Night Sky Quality Monitoring Report
Sequoia/Kings Canyon NP, California
Buck Rock, Septmeber 30, 2005
To effectively manage any resource, we need to know what we have and what we've lost. "Light Pollution", the brightness in the nighttime sky due to artificial light, can be seen from almost every park. The NPS has developed a system for measuring sky brightness to quantify the source and severity of light pollution. This system, developed with the assistance from professional astronomers and the International Dark-sky Association, utilizes a research-grade digital camera to capture the entire sky with a series of images. Data clearly shows that even remote national parks are not immune from stray artificial light. Sky brightness is measured in astronomical magnitudes in the V-band, abbreviated as "mags". The V-band measures mostly green light, omitting purple through ultraviolet and orange through infrared. The magnitude scale is a logarithmic scale. A difference of 5 magnitudes corresponds to a 100x difference in brightness. Lower values (smaller or more negative) are brighter. Further information on astronomical magnitudes can be found on this Sky and Telescope webpage. Data images are shown in false color, with yellow, red, and white corresponding to brighter sky and blue, purple and black corresponding to darker sky.A more detailed explanation is available.
| Category | Details | Image |
|---|---|---|
| Park | SQNF |
 Narrative: Site one half mile south of Buck Rock lookout on a dome rock just east of the road. Excellent site for public, not so good for telescopes because of rough ground surface. Several large trees close by unavoidably block horizon, light dome calculations will be inaccurate. Sky very bright to west and south, Milky Way slightly washed out at zenith, completely in southwest. Seeing excellent, transparency excellent. Gegenschein not visible, M33 barely visible.
|
| Site Name | Buck Rock | |
| Longitude | -118.86051 | |
| Latitude | 36.7317 | |
| Elevation (m) | 2542 | |
| Date (UT) | Septmeber 30, 2005 | |
| Time Start (UT) | 3:16:38 | |
| Data Quality | Very Good | |
| Equipment | SBIG 50mm f/2 6084 | |
| Observers | D.Duriscoe | |
| Air Temp (°F) | 56.5 | |
| Rel Humid (%) | 40 | |
| Wind Sp (mph) | 4 | |
| CCD Temp (°C) | -20 | |
| Exp (seconds) | 15 | |
| Bortle Class | 4 | |
| ZLM | 6.6 |
| Data Set Number | Time (UT) | Extinction Coefficient (mag/air-mass) |
Std Err Y Extinction Stars (mags) |
Zenith (mag/sq arc-sec) |
Whole Sky (mags) |
Sky Above 20° Altitude (mags) |
Brightest (mag/sq arc-sec) |
Darkest (mag/sq arc-sec) |
Links to Sky Maps |
|---|---|---|---|---|---|---|---|---|---|
| 1-Start End |
3:16:38 3:37:31 |
0.139 |
0.040 |
21.32 21.13 |
-7.58 |
-6.86 |
18.62 |
23.12 |
PAN HEMI |
| 2-Start End |
4:16:43 4:37:38 |
0.140 |
0.038 |
21.24 21.22 |
-7.66 |
-6.97 |
18.70 |
23.07 |
PAN HEMI |
| 3-Start End |
5:16:49 5:37:42 |
0.139 |
0.039 |
21.31 21.27 |
-7.68 |
-7.02 |
18.84 |
23.02 |
PAN HEMI |
| 4-Start End |
6:16:54 6:37:47 |
0.142 |
0.042 |
21.39 21.47 |
-7.62 |
-6.96 |
18.95 |
23.11 |
PAN HEMI |
| 5-Start End |
7:16:58 7:37:54 |
0.142 |
0.040 |
21.59 21.62 |
-7.49 |
-6.82 |
19.09 |
23.19 |
PAN HEMI |
| City | Distance (km) |
Azimuth | 1st Data Set Brightness (mags) |
Image |
|---|---|---|---|---|
| Bakersfield | 153 | 184.9 | -2.66 |
 |
| Porterville | 76 | 191.5 | -5.72 | |
| Visalia | 61 | 222.6 | ||
| Reedley | 55 | 254.7 | ||
| Fresno, CA | 83 | 274.0 | ||
| Los Angeles | 293 | 171.9 | -2.93 | |
| Total | -5.87 |