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Landsat Missions




Frequently Asked Questions about the Landsat Missions


General

1 - What are the naming conventions for Landsat MSS, TM and ETM+ scene IDs?
2 - What are the differences between Landsat 7 ETM+ and Landsat 5 TM?
3 - What is the orbit of Landsat 7?
4 - Where can I locate a WRS-2 graphic?

Data Access

5 - Why is there limited Landsat 5 coverage over my area of interest in the USGS Landsat archive?
6 - Where can I find Landsat 7 ETM+ product information (e.g. pricing, spatial resolution, formats, etc.)?
7 - Are there any restrictions on the use or redistribution of Landsat 7 data?
8 - After a scene is collected, how soon will it become available for search and order?
9 - Can an acquisition request be made for a specific date and location?

Metadata and Browse Images

10 - How is the percentage of cloud cover calculated and is it always accurate?
11 - Why is the ACCA always reported as "0" over night scenes?
12 - How can I find the acquisition time for an image?
13 - What band combination is used for Landsat 7 browse images?
14 - Why is there so much color variation among the Landsat 7 browse images?
15 - Why are some browse images black?
16 - Why do some browse images have a 'color shift' midway through the scene?
17 - What is a Partial Aperture Calibration (PAC) scene?
18 - Why do some Landsat browse images appear pixelated?

Image Processing

19 - How are the non-functioning detectors on Landsat 4 handled in EROS processing?
20 - What is the difference between the three processing levels (L0R, L1R, L1G) for Landsat 7 ETM+?
21 - Where can I find detailed information on the processing and geometric correction of Level 1G products?
22 - What is the difference between LPGS and NLAPS?
23 - What is the geometric accuracy of a systematically corrected Level 1G product?
24 - How does the use of definitive ephemeris improve L1G processing?
25 - Has definitive ephemeris always been used for Landsat 7 data provided by USGS?
26 - Does Landsat 7 ETM+ Level 1 processing include atmospheric correction?
27 - What is the difference between path-oriented (nominal) and map-oriented (north-up) systematic Level 1G images?
28 - How can the acquisition dates of the scenes used to fill the SLC-Off image be determined?
29 - Why are there lines across my Landsat TM image?
30 - What is the difference between map (north up) and path (satellite) orientation?

Data Delivery/Orders

31 - Where can I pick up my FTP order?
32 - What are all these files in my order?
33 - What files and documentation are provided with a Landsat 7 product?

Data Characteristics

34 - What is the number of bits for the Level 1 radiometric (L1R) product?
35 - How can the number of lines and samples (or rows and columns) be determined for a scene?
36 - What is the minimal change in temperature that is detectable by the Landsat 7 thermal bands?
37 - What is the difference between the 6L (low-gain) band and the 6H (high-gain) band?
38 - Why does band mismatching occur along the edges of Landsat 7 images?

Radiance/ Reflectance/ Temperature Calculation

39 - How is radiance calculated from a Level 1 product?
40 - Do thermal values in bands 6L and 6H represent absolute or relative temperatures?
41 - How accurate is the radiometric calibration?
42 - How is radiance calculated for early FAST format orders?
43 - How is reflectance calculated?
44 - How is at-sensor temperature calculated for the thermal infrared bands (6L and 6H)?
45 - Calibration Parameter File (CPF) version vs. Effective Date

Gain Changes

46 - What is a gain change?
47 - Why do gain changes occur?

Applications and Interpretation

48 - What could be causing the "seamline" in our mosaic of multiple ETM+ images?

Remote Sensing

49 - What is Remote Sensing?
50 - What is the Electromagnetic Spectrum?
51 - What Factors Affect Remotely Sensed Images?
52 - How is Electromagnetic Radiation Measured?
53 - What are some Applications for Remote Sensing?




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Page Last Modified: May 09, 2008