Radar calibration (via satellites)

mar13

Satellites with a known cross section (usually spherical) can be used to calibrate ground based radars. At AO we have: sband, 430, and 46.8 Mhz radars.

A list of radar calibration satellites by launch year can be found (here).
more sat info: http://www.astronautix.com/fam/miletsat.htm
tle for radar calibrations satellites are available from celestrack under miscellaneous satellites.

tle's available for radar calibration satellites (as of 08mar13was):

Calsphere 1 - . Payload: Dragsphere 1. Mass: 1.00 kg (2.20 lb). Nation: USA. Agency: USN. Class: Military. Type: Radar calibration target. Spacecraft: Calsphere. USAF Sat Cat: 900 . COSPAR: 1964-063C. Apogee: 1,034 km (642 mi). Perigee: 997 km (619 mi). Inclination: 90.1000 deg. Period: 105.50 min. Summary: Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). .
Calsphere 2 - . Payload: Dragsphere 2. Mass: 10 kg (22 lb). Nation: USA. Agency: USN. Class: Military. Type: Radar calibration target. Spacecraft: Calsphere. USAF Sat Cat: 902 . COSPAR: 1964-063E. Apogee: 1,078 km (669 mi). Perigee: 1,049 km (651 mi). Inclination: 90.2000 deg. Period: 106.50 min. Summary: Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). .
Calsphere 4A - . Payload: NRL PL 158?. Mass: 2.00 kg (4.40 lb). Nation: USA. Agency: USN. Class: Military. Type: Radar calibration target. Spacecraft: Calsphere. USAF Sat Cat: 1520 . COSPAR: 1965-065H. Apogee: 1,179 km (732 mi). Perigee: 1,077 km (669 mi). Inclination: 90.1000 deg. Period: 107.90 min. Summary: Surveillance Calibration; white 14 inch dia. sphere. .
LCS (Lincoln Calibration Sphere) were hollow metal spheres with a precisely defined radar cross-section to calibrate ground based radars. The satellites were manufactured at Rohr Corp., Chula Vista, California, for the Lincoln Laboratory. They consisted of a 1.12 m diameter hollow Aluminum sphere with a optical unit cross section of 1 m² and a wall thickness of 3.2 mm.

LCS 1 - . Mass: 34 kg (74 lb). Nation: USA. Agency: USAF. Class: Military. Type: Radar calibration target. Spacecraft: LCS. USAF Sat Cat: 1361 . COSPAR: 1965-034C. Apogee: 2,795 km (1,736 mi). Perigee: 2,786 km (1,731 mi). Inclination: 32.1000 deg. Period: 145.60 min. Summary: Aluminum sphere used for radar calibration. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). .
LCS 4 - . Mass: 1.00 kg (2.20 lb). Nation: USA. Agency: USA. Class: Military. Type: Radar calibration target. Spacecraft: LCS. Decay Date: 1972-06-11 . USAF Sat Cat: 5396 . COSPAR: 1971-067F. Apogee: 910 km (560 mi). Perigee: 779 km (484 mi). Inclination: 87.6000 deg. Period: 101.80 min. Summary: Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). .

Tempsat 1 - . Mass: 9.00 kg (19.80 lb). Nation: USA. Agency: USN. Class: Military. Type: Radar calibration target. Spacecraft: Tempsat. USAF Sat Cat: 1512 . COSPAR: 1965-065E. Apogee: 1,188 km (738 mi). Perigee: 1,082 km (672 mi). Inclination: 89.9000 deg. Period: 108.00 min. Summary: Surveillance Calibration; black 14 inch dia. sphere. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). .
OPS 5712 (P/L 160)

Surcal 160 - . Payload: NRL PL160 / Agena D 2704. Mass: 2.00 kg (4.40 lb). Nation: USA. Agency: USAF. Class: Military. Type: Radar calibration target. Spacecraft: Surcal. USAF Sat Cat: 2825 . COSPAR: 1967-053B. Apogee: 927 km (576 mi). Perigee: 923 km (573 mi). Inclination: 69.9000 deg. Period: 103.50 min. Summary: 20 inch dia. calibration sphere. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). .

OPS 5712 (P/L 153)

Surcal (153) - . Payload: NRL PL153 / OPS 5712. Nation: USA. Agency: NRL. Class: Military. Type: Radar calibration target. Spacecraft: Surcal. USAF Sat Cat: 2874 . COSPAR: 1967-053H. Apogee: 912 km (566 mi). Perigee: 905 km (562 mi). Inclination: 70.0000 deg. Period: 103.20 min. Summary: Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). .

SURCAL 150B - . Payload: NRL PL150B. Mass: 2.00 kg (4.40 lb). Nation: USA. Agency: NRL. Class: Military. Type: Radar calibration target. Spacecraft: SURCAL. USAF Sat Cat: 2909 . COSPAR: 1967-053J. Apogee: 816 km (507 mi). Perigee: 805 km (500 mi). Inclination: 70.0000 deg. Period: 101.10 min. Summary: 16 inch dia. calibration sphere. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). .

Description of target satellites:

(Lincoln Calibration Sphere) were hollow metal spheres with a precisely defined radar cross-section to calibrate ground based radars. The satellites were manufactured at Rohr Corp., Chula Vista, California, for the Lincoln Laboratory. They consisted of a 1.12 m diameter hollow Aluminum sphere with a optical unit cross section of 1 m² and a wall thickness of 3.2 mm.

SURCAL:

American military target satellite. 15 launches, 1962.01.24 (Surcal) to 1969.09.30 (Surcal).
SURveillance CALibration (SURCAL) satellites were produced in cooperation with the NRL group that had designed and developed the Naval Space Surveillance (NAVSPASUR) system. The satellites provided objects with known shapes, masses, and dimensions, thereby providing a means to calibrate the space tracking system. NAVSPASUR was the successor to NRL's innovative Vanguard tracking system, the Minitrack. Launched between 1962 and 1965, the SURCALs were built in different shapes and sizes.

First Launch: 1962.01.24.
Last Launch: 1969.09.30.
Number: 15 .

CALSPHERE:

American military target satellite. 11 launches, 1964.10.06 (Calsphere 1) to 1971.02.17 (Calsphere 5). Radar calibration objects (but also cover for other classified subsatellites).
First Launch: 1964.10.06.
Last Launch: 1971.02.17.
Number: 11 .

Computing orbits:

I've added the radar.tle file to the daily tle updates here at AO (/share/megs/phil/predict/tle/updatetle.sc). The idl routines to compute satellite orbits can now compute locations for these satellites. The steps for doing this are:

The satellite orbits are a few hours. You need to check many orbits/day to see when one comes close to AO

The idl script /share/megs/phil/svn/idl/sat/satleopass.pro can be used to print out close passes to AO
You probably need to copy this to a local directory to edit it.
An example running this on 08mar13 gave:
.run satleopass
yyyymmdd hh:mm:ss   az    za      range SatName
       UTC          src            Km
20130308 06:14:33 159.2 12.71   2839. LCS1
20130308 14:16:15   30.0   5.07   2794. LCS1
20130308 21:38:41 101.9 12.09    922. OPS5712(P/L153)
20130309 04:26:07   97.8 11.13    998. CALSPHERE1
20130309 06:31:26 164.1   1.44   2792. LCS1
20130309 07:52:17   96.4 15.51    747. SURCAL150B
20130309 08:38:05   73.0 11.22    930. OPS5712(P/L153)
20130309 14:32:58 204.4   5.65   2796. LCS1
20130309 21:43:37 302.6 18.76    948. OPS5712(P/L153)
20130309 22:58:51 234.5 11.99    771. OPS5712(P/L160)
20130310 04:37:34 102.1   1.33   1066. CALSPHERE2
20130310 06:48:07 331.2   8.91   2815. LCS1
20130310 11:38:54   98.3   5.88    756. OPS5712(P/L160)
20130310 14:49:31 211.5 16.81   2871. LCS1
20130310 16:30:39 258.8   8.06   1006. CALSPHERE1
20130310 23:12:48   98.6 16.62   1125. TEMPSAT1

You can the plot then plot the passes for all the satelllites around the transit time of interest

idl71
@phil&@satinit
First plot the passes for all the satellites near the time of interest:

satpassplt,yymmdd=yymmdd,hhmmss=hhmmss,satAr=satAr,tlefile='radar.tle'
You can look at the individual satellite info in the satAr[] array

Plot a finer time resolution of the orbit as it passes overhead AO

The satpassplt has the approximate transit time for each satellite. Pick the transit time for the satellite of interest.
set hhmmss to about 2 minutes before the transit time the
npnts=satpass(satNm,passI,yymmdd=yymmdd,hhmmss=hhmmss,nsecs=240,tlefile='radar.tle')
PassI will then have az,za positions at 1 second intervals +/0 120 secs from the transit. You can plot out the az,za
plot,passI.az,passI.za

Some notes on pointing accuracy:

The routines currently use the most recent tle file. Older tle files are saved in the tle archive: (/share/megs/phil/predict/archive)
As of 11mar13 the predict software uses the observatory position from gps. It should probably be switched to use the observatory position used when the pointing model is made. You would then point to the az,za with the pointing model corrections included.

the change needs to go in:/share/megs/phil/predict/arecibo.qth

gps vw

arecibo
18.3443
66.7529
382

Pointing model values

Arecibo
18.3539
66.7530
382

azf=az - 180.. predict returns the source azimuth
pnt tr azf za -cf (-cf says to include model corrections).

processing: x101/130307/radarcal.pro
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