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IC4593 Planetary Nebula

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#1 Anthony236J

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Posted 10 July 2018 - 11:44 PM

Tonight was a quick session of only a few objects, one of which was planetary nebula IC4593.  Sky Safari showed a star with (suspiciously) the same 10.8 magnitude about 11.1 arcseconds away from the location of the planetary nebula, so at the time of sketch I was unsure if I was observing that star, the nebula itself, or both (and I could not resolve more than one point at highest magnification).  A later search revealed a Simbad result, accompanied by an image, that shows no other star that bright within 1 arcminute of the nebula. This has me believing that I did spot the nebula, but if anyone has more knowledge or experience with this area, please let me know.

 

The object was apparent even at 22x, but could not resolve to anything more than a point source up to my maximum available power of 117x (at which point star diffraction patterns start to inhibit differentiation of very small extended objects).

 

IC4593 2018 07 06 Borg55FL

 


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#2 Jef De Wit

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Posted 11 July 2018 - 05:28 AM

I needed in my 8 cm refractor UHC to see the PN as a non-stellar object. Without UHC it was just a star. I guess 55 mm (without filter?) isn't enough to see the shell of the PN.



#3 Anthony236J

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Posted 11 July 2018 - 10:03 AM

Hey Jef, thanks for your response! You are right in that no filter was used. With an angular size of 0.2 arcminutes, I can see how more aperture would be helpful to glimpse the shell at higher power.  When you observed it with your refractor, did you need the UHC filter because the shell was too faint, or too small?  I think from my observation, the light from both the central star and surrounding nebula was visible, but just not enough apparent angular size to appear as an extended object. It is difficult to tell from images and there are few reports accessible on central star magnitude (~11.3 from what I've read so far).



#4 niteskystargazer

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Posted 11 July 2018 - 03:10 PM

Anthony,

 

Nice sketch of  IC4593 Planetary Nebula smile.gif .

 

CS,KLU,

 

thanx.gif ,

 

Tom



#5 Raul Leon

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Posted 11 July 2018 - 04:46 PM

Hey Anthony,

                       I had to use a 7mm eyepiece in my 14.5 dob at 226x magnification just to see the central star, this is a very small object. Raul



#6 Anthony236J

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Posted 11 July 2018 - 05:53 PM

Thanks Tom!

Raul, good to know, thanks. Sounds like contrast is quite low within the shell then, so I'll consider this a confirmed viewing of the nebula itself :)

#7 iainp

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Posted 12 July 2018 - 02:10 AM

Hi Anthony, here's my sketch of the nebula (AKA the white eyed  pea nebula) at a magnification of 900x through a 20" dob (and a link to the original post). I got some of the shell, but looking online it seems there's more of it but not visible even with the 20". Just to be clear, it didn't actually look this big, shown like this to reveal as much detail as possible. Even at 900x it's a tiny thing!

Iain.

Iain https://www.cloudyni...ll-blue-at-900x

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Edited by iainp, 12 July 2018 - 02:15 AM.

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#8 Jef De Wit

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Posted 12 July 2018 - 03:45 AM

When you observed it with your refractor, did you need the UHC filter because the shell was too faint, or too small?

In a 8 cm (with magnification around x100) the shell is small, but most of all difficult to see because it is faint.



#9 Anthony236J

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Posted 12 July 2018 - 09:07 PM

Iain, that's an excellent sketch of this tiny object, showing *slightly* more detail than my sketch ;)

 

I believe I had a misuse of terminology. I used the word "shell" to describe what I should have just called the "nebula", in general.  After checking several sources online, I'm still a little unsure about the terminology for describing the structure of planetary nebula (shell, disk, halo...).  But from what I understand, the central part of this nebula is actually relatively bright, whereas the outer shell is considerably fainter (and benefits from the UHC filter, as you mentioned, Jef).  Does this sound correct?

 

I will try to revisit this object with my larger telescope to get a better idea of what was glimpsed with the refractor.



#10 iainp

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Posted 12 July 2018 - 11:16 PM

Thanks Anthony, yes the big aperture really pulls out the detail on these small PNs by allowing massive magnifications! I was amazed at the colour in this one too, even at 900x. I'm not sure about correct terminology either, but always been happy to talk about inner and outer shells etc. Re filters, I found this one was better with no filter at all, and that's often the case, especially when looking for subtle detail in outer shells, but that may be just because of the big aperture. I've had most success with an OIII filter, which on many PNs is absolutely fantastic. It's great for identifying small and stellar PNs too, using the blinking method, which as you probably know, is when you briefly pass the filter between the eyepiece and the eye, making all the stars much dimmer but the PN appears brighter in comparison.


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