Star photography during solar eclipse by fixed focus aerial cameras aboard jet aircraf

Gibson, J.

English

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25 tiarch 1968 
Final Report on PIASA Grant NGR OW06003 
James Gibson 
Van Vleck Observatory, Wesleyan Univ., Viddletown, Conn. 
This grant supported an attempt t o  observe f a i n t  comets i n  the v i c in i ty  of 
t he  sun during t h e  t o t a l  ecl ipse of November 12,  1966. 
preparation, three fixed-focus K-37 ae r i a l  cameras were flotm aboard an A i r  Force 
NC-135 j e t  which remained i n  t h e  moon's shadow f o r  204 seconds at an a l t i t u d e  of 
34,000 feet. 
After two months' 
A t o t a l  of 110 exposures were made; no comets were recorded. 
These photos were intended t o  augment a ground-based comet search described 
elsewhere (Courten, H . C . ,  and Ganberg, R . W . :  Photographic Search fo r  Comets durin.g 
12  November Solar Eclipse,  Astron. Jour, 72, page 791(A), 1967. 
r i g id ly  attached t o  the  a i r c r a f t ,  with no means of guidance t o  of fse t  angular 
motions of the a i r c r a f t ,  and with no protection from vibration. 
2475 emulsion on gk.-inch-wide E s t a r  base was confomed under vacuum t o  the  curved 
f i e l d  of t he  camera objectives.  
The cameras were 
Eastman Kodak m e  
The longest exposures were 1 second i n  white l i g h t  
( 3900-7000 2). 
A technique f o r  checking the focus s e t t i n g  of a fixed-focus camera was 
developed. 
use of t h i s  method u n t i l  a f t e r  t h e  eclipse. 
recorded a l l  f ie ld  stars brighter than magnitude 3.0 with 1/25-second ex;posures 
during the ecl ipse.  Short exposures were used t o  minimize smearing of inages 
caused by ro l l i ng  of the aircraf t .  
camera, so t h a t  a f e w  might be obtained i n  the ins tan ts  when the  a i r c r a f t  was not 
ro l l i ng .  
f l i g h t s ,  were not affected by roll. 
experimental approach, 
magnitude V=69174, according t o  photometry bv H.  Cuetter at the  U.S. Naval Observatory 
Flagstaff  Station. 
stars, have not yet  been completed. 
Weather conditions and o ther  camera probleas prevented the  e f fec t ive  
The one camera which was w e l l  focused 
:lany exposures were made on r o l l  film w i t h  each 
Ten percent of t he  one-second exposures, both i n  ecl ipse and on l a t e r  night 
I 
I This demonstrated the  va l id i ty  of t h e  The f a in t e s t  s t a r s  on the l a t e r  night exposures were of 
Experinents i n  composite pr in t in? ,  which nay show s t i l l  f a i n t e r  
Densitometer t racings of s ta r - f ie ld  exposures indicate  t h a t  films processed i n  
"orris tanks are  unevenly developed. Some forn: of machine processinq i s  advisable. 
Longer-focus camerae with t he  same 12-cm. aperture should be used, wi th  shorter  
e q o s u r e s  on the  same emulsion. This vi11 decrease the  l imit ing magnitude, but t he  
sky background, which limited t h i s  attempt, will decrease more rapidly.  
compromise may take a focal  length about 50% grea ter  than t h a t  used, with exposures 
of 2/3 of a second. 
are s t i l l  under discussion. 
The best  
A number of t he r  recommendations based on these exFeriments 
Support of these experiments by t h e  Atomic Ener,V Commission (providing window 
space on the  a i r c r a f t  and camera mountings), is gra te fu l ly  acknowledged. 
https://ntrs.nasa.gov/search.jsp?R=19680012577 2020-03-12T09:06:51+00:00Z


Search for faint comets near the sun during totality of November 12, 1966, solar eclipse Final report

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