HE README

Background
The 1910 appearance of Halley’s comet stimulated much excitement.  The HE Series 
plates are those taken by Ferdinand Ellerman on an expedition sent to Hawaii to 
photograph the comet. The expedition is described in Ellerman, F., 1910, Pub. 
Astron. Soc. Pacific, 22, 165. The logbook associated with these plates is 
Ellerman’s journal of his travels.  Both of these publications give details 
about the telescopes used and the plates secured.

The Telescopes
The observing location was longitude = 157° 48.5’ W, latitude = 21° 15.5’ N.  The 
HE series consists of 60 plates taken with a 6-inch Brashear portrait lens of 
32-inch focal length. The HE-Tesser series consists of 11 plates taken with a 
2.25-inch aperture f/4.5 Tessar lens of 9.875-inch focal length.

The Plates
Sixty 8 x 10-inch HE Series plates were taken with the 6-inch lens, with the 
first on 1910-04-13/14 and the last on 1910-06-11.  Exposure times ranged between 
2 and 163 minutes. Eleven 8 x 10-inch HE-Tessar Series plates were taken with the 
Tessar lens between 1910-05-04/05 and 1910-06-01. Exposure times were between 15 
and 136 minutes.
 
The Searchable file
The “HE-PLATES-U16.csv” file can be browsed or downloaded to search for plates 
of interest. This file list the HE plates by plate number (essentially in chrono-
logical order) followed by the HE-Tessar plates. Any cell that is blank indicates 
there is no information available or it has yet to be calculated (for example, 
the equatorial coordinates of the plate centers).  

Description of the columns of the csv file:
Rcd - Record number in the catalog
Code - Plate series - HE and HE-Tessar (probably means Halley-Ellerman)
Plate No - Running number of plate
Date - The date the plate was exposed as recorded.  
Object - The target object of the exposure (Comet Halley)
RA - Right ascension of the plate center (to be calculated) 
Dec - Declination of the plate center (to be calculated) 
Exp (min) -  Exposure length (in minutes)
Start - Start of the exposure (G.M.T. converted from recorded local time)
End - End of the exposure (converted from recorded local time)
Time - Type of time used (G.M.T., derived from local time)
Plate size - physical size of the plates, in inches
Plate Emulsion - Emulsion type (no filters used)
Observer - Recorded observer (F. Ellerman)
Location - Location of plate when file was prepared (at Yerkes)
Plate Quality - The quality of the the developed plate as noted by Ellerman
Sky - The viewing conditions of the sky a the time of observation
Notes - Notes from the log book.


Updated:  2024 March 16  AF