21P Comet With NGC 2234
Taken by JOHAN GLASS on September 20, 2018 @ Birmingham
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Date Taken: 2018:09:20 09:03:16
 
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Very dark at 4 am, then all the city lights appeared.
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There’s something wrong with this picture and/or the description. Comet 21P/Giacobini-Zinner did not pass over NGC 2234 (at its closest, 21P was a bit more than a degree from the center of NGC 2234’s apparent position at 02:00 UT on Sept 20). I say apparent position because it’s not clear that NGC 2234 is a real object, perhaps just an asterism or even a mistake. 21P did pass over M35 (NGC 2168) on Sept 15, but the pictured object looks like a globular cluster, quite different from M35, an open cluster. One also wonders what the four different versions are supposed to represent (beyond the third one having an annotation).
Posted by JoeStieber 2018-09-21 01:59:47
Hello Joe. I confirmed the stacked image with Astrometry.
The 3rd image is the Astrometry successful reply. NGC 2234 is an Asterism and it is also an Open Galaxy Cluster. There is not much known about it from what I read. My books do not contain any info on it, so I am relying on the web. The Simbad website has some but not much info. I doubted the Astrometry also, but went to Stellarium and it shows 21P right next to NGC2234 on Thusday morning 4:45 a.m. c.s.t.
Posted by jghops 2018-09-21 05:25:54
Joe, that eas the only vomet close to NGC 2234 according to Stellarium. If it is not 21P, please let me know what comet it is.

If you save any of these images to your pc, you can upload it to Astrometry and it will give you the NGC 2334 exactly where the semi-bright cluster is in my image. I stackked in DSS. CAMERA IS CANON T3 AT 250mm , 1 min. Exp. X 24. Mounted on an ASGT CELESTRON.
Posted by jghops 2018-09-21 05:32:05
I have not modified the picture. It is a stack of 24, 1 min. Exp., at 250 mm. I edited it firther with AVIARY and Cannon DPP. I LIKE THE WAY AVOARY PULLS THE RED AND YELLOW OUT OF THE STACK. I USED THE ADJUST BUTTONS AND HIGH CONTRAST MODES.
Posted by jghops 2018-09-21 05:39:31
Look at Stellarium, uou will find 21P right next to NGC 2234 FOR 09,20,18 4,45 AM. CST. LOCATION ALABAMA, CENTRAL...

THAT WAS ENOUGH TO CONVINCE ME.
Posted by jghops 2018-09-21 06:02:28
Ok. Stellarium is showing NGC 2234 DECLINATION IS + 16, 44, 38.4. AND STELLARIUM SHOWING 21P COMET AT DECLINATION +16, 45, 02.4. SO, THAT IS ABOUT 40 ARCSECONDS FROM EACH OTHER, NOT ARCMIN BUT ARCSEC....
Posted by jghops 2018-09-21 08:40:06
I posted twice the RA calculation and this website will notpost it.
Posted by jghops 2018-09-21 09:20:32
RA difference of 21P TO 2234 IS 4.781 ARCMIN. CAMERA WILL SHOOT 5 DEG. X 31 ARCMIN AT 250MM.
Posted by jghops 2018-09-21 09:21:53
5 dwgrees by 21 arcmin, typo
Posted by jghops 2018-09-21 09:23:15
21 arcmin is enough to shoot distance between 21P and 2234, 4.78 arcmin.
Posted by jghops 2018-09-21 09:24:38
Radius of 2234 appears to be distance from comet 21P to center of NGC2234(4.78 arcmin) SO, DIAMETER OF 2234 COULD BE 9.52 arcmin. About half of what my carea shoots at 250mm.
Posted by jghops 2018-09-21 09:27:53
You said 21P was more than a degree from NGC2234. NOT CORRECT ACCORDING TO STELLARIUM. STELLARIUM SAYS RA OF 2234 WAS 06,30,26.43. AND 21P WAS 06, 21, 39.55. A DIFFERENCE OF 4.781 ARCMINUTES, NOT A FULL DEGREE AT ALL, ABOUT ONE TWELTH A DEGREE.
Posted by jghops 2018-09-21 09:37:20
Woops, error. RA OF NGC 2234 WAS 30.4405, AND RA OF 21P WAS 21.6463 ACCORDING TO STELLARIUM. SO THE DIFF IS 8.7942 ARCMIN. BETWEEN THE TWO OBJECTS. SO, THE DIAMETER OF NGC2234 WOULD BE 17.5884 ARCMIN.

BUT STILL, THERE IS NOT A FULL DEGREE DIFFERENCE BETWEEN THE TWO. IT WOULD BE 0.29314 DEGREES DIFFERENCE.
Posted by jghops 2018-09-21 10:15:55
Error again, toted...

8.7942÷ 60 = 0.14657 degrees difference between the two objects.
Posted by jghops 2018-09-21 10:18:51
It might be your geographic location on Earth, but at my location, it was only 0.14657 degrees difference b/t the two.
Posted by jghops 2018-09-21 10:35:53
13 thumbs up
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