Saturday, January 11, 2014

Finally - Conjunction Day!

I feel like a slacker, missing a blog post yesterday - first day not posting since last year!  Melinda and I travelled to Phoenix last night attending the Saguaro Astronomy Club's monthly meeting.  They had a great speaker, Stephen Levine from Lowell Observatory talking about commissioning the 4.3 meter Discovery Channel Telescope in Northern Arizona.  Polished at the Optical Sciences Center at the University of Arizona, I happened to mention it this week to Norm Schenck who did a lot of the work on the mirror there, and fortunately he was interested enough in "his" scope to come along and hear about how the project is going.  We didn't get home till 2am, but was a great time!

Today (Saturday), friends Donna and Bernie came down from Phoenix to join us in our first trip of the year to Whitewater Draw to check out the cranes.  More about that trip on another post, but on the way out of town, since both are amateur astronomers, I twisted their arm into stopping by the Mirror Lab to look for the planet Venus, passing through inferior conjunction between Earth and the Sun today, only about 5 degrees north of our star.  To make the observation easier, we observed from the shadow of a "tall" building, in this case, where I normally park at work in the shadow of the building.  That way, while searching near the sun there was no chance of sweeping across the brilliant disk and risking eye damage.  Since Venus was due north of the sun, it was a relatively straightforward matter to step upwards and locate it, though we found that binoculars absolutely had to be focused on infinity to spot it.  But we all finally saw it, Bernie at left is locating it in his 200mm telephoto, and I centered it in the William Optics 11cm F/7 triplet APO (770mm focal length).  After taking a few exposures, Bernie mounted his camera on the scope and did the same, shown at right.

Of course, it is a tripod-mounted shot, non tracking, but the exposure shown here is only 1/3200 second at F/7 and ISO 200 so tracking wasn't needed.  I used a time delay with mirror lockup to minimize vibration.  The image shown here is at full camera resolution.  At only 5 degrees from the sun, it was something less than half of 1% illuminated, so it couldn't be much of a skinnier crescent.  Some folks wonder what is blocking the disk of Venus, why does it look this way?  Well, like the moon, it goes through phases, and when it moves between the Sun and Earth, we are mostly seeing the unilluminated side of the planet.  It would have been nice to get it at a larger scale, but would have required a bigger scope and tracking mount - perhaps at the next conjunction in a year and a half!

No comments: