1. INTRODUCTION

A general study of the manner in which interstellar dust is distributed throughout spiral galaxies was begun in 1969. A preliminary report (Lynds 1970) outlines the regularities found in the dust distribution for late-type spirals and a second progress report (Lynds 1972) confirmed the conclusion that the dust lanes of a galaxy clearly define the basic spiral pattern of the object. The second report emphasized the relationship between the Interstellar dust and the bright HII regions detected in H interference-filter photographs of the spirals.

This atlas contains the photographs obtained with the University of Arizona's 2.3-meter telescope during the course of this study. Table 1 lists the objects observed and the exposure times of the photographs, which were taken with a Carnegie image tube with various red interference filters or with a broad-band blue filter. All of the interference filters had half-widths of about 75 Å centered on the wavelengths identified in the table. The blue filter, CS5-61; had an effective wavelength at about 4300 with a half-width of about 1000 Å. Two different image tubes were used; the first had a red sensitivity greater by more than a factor of 2 than the second; the exposure times of Table 1 reflect this. Approximately equal exposures were made for the ON and OFF H photographs; however, the red sensitivity of both image tubes dropped off rapidly between 6563 and 6782. The plates were calibrated with a step-wedge recorded through the image-tube system and detailed studies of the colors and emission measures of selected objects are now in progress (Lynds, Furenlid, and Rubin 1973; Lynds and Furenlid 1973).

Most of the photographs of galaxies in this atlas are accompanied by a sketch which is designed to reproduce only the location of the heaviest dust lanes (pencil) and the brighter HII regions (ink marks) of the galaxy. Each galaxy has a few special comments which follow and the reader is directed to the remarks on NGC 4321 which is used to illustrate the general systematics of the distribution of dust and H II regions for the sample of galaxies contained in this study. As already stated (Lynds 1970, 1972), the dust lanes of a galaxy better define the basic spiral pattern than do the HII regions; the HII regions are, however, closely tied to the location of the dust.

All of the photographs are reproduced to the same scale of 1".9 mm^-1. East is to the left of north; and north is at the top, unless otherwise noted on the prints.

TABLE 1
ATLAS GALAXIES

EXPOSURE TIME (minutes)
OBJECT
NGC	6563	6607	6650	6782	Blue
NGC 0151	60	...	60	...	4
NGC 0157	...	45	...	45	5
NGC 0613	44	...	44	...	4
NGC 0972	60	...	60	...	4
NGC 1087	...	50	50	...	3
NGC 1097	60	...	60	...	4
NGC 1300	60	...	60	...	4
NGC 1784	...	60	...	60	4
NGC 2146	15	...	15	...	3
NGC 2403	60	...	60	...	2
NGC 2532	46	...	46	...	3
NGC 2655	45	...	45	...	3
NGC 2782	...	60	...	90	3
NGC 2903	30	...	30	...	3
NGC 3351	60	...	...	...	5
NGC 3368	15	...	...	...	1/6, 1
NGC 3623	20	...	...	...	1/2, 5
NGC 3627	20	...	...	...	1/4
NGC 3646	60	...	60	...	3
NGC 4303	...	30	30	...	3
NGC 4314	45	...	45	...	1/4
NGC 4321	...	45	45	...	3
NGC 4579	...	45	...	45	2
NGC 4736	8	...	30	...	8
NGC 4826	10	...	...	...	1/4, 1
NGC 5194	30	...	30	...	1/2
NGC 5195	25	...	25	...	1/2
NGC 5383	...	45	...	45	2
NGC 5713	...	45	45	...	5
NGC 6118	30	30	...	...	2
NGC 6181	...	30	...	30	3
NGC 6207	20	...	...	...	...
NGC 6340	...	45	...	45	2
NGC 6503	30	...	...	...	...
NGC 7013	47	...	...	...	3
NGC 7137	45	...	45	...	3
NGC 7177	50	...	60	...	3
NGC 7479	...	60	...	66	5
NGC 7625	...	60	...	60	5
NGC 7723	...	60	52	...	4
NGC 7741	60	...	60	...	3