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Home / General Information / Frequently Asked Questions

1 - What are the differences between Landsat 7 ETM+ and Landsat 5 TM?

2 - What is the orbit of Landsat 7?

3 - Where can I locate a WRS-2 graphic?

4 - Where can I find Landsat 7 ETM+ product information (e.g. pricing, spatial resolution, formats, etc.)?

5 - Are there any restrictions on the use or redistribution of Landsat 7 data?

6 - After a scene is collected, how soon will it become available for search and order?

7 - Can an acquisition request be made for a specific date and location?

8 - How is the percentage of cloud cover calculated and is it always accurate?

9 - Why is the ACCA always reported as "0" over night scenes?

10 - How can I find the acquisition time for an image?

11 - What band combination is used for Landsat 7 browse images?

12 - Why is there so much color variation among the Landsat 7 browse images?

13 - Why are some browse images black?

14 - Why do some browse images have a 'color shift' midway through the scene?

15 - What is a Partial Aperture Calibration (PAC) scene?

16 - What is the difference between the three processing levels (L0R, L1R, L1G) for Landsat 7 ETM+?

17 - Where can I find detailed information on the processing and geometric correction of Level 1G products?

18 - What is the difference between LPGS and NLAPS?

19 - What is the geometric accuracy of a systematically corrected Level 1G product?

20 - How does the use of definitive ephemeris improve L1G processing?

21 - Has definitive ephemeris always been used for Landsat 7 data provided by USGS?

22 - Does Landsat 7 ETM+ Level 1 processing include atmospheric correction?

23 - What is the difference between path-oriented (nominal) and map-oriented (north-up) systematic Level 1G images?

24 - Where can I pick up my FTP order?

25 - What are all these files in my order?

26 - What files and documentation are provided with a Landsat 7 product?

27 - What is the number of bits for the Level 1 radiometric (L1R) product?

28 - How can the number of lines and samples (or rows and columns) be determined for a scene?

29 - What is the minimal change in temperature that is detectable by the Landsat 7 thermal bands?

30 - What is the difference between the 6L (low-gain) band and the 6H (high-gain) band?

31 - Why does band mismatching occur along the edges of Landsat 7 images?

32 - How is radiance calculated from a Level 1 product?

33 - Do thermal values in bands 6L and 6H represent absolute or relative temperatures?

34 - How accurate is the radiometric calibration?

35 - How is radiance calculated for early FAST format orders?

36 - How is reflectance calculated?

37 - How is at-sensor temperature calculated for the thermal infrared bands (6L and 6H)?

38 - Calibration Parameter File (CPF) version vs. Effective Date

39 - What is a gain change?

40 - Why do gain changes occur?

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

Metadata and Browse Images

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Radiance/ Reflectance/ Temperature Calculation

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