Objects Revisited

 Long Exposures

I've been revisiting previously imaged objects. Now I'm devoting an entire night to just one object using longer exposures and Seestar's AI Denoise feature. On December 16th I used mosaic mode and light pollution filter to capture the entire Rosette Nebula in the constellation Monoceros. The following image is a 150-minute (2.5-hour) exposure, the longest exposure I've ever done with Seestar up to this point.

The dark central cavity contains open star cluster 2244 whose energetic stars clear the cavity and cause surrounding gases to glow. Strings of dark obscuring dust are nicely silhouetted along the upper cavity edge. I probably went overboard using AI Denoise to darken the background. Too many faint details may have been lost. (Click to enlarge all images.)

A few days later on December 21-22 I attempted another filtered mosaic mode capture of NGC2264, (the Cone Nebula, and Christmas Tree Cluster), also in Monoceros. The next image is only a 100-minute exposure, but it turned out much better than a previous attempt made last year.

The Cone Nebula is in the upper right. This dark column of gas and dust is outlined by excited gases. The Christmas Tree star cluster is horizontal in the image above. The triangular shape is more apparent in the next rotated image.

The upper tip of the Christmas Tree is a bright star just below the Cone Nebula. The triangular Tree's base is just above the brightest star near image center. I allowed more red nebular background to remain in the final image this time.

Nearly a month of cloudy sky and bright moonlight passed until January 11th when I captured a 112-minute exposure of NGC2359, Thor's Helmet, in Canis Major. Enlarge the next image to full size for the best view. Notice the dense distribution of background Milky Way stars, including some colorful ones! The "wings" of Thor's Helmet show up reasonably well. The central spherical bubble of glowing gas is created by strong stellar winds emitted by the hot, energetic central Wolf-Rayet star.

Clear sky continued on January 12th. Galaxies M81 and M82 are a popular astrophotography target in Ursa Major. The next image is a 143-minute exposure of this pair using mosaic mode. M81 is on the right, M82 on the left. Unfortunately, the pair is slightly off center. After a few minutes of an initial well centered exposure I noticed an airplane's bright lights had streaked directly over M82. I terminated this first exposure and immediately started a new exposure. In the brief interval between exposures Seestar's slight movement had shifted the image slightly off center.

A few nights later on January 15th conditions were good again. Moonlight was absent, and all my neighbors' lights were miraculously off. I used mosaic mode and the light pollution filter to capture a 155-minute exposure of IC2177, the Sea Gull Nebula. This expanse of glowing gas spreads across the boundary of constellations Monoceros and Canis Major. It seems that the bright, roughly circular patch of nebulosity with intruding dark lane located in top center is called IC2177. This is the Sea Gull's "head". The "wings" are spread out horizontally across the image. A rich distribution of Milky Way stars, including some obvious clusters, add to the scene.

I'm pretty happy with the previous image! The two-hour 35-minute exposure is now the longest I've ever done with Seestar. Actual telescope time is usually about twice the exposure time because Seestar continuously rejects sub exposures with tracking errors. I might be able to get a 3-hour exposure at some point, but this will challenge my ability to stay awake for hours after midnight.