Casitas de Gila, Gila, NM, March 23-25, 2023

In March, I made my annual Spring trip to New Mexico for galaxy season.  Leo was leading the way for the constellations rich in galaxies for observing and photographing.

Description:

NGC 2903 is an isolated barred spiral galaxy in the equatorial constellation of Leo, positioned about 1.5° due south of Lambda Leonis.  This bright galaxy is another object Charles Messier failed to find in his comet exclusion quest.  It was discovered by William Herschel, who cataloged it on November 16, 1784.  He mistook it as a double nebula, as did subsequent observers.  It wasn't until the nineteenth century that the Third Earl of Rosse resolved it into a spiral form.  J. L. E. Dreyer assigned it the identifiers 2903 and 2905 in his New General Catalogue; NGC 2905 now designates a luminous knot in the northeastern spiral arm.  This field galaxy is located about 30 million light-years away from the Milky Way and is a member of the Virgo Supercluster.  The morphological classification of this galaxy is SBbc, indicating a barred spiral (SB) with moderate to tightly wound spiral arms (bc).  De Vaucouleurs and associates assigned it the class SAB(rs)bc, suggesting a weaker bar structure (SAB) with a partial ring (rs). The bar structure appears stronger in the near infrared band.  NGC 2903 exhibits an exceptional rate of star formation activity near its center, also bright in radio, infrared, ultraviolet, and x-ray bands.  This galaxy is a little smaller than our own Milky Way, about 80,000 light-years across (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 well over one amp 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.

Image processing was straight forward for this galaxy.  However, I had to trim the heat-induced diffraction spikes from the brightest stars.  Once again, Russ Croman’s XTerminator tools recovered details and helped to produce an acceptable image.  The SPCC color calibration tool did a decent job on the galaxy.  I did not push the blue, and without Hydrogen-alpha filter data, the magenta star forming regions did not appear.

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: 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

Luminance    2 min x 111 subframes (222 min), Gain 100, Offset 32, 1x1 binning
Red        4 min x 22 subframes (88 min), Gain 100, Offset 32, 1x1 binning
Green    4 min x 23 subframes (92 min), Gain 100, Offset 32, 1x1 binning
Blue.      4 min x 25 subframes (100 min), Gain 100, Offset 32, 1x1 binning

Total integration time:  8.4 hours