Mons Rümker

[astroavani]

THE LUNAR DOME COMPLEX MONS RÜMKER
The lunar volcanic complex Mons Rümker lies in the northwestern part of the Oceanus Procellarum, has a diameter of about 65 km and maximum altitude around 1.1 km above the surrounding surface, is the largest known volcanic building on the Moon, a huge dome of volcanic origin, composed of a cohesive grouping of domes, that is, a complex of overlapping domes of smaller domes, most with low slopes and a few steeper ones and for this it presents itself as a discrete formation. It is estimated that the estimated lava volume to create Mons Rümker was about 1,800 km³.
According to current studies it is composed of a series of overlapping lava flows. Mons Rümker is aligned with the Aristarchus plateau and the Marius Hills along the axis of Oceanus Procellarum. Several individual domes can be distinguished on the plateau. Rümker is the only dome with the name of a crater. Rümker tricked the selenographers, who in the 19th century thought it was a ruined crater.

Lunar domes are smooth undulations between 3 and 20 km wide, and at most 1 km in height. They can be of various shapes and sizes, but the most common are of hemispherical shape with a low profile. Most have very low tilt angles and are the best evidence of volcanic activity on the moon. Many have a small central crater at the peak, which occurs after the end of the magma flow with consequent falling collapse inside. Domes without a peak crater are still of volcanic origin, but appear to have had its central opening covered with lava.

Observing lunar domes is a challenging activity that requires dedication and time coupled with good observing conditions. Most domes can not be observed when away from the terminator. As its distance from the terminator increases, it loses contrast and begins to blend with the local terrain, and for all practical purposes the dome disappears from view. For the reasons mentioned, most authors recommend that observations of the domes should be performed near the terminator, where the solar altitude does not exceed 4-5 degrees. Other observers suggest 8 degrees of solar altitude as the maximum, but notably between 4-5 degrees of solar altitude, the smaller low-profile domes and the details of the larger domed surface become very visible. There are only a few domes that can withstand high solar altitudes without disappearing in their local areas, one of them can be seen in the photo and is indicated as Mairan T.

Even a small 3 "refractor telescope will show the larger domes on the moon, but for a more serious work a refractor of no less than 4" or a reflector, not less than 6 "is needed.Another item that is almost indispensable is a good equatorial mount that can provide constant monitoring Because domes are objects that are difficult to observe, it is often necessary to use high powers in the telescope, which prevents the use of a handheld telescope for long observations. and well collimated 8 "mounted on an equatorial one can make excellent observations and records. Colimation of the optics should be emphasized to have a clear and good image that is paramount in order to provide the observer with the ability to capture those evasive domes, especially when atmospheric conditions are not perfect, which will happen most of the time. It is recommended whenever possible the use of high power. In good viewing conditions there is no reason why good optics can not be pushed to achieve its maximum. Increases in the order of 200 to 300X are desirable, filters can also be used, but they are not a fundamental requirement. It is also important to mention that effective observation of the dome can not be performed with the moon too low, near the horizon. A minimum altitude of 45 degrees from the horizon is usually necessary to reduce atmospheric effects. A good seeing is important although some of the larger domes can be observed with some turbulence.

Source: LPOD - Charles Wood
             VTOL - Vaz Tolentino Lunar Observatory
             THE ALS LUNAR DOME SECTION - Guido Santacana and Eric Douglas - American Lunar Society
              JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 11 - Bruce A. Campbell, B. R. Hawke, and Donald B. Campbell
Research and adaptation: Avani Soares
https://www.astrobin.com/full/328975/B/?nc=user

[laudropb]

Great image and write up Avani. I have always had difficulty observing these domes. As you have said the seeing conditions have to be nearly perfect.

[johnfosteruk]

Amazing image Avani and one of your best writeups yet. 

[RT65CB-SWL]

Another great image and write up Avani. 

[Ruud]

A great image! Mairan T must be really steep for a dome.

[michaelmorris]

Great image - quite possibly the best image of Mons Rümker I've ever seen.

[Mr Spock]

A stand out feature and superb image to showcase it. Very nice indeed.