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Contains:  NGC 6883, NGC6883

Image of the day 05/22/2020

Getting plate-solving status, please wait...
    WR134 | A Wolf-Rayet Star Blows an OIII Bubble, 


            Kevin Morefield
    Powered byPixInsight

    WR134 | A Wolf-Rayet Star Blows an OIII Bubble

    Technical card

    Imaging telescopes or lenses:Planewave CDK14

    Imaging cameras:QHYCCD QHY600M

    Mounts:Paramount ME II

    Guiding telescopes or lenses:Planewave CDK14

    Guiding cameras:Starlight Express UltraStar Mono

    Software:CCDWare CCDAutoPilot 5Adobe Photoship CCCCDWare CCDStack 2PixInsight

    Filters:Astrodon OIII 3 nmAstrodon Ha 5 nm

    Dates:May 11, 2020

    Astrodon Ha 5 nm: 75x600" (gain: 56.00) -10C bin 2x2
    Astrodon OIII 3 nm: 75x600" (gain: 56.00) -10C bin 2x2

    Integration: 25.0 hours

    Darks: ~20

    Flats: ~20

    Bias: ~20

    Avg. Moon age: 19.17 days

    Avg. Moon phase: 79.60%

    Bortle Dark-Sky Scale: 3.00 job: 3511598

    RA center: 20h 10' 16"

    DEC center: +36° 8' 58"

    Pixel scale: 0.608 arcsec/pixel

    Orientation: 89.688 degrees

    Field radius: 0.488 degrees

    Resolution: 4800x3211

    Locations: Sierra Remote Observatory, Auberry, California, United States

    Data source: Own remote observatory

    Remote source: Sierra Remote Observatories


    This Wolf-Rayet star in Cygnus is surrounded by a symmetrical bubble its intense winds have produced. This shows as a faint, prickly blue globe in OIII. The winds seem to also have displaced the Hydrogen field the star resides in. A similar curve is seen in the Ha data and of course you have the beautifully bright shock front in both Ha and OIII.

    This was shot in Bi-color, however I tried a different combination from usual to try and retain the dim OIII bubble as best I could. To increase the contrast I subtracted 1/5th of the Ha data from the OIII and used that for Blue. In effect, I think this removed the H-beta from the OIII which should leave me with a more pure OIII response. However, I'm using a 3nm OIII so there really should not be much Hb getting through any way.

    In any case, using Ha for Red, OIII for Green, and OIII-(Ha/5) for blue produced some nice star colors and gave the nebula more color contrast than straight HOO.

    I used Herbert Walker's excellent MaskGen script in PI to create a starmask. This uses the Gaia star database plate solve your image and create a star mask. Using the star catalog is such a great way to correctly identify stars. I chose to go down to 20th magnitude.

    That mask was opened in Photoshop and I used it to create a selection over the Ha and OIII masters in PS. I used the Fill command to remove the stars from each master and then combined them into the HOO mix I mentioned. I don't usually combine NB data in PS, but it was convenient this time.

    After working the starless data with high pass, Topaz De-noise AI, color and curves, I added the stars back in via a lighten layer. I had also created a similarly modified HOO version in CCDStack.

    I'll definitely try this process again when I have HOO data. I've added the Ha and OIII starless masters as well so you can see the structures more clearly.

    EDIT: I see that the WR star is not identified by the Plate solve. It is the bright red star just above and left of the blue star in the center of the bubble.
    EDIT2: I added a further processed and inverse version of the OIII. This much better displays the perfectly symmetrical sphere in OIII.

    And cheers to galaxy season being over!



    Kevin Morefield
    License: None (All rights reserved)


    • Final
      WR134 | A Wolf-Rayet Star Blows an OIII Bubble, 


            Kevin Morefield
      WR134 | A Wolf-Rayet Star Blows an OIII Bubble, 


            Kevin Morefield
      WR134 | A Wolf-Rayet Star Blows an OIII Bubble, 


            Kevin Morefield
      WR134 | A Wolf-Rayet Star Blows an OIII Bubble, 


            Kevin Morefield


    Description: Ha


    Description: OIII


    Description: Further processed and inversed OIII to better show the symmetrical shell.

    Sky plot

    Sky plot


    WR134 | A Wolf-Rayet Star Blows an OIII Bubble, 


            Kevin Morefield

    In these public groups

    Narrowband imaging