Night Sky Quality Monitoring Report
Walnut Canyon NM, Arizona
West Rim View, June 19, 2004
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 | WACA |
 Narrative: Site at West Rim View, end of paved trail from parking area. NOTE: CLOSED TO THE PUBLIC AFTER DARK. Pretty clear, seeing good, transparency very good, some breezes. Sky to zenith and east quite dark, lots of detail in Milky Way, faint stars easy to see. Light domes of Phoenix and Flagstaff separated from here, Flagstaff brighter but not much. Flagstaff glow bright enough to disturb night vision, looking to east shows slight illumination of the land. Considering the proximity to town, an excellent sky.
|
| Site Name | WEST RIM VIEW | |
| Longitude | -111.50547 | |
| Latitude | 35.16986 | |
| Elevation (m) | 2045 | |
| Date (UT) | June 19, 2004 | |
| Time Start (UT) | 5:30:18 | |
| Data Quality | Excellent | |
| Equipment | SBIG 50mm f/2 6084 | |
| Observers | D.Duriscoe | |
| Air Temp (°F) | 65 | |
| Rel Humid (%) | 21 | |
| Wind Sp (mph) | 6 | |
| CCD Temp (°C) | -20 | |
| Exp (seconds) | 15 | |
| Bortle Class | 3 | |
| ZLM | 6.8 |
| 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 |
5:30:18 5:50:46 |
0.165 |
0.048 |
21.65 21.68 |
-7.49 |
-6.78 |
18.11 |
21.86 |
PAN HEMI |
| 2-Start End |
6:03:51 6:24:26 |
0.163 |
0.048 |
21.67 21.66 |
-7.45 |
-6.78 |
18.33 |
21.84 |
PAN HEMI |
| 3-Start End |
6:37:32 6:58:06 |
0.161 |
0.046 |
21.69 21.71 |
-7.38 |
-6.72 |
18.50 |
21.87 |
PAN HEMI |
| City | Distance (km) |
Azimuth | 1st Data Set Brightness (mags) |
Image |
|---|---|---|---|---|
| Flagstaff, AZ | 11 | 281.7 | -5.78 |
 |
| Phoenix, AZ | 188 | 196.2 | -2.17 | |
| Total | -5.85 |