Peter's Astronomy Page

Hear the crickets or not:

Peter's Astronomy Page
(Last updated October 11, 2008)

N 30° 11' 41" W 97° 52' 36"
Click Here for a current sky map at this location.
Click Here for current sky conditions at this location.

Click here to see the circuit for the variable frequency power supply used for guiding.
Click here to see a more modern circuit that I have built and tested but not used with the telescope yet.
Click Here to go to the Austin Astronomical Society home page.
Click here to see my Java Orbit simulator.

Welcome to the third millennium! These images were made with a Logitech QuickCam pro 3000 attached to my RV-6 and processed with the techniques and free software from the QCUIAGweb page and yahoo group.

For the best view of these images adjust your monitor
to distinctly show the difference between all 17 shaded boxes below.

	Mercury, July 20, 2004, 2:04UT 1/5 Second exposures. Gain 25. best 64 of 600 frames stacked, RGB shift, wavelet sharpening The orange color comes from imaging it close to the horizon and not from the planet itself. Click here to see more Mercury images.
	Venus, May 3, 2004, 1:25UT 1/100 Second exposures. Gain 0, Gamma 50, Brightness 50. all 600 frames stacked, Gamma curve adjusted, slight sharpening Click here to see more Venus images.
	Mars, November 2, 2005, 5:22 UT, CM=275 1/25 Sec., 10 FPS, Gain 0, Gamma 0, Brightness 100. White Balance previously frozen on the Moon. Astronomik IR blocking filter. Best 64 of 4665 frames stacked Registax2 Wavelet 5 at 30 Green highlight +10 in PhotoStudio Click here to see more Mars images.
	Jupiter, May 7, 2005 at 3:30 UT. 1/10 Sec, Gamma 50, Brightness 50, 10 fps 300 best frames stacked with 2X resample and wavelet sharpening in Registax. Resampled back to 1x, crop and tone adjustment in photoStudio. Click here to see more Jupiter images.
	Saturn, March 22, 2006, 4:39 UT 1/5 Sec, Gain 10, Brightness 75, Gamma 25. White balance frozen previously. Best 150 of 1005 frames stacked. Wavelet 5 @ 50 and histogram blue shift in Registax 1. Tone adjustment in PhotoStudio. Click here to see more Saturn images.
	Uranus, August 1, 2004, 10:01 UT 1/5 Sec, Gamma 0, Gain 65, Brightness 60, 5 fps Best 700 of 2000 frames stacked with 2x resample in Registax. PhotoStudio processing: Shadow -30, Highlight -10 Unsharp mask 13 pixel, Resampled back to 1x. Click here to see the 2x image.
	Neptune, August 14, 2004, 5:44 UT 1/5 Sec, Gamma 30, Gain 75, Brightness 45, 5 fps Best 1500 of 3000 frames stacked with 2x resample in Registax. PhotoStudio processing: Shadow -30, Midtone +20, Highlight -20 Unsharp mask 8 pixel, Despeckle, Resampled back to 1x. Click here to see the 2x image.

Moon on July 25, 2004, 2:59 UT
Captured in color, converted to gray scale during processing.
1/50 Sec., Gain 0, Gamma 50, Brightness 50, 256 best frames stacked for each tile.
Processing in Registax: Stack double size, wavelet 4 at 15.
12 small tiles stitched together in iMerge to make this large image.
Click here to see the full size moon image.
Click here to see more Moon images.

Here are two of the best photographs I ever took using film through the RV-6, before web cameras were available.

Globular star cluster M13, July 16, 1975.
RV-6 telescope at prime focus, FL=48 inches.
15 Minute exposure, 103a-F film developed in D-19.

Mars, September 16, 1988.
RV-6 telescope with a CP4 barlow, EFL=192 inches.
(This is the same barlow that gives EFL=144 inches for the webcam,
but the film camera and T adapter are longer than the webcam and Mogg adapter
so the film ends up farther from the barlow than the CCD resulting in more amplification.)
1/3 second exposure on Technical pan film developed in Technidol.

Here is a formula I developed for calculating how long your camera can stare at a planet without the planet's rotation smearing the image.

T = S * R * 3600 / D / 3.14
Where:
T = Total capture time in seconds
S = Smearing, in arc seconds at the center of the disk
R = Rotation rate in hours per rotation
D = Diameter of the planet in apparent arc seconds

For example, I decided acceptable smearing would be half Dawes limit. That is 0.38 arc seconds for my 6 inch. Mars makes one rotation in 24.6 hours and had an apparent diameter of about 25 arc seconds at opposition. The formula says I can capture for 428 seconds. If I had a 12 inch telescope looking at Jupiter making one rotation in 9.9 hours when it is 45 arc seconds in apparent diameter, the time limit is 48 seconds.

Alternatively you could just image as long as you want and then use this re-arranged formula to calculate how much smearing you actually got.
S = T * D * 3.14 / R / 3600

Image scale can be calculated with this formula from the HiRez Imaging document in the support section of the old SAC web site.
S = 205 * P / FL
Where:
S = arc Seconds per pixel
P = Pixel size in microns
FL = Focal Length in millimeters

The Nyquist criterion says the detector should have at least twice the resolution of the optics to avoid loosing information. My QuickCam has 5.6 micron pixels and the resolution of my 6 inch is 0.72 arc seconds (Dawes limit). Twice the resolution would be half the size, or 0.38 arc seconds, so 0.38 = 205 * 5.6 / FL. Solving for FL gives 3021 millimeters or 119 inches. The CP barlow gives a 144 inch FL when used with the QuickCam, more than enough magnification to record all detail the telescope could ever show.

This background image is a 1600x1600 animated gif depicting part of the real night sky (can you identify which part?)
generated from data in the BSC5P bright star catalog with the help of a C program I wrote. Click Here to see it separately.