Casitas de Gila, Gila, NM, March 24-28, 2023

In March, I made my annual Spring trip to New Mexico for galaxy season.  I wanted to image an irregular galaxy as an example for presentations.  However, I saw some potential, but there were many challenges to produce a decent rendition.  This irregular galaxy was the second target of the night, which added several issues (dew heater ring distortions, clouds, etc.).  Also, I used this target to test if 2x2 binning with the ZWO ASI 2600MM Pro camera could reduce oversampling and provide better detail than 1x1 binning.

Description:

NGC 4214, also known as NGC 4228, is a dwarf barred irregular galaxy located around 10 million light-years away in the constellation Canes Venatici.  NGC 4214 is a member of the M94 Group.  The galaxy is both larger and brighter than the Small Magellanic Cloud.  It is a starburst galaxy with the largest star-forming regions (NGC 4214-I and NGC 4214-II) in center.  NGC 4214-I contains a super star cluster rich in Wolf-Rayet stars while NGC 4214-II is younger, age less than 3 million years, and it includes several star clusters and stellar associations. (Wikipedia, NASA).

Imaging and Processing:

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 Niná 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.  The last complication was the effect of my new Celestron dew heating ring on bright stars.  Two distinctive diffraction spikes appeared and at least on thread on Cloudy Nights indicated that this was caused by the dew heater.  I had noticed that the dew heater is very effective, but it draws over one to two amps of current!  Since the ground was moist and the temperature dropped significantly, the dewpoint rose and the dew controller kicked in, making the diffraction spikes appear, especially later in the night.  The stubby spikes grew as the dew heater power was increased by the Pegasus Astro Ultimate Powerbox 2 (the aggressiveness needs to be reduced significantly).

Image processing was a real challenge.  First, 2x2 binning introduced many small bright and dark artifacts on every channel.  I used drizzle integrated masters.  Both drizzled and non-drizzled images had these artifacts.  These were removed with numerous Clone Stamp tool applications to the luminance, RGB combined color and Ha masters.  I had to trim the heat-induced diffraction spikes from brighter stars with the Clone Stamp tool.  Once again, Russ Croman’s XTerminator tools recovered details and helped to produce an OK image.  However, I backed off on sharpening to reduce the enhancement of bright and dark binning defects.  The hydrogen-alpha filter master was added to the RGB color calibrated image to enhance star forming regions without oversaturation.  The result lacks sharp detail and some of the artifacts remain.

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, Luminance, Red, Green, Blue

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, 2x2 binning
Luminance    2 min x 128 subframes (256 min), Gain 100, Offset 32, 2x2 binning
Red        4 min x 22 subframes (88 min), Gain 100, Offset 32, 2x2 binning
Green    4 min x 22 subframes (88 min), Gain 100, Offset 32, 2x2 binning
Blue.      4 min x 21 subframes (84 min), Gain 100, Offset 32, 2x2 binning

Total integration time: 10.3 hours