In 1969, a two-color survey of the galactic plane was begun using the Palomar Observatory 48-in Oschin Schmidt telescope under the direction of Allan Sandage and sponsored by a NASA funded grant awarded to him. The intent of the survey was to support the Uhuru X-ray satellite (launched in 1972) in an effort to identify the optical counterparts of newly detected X-ray sources. The following briefly describes the survey, and the current renewed program continuing the examination and analysis of plates obtained in the original survey.
The survey comprises >100 Schmidt plates covering the majority of the Northen Galactic Plane and extending to ±9° from the center of the Plane. Each 14x14-inch plate (6°.6 on a side) was exposed through the Blue (GG13) and UV (UG1) filters with images offset by 12 arcsec. The exposure times were selected such that the U-B color was balanced at U-B=0 for equal sized images. The hotter the star, the bluer (larger) the UV image. Plates were taken primarily by Dr. Allan Sandage, Dr Jerome Kristian, Dr. Robert Brucato, and myself.
Although the initial survey of identified X-ray sources failed to produce correlations, it was felt a complete examination of the plates would still be useful for the potential identification of low-luminosity objects, white-dwarfs, cataclysmic variables, Be shell stars, etc. Many of the detected UV sources, would, of course, turn out to be normal hot stars. Lanning began the visual examination of the survey plates completing 17 during the course of the NASA funded program. The first catalog from this survey was published in 1973 (see references below). Objects were catalogued by the SIMBAD database with the designation LAN+source number. Following that convention, new sources have been listed in recent publications accordingly.
Lanning has resumed examination of the plates in the two-color photographic survey in 1992 (no active work on the survey was done during the period 1974-1992). To date (September 2004) the survey has produced 734 published sources ranging in color from U-B = 0 to U-B = -1.5, including seven cataclysmic variables, for example, Lanning 10 (V363 Aql) and Lanning 90 (V1776 Cyg), along with many verified and probable white dwarfs, Be stars, etc. A clear potential for identification of low-luminosity stars, binary systems and old novae is demonstrated. Several additional papers which will include sources detected on scans of ten additional plates are in work. The complete survey is comprised of 124 plates. To date, 48 plates have been visually scanned (or ~39% of the survey)[see the published works for an explanation of why visual scanning has remained the preferred method].
Contained within this WWW link are the papers published to date which include the tabular lists and descriptions of UV objects detected. Finding charts for all the UV sources are also provided. The published information includes...
Other related articles resulting from followup observations of selected sources are noted below...
|LIVE from HST - Lanning (Bio/Field Journal)||AstroWeb Info||International Year of Astronomy 2009|
|Howard H. Lanning|