Chasing Planets: January's Observations and Challenges

The media has been hawking the auspicious "planetary parade" that allows an observer to see 6 planets during frosty January evenings. Of course two of those (Uranus and Neptune) are not naked eye objects. I do not mind articles that generate interest in our hobby, but my fear is always the "over promising and under deliver" risk.

However, January was indeed a fun month for us planet observers. Mars was occulted by the nearly Full Moon on the evening of the 13^th, and then two days later came to opposition for this apparition. Jupiter was positioned well and decided to throw a major eruption amid its North Tropical Zone southern jet stream on January 10^th, garnering a lot of attention. Venus also ascended the Zodiac after lying close to the southwestern horizon most of its current evening apparition, reaching greatest elongation on the 10^th heading for its highest altitude in the western sky on February 2^nd. The only downside has been the weather with classic winter turbulent seeing amid very cold temps.

Mars Occultation

The skies were clear but quite cold for the occultation of Mars. I set up the 10" Cyrus telescope and verified its collimation. The Moon served as a convenient focus target as I set up about 20 minutes before the scheduled disappearance. I knew that the difference in brightness would be a challenge and thought I'd have time to fiddle with the gain setting right before the occultation, but it happened so fast that I really did not get a great capture with the Moon very overexposed. Still, it was a very cool event to watch the Moon relentlessly approach the red orb and cover it up with about 30 seconds.

The Moon ready to cover Mars

January 17th Session

The evening of the 17th was predicted to have average seeing and temperature right around the freezing mark, which is fairly good for this region in winter. I again set the Cyrus scope out early to cool and verified its collimation. As Venus emerged from encroaching twilight I set to work on capturing our sister planet. 

Starting with the Deep Red filter (642+nm) and no Barlow, Venus provided a bright target upon which to focus. Doing a 5 minute capture resulted in a nice image, showing the planet past dichotomy and a common cue-ball appearance. I have yet to truly discern any cloud details in IR light.

Swapping out the Deep Red filter for an IR-block and UV set, I retargeted the planet and adjusted the settings to bring up the brightness in the fainter UV light. I could make out even on the on-screen image that there was uneven brightness in the sunlight reflecting off the Venusian cloud tops.

Processing produced a nice greyscale image with a some cloud structure. Interestingly, a well defined cusp cap was not really seen, although you might argue one was around the south pole region. This is somewhat in agreement with the UV Venus images I have been seeing submitted to the ALPO for the current evening apparition; cusp caps are not as prominent as I believe they were during the last apparition.

By now Saturn was visible in the deepening twilight, close and to the left of Venus. I figured why not give it one last capture since the upcoming mid-March solar conjunction and my obstructed western horizon meant it would soon be inaccessible. I added the Barlow back into the imaging path and returned to the Deep Red filter. Seeing was not very good, and the rings had closed up again compared to a few months ago. I had enough juice in the laptop for two 2-minute captures, resulting in a sub-par image where it is hard to even detect the globe's shadow being cast against the rings. Au revoir Saturn - until we meet again in the late spring!

Getting the AC adapter hooked up to the laptop I next swung over to Jupiter. My hopes were to get multiple captures into the evening if the weather held, recording not only the very recent North Tropical Zone southern jet stream eruption but also that continually expanding disturbance in the South Equatorial Belt that started back in November.

The seeing ended up being fairly good over the course of about 5 hours, allowing me to capture a lot of interesting features, including that NTrZ outbreak. As we began to close in on midnight the gods conspired to end my run as the cirrus clouds began to thicken and the tracking on the Celestron mount suddenly had a stall (it is always amazing how quickly the planet exits the frame when this happens). Rather than fight to recenter and continue amid the deteriorating seeing and transparency I decided to wrap things up on Jupiter.

In the middle of my Jupiter captures I had to take a break due to the location of the planet. When an object is high and near the meridian, the Cyrus telescope tube runs up against one of the tripod legs. The resolution would be to raise the tube up off the saddle, somewhat like extending with a pier. But that would be a lot of effort and so is not likely to happen in the near future (if at all). 

But rather than waste the time I opted to do a run on Mars which had just passed opposition a few days earlier. While at only about 13" in size the disk was large enough to take in some nice albedo features such as Syrtis Major setting and Sinus Sabaeus and Sinus Meridiani on the central meridian. The NPC was also a brilliant white and was a good feature to leverage in trying to get the best possible focus. Hopefully I will get in a few more sessions with Mars for this apparition, but it's going to shrink in size quickly now that it is past opposition.

While I did not achieve all my goals for the evening (I missed seeing the SEB disturbance on Jupiter), it was quite a good night for the middle of January. It reflects why planetary observing provides such a rich experience for the amateur astronomer.