Saturday, March 28, 2009
Sh2-223, 224 and 225
In HST-palette 
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This was the moust difficult target.
The image spans about five degrees horizontaly, there is two
old Supernova remnants in the same field of view!
Extremely low surfage brightness and large angular size makes
this trio from the Sharpless catalog a very challenging to shoot.
There is a very dense Star field. Note. the "noise" in the image is
not a noise but Stars!
I think, this is more difficult than a SH2-240.
It can be seen in my older post, here:
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I spend three nights for H-alpha and here is the result.
I think, this must be the firs NB color composition from this target?
Least I wasn't able to find any.
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Total exposure time for H-alpha channe is 11h.
Taken with very fast optical configuration @ f1.8.
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Details;
-Camera, QHY9
- Optics, Canon EF 200mm f1.8 @ 1.8
- Guiding, QHY5 and PHD-guiding
- Platform, LX200 GPS 12"
- Exposures, 7x1200s with 7nm H-alpha filter and 13x2400s, 5x300s O-III Binned 4x4 and 5x300s. S-IIBinned 4x4 . Darks, Flats and Bias frames calibrated.
Total exposure time for H-alpha line is 11h!
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4 comments:
AWESOME image! I've been trying to see both Sh2-223 and Sh2-224 visually for a while, I was kinda skeptical that Sh2-223 was actually a SNR until I saw this image. I'm curious- can you tell what the relative fluxes (brightnesses) of the h-alpha vs OIII lines were?
Thanks!
This is generally a very dim target.
I haven't the actual data here, but I can say, O-III line is extremely weak compared to H-a, witch is weak as well. My opinion is, O-III line is not visually detectable.
(In my image, O-III line was imaged camera binned down 4x4 and still there was just a hint of O-III visible in extreme stretched image.)
On the POSS plates, Sh2-223, Sh2-240, Sh2-224, Sh2-94, Sh2-97, which are all either SNRs are parts of SNRs, seem roughly equally bright. I've been able to see Sh2-240 and Sh2-91/94/97, so I've got reason to believe that Sh2-223 and Sh-224 could be observable as well. If you can get to your OIII data, I would be highly interested in it. It can tell me where the regions of strongest OIII flux are. My yahoo email account is tatarjj. So... tatarjj@ you know what .com. I'd also be VERY interested in seeing OIII data for Sh2-240 in fact.
Thanks!
Interesting!
I'll come back to you, if or when I will find the needed data. I have it in a separate HD, I hope/think...
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