Measuring the Sky

Above is a sketch showing approximately what's seen when one looks through a Celestron Micro Guide eyepiece. The linear scale has a real length of 6 millimeters. Adjacent scale divisions are 1/10 of a millimeter apart. I'll be using the Micro Guide eyepiece to make a variety of measurements while using Excalibur - my 13cm refractor.

The separation distance between scale divisions will of course vary depending upon the magnification that the eyepiece provides with a given telescope. My measurements indicate that the divisions are about 24.80 seconds of arc apart when the eyepiece is used with Excalibur without a barlow. With my three barlows the divisions become 11.06, 10.36, and 7.84 arc-seconds apart.

The linear scale will be used to measure linear distances such as the separation of double stars. The outermost circular scales will be used to measure position angles.

I was stricken be a sore throat on the 5th of October. Some congestion and an occassional cough remains. Hopefully it's not progressed to bronchitus or pneumonia. Currently I'm not sure if this situation is getting better or worse, but at the moment I'm feeling healthier than I was earlier. I might be feeling up to at least a brief observing session tonight. I stepped outside this morning in time to catch sight of Saturn in the east-southeast with the unaided eye.

RA 20h 40m to 21h 00m, Dec -09 to -15

Last night I observed and sketched two double stars as well as M72, M73, and an un-named (as far as I know) small asterism similar to M73.

The session actually began with a sighting of the International Space Station gliding across the sky. The ISS appeared to be somewhat brighter than Jupiter -- a rather brilliant, white, moving light in the sky. Of course, as the ISS entered the earth's shadow it rapidly dimmed.

The seeing was 'good' -- a '6' on the modified Pickering Scale. I used 477x for the seeing check.

My NELM was 6.5.

Observations and sketches were all made at 135x, though other magnifications were used at times.

RA 20h 20m to 20h 40m, Dec -09 to -15

The mushroom cloud shown above was visible in the west this afternoon, but fortunately the smoke drifted south of me and the fire may have been successfully supressed by nightfall. The photo is an enlarged (and somewhat enhanced) portion of the original telephoto. The fire was not as close it may appear above. My sky appeared to be 'crystal clear' by the time I had begun my observing session.

In this region of sky (see title) I observed, split, and sketched seven double stars in the course of a little over an hour with the 13cm refractor. One was particularly nice, showing some color at low power. Another was a particularly close 'split'.

Seeing was much better on this evening (Tuesday evening, September 30th locally or October 1st UT) than it was on the previous evening. I rated it as being "Excellent" -- an "8" on the modified (for a 5-inch scope) Pickering Scale.