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Cosmic Challenge: Jonckheere 900

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#1 PhilH

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Posted 04 March 2017 - 08:17 AM

Few amateur astronomers are familiar with the name Robert Jonckheere. Jonckheere was a French double-star observer who conducted research at a number of observatories over his six-decade career, including the Strasbourg Observatory in France, the Royal Greenwich Observatory in England, as well as McDonald Observatory in Texas.

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#2 Redbetter

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Posted 04 March 2017 - 08:31 AM

I wasn't aware of this one.  Looks like a challenge for the local poor seeing in large aperture.  I will give it a try this coming month conditions permitting. 


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#3 optinuke

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Posted 06 March 2017 - 11:41 PM

I'm new to the Cosmic Challenge...sorry to say I hadn't hit upon it previously.  This month's object, J 900, caught my attention.  Two weeks ago I began observing a list of about 600 planetary nebulae visible from my latitude (derived from the SAC database with some data filters).  I observed J 900 on February 24 from my somewhat light-polluted location at the edge of the Las Vegas valley.  My "planetary nebula" scope for this non-dark-sky location is a Meade 16" LX200 classic.

 

Through the 16", at 150x J 900 was visible and revealed its emission line nature when flashed with a narrowband filter as you note.  At 400x, it presented a small disk.  Without a filter at 400x, it still showed up and was a pleasing small object next to the 12.5 mag. star you noted.  This is definitely an object that can be seen well under less than dark skies.  In fact, it probably won't look that much better under a dark sky since the high magnification needed to see it spreads out the background skyglow.

 

Just a couple notes that made things easier:

 

- For objects NOT in the LX database, the RA and Dec should be precessed to 2017.  As I discovered my first night out entering RA and Dec manually, using J2000 coordinates will result in a significant error (for the 16", about half the FOV in my lowest power eyepiece).  Using precessed coordinates to the current year results in much better pointing accuracy.

 

-I downloaded 30 min x 30 min POSS2 red images (and mirror-reversed them for the SCT) for use as finder charts. 

 

Jay


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#4 kb7wox

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Posted 07 March 2017 - 01:36 AM

Also as:PK194+02.1 and in SIMBAD its PN VV 28

listed as J900 in Burnham's Vol 2 on p 911 as " vS, B, mag 12. diam 10"; nearly stellar."



#5 The Ardent

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Posted 07 March 2017 - 05:42 PM

It's also part of the AL Pn observing program. I remember observing it years ago. I'll give it a try again later this month.

#6 Dave Mitsky

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Posted 07 March 2017 - 10:22 PM

I learned about J900 from an article in Astronomy back in the 1990s and have observed it a number of times since then. 

 

https://futurism.com...jonckheere-900/

 

I've also seen J320 in Orion. 

 

http://www.pbase.com...image/150620355



#7 oalithgow

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Posted 08 March 2017 - 12:50 PM

Only recently found this articles....really loving them. It reminds me of the SmallWonders by Tom.

And now that i have a deacent telescope and hercules is on the horizon, guess i will start this challengues with the 1st one "Gallaxies around M13"

 

Thanks a lot for thaking the time to write this articles Phil.



#8 Redbetter

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Posted 09 March 2017 - 12:38 AM

Got it tonight despite the overbearing moon.  With the moon and in town I used the 10" f/5.  Seeing was  probably 3/10 for the 10" at the time.  Transparency was good. 

 

At 114x it was non stellar, but uncertain.  At 250x it was clearly a non-stellar fuzzy patch with a star a few arc seconds away to the south.  A Farpoint UHC made the patch stand out more and the star faded.  I didn't try to analyze the shape further due to the seeing and moon.

 

In the original Uranometria set it is plotted under PK 194+2.1 as mentioned above.


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#9 PhilH

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Posted 09 March 2017 - 05:16 AM

Got it tonight despite the overbearing moon.  With the moon and in town I used the 10" f/5.  Seeing was  probably 3/10 for the 10" at the time.  Transparency was good. 

 

At 114x it was non stellar, but uncertain.  At 250x it was clearly a non-stellar fuzzy patch with a star a few arc seconds away to the south.  A Farpoint UHC made the patch stand out more and the star faded.  I didn't try to analyze the shape further due to the seeing and moon.

 

In the original Uranometria set it is plotted under PK 194+2.1 as mentioned above.

Nice job, especially with that Moon so nearby!  waytogo.gif



#10 sgottlieb

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Posted 18 March 2017 - 11:09 PM

My first observation of J 900 was over 35 years ago with a C-8.  I'm sure I took a look since it was listed in Burnham's or perhaps plotted on Becvar's Atlas of the Heavens.

 

8" (12/21/81): At 100x, fairly faint, stellar. Used 250-333x to confirm disc.  Seemed slightly elongated at high power with a 13th magnitude star just south. Takes high power well.

 

A few years later I also observed it with my 13" Odyssey I and noted a bluish color.

 

13" (1/11/86): at 144x appears moderately bright and very small but definitely non-stellar.  Takes high power well and an obvious disk is seen at 214x.  A mag 13 star is just off the south edge [11" from the center].  The disc is quite prominent at 535x, slightly elongated NW-SE with a bluish tinge.

 

With my 17.5" I noted a "brighter central spot", though I don't know if I was glimpsing the CS or the brighter lobe.

 

17.5" (12/28/00): At 280x appears a bright, compact, high surface brightness disc, ~8" in diameter with a bluish color.  Forms a close double with a mag 13 star off the south edge.  At 380x, the planetary was slightly elongated and a brighter central spot was highly suspected several times.

 

Steve




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