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5/21/2010

Crater Romer Observation and Sketch and Limiting Magnitude

Well last night the clouds departed for a few hours and I took the XT8 out to do some lunar observing. I cooled the scope and put in the 13mm Stratus to get some bearings on where I was. I pulled out my Sky & Telescope's Mirror-Image Field Map of the Moon laminated since I was using my reflector/dob. I quickly got my bearings and then moved to using the 5mm Hyperion to view Romer and Romer A. I teased with using the 5mm Hyperion with a 2x barlow but the image moved out of the field of view too quickly. However, detail was okay but heat from my house was rising and interfering with the view at 480x. Magnification at 240x was the best so I used this to conduct my sketch.

To begin I formed an outline of the general area, and formed each crater and four craters right above Romer A. The rilles just to the south of Romer were clearly evident. After sketching the outline I attempted to bring in detail on the crater wall. I really failed at this and I know why after completing the sketch. I was trying to sketch to big an area instead of just focusing on one or two craters. As a result my craters were too little in the end, impacting the amount of detail. Beginner's mistake and one I will learn from. I then used a 4H pencil to darken in the craters while leaving a crescent.

Next I used a H pencil to sketch in roughly a gray color in the background and then used a blending stump to even out the color. Moving back to the craters I use another blending stump to even out the tones in the craters. I realized in doing this that I need to buy a few blending stumps just for lunar sketching that are different than those I use for DSO's. Next, I went to the 2H and HB pencils to sketch in details, and then used the blending stump yet again and here I made another mistake. I over blended on the details and as a result, the sketch is lacking in a 3D appearance.

So though I am displeased with the end product, the learning experience was incredible and I feel I have opened up a whole new area of observing that I have been neglecting, lunar observing. Instead of taking two weeks off each month, I have something besides double stars (which I love and enjoy viewing) to do. The sketch won't be here until I can scan it later. I had a minor surgical procedure done and am still recovering. My scanner again is not top notch, and though unhappy with the sketch, I think it is important that I post it so others can have a laugh, and then hopefully learn with me or watch my learning curve on this. If nothing else, I should learn from looking back on old sketches and observing sessions.

Last thing I learned, is on the many cloudy and rainy nights of late, I need to take even more time practicing on this. Overall though I have enjoyed the process.



























Here is a rough digital enhancement of the sketch above:




Part II Limiting Magnitude:

Though I am not a huge proponent of limiting magnitude because it varies by observer, if you remember that and don't compare your view to an observing partner, since your eyes vary, it can help you to determine the viewing conditions that you are seeing. I prefer my Sky Quality Meter or SQM now that I have been using it. So here are some links if your interested in Limiting Magnitude to read and use:

Limiting Magnitude by Constellation

Saguaro Astronomy Club Determining Limited Magnitude

International Meteor Organization (IMO) Limiting Magnitude

Telescope Limiting Magnitude Calculator

I threw the last one in for fun, realizing that conditions vary greatly in different parts of the country. Enjoy.

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