After imaging M 51 and with a desire to see if the improved guiding was maintained when imaging my more usual area of sky I found this patch of bright nebulosity in Vulpecula. It is Sharpless 2-90 and I was able to obtain a dozen subs before the sky was noticeably beginning to lighten at 2.30am revealing how short the available imaging period is at this time of year. It was pleasing to see the guiding maintained the improved performance with the scope at its more usual balance setting. Details: 10" f4.3 Newt. 12x 10minute exposures @ iso1600 with CLS in DSS, FIV, CS2 & XAT.8.6.11
Sh2-90
After imaging M 51 and with a desire to see if the improved guiding was maintained when imaging my more usual area of sky I found this patch of bright nebulosity in Vulpecula. It is Sharpless 2-90 and I was able to obtain a dozen subs before the sky was noticeably beginning to lighten at 2.30am revealing how short the available imaging period is at this time of year. It was pleasing to see the guiding maintained the improved performance with the scope at its more usual balance setting. Details: 10" f4.3 Newt. 12x 10minute exposures @ iso1600 with CLS in DSS, FIV, CS2 & XAT.
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2 comments:
I am trying to SEE this Sharpless nebula by eye, since it's given in the Sky & Telescope pocket atlas, and I am going to attempt to view all the included Sharpless nebulae visible from my 37d latitude. I went looking on the net for a good image, and yours is *spectacular*.
It's even better than the Palomar Second Survey red image.
My one suggestion is that for such folks as me, it's very useful to know the image orientation. This sort of object does not leap out at one. Apparently, your image is correct but is rotated about 90 degrees. The top is west, and left is north.
It would be helpful for you to note this sort of info and, if possible, the brightest star near the object you are photographing. I believe the star is HIP 97573, mag. 6.47.
There are a lot of advanced visual amateurs who spend some time tracking down superb amateur images, to be used as printouts to be followed for very difficult observations. Now, the best modern CCD images can surpass the standard survey plates in many instances--particularly with respect to faint PNs and diffuse nebulae!
Yours,
Steve Waldee
San Jose, CA. amateur astronomer
Only a tiny bit of the intense red nebulosity (HII) shows up in H-beta on the Palomar blue survey plates, and that's what the dark adapted eye may...MAY...be able to perceive. My initial experiments, over a two hour period during the nebula's placement near culmination, have yielded a tentative sighting of some of the nebulosity in a 4.7 inch f/5 refractor, located at 3400 feet elevation in the Santa Cruz mountain range a couple of miles from the central California Pacific coast. Due to the small aperture of the refractor, the only filter that could be used was a type that reduces only sodium vapor wavelengths and a bit of skyglow -- an "LPR" type -- as the standard hydrogen and oxygen nebular filters simply made the sky too dark. Traces of the nebula were seen with no filter, and with the LPR filter, at magnifications of about 60x to 80x, but not at lower power (where the image scale was too small.) The only part of the nebulosity that could be detected by eye was a bit that is in the 'left' side curvature of nebulosity (N) in your image; the entire U-shape could not be discerned. Based on this, I would say that it should be reasonably easy to detect in a 17 inch scope; hard in a 10 inch; and increasingly difficult for smaller apertures--in which the sky conditions and your dark adaptation and gear will be the limiting factors.
That such a nebula is SO spectacular in a color photo, will not (of course) guarantee that it even CAN be seen by eye, since it would appear that most of the wavelength is at H-alpha. But there is also always a bit of H-beta (486.1 nm) if there's H-alpha: and so it can show up on blue sensitive film, and to a lesser extent by eye: but I would say so far that it is darned near the most challenging Sharpless nebula that I've tried to see. And, it was done on a rare night of superb transparency, with a humidity of only 10% and flawlessly stable star images: not the sort of thing you'd expect in most of the UK or continental Europe. Perhaps parts of Austrian mountain ranges, or Italy could be suitable, or of course the Canary Islands. In the United States, where I live, the nebula would be very difficult at lower elevations in humid, tremulous air--and with ANY light pollution. That means that it might likely be nearly impossible unless you observed in western states at high altitudes.
Once again, Pete: thanks for your marvelous image!
Steve Waldee
San Jose, CA. amateur astronomer
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