HE README

Background
The 1910 appearance of Halley’s comet stimulated much excitement.  The HE Series 
plates are those taken by Ferdinand Ellerman on en 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
There is a “Full.csv” file that 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. A Additional-Notes file provides 
any detailed notes on a plates from the log books not included in the Full.csv file. 
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 center).  

Description of the columns of the csv file:
Record number - Record number in the catalog
Plate series - HE and HE-Tessar (probably means Halley-Ellerman)
Plate number - 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) 
Length of exposure -  Exposure length (in minutes)
Exposure Start - Start of the exposure (converted from recorded local time)
Exposure Mid - Mid-time of the exposure (to be calculated)
Exposure End - End of the exposure (converted from recorded local time)
Time type -  Type of time used (G.M.T., derived from local time)
Emulsion + Filter - Emulsion type and filter (no filters used)
Plate dimensions - physical size of the plates, in inches
Observer - Recorded observer (F. Ellerman)
Location -  Location of plate when this catalogue was prepared: Yerkes = in the 
     Yerkes plate vault)
Notes - Brief notes from the log book. Longer notes are in the Additional-Notes file.


Updated:  2022 October 12