wvreeven
July 22nd, 2019, 09:33 AM
NGC 6309, Box Nebula, Exclamation Mark Nebula, PK 009+14.1, PGC 3517781
Planetary Nebula
Constellation: Ophiuchus
RA: 17 14 04.3
DEC: -12 54 37.9
Visual magnitude: 11.50
Dimensions: 0.427' x 0.299'
This is one of the two objects called the Box Nebula, the other being NGC 6445 which was OOTW before (http://www.deepskyforum.com/showthread.php?905-Object-of-the-Week-July-31st-2016-NGC-6445-the-Box-Nebula&highlight=6445). However, NGC 6309 sometimes is referred to as the Exclamation Mark Nebula, which seems to be a more fitting name. Unfortunately the origins of both names are unknown to me though the Exclamation Mark name may originate from Stephen O'Meara's book The Secret Deep.
NGC 6309 was discovered visually in 1876 by Wilhelm Temple. He used the 11” (280 mm) refractor of the Observatorio Arcetri of Florence, Italy. The nebula is classified as a bipolar nebula because it contains two bright blobs which are offset asymmetrically around the central star. This Hubble image of the central part shows a dimmer bar running through the lower part of the nebula perpendicularly to the major axis of the nebula
3583
This is also visible in this spectacular drawing created by Belgian amateur Tom Corstjens
3582
However, this SDSS/NOAO composite image shows that there is a bigger deal to this nebula
3584
As a matter of fact, the nebula takes the appearance of a spiral galaxy! Perhaps that explains the PGC designation?
My observations using my 20” dob on August 9, 2013, were done with a not very high magnification which probably made me miss some of the finer details. However, I did manage to see part of the outer shell of the nebula. It is unclear whether this is part of the “spiral structure” or not though:
Found during twilight. At 366x an elongated glow with a star at the north-west side. The nebula is north-west south-east oriented. The nebula appears shaped like the number 8 with the impression of a dark lane running through it. At lower magnifications the south-east side appears a bit brighter. The south end seems to be elongated. I can't say whether that is part of the nebula or perhaps a faint star. An OIII filter increases the brightness of the nebula but doesn't make the details clearer.
As always,
"Give it a go and let us know!
Good luck and great viewing!"
Planetary Nebula
Constellation: Ophiuchus
RA: 17 14 04.3
DEC: -12 54 37.9
Visual magnitude: 11.50
Dimensions: 0.427' x 0.299'
This is one of the two objects called the Box Nebula, the other being NGC 6445 which was OOTW before (http://www.deepskyforum.com/showthread.php?905-Object-of-the-Week-July-31st-2016-NGC-6445-the-Box-Nebula&highlight=6445). However, NGC 6309 sometimes is referred to as the Exclamation Mark Nebula, which seems to be a more fitting name. Unfortunately the origins of both names are unknown to me though the Exclamation Mark name may originate from Stephen O'Meara's book The Secret Deep.
NGC 6309 was discovered visually in 1876 by Wilhelm Temple. He used the 11” (280 mm) refractor of the Observatorio Arcetri of Florence, Italy. The nebula is classified as a bipolar nebula because it contains two bright blobs which are offset asymmetrically around the central star. This Hubble image of the central part shows a dimmer bar running through the lower part of the nebula perpendicularly to the major axis of the nebula
3583
This is also visible in this spectacular drawing created by Belgian amateur Tom Corstjens
3582
However, this SDSS/NOAO composite image shows that there is a bigger deal to this nebula
3584
As a matter of fact, the nebula takes the appearance of a spiral galaxy! Perhaps that explains the PGC designation?
My observations using my 20” dob on August 9, 2013, were done with a not very high magnification which probably made me miss some of the finer details. However, I did manage to see part of the outer shell of the nebula. It is unclear whether this is part of the “spiral structure” or not though:
Found during twilight. At 366x an elongated glow with a star at the north-west side. The nebula is north-west south-east oriented. The nebula appears shaped like the number 8 with the impression of a dark lane running through it. At lower magnifications the south-east side appears a bit brighter. The south end seems to be elongated. I can't say whether that is part of the nebula or perhaps a faint star. An OIII filter increases the brightness of the nebula but doesn't make the details clearer.
As always,
"Give it a go and let us know!
Good luck and great viewing!"