Casitas de Gila, Gila, NM, March 25-26, 2023

In March, I made my annual Spring trip to New Mexico for galaxy season.

Description:

Jones-Emberson 1 (PK 164+31.1), also known as the Headphone Nebula, is a 14th magnitude planetary nebula in the constellation Lynx at a distance of 1600 light years.  It is a larger planetary, about 4 light-years across, but with low surface brightness.  The 16.8-magnitude central star is a very blue white dwarf.  Discovered in 1939 by Rebecca Jones and Richard M. Emberson, its "PK" designation comes from the names of Czechoslovakian astronomers Luboš Perek and Luboš Kohoutek, who in 1967 created an extensive catalog of all the planetary nebulae known in the Milky Way as of 1964.  For imaging, the Headphone nebula is faint, but has fairly strong Hydrogen-alpha and Oxygen-III emissions from gas ionized by the ultraviolet light from the central star (Wikipedia). So, this nebula can be a challenging target.

Previous trips to New Mexico were very productive, with many clear nights and good seeing.  For the 2023 expedition, where do I begin?  First, there was a strong La Nina in the Eastern Pacific, causing cooler and wetter weather from Washington to the Southwest.  Then came atmospheric river after atmospheric river.  Accompanying the rain and clouds was the Jet Stream raging overhead.  So, out of 14 nights, only four were “clear”.  Of those, only one night was excellent.  For the other three nights, intermittent clouds or haze rolled through, or the seeing was below average to poor.  All of this was compounded with my transition from a 4” refractor to a 9.25” SCT to capture galaxies and other smaller objects.  Now, I had to relearn how to image with long focal length and to use an off-axis guider with few stars around galaxies.  Furthermore, there was the collimation challenge, as I had not used the SCT for a year and the seeing was below average.  Then I had to achieve focus for both the imaging camera and the guide camera with challenging atmospheric conditions.  Finally, Sequence Generator Pro had difficulty achieving focus when using the Chroma 5nm Ha and 3nm OIII filters, even though the exposure times were long, and the gain was set to 200 with 2x2 binning.

Since the Headphone nebula was near the Meridian, I decided to capture Ha and OIII narrowband filter data as the first target of the night.  It proved to be very difficult with the seeing and lack of good stars for guiding.  Over two nights, only a very limited number of subframes were captured.  Furthermore, the WBPP script in PixInsight rejected half of the Ha subframes.  Once again, BlurXTerminator, NoiseXTerminator and StarXTerminator came to the rescue and salvaged the image, resulting in good detail, but with some remaining noise in the midtone regions.

Imaging details:

Celestron 9.25" Edge HD SCT (FL = 2350mm at f/10)
Celestron Off-axis Guider with ZWO ASI 174 mini guide camera
Losmandy G11 mount with Gemini 2 controller
ZWO ASI 2600MM Pro cooled monochrome camera (-10C)
36mm Chroma filters: 5nm Hydrogen-alpha, 3nm Oxygen-III

Software: Sequence Generator Pro, PHD2 guiding, Losmandy Gemini 2 ASCOM driver,
    SharpCap Pro with QHY Polemaster camera for polar alignment, 
PixInsight and Photoshop 2023

Hydrogen-alpha    10 min x 10 subframes (100 min), Gain 100, Offset 32, 1x1 binning
Oxygen-III    10 min x 12 subframes (120 min), Gain 100, Offset 32, 1x1 binning