On the evening of September 19th, I was gearing up to record one of the final Titan shadow transits of the season. An ALPO colleague had tipped me off to the upcoming event, a rare alignment that won’t grace our skies again until August 2038. If I’m still around at 83, I’ll be chasing it again. Luckily, for this particular event the forecast from Astropheric promised above-average seeing, and I was eager to make the most of it.
Knowing the transit window would be brief (just 2.5 hours, with only a portion ideal for imaging) I prepped the scope early, aligning the finder and checking collimation before trying (unsuccessfully) to grab a few hours of sleep. By 1 a.m., I was back outside, scope thermally settled, laptop in hand, and Saturn hanging clear in the sky.
I began imaging with the ASI178MC, focusing on the northern polar region where Titan’s shadow should have been visible. But something seemed off. The shadow normally is like taking a paper punch to the globe, creating a very high-contrast object that is readily detected. Even the disk of Titan, with a much lower albedo level compared to the clouds, should have been evident. I dutifully continued on capturing AVI runs, thinking perhaps I just needed to be closer to mid-transit for it to be visible on the laptop monitor.
As we approached 2 a.m. I decided to do a quick processing run to investigate the situation. The mystery was promptly solved by the outcome: I had miscalculated the Universal Time conversion. The transit wasn’t happening for another 24 hours. A rookie mistake - one I’d like to blame on the emotional fog of having been laid off from my SSA contract earlier that day. That’s my story, and I’m sticking to it!
Still, the seeing was solid, so I pressed on. I captured both white light and Baader 685nm “Deep Red” filtered images, the latter always better at teasing out Saturn’s atmospheric banding. Of course, the grayscale results of the Baader image lack the visual charm of color, but I’d recently watched a tutorial by Damian Peach on blending R-IR data as a luminance layer with color images. The video skipped a few key steps, so I played around in Photoshop and sought the advice of my friend Steve Stewart (a PS master), experimenting until I found a technique that worked. The final composite was well worth the effort - sharp, detailed, and visually satisfying.
One surprise emerged during processing: the rings were noticeably brighter than in my earlier summer captures. Comparing the September 19th image to one from July, the difference was striking. Then it hit me. Saturn was mere hours from opposition on the 21st. Could this be the Seeliger effect, the so-called “opposition surge”? It certainly looked that way. The rings, previously muted, had taken on a luminous sheen, likely due to the Sun-Saturn-Earth alignment minimizing shadows and maximizing reflectivity.
I’ll be curious to see if the rings dim again in my next imaging session. For now, I’ll chalk this night up as a win despite the missed transit. The imaging run delivered a beautiful Saturn and a reminder that even a seasoned observer with half a century behind the eyepiece can still slip up.
