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Landsat Missions




Frequently Asked Questions about the Landsat Missions


Missions and Sensors

1 - What is Landsat and when did it begin?
2 - Where can I locate historical documents relating to the Landsat missions?
3 - What future missions are planned?

Data Acquisition

4 - What is the orbit path of Landsats 7 and 5?
5 - What is the Worldwide Reference System (WRS)?
6 - What are the band designations for the Landsat satellites?
7 - How are acquisitions planned for Landsats 7 and 5?
8 - Can an acquisition request be made for a specific date and location?
9 - How can I find the acquisition time for an image?
10 - Why is the thermal band on Landsat 7 (band 6) acquired in both low and high gain?

Data Access and Delivery

11 - Where can I find the latest information about Landsat data products?
12 - After a scene is collected, when will it become available for search and order?
13 - How do I search and order Landsat scenes?
14 - How do I search and order ascending (nighttime) scenes?
15 - What is the typical delivery time for a Landsat order?
16 - What files will be provided with a Landsat scene?
17 - What are the naming conventions for Landsat MSS, TM and ETM+ scene identifiers?
18 - Are there any restrictions on the use or redistribution of Landsat data?
19 - Are all acquired Landsat 5 images available in the USGS Landsat archive?
20 - What is Landsat 7 ETM+ SLC-off data?
21 - How do Landsat 7 ETM+ SLC-off data products compare to previous Landsat 7 data?

Browse Images and Metadata

22 - What band combination is used for Landsat browse images?
23 - Why is there so much color variation among the Landsat browse images?
24 - Why do some browse images have a color shift midway through the scene?
25 - Why do some Landsat browse images appear pixilated?
26 - Why are some browse images black? (Earth Explorer)
27 - What is a Partial Aperture Calibration (PAC) scene?
28 - How is the percentage of cloud cover calculated?
29 - Why is the cloud cover reported as "0.00" for night scenes?
30 - Why are there gridlines on the SLC-off browse images?

Image Processing

31 - What are the processing levels for Landsat data?
32 - What is the difference between LPGS and NLAPS processing?
33 - What are the differences in the data format options?
34 - What is the difference between path-oriented (nominal, satellite) and map-oriented (north-up) images?
35 - What is the geometric accuracy of a Landsat 7 ETM+ systematically corrected Level 1G processed product?
36 - What is definitive ephemeris?
37 - Does Landsat 7 ETM+ Level 1 processing include atmospheric correction?
38 - How are the non-functioning detectors on Landsat 4 handled in processing?
39 - What is Level 0Rp processing?
40 - What is L1R processing?
41 - What is Level 1G, 1Gt, 1T SLC-Off processing?
42 - What is Level 1G, 1Gt, 1T Interpolated processing?
43 - What is Level 1G, 1Gt, 1T Gap-filled processing?
44 - What is Level 1T Segment-based Gap-fill processing?
45 - How do I fill in the gaps in my SLC-off image?
46 - Which images will work best to fill in the gaps?

Data Characteristics and Anomalies

47 - What is the number of bits for the Level 1 radiometric (L1R) product?
48 - How are the number of lines and samples (rows, columns) determined for a scene?
49 - How do I fill the gaps in SLC-off scenes?
50 - How can the acquisition dates of SLC-off fill scenes be determined?
51 - What are the common anomalies found in Landsat data?
52 - Why are there lines across my Landsat TM image?

Calibration and Technical Details

53 - How accurate is the radiometric calibration of Landsat images?
54 - What are Calibration Parameter Files?
55 - What is the difference between the CPF Effective date and Version date?
56 - What is a gain change?
57 - What is the difference between the 6L (low-gain) band and the 6H (high-gain) band?
58 - How is radiance calculated?
59 - How is at-sensor reflectance calculated?
60 - How is at-sensor temperature calculated for the thermal infrared bands (6L and 6H)?
61 - What is the minimal change in temperature that is detectable by the Landsat 7 thermal bands?

Applications and Interpretation

62 - What are the best spectral bands to use for my study?
63 - Can Landsat MSS images be compared to Landsat TM and ETM+ images?
64 - How does the orientation of an image affect the use of image processing software packages?
65 - What could be causing the "seamline" in a mosaic of multiple images?




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Page Last Modified: November 06, 2008