makes it more interesting to see the DSO. 

 

Screen Shot 2016-07-04 at 15.43.44.png

 

On the 8" f/4, that's the one scope I definitely wouldn't get rid of unless it was to replace with something similar. And the Skywatcher Quattro is a really economical scope, especially in the steel tube version. Mine is the carbon fibre tube model but I'm not sure if that really adds much for EAA-length exposures. The only thing is that you have to be up for checking collimation at the start of each session unless it is permanently mounted. An autocollimator is essential. If I could change one thing it would be the secondary adjustment mechanism.

 

Martin


Edited by MartinMeredith, 04 July 2016 - 08:53 AM.


#7 Alex Parker

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Posted 04 July 2016 - 09:06 AM

 

On the 8" f/4, that's the one scope I definitely wouldn't get rid of unless it was to replace with something similar. And the Skywatcher Quattro is a really economical scope, especially in the steel tube version. Mine is the carbon fibre tube model but I'm not sure if that really adds much for EAA-length exposures. The only thing is that you have to be up for checking collimation at the start of each session unless it is permanently mounted. An autocollimator is essential. If I could change one thing it would be the secondary adjustment mechanism.

 

Martin

 

I am very accustomed to collimating Newts - my visual scope is a truss Dob that I assemble every time I use it, so collimation is done each time.  How good is the focuser on the Skywatcher?  I bought a 120mm Skywatcher frac a while back because reviews said the objective was excellent (it is), but the focuser turned out to be horrible - I ended up replacing it with a Moonlite model.

 

Have you considered just replacing the secondary and its holder with a better one to make collimation easier?  Might even prevent it going out of whack as easily?



#8 MartinMeredith

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Posted 04 July 2016 - 10:11 AM

 

 

On the 8" f/4, that's the one scope I definitely wouldn't get rid of unless it was to replace with something similar. And the Skywatcher Quattro is a really economical scope, especially in the steel tube version. Mine is the carbon fibre tube model but I'm not sure if that really adds much for EAA-length exposures. The only thing is that you have to be up for checking collimation at the start of each session unless it is permanently mounted. An autocollimator is essential. If I could change one thing it would be the secondary adjustment mechanism.

 

Martin

 

I am very accustomed to collimating Newts - my visual scope is a truss Dob that I assemble every time I use it, so collimation is done each time.  How good is the focuser on the Skywatcher?  I bought a 120mm Skywatcher frac a while back because reviews said the objective was excellent (it is), but the focuser turned out to be horrible - I ended up replacing it with a Moonlite model.

 

Have you considered just replacing the secondary and its holder with a better one to make collimation easier?  Might even prevent it going out of whack as easily?

 

 

I find the 2-speed focuser fine (and that's speaking as someone with FeatherTouch on my other 2 scopes). I rarely spend more than 30 seconds focusing since discovering the joys of Bahtinov masks. 

 

I'm not sure you can compare an Obsession with a Skywatcher in the collimatability department ;-)

 

I'd like to replace the secondary mechanism if I can find one that is demonstrably smooth to use -- any recommendations? I've already done the washer and Bob's Knobs mods but they're not enough. It isn't a big deal as it happens during cool-down time, but I could do without it on colder nights.

 

Martin



#9 Relativist

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Posted 04 July 2016 - 10:59 AM

That's the exciting part IMO about NGC 4725 as the challenge object is we have the chance of getting a string of observations of Makemake from different locations and times. A few months back we were able to do such a study with the cooperation of NSN broadcasters that is documented on YouTube of both Makemake and Haumea. Hopefully we will get a lot of participation here.

Challenge solar system object will be Makemake. Easy DSO will be NGC 4725. I'm not sure what the challenge DSO as there is quite a bit to choose from in this field of view and nearby with the arp object, probably either will be good.

#10 Alex Parker

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Posted 04 July 2016 - 11:18 AM

 

 

 

On the 8" f/4, that's the one scope I definitely wouldn't get rid of unless it was to replace with something similar. And the Skywatcher Quattro is a really economical scope, especially in the steel tube version. Mine is the carbon fibre tube model but I'm not sure if that really adds much for EAA-length exposures. The only thing is that you have to be up for checking collimation at the start of each session unless it is permanently mounted. An autocollimator is essential. If I could change one thing it would be the secondary adjustment mechanism.

 

Martin

 

I am very accustomed to collimating Newts - my visual scope is a truss Dob that I assemble every time I use it, so collimation is done each time.  How good is the focuser on the Skywatcher?  I bought a 120mm Skywatcher frac a while back because reviews said the objective was excellent (it is), but the focuser turned out to be horrible - I ended up replacing it with a Moonlite model.

 

Have you considered just replacing the secondary and its holder with a better one to make collimation easier?  Might even prevent it going out of whack as easily?

 

 

I find the 2-speed focuser fine (and that's speaking as someone with FeatherTouch on my other 2 scopes). I rarely spend more than 30 seconds focusing since discovering the joys of Bahtinov masks. 

 

I'm not sure you can compare an Obsession with a Skywatcher in the collimatability department ;-)

 

I'd like to replace the secondary mechanism if I can find one that is demonstrably smooth to use -- any recommendations? I've already done the washer and Bob's Knobs mods but they're not enough. It isn't a big deal as it happens during cool-down time, but I could do without it on colder nights.

 

Martin

 

 

I also love my Bhatinov mask, don't know how I lived without it so long.  

 

I grabbed a screen shot of focusing (on Deneb) before doing Lum exposures of M27 (no filter):

 

noFilter.jpg

 

Interestingly, through a narrowband filter you get a double diffraction effect - this is the same thing but through an Ha filter:

 

Screen Shot 2016-07-02 at 11.45.40 PM.jpg

 

I have every intention of spending some pencil and paper time convincing myself that I understand how this happens from a particle/wave standpoint...



#11 Alex Parker

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Posted 04 July 2016 - 11:21 AM

 

 

I'd like to replace the secondary mechanism if I can find one that is demonstrably smooth to use -- any recommendations? I've already done the washer and Bob's Knobs mods but they're not enough. It isn't a big deal as it happens during cool-down time, but I could do without it on colder nights.

 

Martin

 

 

My Obsession came with an Astrosystems secondary holder, and when I upgraded to a larger one, I got the same type.  They work very well.  I don't have a lot of experience with alternatives however.  In the ATM world people seem to either use Astrosystems or DIY.



#12 Alex Parker

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Posted 04 July 2016 - 11:26 AM

 

 

On the 8" f/4, that's the one scope I definitely wouldn't get rid of unless it was to replace with something similar. And the Skywatcher Quattro is a really economical scope, especially in the steel tube version. Mine is the carbon fibre tube model but I'm not sure if that really adds much for EAA-length exposures. The only thing is that you have to be up for checking collimation at the start of each session unless it is permanently mounted. An autocollimator is essential. If I could change one thing it would be the secondary adjustment mechanism.

 

Martin

 

I'm thinking this might be the replacement for my C8

 

http://www.teleskop-...arbon-tube.html



#13 Relativist

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Posted 04 July 2016 - 11:42 AM

Alex, depending on your mount and goals, you might think about a 12" f/4 imaging newt (~1200mm focal length). I'm going to be having mine redone by Dennis at dobstuff this summer, the other option I considered is buying a CF tube from the same outfit you linked to, they sell them pre-cut. In your case if your imaging for long periods another option to consider is a 10" RC as a compromise.

For my use case, since I'm only doing EAA viewing the 12" is the perfect scope on my CGEM, as it gets the most light flux to the pixels on my camera. With my A7s I could even use a larger scope, but that's a longer term project. (Probably next year)

#14 Alex Parker

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Posted 04 July 2016 - 02:52 PM

Alex, depending on your mount and goals, you might think about a 12" f/4 imaging newt (~1200mm focal length). I'm going to be having mine redone by Dennis at dobstuff this summer, the other option I considered is buying a CF tube from the same outfit you linked to, they sell them pre-cut. In your case if your imaging for long periods another option to consider is a 10" RC as a compromise.

For my use case, since I'm only doing EAA viewing the 12" is the perfect scope on my CGEM, as it gets the most light flux to the pixels on my camera. With my A7s I could even use a larger scope, but that's a longer term project. (Probably next year)

My issue is that I want to be able to do good long guided exposures with the same scope.  The 8" f/4 CF Newt is like 16 lbs to start, and once you've added coma corrector, filter wheel, camera, guidescope, guide camera, it's going to be over 20.  From my experience that's probably the heaviest load one ought to put on a CGEM for astrophotography.  If I was just doing EAA with it I might opt for the 10", but that's still 1000mm FL.  I think I'd really like 800mm better.  

 

The 10"RC at f/8 would be 2000mm FL, so in the wrong direction for me.  It's really tough to guide accurately at that long a focal length; I think most people use scopes like that with something like a KAF11000 - big chip, big pixels, big $$$.  And a $6000+ "serious" GEM like a Paramount.



#15 Relativist

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Posted 04 July 2016 - 05:32 PM

Alex, just like the other scopes, the RC could also be reduced so it can be similar in use to an SCT in that regard. In addition, for your use you have the added constraint of wanting long exposures, so your scope/mount choices narrow somewhat from what I choose for myself as someone only doing EAA viewing. Personally I would not change scopes from your 8" edge unless your getting something significant in return, like more aperture for example. especially since the 8" you have can illuminate the Ultrastar well with decent reduction.

 

P.S. also from your results, I think your doing fine at that focal length, what you might consider is further reduction for EAA use instead of changing scopes.

 

P.P.S. for future captures, I made a thread here for the object of the month for July. Some who have posted here might consider posting their captures over there if they wish so we have one thread with all the 'data'.



#16 Alex Parker

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Posted 04 July 2016 - 08:28 PM

Thanks - I appreciate your comments.  I do find myself limited by seeing more than guiding at 1330mm, so I think that's a positive sign.  Except it's HARD to fix your seeing...

 

The further FR thing is why I wish I had never bought an Edge HD.  The "strongest" FR I can find that is actually meant to work with the built-in flattener in the Edge is the Optec 0.63.  If I had a standard C8 I could use a 0.5x FR.  

 

P.S. also from your results, I think your doing fine at that focal length, what you might consider is further reduction for EAA use instead of changing scopes.

 

 



#17 BarryBrown

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Posted 05 July 2016 - 02:49 AM

 

 

The further FR thing is why I wish I had never bought an Edge HD.  The "strongest" FR I can find that is actually meant to work with the built-in flattener in the Edge is the Optec 0.63.  If I had a standard C8 I could use a 0.5x FR.  

 

 

I know how you feel. I'm in the same boat.

 

I've been told that the Antares 0.5x focal reducer works well with the Edge. I've got one on order along with a set of spacer rings. When they arrive I'll be able to run some tests.

 

Another possibility is to use both the Optec and another reducer together. For example: 0.63 * 0.5 gives you approximately f/3.

 

Two more alternatives: spring for a Hyperstar to get a really fast f/2 or ditch the Edge for imaging and get a refractor. For the price of a Hyperstar you can get a nice ED80 triplet -- but it'll be f/6 instead of f/2.



#18 MartinMeredith

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Posted 05 July 2016 - 04:46 AM

 

 

 

On the 8" f/4, that's the one scope I definitely wouldn't get rid of unless it was to replace with something similar. And the Skywatcher Quattro is a really economical scope, especially in the steel tube version. Mine is the carbon fibre tube model but I'm not sure if that really adds much for EAA-length exposures. The only thing is that you have to be up for checking collimation at the start of each session unless it is permanently mounted. An autocollimator is essential. If I could change one thing it would be the secondary adjustment mechanism.

 

Martin

 

I'm thinking this might be the replacement for my C8

 

http://www.teleskop-...arbon-tube.html

 

 

That looks just the job.

 

Back to the secondary issue. I'm thinking now might be the time for me to experiment with replacing the secondary with the camera directly... If I had Mac software that allowed me to check collimation and focus simultaneously it might work out. From which springs a crazy idea: is it possible in principle to design a mask (like the Bahtinov) that could be used to collimate and focus, I wonder? Optics is not my strong suit.

 

Martin



#19 Astrojedi

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Posted 05 July 2016 - 10:31 AM

I would prefer a RC for long exposure imaging over a Newtonian as in my experience they are lighter, easier to balance and generally give a flatter field out of the box. The only issue is collimation but you can nail it down with experience. I don't recommend RCs to newcomers but you should be ok.

 

Newtonians also make good imaging platforms if you are ok with the bulk.

 

If I was to back to imaging (probably next year as I get more time) I would go with probably a 10" RC with a 0.7-0.8 reducer.

 

In my experience Edge HD scopes also make for good imaging platforms as they provide a very flat field. I prefer to be less aggressive with reduction when doing imaging vs. EAA as it minimizes aberrations and curvature.


Edited by Astrojedi, 05 July 2016 - 10:35 AM.


#20 Alex Parker

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Posted 05 July 2016 - 06:51 PM

 

 

 

The further FR thing is why I wish I had never bought an Edge HD.  The "strongest" FR I can find that is actually meant to work with the built-in flattener in the Edge is the Optec 0.63.  If I had a standard C8 I could use a 0.5x FR.  

 

 

I know how you feel. I'm in the same boat.

 

I've been told that the Antares 0.5x focal reducer works well with the Edge. I've got one on order along with a set of spacer rings. When they arrive I'll be able to run some tests.

 

Another possibility is to use both the Optec and another reducer together. For example: 0.63 * 0.5 gives you approximately f/3.

 

Two more alternatives: spring for a Hyperstar to get a really fast f/2 or ditch the Edge for imaging and get a refractor. For the price of a Hyperstar you can get a nice ED80 triplet -- but it'll be f/6 instead of f/2.

 

I ditched my cheap GSO 0.5x for the optec because I found the field distortions irritating.  Not that the kept me from seeing stuff, but they clearly prevented me from exploring using any of my captures for AP.

 

There is a Hyperstar in my future for sure, just not sure when I am going to pull the trigger.



#21 Relativist

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Posted 05 July 2016 - 07:00 PM

I agree, you might try stacking some reducers, and stick to the quality reducers for better results.



#22 Alex Parker

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Posted 05 July 2016 - 07:03 PM

 

 

 

 

On the 8" f/4, that's the one scope I definitely wouldn't get rid of unless it was to replace with something similar. And the Skywatcher Quattro is a really economical scope, especially in the steel tube version. Mine is the carbon fibre tube model but I'm not sure if that really adds much for EAA-length exposures. The only thing is that you have to be up for checking collimation at the start of each session unless it is permanently mounted. An autocollimator is essential. If I could change one thing it would be the secondary adjustment mechanism.

 

Martin

 

I'm thinking this might be the replacement for my C8

 

http://www.teleskop-...arbon-tube.html

 

 

That looks just the job.

 

Back to the secondary issue. I'm thinking now might be the time for me to experiment with replacing the secondary with the camera directly... If I had Mac software that allowed me to check collimation and focus simultaneously it might work out. From which springs a crazy idea: is it possible in principle to design a mask (like the Bahtinov) that could be used to collimate and focus, I wonder? Optics is not my strong suit.

 

Martin

 

I spent a bunch of time looking for justification for building a prime focus parabolic EAA telescope.  My final conclusion is that by the time you have built a focusing mechanism into the camera holder (a helical focuser of some sort) the central obstruction is just as large as the secondary for an 8-10" scope.  And you would still need to collimate.  Also in your case you would need a new tube, as the one you have is not long enough to mount something at the mirror's focal plane.

 

My killer app for this is to build a large Dob as a Stewart Platform (collimate by adjusting truss pole lengths via threaded rod ends) and put something like a QHY8L at prime focus.  You could get away with a 3" central obstruction on a arbitrarily large reflector.  Say a 28" f/3, use one of those ASA reducer coma correctors (since we're spending imaginary money here) to get it down to 1400mm FL.  Put an altaz motor drive on that and go quasar hunting.  Probably down to mag 25 or better.



#23 nytecam

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Posted 06 July 2016 - 02:41 AM

Alex said  "I spent a bunch of time looking for justification for building a prime focus parabolic EAA telescope.  My final conclusion is that by the time you have built a focusing mechanism into the camera holder (a helical focuser of some sort) the central obstruction is just as large as the secondary for an 8-10" scope.  And you would still need to collimate.  Also in your case you would need a new tube, as the one you have is not long enough to mount something at the mirror's focal plane.

 

My killer app for this is to build a large Dob as a Stewart Platform (collimate by adjusting truss pole lengths via threaded rod ends) and put something like a QHY8L at prime focus.  You could get away with a 3" central obstruction on a arbitrarily large reflector.  Say a 28" f/3, use one of those ASA reducer coma correctors (since we're spending imaginary money here) to get it down to 1400mm FL.  Put an altaz motor drive on that and go quasar hunting.  Probably down to mag 25 or better."

 

July Challenge wanders OT into Telescope Making Forum !  But I've successfully done both prime focus imaging onto CCD [no secondary] with a 10" f/4 Dyson mirror and collimation at the eyepiece via threaded rods running full length of the 8" f/7 Newt by tilting the primary.   The former to avoid light loss via a secondary and the latter as a 'guider' - this abandoned the daft 3-screw adjustment  to tilting the primary in two axes 90 deg apart - both work fine over two decades ago ;-)

 

Can dig out some pics if interested?

 

Nytecam


Edited by nytecam, 06 July 2016 - 02:45 AM.


#24 MartinMeredith

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Posted 06 July 2016 - 04:24 AM

To continue OT for a while (since the challenge is now in a separate thread...)

 

Alex: I'm aiming to avoid using a conventional focuser and go instead for some combined Heath-Robinson collimation/focus adjustment mechanism. If using my Quattro I'd fit an extension tube, attached at the 4 spider holes in the existing tube. If this is too challenging at f/4 I have a 10" f/6.3 mirror waiting to be deployed. In that case, I'd be aiming to keep most of the weight at the mirror cell end using an L-bracket arrangement where the mirror support attaches directly to a dovetail, and avoiding a solid tube (black cloth over lightweight supports). Perhaps a pipe dream...

 

Nytecam: yes, if you can dig out photos I for one would be interested to see the arrangement. 

 

Martin



#25 Robrj

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Posted 06 July 2016 - 11:42 AM

July Challenge wanders OT into Telescope Making Forum !  But I've successfully done both prime focus imaging onto CCD [no secondary] with a 10" f/4 Dyson mirror and collimation at the eyepiece via threaded rods running full length of the 8" f/7 Newt by tilting the primary.   The former to avoid light loss via a secondary and the latter as a 'guider' - this abandoned the daft 3-screw adjustment  to tilting the primary in two axes 90 deg apart - both work fine over two decades ago ;-)
 
Can dig out some pics if interested?
 
Nytecam

I'd like to see them.


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