Halley-HD README  

Background 
The 1910 appearance of Halley's comet stimulated much excitement.  The 
HD Series plates are of the Comet taken that year.  Other than this, little is 
known about the HD plates. There is an entry in the Barnard Logbook stating they 
are "Photographs taken by J.C. Duncan at the Harvard College Observatory (size 
5 x 7 and 8 x 10)."  This is followed by a log of the plates. How these came to 
be at Yerkes Observatory has yet to be determined  

The Telescopes 
The log entries for the HD series note three different telescopes used: Brashear  
doublet, Cooke, Bausch and Lomb Tessar. 

The Plates 
There are 25 plates of this series at Yerkes with plate numbers in the range 
7 - 36; all but one are in the Barnard logbook listing.  Thus, a number of the HD 
plates are missing and most likely were never at Yerkes.  The Brashear Doublet 
plates measure 8 x 10-inch (one is slightly smaller) and the Cooke and Tessar 
plates are 5 x 7-inch. Exposure times range from 4 to 68 minutes.  The dates run 
from 1910-April-20 through 1910-June-8.   

The Logbook 
The logbooks associated with the HD plates is one section of the Barnard logbook. 
The book is at the University of Chicago.  It has been scanned is available on-line.       

The Searchable files 
A csv file is available that can be viewed or downloaded to review the HD plates.  
The "Full.csv" file lists the plates by plate number. Any cell in the csv file 
that is blank indicates there is no information available or it has yet to be 
calculated (for example, the equatorial coordinates of the comet at time of 
exposure). An "Additional-Notes" file provides detailed notes on the plates from 
the logbook that are not included in the notes field of the Full.csv file.  

Description of the columns of the Full CSV file 
Record number - Record number in the catalog 
Plate series - HD 
Plate number - Identifying number in the series 
Date - The date the plate was exposed as recorded.  
Object - Halley's Comet 
RA - Right ascension of the plate center (usually blank)  
Dec - Declination of the plate center (usually blank)  
Length of exposure -  Exposure length (in minutes) 
Exposure Start - Start time of the exposure as recorded  
Exposure Mid - Mid-time of the exposure (if computed) 
Exposure End - End time of the exposure as recorded 
Time type -  Type of time uses (E.S.T.) 
Emulsion + Filter - Emulsion type and filter used (no filter used) 
Plate dimensions - physical size of the plates, in inches 
Observer - Recorded observer (J.C. Duncan) 
Location -  Location of plate when this catalogue was prepared: Yerkes 
     = Yerkes,  X = plate destroyed) 
Notes - Notes recorded in the log book.  Longer notes are in the Additional-
     Notes.csv file    

File prepared:  2022 October 12