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Thread: Volcano Nebula IFN

  1. #1
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    Volcano Nebula IFN

    Hi folks,

    Two nights ago I tried to observe one of the integrated flux nebulae described on Mel Bartels' website for the first time.

    I'd been planning to do this for quite some time, but I wasn't sure if the sky is dark enough at my location.
    During my most recent observing session the sky appeared to be really dark, as I was able to see 6.8 mag stars around the zenith with naked eyes.

    With my 12-inch Dobsonian at 47x magnification (6.4 mm exit pupil diameter) I was looking for Mandel-Wilson 3 (a.k.a. Volcano Nebula), which is located roughly one degree north of Messier 82.
    Between the 8.3 mag star TYC4386-00993-1 and the 8.7 mag star TYC4386-00428-1 I saw a very faint and diffuse patch that was slightly brighter than the surrounding sky.
    I moved my telescope field of view back and forth a little to make sure it wasn't some kind of reflection in the eyepiece, but the slightly brighter patch remained stationary with respect to stars. I realized that the sky was slightly darker between the stars TYC4386-00428-1, TYC4386-00342-1 and TYC4386-00586-1, where there is no nebula.
    The length of the structure that I saw was approximately 45 arc minutes and it was slightly curved. It appeared similar to a faint dwarf galaxy.

    Mel did his observations with smaller aperture and larger field of view and he was able to see a larger part of this IFN. I don't know if he is active at this forum.
    What I saw was probably the brightest part of it. Please find attached my sketch.

    Has anyone of you observed this nebula?


    Clear skies

    Robin

    VolcanoIFNRobin.jpg

  2. #2
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    Hi Robin

    Mel Bartels here. A friend pointed out your post. I am so glad you sketched what you saw. Several people have told me that they remember seeing a brightening near M81/2 in times past, maybe. A sketch forces you to declare what you saw, bringing out your observing skills, serves as a record and adds a data point on how this particular IFN looks given scope/field/sky conditions.

    Next up if you choose to come back to this area is the arc that bends away from M81/2 at the tip of what you drew; also on the other end, a nice extension of the arc into the string of stars that's pretty. After that, then the puff of 'volcanic gas' beyond the arc that involves a little grouping of stars. All three together make for just a great view at the eyepiece.

    And you can see it all without some horrible 20 hrs of luminance imaging <my apologies to my digital imaging friends> <smile>!

    As far as naked-eye mag limits, I found them correlated with transparency but not perfectly. There have been nights when the naked-eye mag limit hasn't been great but yet the IFN contrast has been outstanding. I have a set of brighter IFNs that I use for a transparency check that guides me as to how the night will go. Almost all the IFNs that I observe are found through exploratory viewing - I don't know that they are there, what their extend and shape is. So much easier to see once that's nailed down! Another reason to sketch and share.

    Back to the M81/2 area... My best views have come with my 10.5 inch F2.8 2.5 deg FOV scope. But there is clearly fine detail to the IFN in this area that bigger scopes should be able to ferret out, so all interested should try - we don't know all that we can see in this general area and we don't know what scope/FOV combination is best for general viewing and for specific viewing of IFN in this area.

    More sketches!

    Hope this helps... Mel

  3. #3
    Co-Founder DSF.com Jimi Lowrey's Avatar
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    Very cool observation Robin!

    Mel have you tried for Arps loop?
    Clear Skies,

    Jimi Lowrey
    Fort Davis Texas

    48"F4 OMI/TEC
    28'F4 ATM

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    I maybe glimpsed part of Arp's Loop on one side of the galaxy with my 13" - haven't really spent time on it. I'm saving that for my bigger scopes if/when they come on line!

    Mel Bartels

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    Hi Mel and Jimi,

    Thank you very much for your nice feedback! Mel, it's really nice to hear from you!

    With my 12" f/5 Dobsonian at the given sky conditions I was only able to see the lower half of what appears to be shaped like a boot on long-exposure images.
    I still have an old Celestron Comet Catcher 5.5" f/3.5 Schmid-Newtonian and I wonder if this telescope might be even better suited for this task due to its fast f-ratio?

    After searching on the internet for a while, I found this website with a monochrome inverted infrared image of the UMa/UMi region:
    http://www.galaxyimages.com/UNP_IFNebula.html
    At least in the infrared spectral region the nebula around Polaris seems to be even brighter, but it is very large. I wonder if small wide-field instruments are the best option for this. Mel, I found your sketch of this feature in your pdf file of sketches. How would you rate its surface brightness in comparison with the Volcano nebula?


    Clear skies

    Robin

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    Quote Originally Posted by Robin View Post
    I still have an old Celestron Comet Catcher 5.5" f/3.5 Schmid-Newtonian and I wonder if this telescope might be even better suited for this task due to its fast f-ratio?
    The F-ration alone doesn't matter for visual observing. But the short focal lenght allows for a commercial eye piece to yield a large FOV and that should allow you to see it. As usual: give it a go and let us know


    Clear skies, Wouter

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    Hi Wouter,

    That's what I meant. At a given aperture, a faster f-ratio means shorter focal length. However, the 1.25" eyepiece barrel of this telescope might be a limitation, because wide-angle eyepieces usually have a 2" diameter.


    Clear skies

    Robin

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    Hi Robin,

    Sorry to correct you, but "usually have a 2" diameter" should be "always have a 2" diameter". Optics dictate that 1.25" barrels cannot have as large an apparent FOV as 2" barrels. Pity! No chance of replacing the focuser?


    Clear skies, Wouter

  9. #9
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    >>> At least in the infrared spectral region the nebula around Polaris seems to be even brighter, but it is very large. I wonder if small wide-field instruments are the best option for this. Mel, I found your sketch of this feature in your pdf file of sketches. How would you rate its surface brightness in comparison with the Volcano nebula?

    Fainter and indistinct.

    I have 14 'bright' IFN in my catalog. You might be interested in trying for the ones in the bowl of the Big Dipper.

    Mel

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