Tag Archives: Jupiter

The fifth planet from the Sun, and the largest planet in the Solar System. Wikipedia

Rationalizing a GOTO Telescope Mount

I am quickly building an exceptional capability to image wide field objects, some of which appear much larger than the Moon. I hope to someday be be able to engage in a wider spectrum of astrophotography, to include planets, and smaller deep space nebulae and galaxies.

My Losmandy GM-8 mount has the payload capacity to easily handle photography with my TeleVue NP101 4″ refractor along with a guide scope, and two cameras, all of which are best suited for wide field photography because of the main telescope’s short focal length. I could add a goto control panel and servos to this mount for about $1600, but I can find anything that is suitable to be viewed or photographed with this instrument with the technique described in Finding Barnard’s Star. I have a Celestron 11″ reflector that I can put on this mount, but it is so near the mount’s maximum capacity, even before adding a guide scope and cameras, that it is unsuitable for astrophotography. So this set of facts drives the need for a mount with greater capacity, and sticking with the Losmandy line,  with which I am already very comfortable, I will get the Losmandy G-11, which is about $3200 with goto. The Celestron’s longer focal length, and hence its much narrower field of view, and the planetary and exceedingly dim deep space objects that I seek warrants the goto capability.

Before I make that plunge, I need to finish checking out the used Celestron that I bought last year. I took a few shots of Jupiter and Mars in April (all images in this paragraph can be found in the Gallery) that didn’t turn out very well. For comparison, look at the Jupiter and Saturn images that I took with the 4″ NP101 in 2012 and 2013. Dew was a huge problem on the night of the Jupiter pictures I took with the C11. I am hoping that improper focus is the only remaining problem in the Mars picture. Summer set in before I could gain enough experience with this instrument and start the tedious work of eliminating problems. Jupiter is quickly becoming an early evening object again, so I can resume this work in December or January.

I can claim some success with my Jupiter images. The dimensions in pixels in the full res images is almost exactly what I had calculated before taking the photographs, and is what is needed to capture the detail that I am looking for. Check out the Jupiter images that James Willinghan took with a 12″ Meade, and posted to the Howard County Astronomical League (HAL) Facebook page (June 2013) to get some idea of what I am trying to achieve. While you’re there, you check out the progress on the observatory that the club is building in some of the more recent postings. I somehow became the only mug that is clearly identifiable in the banner image. I can also be seen in some of the pictures taken when we cleaned and repaired the dome (Sept 2014), and when we set up the telescope to check out (April 2014) dimensions and clearances required. I have only posted one photo (Nov 2013) on this page so far.

As a last resort after trying everything within my capability to eliminate problems, I will have Marty Cohen at Company Seven check for optical defects, and make needed repairs if the telescope is worth putting more money into. I bought it second hand, and for almost nothing, just to get some experience with reflector telescopes. If the Celestron is not worth saving, then I will buy a new telescope, probably the Meade 12″, at the same time that I buy the new mount.

© James R. Johnson, 2014.
jim@jrjohnson.net

Conjunction of Venus and Jupiter

Chris Miskiewicz announced that he would be opening one of the Howard Astronomical League dark sites last Monday morning to observe the close conjunction of Venus and Jupiter. I set an alarm for 3:15am, and immediately went outside to check the weather. Upon determining that it was mostly cloudy, I thought it not worth the effort, so I tried to go back to sleep. Fifteen minutes later, I felt that I could not go back to sleep and I knew that Chris would be at the site no matter what, so I jumped in the Jeep and drove out there. The conjoined planets had not yet risen above the eastern horizon when I arrived, but the sky was mostly clear in the area where they would be rising in about 20 minutes. While waiting for them to rise, I took in Orion and the waning crescent moon, which were both already well above the horizon in the same area. They were a beautiful pair both with the unaided eye and in the telescope, so this was a very rewarding trip! Chris’ image below is very close to what I saw without the telescope.  I packed up my equipment and headed toward my day job at about 5:35am.

Chris Miskiewicz - Jupiter Venus Conjunction 18Aug2014
Chris Miskiewicz, Jupiter and Venus Conjunction, August 18, 2014.

 

The Moon’s Planetary Conjunctions During May 2014

When two Solar System objects arrive at their closest approach to one another as viewed from Earth, they are said to be in conjunction. This month I will examine the Moon’s close approaches to all five of the visible planets that were known to the ancients. As both the Moon and the planets are in constant motion, the actual conjunction is represented by an instant in time. Because of their slow apparent motion, the close approaches (visits?) can be observed for many hours before or after a conjunction.

As previously mentioned, the planets and the Moon never wander far from the ecliptic. One implication of this fact is that as the Moon completes its 28-day orbit around the Earth, it will be in conjunction with each of the planets once. This month, the young (thin) crescent Moon will first visit Jupiter near the western horizon in Gemini on May 3rd (closest) and 4th. Try to observe on both evenings and note that the Moon has moved eastward. Also note Jupiter’s position among Gemini’s stars, perhaps by making a sketch of Gemini that indicates Jupiter’s position. This sketch will come in handy near the end of the month.

Next up is a very interesting series of close encounters with three bright and colorful objects (Mars, Spica and Saturn) in the east at dusk on May 10th through the 14th. There are lots of things to observe over the course of these five evenings. First, the waxing gibbous Moon will grow larger each evening until it reaches full Moon on May 14th. Next, note that its location is a little farther east each evening. These two phenomena are the result of the Moon moving along its orbital path around the Earth, which changes its angle relative to the Sun. Also note that the point at which the Moon became full last month was closer to Mars (read about the lunar eclipse in April’s Scope Out), and this month the full Moon occurs closer to Saturn. This eastward slide of the full Moon from one month to the next happens because of the Earth moving along its orbital path around the Sun. And finally, note the distinct colors of the three objects: Mars is red, Spica is blue, and Saturn is yellow. The Moon will be near Mars on May 10th, and between Mars and Spica on May 11th. It will be between Spica and Saturn, but closer to Spica on the 12th, and closer to Saturn on the 13th. And finally it will be on the eastward side of Saturn on May 14th, the last evening of this string of encounters.

Another rewarding and challenging opportunity to observe the Moon arrives near month’s end as it transitions from a thin waning crescent in the eastern sky at morning, to a thin waxing crescent in the evening sky in the evening. First, observe the Moon as a thin waning crescent on the eastern horizon during its close encounter with Venus just before sunrise in the pre-dawn hours of May 25th. A careful observer might see an even thinner crescent very low on the horizon and closer to the sunrise point the next morning. After this, the Moon cannot be seen because it is lost in the Sun’s glare as it approaches new Moon (conjunction with the Sun) on May 28th. A young Moon (thin waxing crescent) emerges from the Sun’s glare on May 30th, and can be seen very low on the western horizon near Mercury. On the next evening, it will appear a little higher above the horizon, and it will once again visit Jupiter. Check the sketch that you made at the beginning of the Month. Has Jupiter moved among the stars since its last visit with the Moon on May 3rd and 4th?