In Cllrn'" of Fi.~. -I ;llld ill I:;g, ~) t!'(· illuminated objuct
l~ assllmeJ t) he Cl sphcrc. In curve 1\ of l;i~~. ,t thu object is the
Orbiting Solar Ohservatory (OSO) with its sails broaJsldc to the
observer (Roach, .J .P.., 19(7). '111e plots for the sphere are hased
on the assumption that a slln-illwninated sphere of diameter 1 meter
at {l distance of 1000 kilometers has an apparent magnitude of 7.84
(Pilkint;ton, 1967). From this, a ?encral relationship between ap-
parent magnitude, m, dj,:lIncter, d In meters, and slant distance, r
in ld 10metcl's; h obtained:
m '" -1.J6 - 5.0 log d + :.i.0 log r . • (1)
Fi;Z. 5 indicates that arti facts 1 m. in diameter are hrighter than
m = +5 and therefore visjl11e to the normal unaided eye to distances
of 100 km.ilw same spacecraft becomes brighter than Venus at her
brl~htcq (m ::: -3) if closer to the obst:'rver than 10 kill. Tn the
cast:' of ;l J1on-<;phcrical ohject with an albedo that is less than
uruty, c<.ju(ition (1) is only a (~llidc and the refercn-:es in the hib·-
liography should be con~ulterl fur Jetails.
Fig. S is pertint~nt to the observation of the Clenn "fireflies"
and the "uriglow" (see pD. ;;l)3~304) and shcw~ that se€~n
close up, i.e.; at 1 to 10 In., even very small 5un-illuminat~d pa-jticles
aN dazzlingly bright. . _
~cgend
I-ig. S '\l'purl'Jlt lllagllitl.,I" ... r sphcres illuminateJ by the
sun as a fund lOll of till' diameter of the ~·pheres. It.i s assumed
that the Jistallce from tl1e oh:,l'rVl'Y to the spheres is 1 meter
lClln'c :\1 ~111J 10 mc!ers l(:II1'Vl' B1. Sec l'Cjll:ltioll (1) p. n(J.
Fig. ,l, Thl' appan'llt visual magllitlHlc 01.' ohject:, illlll1liJlatcu by
tl1l' sun as a f\lllct i 011 (11' d lstallCL' bL'lIvl'l.'1l ohservt'1' and obj eel. Cllrve
.\ i ~ for a s}l h t' 1'(' () l' 1 Il1et l' r d i a ll1et c l' (s I'l Ie q lW ri 011 ] j n t (' xt J. <: lJ r v ('
B lS fot' the usa :;pacccraft assuming us aHwdo of lJ.4, u \onoow
tl'ansl1lis~;iol1 of O.S, a SOLII' cosine of ().~), and thl OSO sails broaJ-
,;idc t'J tit!"' ob.~I.'l'vl'r (I{o<ll.-h. ,J.R., 19()(,,)
285
III ClIr\',' ,\ of !'i~, ·1 :1I1d i Jl Fi g. th.· illuminated obj<.:ct
l~ assllll)('J t) he :1 ~plll'I'(,. In eurve 1\ of I:i~',. ,~ th·.,: object is tile
()rbiting Sobr ()b~ervatory (OSO) with its sails broadside to the
observer (Roach, .J. P,., J96'1). '111e plots for the sphere are ha5ed
on the assumption that a stln-illumin[lted sphere of diameter meter
at n distance of 1000 kilometers has [In apparent magnitude of 7.84
(Pi lkint;ton, 1%7). From this, a !!,encral relationship between ap-
parent magn i tude, m. JLuneter, d in Illeters, and 'i lant di s tanee, r
ill \.;] 1ometers, i~ obtained:
m" -7.ll) - 5.0 log d + :'.0 log r .. (1)
Fl;z. 5 indic(ltl'5 that artifact:, 1 m. in diameter are hrighter than
m : +S and therefure vi5ij,le to the normal unaided eye to distances
of lOll km.ilw same ~pacccraft becomes brighter than Venus ather
brightest (Ill " -3') if .:losor to the obscrver than 10 kill. Tn the
caSt' of ;l non"-;pncril'al ohJect with an albedo thnt is lc~s than
IHl] ty, e'lu;.,tjon (1) is (lnly ;] ,Flide :llltl the references in the hib ..
I iograph: c;hould bl' COi1~;llltcd rur Jctnils.
Fig. 5 is pertir,,'nt to the observntion of the Glenn "fireflie3"
and the "ul'iglow" lind shewf th,lt set:n
close up, i.c.; at 1 to 10 1i1" even very small sun-illuminat';)d pa'rticles
a N cia z zli n!! 1y b rig h t. .._________. ________________ .__ . _____ .___________. __ _
Ii g, S :\I'parCJlt l1la.~llitl.,I,· Jr sphel'cs i 11untinateJ by the
sun as a fund iOIl of ti'L' dian10ter of the '-pherl's. It is assumed
that the dist.<llce frolll the observl'r to tIlt' spheres is 1 meter
lLul'\'e :\1 ~lllJ lO Illl't('r~ ((:\,!'v(' Ill. Sec ('quat iOll (J) p. n("
Fig. ,I. Till' appar(.'llt \'i~ual magJlillldl' oi,' objcct:; illlllllit1<ltcd by
till' sun a~ a flllh:t i llll of d istallcl' ]Jl'1\~l·'.'n llhsl'rVel' and obj eCl. Cllrvc
.\ is for (l spht'n' of I 111l'tl'r diameter (SCl '.'quatioll 1 ill text). eliI'Ve
II is fot' the USO :;pal'ecl':d't assllllliil~ us ullwdo of U.4, a WJI100W
tl'~lI1sllli:;sion uf U.S, a sol:11' cosinl' of ()'~" and till' OS() s(lils broad-
.,ide t'J t\1(' Ob:-;l')'Vl'l' (J{oadl, .1.R., 19()7,j
285