Here is at least three NGC objects, NGC 1858, 1850 and 1854/5.
Two hours of 20 minute Ha, combined with half and hour of R, G and B in five minute subs.
8" RC with SBig setup.
There is one interesting star in this that lights up in the Ha but not in the red channel, it is cropped from the original subs and the combined, anyone have any ideas as to why this is so?
Cheers
Stuart
Last edited by rat156; 31-12-2009 at 10:37 AM.
Reason: Fixed the NGC numbers (don't post at 4am!)
But the Ha emission line is covered by the Red filter.
Here's an animated gif of the region. I normalised on a star and the background, there is a corresponding increase in intensity of all the Ha in the picture, as well as the star in question, so I suppose it could be filter related in that the Ha filter has a much lower background count?
Ha will always have a lower background count than a R filter...
Ps - Great image mate, Another in your series of obscure targets... I must say, its not common to see someone post consecutive, high resolution images of nebulae in another galaxy... Impressive.
Looking at the animation, I think the target is visible in both images, it is just a hell of a lot more prominent in the Ha image... That would indicate that its a Ha target, so, planetary nebula is a fair guess I would imagine.. The reason it shows so much brighter in Ha is that nothing else is hiding it (ie - skyglow/moon glow etc..)
Ha will always have a lower background count than a R filter...
Ps - Great image mate, Another in your series of obscure targets... I must say, its not common to see someone post consecutive, high resolution images of nebulae in another galaxy... Impressive.
a very nice wide field it is... Although, from memory back when I had the 8" RC and ST10, your field of view is... well... claustrophobic... to say the least
But the Ha emission line is covered by the Red filter.
Here's an animated gif of the region. I normalised on a star and the background, there is a corresponding increase in intensity of all the Ha in the picture, as well as the star in question, so I suppose it could be filter related in that the Ha filter has a much lower background count?
Cheers
Stuart
Hello Stuart
I suspect the your red filter transmission is trailling off at the Ha wavelength. This probably has a greater effect than the lower background count through the Ha filter.
The size of the field of view does not depend on the target? More, some targets seem small despite the claustrophobic FOV..
Hi Alex,
I think what Trevor was eluding to, as indeed I was is that this stuff is in the LMC, which, by comparison to most of the other stuff you'll see here, is a long way away, hence widefield. Taken to an extreme, I capture extremely widefield images of other galaxies often. So I substitute a wide angle lens (and the corresponding ease of tracking) for a 1625 mm FL scope and a target that's a long way away. I'm starting to think I'm nuts!!
It is a planetary nebula in the LMC. [Humayun was correct in his guess!]
Anyone wanting to investigate 'odd' objects in their images should take the time to become familiar with the Aladin program of the Centre Donnees Stellaire. It is a simple executable downloadable from: http://aladin.u-strasbg.fr/aladin.gml
which allows you to plot catalogue identifiers overlaying survey images, with tools to easily extract the catalogue info. There are versions for all platforms. For investigating what is on your images, it makes any commercial planetarium software a child's toy.
Some nice detail there Stuart, for only 20min Ha, more should do the trick nicely.
Quote:
Originally Posted by rat156
... Needless to say I can't get the camera down to -5 ATM.
Cheers
Stuart
I cant get to -10 often in the summer, so I use water cooling... and now I always do .
Once its set up, its easy, set and forget, never a bother. Tipping a bit of ice in the bucket 1st up (if required) is a routine that gets you in the groove, and its satisfying to watch the temp plummet regardless of ambient .
It is a planetary nebula in the LMC. [Humayun was correct in his guess!]
Anyone wanting to investigate 'odd' objects in their images should take the time to become familiar with the Aladin program of the Centre Donnees Stellaire. It is a simple executable downloadable from: http://aladin.u-strasbg.fr/aladin.gml
which allows you to plot catalogue identifiers overlaying survey images, with tools to easily extract the catalogue info. There are versions for all platforms. For investigating what is on your images, it makes any commercial planetarium software a child's toy.
Dave
Thanks Dave,
I actually stumbled upon Aladin and identified the object myself late yesterday. It's a great tool for this type of thing. I had no idea that there were so many planetary nebulae in the LMC! I found a paper by Reid and Parker reporting the discovery of 471 PNe in the LMC, published in 2006. This one was one they confirmed, so it had been previously identified. Interestingly they used pretty much the same method (albeit with a much larger scope) to find the PNe.
Some nice detail there Stuart, for only 20min Ha, more should do the trick nicely.
I cant get to -10 often in the summer, so I use water cooling... and now I always do .
Once its set up, its easy, set and forget, never a bother. Tipping a bit of ice in the bucket 1st up (if required) is a routine that gets you in the groove, and its satisfying to watch the temp plummet regardless of ambient .
Identification
.
SBIG camera cooling method in the summer months
