Hemisphere:  Northern  ·  Constellation: Cassiopeia (Cas)  ·  Contains:  PK136+05.1

Image of the day 02/02/2021

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    Heckathorn-Fesen-Gull 1 (HFG1), 


            Luca Marinelli
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    Heckathorn-Fesen-Gull 1 (HFG1)

    Imaging telescopes or lenses: Teleskop Service ONTC 10" f4 Newton

    Imaging cameras: ZWO ASI294MM Pro  ·  ZWO ASI1600MM Pro

    Mounts: Astro-Physics 1100GTO

    Guiding telescopes or lenses: Teleskop Service ONTC 10" f4 Newton

    Guiding cameras: Starlight Xpress Ultrastar Mono

    Software: Topaz Labs Denoise AI  ·  Main Sequence Software Sequence Generator Pro Sequence Generator Pro  ·  Starnet ++  ·  Astro-Physics Command Center (APCC) Pro Software  ·  Photoshop CC  ·  PIXINSIGHT 1.8  ·  PHD2 Guiding PHD2 v2.6.5

    Filters: Astrodon Narrowband 3nm SII  ·  Astrodon Narrowband 3nm Ha  ·  Astrodon Tru-Balance Gen2 E-Series - B 36mm  ·  Astrodon Tru-Balance Gen2 E-Series - G 36mm  ·  Astrodon Tru-Balance Gen2 E-Series - R 36mm  ·  Astrodon Narrowband 3nm OIII

    Accessory: QHYCCD OAG-M  ·  Tele Vue Paracorr Type 2  ·  Pegasus Astro Ultimate Power Box  ·  QHYCCD QHYCFW3-M

    Dates:Sept. 12, 2020Sept. 20, 2020Nov. 1, 2020Nov. 27, 2020Dec. 6, 2020Dec. 14, 2020Jan. 2, 2021Jan. 9, 2021

    Astrodon Tru-Balance Gen2 E-Series - B 36mm: 30x60" (gain: 50.00) -15C bin 1x1
    Astrodon Tru-Balance Gen2 E-Series - G 36mm: 30x60" (gain: 50.00) -15C bin 1x1
    Astrodon Tru-Balance Gen2 E-Series - R 36mm: 30x60" (gain: 50.00) -15C bin 1x1
    Astrodon Narrowband 3nm Ha: 37x360" (gain: 120.00) -15C bin 2x2
    Astrodon Narrowband 3nm Ha: 360x360" (gain: 139.00) -15C bin 1x1
    Astrodon Narrowband 3nm OIII: 29x360" (gain: 120.00) -15C bin 2x2
    Astrodon Narrowband 3nm OIII: 37x420" (gain: 120.00) -15C bin 2x2
    Astrodon Narrowband 3nm OIII: 332x360" (gain: 139.00) -15C bin 1x1

    Integration: 81.6 hours

    Darks: ~50

    Flats: ~20

    Flat darks: ~50

    Bias: ~99

    Avg. Moon age: 18.61 days

    Avg. Moon phase: 50.76%

    Bortle Dark-Sky Scale: 5.00

    Astrometry.net job: 4176884

    RA center: 3h 3' 1"

    DEC center: +64° 57' 21"

    Pixel scale: 1.371 arcsec/pixel

    Orientation: -89.646 degrees

    Field radius: 0.497 degrees

    Resolution: 2100x1556

    Locations: Home Observatory, Schenectady, New York, United States

    Data source: Backyard


    Heckathorn-Fesen-Gull 1 (HFG1, PK136+05) is a very old (~100,000 year old) and extremely faint planetary nebula in the constellation Cassiopeia. It was discovered in deep OIII images by Heckathorn, Fesen, and Gull in 1982 using the emission line survey of Parker et al (1979). The central star is a binary variable pair V664 Cas (13.7 magnitude). HFG1 is the first well observed PN, which reveals a cometary-like structure. As HFG1 moves through the interstellar medium and V664 ejects material, a bluish bow shock is formed and a red long trail of emissions is left in its wake.

    This was the most challenging deep sky object I have imaged so far. It is an HOO palette with RGB stars. I collected 100 hours of exposures altogether and was able to use 82 of those, after eliminating unusable exposures due to clouds or poor seeing. The Ha signal in particular is very faint and requires extreme care to stretch. For this reason, I decided to downsample the linear images by a factor of 2 to boost SNR. There is very little high-frequency detail in this nebula and high-SNR is of paramount importance.

    This was also the first image with my new ZWO ASI294M Pro camera. Most of the data was collected with the ASI1600MM Pro (gain=139) but 11 hours of data out of 82 were acquired with the ASI294MM Pro (gain=120, 11M mode or 2x2).

    Unlike my usual workflow for HOO images, which relies heavily on post-processing in Photoshop, this image was processed primarily in Pixinsight. I only exported the final starless HOO image to Photoshop for final contrast and color adjustment and merge with RGB stars.

    Boumis, Meaburn, Lloyd, Akras, arXiv:0903.2852v1 [astro-ph.GA] 16 Mar 2009, Mon. Not. R. Astron. Soc. (2009)
    Heckathorn J. N., Fesen R. A., Gull T. R., 1982, A&A, 114, 414
    Parker R. A. R., Gull T. R., Kirshner R. P., 1979, An emission-line survey of the Milky Way



    • Final
      Heckathorn-Fesen-Gull 1 (HFG1), 


            Luca Marinelli
      Heckathorn-Fesen-Gull 1 (HFG1), 


            Luca Marinelli


    Description: Comparison of integration of 20 subs of OIII data from the ASI294MM (left) and ASI1600MM (right). Subs are all registered to a reference frame from the ASI1600MM to normalize the pixel size difference. Crop to highlight sensitivity difference near the core of HFG1. Overall, I feel that the ASI294MM is a sizeable improvement over the ASI1600MM if the bigger pixels in bin 2x2 mode are not a showstopper.

    Uploaded: ...

    Sky plot

    Sky plot


    Heckathorn-Fesen-Gull 1 (HFG1), 


            Luca Marinelli