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Produced by the NASA Center for Aerospace Information (CASI)
A SEARCH FOR EARTH-CROSSING ASTEROIDS

(NAGW-232 )

SEMIANNUAL STATUS REPORT

L. G. TAFF AND D. F. KOSTISHACK

LINCOLN -LABORATORY, M.Z.T.

LEXINGTON, MA 02173 ?a

COVERING JULY 1, 1983 TO DECEMBER 31, 1983

(NASA -CR-175374) A SEARCH FOR N84-18'139

EARTH-CROSSING ASTEROIDS Semiannual Status

Report, 1 Jul. 31 Dec. 1983 (Lincoln laab.)

12 p HC A02/MF A01 CSCL 03B Uncl,as

G3/91 18252
^t.

-2-

This fifth brief Semiannual Status Report is submitted un

the provisions of NASA regulations for Research Grants. One

reason that it can be brief is the extensive Supplement prepare

t.o our last Semiannual Status Report. A revised copy of that

document is appended. It is not only a historical review of al

of Lincoln Laboratory's MI.T.) work on Earth-approaching mino

planets, it also presents the observational and theoretical bas

for asteroid detection and discrimination by semi-automatic or

automatic means.

As is usual, our observing work is presented both in tabu

form (Table 1) and graphical form (Fig. 1). I've also included 

figure (No. 2) which shows the vast improvements made in both

resolution element size and sensitivity in our EBSICON cameras.

This is principally due to the efforts of Dr. R. Weber and has

occurred in parallel with our CCD work (see below). (Figure 3

shows the completed CCD camera). Finally, Figure 4 is an

up-to-date illustration of what an asteroid detection now looks

like. Shown are four phases during the realignment of the live

(white) and reference (black) frames. As one passes through th

sequence you can see that the stars' image,-) overlap and become

grey, while th o displaced images of the asteroid (#899 on day 3

of 1983 at S = 14 M 25) do not cancel. The dots in the lower

lefthand corner are blemishes - they appear in all images with 

same displacement.
Time No. of No, of No. of No. of Discoverie

Period Objects Observations Nights Square Degrees

1979-80 F5 96 5 200 2

inclusive

1981 209 580 53 2785 33

Jan. 22 58 3 200 0

Feb. 9 48 6 345 0

March 8 24 6 300 0

Apr. 10 39 3 160 0

May 11 71 4 220 0

June 4 11 2 80 0

Aug. 37 133 8 550 8

Sept. 28 42 4 190 2

Oct. 46 86 5 275 14

Nov. 0 0 2 55 0

Dec. 34 68 10 410 9

1982 226 370 42 4612 27

Jan. 4 4 1 27 0

Feb. 38 58 5 275 8

March 39 66 6 345 5

Apr. 20 57 6 330 2

May 43 50 6 275 2

Sept.' j6 67 8 1390 1

Oct. 19 36 3 580 1

Nov. 76 10 3 580 3

Dec. 20 22 4 810 5
 i

Table 1. Asteroid Searches (Cont.)

Time No. of No. of No. of No. of Discoverie

Period Objects Observations Nights Square Degrees

1983 108 233 49 13010 5

Jan. 25 48 4 930 3

Feb. 13 43 7 1860 1

March 12 30 8 1740 0

Apr. 11 22 6 1680 0

May 10 20 8 2090 0

Sept. 14 24 3 765 0

Oct. 0 0 1 115 0

Nov. 12 24 6 1975 0

Dec. 11 22 6 1855 1

4

.. -

.^.-:^ r{ ^.-G1^M4'^ ^+.^.AY•. ^t.Yr•fn.^..`.r.. ^wR^. ^.. . VY y. ^•
^I

t'

t, I f

The pictures are Polaroid pictures of the television monito

screen, cut, mounted; and rephotographed. The actual image is

evert better than the one portrayed here.

The meeting at NASA Headquarters in September has inspired 

to :Firm up the statistical. .basis for searching for Earth--

approaching asteroids. A summary of this work, in the form of a

Astronomical. Journal preprint, is enclosed too.

The CCD camera (Fig. 3) has been completed, tested, taken

apart, revamped, and will be tested again during the March 2 New

Moon. The :sensitivity tests requested by NASA Headquarters were

performed on our EBSTCON cameras as well as the old version of th

CCD camera. They are summarized in Table 2. The reference field

were a field in Aquila, SA 71, or SA 94. The results, in Table 

are reduced to top of the atmosphere and are in the B system.

-5-
Prime

Zoom Full

16fi25 16m5

16.5

0

Table 2.

Static Limiting Magnitudes (B)

Telescope Configuration Cassegraim

Zoom Full

Camera

EBSICON 1.63P5 16'^F25

CCD

-6-
191;.

-7-

BIBLIOGRAPHY

O bservations made at the Lincoln Laboratory ETG under the

direction of L. G. Taff:

M. P. C. 8050, July 1983

Preprint to on Astronomical Journal. The Discovery

Circumstances of Earth-Approaching Asteroids

Supplement to the Semiannual Status Report
Figure Captions

Figure 1. Graph of celestial sphere coverage (in square degrees)

as a function of lunation.

Figure 2. Curves of resolution element density (left) and

responsitivity (right) for new and old S3SICON cameras

used in search work.

Figure 3. Open view of completed two-chip CCD camera.

Figure 4. Four (left to rightp top to bottom) successive views of

electronic asteroid detection.
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