ANSWERS TO QUESTIONS CONCERNING STELLAR/TERRAIN EPHEMERIS AND DATA BLOCKS

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP79B00873A001800020003-1
• Release Decision: RIPPUB
• Original Classification: T
• Document Page Count: 3
• Document Creation Date: December 28, 2016
• Document Release Date: October 24, 2012
• Sequence Number: 3
• Publication Date: June 21, 1971
• Content Type: MEMO

Declassified in Part - Sanitized Copy Approved for Release 2012/10/24: CIA-RDP79B00873A001800020003-1
MEMORA DNUM FOR:
? ATTENTION
SUBJECT
21 June 1971
Copy
Chief, Research & Engineering Division, TSG/NPIC.
Answers to Questions Concerning Stellar/Terrain
Ephemeris and .Data Blocks
. 1. ?At this time, it is impossible to obtain an official reply
from SAMS? (not OSP) regarding the questions that you have asked me
to answer. You must be aware that SAMS? is on a 24-hour schedule
and willnot be able to reply for several weeks. I have, however,
varified the answers to your questions from documentation on file
and have also conferred
2. .Information regarding data block reader in Stellar/Terrain
(S/T) 'system:
? Question: What information is contained in the S/T
data block that is not in the S/T ephemeris?
Answer: Stellar data block
(1) Camera time of port stellar shutter -2-
open.
? (2) Camera time of port stellar shutter I
closed. ,
(3) Camera time of terrain mid-exposure to
0.1 millisecond accuracy.
(4) Terrain exposure input command.
(5) Overlap command
(6) Index bit
? Terrain data block
(1) Camera time of starboard stellar shutter
1
2 closed.
(2) Camera time of starboard stellar shutter
1
2 closed.
(3) Camera time of terrain mid-exposure to 0.1
millisecond accuracy.
(4) Terrain exposure command
(5) Overlap command
(6) Index bit,
aoldafNMadomiic
dowgradingand
TOP.SECRETe
Declassified in Part - Sanitized Copy Approved for Release 2012/10/24: CIA-RDP79B00873A001800020003-1
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h. Question: What information is contained in the total
SIT ephemeris?
Answer:
1. Nadir Lat and Long
2. Time at center of format to one millisecond
3. Rev Number
?
4. Frame number'
5. Camera ID
6. Date
7. Solar elevation :
8. Altitude
9. Inertial Velocity
10. Ground Track Azimuth
11. IMC rate
12. Time Correlation Parameters
- 13. Focal length
14. Right ascensi and declination of each steltr ?
? ??.?
?
N.
???:.!?-,? -r .1" 7.7e .
optical axis..
15. A 20-point ephemeris (XYZ, XD YD ZD, XDD YDD ZDD)
Lat and Long of four corners of each terrain ?
camera operation
17. Filter ?
18. Film
19. DMU firings and special events
? Question: Is the SPARS (automatic attitude) system a
permanent modification from i/13 on-or experimental?
Answer: It has been recomMended by MC&G that there be a
SPARS system on for test purposes and
that SPARS be on all missions
. Question: Will automatic attitude information (SPARS) be
- -in the S/T ephemeris or only in the SIT data block.
?: Answer: Only in the data blocks; one-half on the stellars
and one-half on the terrain.
?
Question: Can we get the layout of row i6 (SPARS automatic
attitude column) of the S/T data blocks?
Answer: No, because it hainot,been designed_ap of this
writing.
?
Chief, Reconnaissance Systems Branch,
RED/TSG/NPIC
TOP SECRET,.
Declassified in Part - Sanitized Copy Approved for Release 2012/10/24 :_CIA-RDP79B00873A001800020003-1
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Declassified in Part - Sanitized Copy Approved for Release 2012/10/24: CIA-RDP79B00873A001800020003-1
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Distribution:
Cy 1 - Addressee
2 --?NPIC/TSG
38c4 - ,NPIC/TSG/RED/R6B
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Declassified in Part - Sanitized Copy Approved for Release 2012/10/24: CIA-RDP79B00873A001800020003-1