I. INTRODUCTION
The continuing program to identify UV sources in the galactic plane was first described by Lanning (1973), hereafter referred to as Paper I. Briefly, this two-color photographic survey was originally taken to support the Uhuru X-ray satellite with the anticipation of identifying the associated optical counterparts of newly detected x-ray sources located in the galactic plane. The survey employed the Palomar 48-in (Oschin) Schmidt telescope and was centered on the galactic plane with overlapping regions covering the galactic latitudes +/- 9 degrees, and extending throughout most of the northern plane (l = 0 - 227 ). Plates were double-exposed with one image in the UV (UG1 filter) and the second in the Blue (GG13). The telescope was offset between exposures separating the images by 12 arcseconds. The color difference was calibrated such that equal sized images were achieved for U-B = 0, with the exception of some calibration offset on a few plates. Thus, a larger image in the U filter suggests the presence of a bluer object as in the case of low-luminosity stars, white dwarfs, novae, CVs, normal early B stars, etc. This multi-color photographic technique has been described, for example, by Haro and Herbig (1955). UV bright sources in this survey are easily identified using this technique and typically range in U-B = 0 to U-B = -1.5.
The data presented in this study represent a careful visual examination of three plates from the survey. All sources described herein are the result of a general survey of the entire 43 square degree field on each of the Schmidt plates examined and do not necessarily correspond to previously discovered x-ray sources.
Positional errors for some sources listed in a previous catalog of this series resulting from an invalid scan header on an archived optical disk at STScI are also discussed in the Appendix.
Paper I provided a list of 82 UV sources identified from the examination of 17 plates in the survey. An additional 53 sources were presented in Paper II (Lanning and Meakes 1994) from the examination of 3 plates. Although the difference in total number of sources reported in Papers II and III might appear to vary significantly from that in Paper I, a review of the regions examined to date shows a clear trend in higher rates of detection of sources bright in the UV at the edges of the Galactic Plane, i.e. for plate centers at +6 deg. or -6 deg. latitude. It is very likely the majority of these sources are normal hot, early-type stars not suffering from the greater reddening effects experienced in the central regions of the plane. All plates examined in Papers II and III were centered at a galactic latitude of +6 degrees.
II. THE FINDING LIST
Table I contains the list of sixty ultraviolet objects found on the plates examined in this portion of the survey. Each plate was scanned in a raster pattern on a plate rack containing a stereoscopic microscope. The fields were overlapped slightly to prevent omission of potential sources at the edges of the microscope field of view. The blue magnitude and color for each source has been determined by visual inspection of the plates. Photoelectric measurements determined by Hoag et al. (1961) for galactic cluster fields were used to calibrate the magnitudes and colors of sources on the plates. For plates containing no galactic clusters, photometry provided by Blanco et al. (1970) and Giclas, Burnham, and Thomas (1971) was used. Owing to variations in plate balance and the general uncertainties of obtaining accurate visual estimates from photographic plates, the magnitudes and colors listed in the Table should not be considered accurate to better than +/- 0.5 mag. The survey was restricted to objects with m(B) ~ 10 or fainter due to problems of merged images for the brighter sources. The format of Table I consists of 1) the source number, 2) Right Ascension (equinox J2000), 3) Declination (equinox J2000), 4) estimated photographic blue magnitude, 5) estimated U-B color difference, and 6) corresponding identifications with other known sources and/or general notes. Source numbers follow the convention established by the SIMBAD(Sets of Identifications, Measurements, and Bibliography for Astronomical Data) database entries for Paper I. Sources have been listed in order of discovery on the relevant plates examined, not in order of right ascension.
The GS Astrometric Support Program (GASP) was used in the determination of accurate positions for sources listed in Table I. Positions were measured from images retrieved from the Space Telescope Science Institute collection of Guide Star digital plate scans. The images were compared with the fields on the two-color plates for source verification. The accuracy of positions from the Guide Star Catalog images has been estimated to be on the order of 0.2-0.8 arcsec (Russell et al. 1990), the variability believed to be the result of plate characteristics and edge effects. Positions listed in the table have, therefore, been rounded to the nearest 0.1 sec.
All sources were searched for possible correlations with previously identified objects using the SIMBAD database. A radius of 5 arcmin around each position listed in Table I was used in the search. References and identifications for all targets returned were examined and noted as appropriate in the table. The search was completed on a database updated effective January 1995.
Table 1
Finding List of UV Sources
Source No. RA(J2000) DEC(J2000) m(B) U-B
Lanning 136 02 01 31.7 +69 42 52.6 17.8 -0.8
Lanning 137 02 51 58.3 +69 29 45.1 10.5 -0.2
Lanning 138 02 31 45.1 +69 23 32.0 11.0 -0.3
Lanning 139 02 18 08.7 +69 09 00.5 17.0 -0.3
Lanning 140 02 23 57.1 +68 49 08.7 16.0 -0.3
Lanning 141 02 06 29.6 +68 28 02.9 17.5 -0.3
Lanning 142 02 28 50.0 +68 35 37.9 17.2 -0.7
Lanning 143 03 03 27.8 +68 29 54.1 16.5 -0.3
Lanning 144 02 30 35.7 +68 29 36.5 16.7 -0.5
Lanning 145 02 18 18.9 +67 02 25.4 18.0 -0.4
Lanning 146 02 38 07.8 +66 57 36.9 17.8 -0.5
Lanning 147 02 05 37.9 +65 59 36.0 18.0 -0.3
Lanning 148 02 59 20.1 +65 05 45.1 10.5 -0.2
Lanning 149 03 03 47.0 +64 54 36.1 12.6 -0.6 Note a.
Lanning 150 02 15 34.6 +64 53 22.2 16.0 -0.5
Lanning 151 03 00 56.7 +64 10 54.3 17.5 -0.6
Lanning 152 02 44 08.2 +64 06 35.9 17.0 -0.5
Lanning 153 02 29 19.2 +64 03 30.3 16.5 -0.4
Lanning 154 02 41 18.0 +64 00 14.2 16.2 -0.6
Lanning 155 01 18 55.7 +71 20 11.4 18: -0.3
Lanning 156 01 12 21.4 +71 11 22.0 15.5 -0.5
Lanning 157 02 18 21.4 +70 47 48.1 18.0 -0.8
Lanning 158 02 19 06.3 +70 08 39.8 16.5 -1.0
Lanning 159 01 55 10.9 +69 42 41.3 17.0 -0.3 Note b.
Lanning 160 01 21 57.1 +69 24 50.6 17.6 -0.4
Lanning 161 01 19 41.4 +68 51 10.8 18.0 -0.5
Lanning 162 01 28 50.5 +68 03 55.1 17.3 -0.3
Lanning 163 01 33 38.3 +68 03 32.7 16.5 -0.5
Lanning 164 01 42 39.9 +67 36 14.3 17.6 -1.0
Lanning 165 01 51 09.9 +67 39 31.3 13.5 -0.6 Note c.
Lanning 166 01 56 06.2 +67 14 45.5 18: -0.6
Lanning 167 02 18 18.9 +67 02 25.4 17.6 -0.8
Lanning 168 01 35 04.0 +66 43 30.1 16.0 -0.3
Lanning 169 01 32 42.9 +66 35 47.3 16.5 -0.2
Lanning 170 01 59 50.4 +66 37 57.5 17.8 -0.4
Lanning 171 02 14 52.9 +65 57 59.0 17.0 -0.5
Lanning 172 01 47 09.4 +65 38 39.5 18.0 -1.0
Lanning 173 01 36 45.0 +65 41 48.3 16.6 -0.6
Lanning 174 03 41 17.1 +62 42 03.1 16.8 -0.7
Lanning 175 03 59 51.1 +62 29 01.3 19.0 -0.6
Lanning 176 03 56 51.0 +62 26 20.0 12.5 -0.2
Lanning 177 03 51 15.7 +61 52 46.4 17.0 -0.5
Lanning 178 03 43 18.2 +61 37 18.0 17.5 -0.4
Lanning 179 04 06 59.5 +60 55 14.6 14.2 -0.1: Note d
Lanning 180 04 25 07.8 +60 29 06.8 10.5 -0.5: Note e
Lanning 181 04 25 05.2 +60 28 41.5 11.8 -0.3 Note f
Lanning 182 03 38 44.1 +60 30 56.4 12.0 -0.4
Lanning 183 04 23 08.3 +60 02 39.8 11.4 -0.4 Note g
Lanning 184 04 20 00.2 +60 05 21.8 11.0 -0.4
Lanning 185 04 19 28.8 +60 05 10.2 11.2 -0.4
Lanning 186 03 45 14.4 +60 11 57.5 17.0 -0.3
Lanning 187 03 36 08.1 +60 03 46.8 18: -0.5: Note h
Lanning 188 04 16 02.5 +59 44 02.4 17.5 -0.6
Lanning 189 03 37 52.6 +59 32 20.0 10.5 -0.3 Note i
Lanning 190 03 48 30.2 +59 43 17.1 17.5 -0.4
Lanning 191 04 04 23.8 +58 58 36.2 16.8 -0.3
Lanning 192 03 51 43.8 +58 45 04.1 16.5 -0.4
Lanning 193 04 22 46.1 +58 22 11.4 16.5 -0.4
Lanning 194 03 46 41.6 +57 28 29.3 17.4 -0.4
Lanning 195 03 45 38.1 +57 07 56.4 16.5 -0.2
Notes:
a) Lanning 149 is the 14 hour binary V664 Cas located in the planetary nebula
HFG1 (PN G136.3+05.5)
b) Lanning 159 may be variable. See text
c) Lanning 165 is the white dwarf WD 0147+674 = GD 421 (DA2/DAwk)
d) Lanning 179 is the central star of PN G144.1+06.1 = NGC 1501
e) Lanning 180 is the star BD+60 806
f) Lanning 181 is located in the same field as Lanning 180
g) Lanning 183 is the reddened OB star SS 14
h) Lanning 187 is the central star of PN G142.1+03.4 (see text)
i) Lanning 190 is identified as LS I +59 193; OB(^-) [incorrect ID in
published paper...should be associated with Lanning 189; HHL 11/06/95]
III. THE FINDING CHARTS
Finding charts for all sources listed in Table 1 are provided in Figs. 1-7. All the charts have been reproduced from the STScI GASP system. Images were retrieved from the guide star image archive and converted to postscript format. These files were then transferred to the Solitaire 8XP imaging system for reproduction by the on-site photolab. The scale for all charts is approximately 11 arcsec/mm, with a full field of 8 arcmin on a side. Each identified source is centered in a 20 arcsec diameter circle. In some cases, however, the circle has been enlarged slightly for the brighter sources, or in order to prevent the obstruction of a nearby field star which could be used for field identification. An arrow pointing to the UV source has been included for those sources in crowded regions or merged with close field stars. All charts are displayed with north up and east to the left.
IV. DISCUSSION
Some of the more interesting objects found are discussed below. Information on image characteristics or potential intrinsic properties of some of the sources listed in Table 1 is also provided.
-
Lanning 149: The position for this source coincides with the center of
the planetary nebula HFG 1 (PN G136.3+05.5) discovered by Heckathorn,
Fesen, and Gull (1982). They detected the nebula in [OIII]
interference-filter imagery showing it to be approximately 15 arcmin
in diameter, but asymmetric. No nebulosity was visible on the
two-color plate examined in this survey. The 14th magnitude central
star is noted by Bond (1994) as a reflection effect binary (V664 Cas)
based on the photometric variations of this short period (13h57m)
binary (Grauer et al 1987). The central star examined on the
two-color plate in this study was estimated to have a U-B ~ -0.6 and
a m(B) ~ 13.
Lanning 159: The color of this source appears slightly blue at U-B ~ -0.3 . The image is much brighter than other stars in the immediate field of view. However, on the Palomar Observatory Sky Survey (POSS) Blue print, the object is of comparable or slightly fainter brightness. The UV image of the candidate source overlaps with the B image of an adjacent star to the west. This overlapping star, however, is very faint on the POSS Blue print (near the plate limit), and noticeably redder on the Red plate, suggesting a small UV contribution, if any. Therefore, the UV identification of Lanning 159 is believed to be valid and suggests the source is probably variable. The object could be a nova-like source which was brighter in the UV at the time the two-color plate was exposed, or perhaps an eclipsing binary caught during eclipse allowing the blue component to dominate during the exposure. Neither case would be unprecedented. Paper I describes two such sources, Lanning 17, an apparent nova which was observed to be very blue on the two-color plate but was coincident with a faint red source on the POSS E plate, and Lanning 31, which was noted to be the eclipsing algol RY Aur observed during eclipse. The plate on which this source was detected was taken JD2440506.8440 (12 Oct. 1969 UT).
Lanning 165: This source is identified as the (m(B) = 14.17) DA2/DAwk white dwarf WD 0147+674 = GD 241 (McCook and Sion 1987, Greenstein 1984). The estimated blue magnitude on the two-color plate is only slightly beyond the estimated errors at m(B) ~ 13.5, and does not necessarily suggest the source is variable. This source has also been detected by ROSAT, RE J0151+673 (Pounds, et al. 1993).
Lanning 180: This source is identifed as AG+60 431 (BD+60 806). Normally, (as noted in the text) a source as bright as this object, m(B) ~ 10.5 is not given a value for the U-B color in this survey due to the uncertainty of accurate measurements for merged images. However, the color of the object on this plate appeared blue and was therefore given a U-B estimate of ~ -0.5:. The SIMBAD database indicates the spectral type is F5. Bidelman (private communication) confirms the spectral type identification from a Case survey plate, noting also that the star appears to be weak-lined.
Lanning 183: Bidelman (private communication) found that this object is SS 14 (Stephenson and Sanduleak 1977). The star is classified as OB(^-)r:w, i.e. a reddened OB-type star with weak Hydrogen emission. Spectra obtained by Shafter (private communication) with the grism spectrograph of the Mt. Laguna Observatory 1.0-m telescope and Schultz (private communication) with IUE support this classification.
Lanning 188: Coincident with the planetary nebula PN G142.1+03.4 (Acker 1992), the nebulous images on the plate definitely indicate a blue object on the two-color plate. The U-B is estimated to be ~ -0.5. However, no stellar source within the nebular image was evident. [incorrectly identified in published text; is really Lanning 187]
Three UV sources detected during the examination of plates in the current work represent recoveries of previously identified Lanning stars found on plates in overlapping regions. The source Lanning 3 in Paper I was listed as a strong UV source with U-B bluer than -0.8 and a m(B) ~ 18:, but was estimated in this study at m(B) ~ 17. Given the uncertainties noted, these differing magnitudes do not necessarily suggest the presence of variability. Lanning 24 was also recovered in the current work. The magnitude estimate in Paper I was given as m(B) 19: with a moderate UV excess, i.e. between U-B ~ -0.5 and U-B ~ -0.8. The estimate on the overlapping plate, however, places the star at m(B) ~ 16.5 and redder in color with U-B ~ -0.2 suggesting this source may be variable. The strong UV source Lanning 4 was recovered on the same overlapping plate as Lanning 24. Although the m(B) ~ 15.5 is within the quoted errors of that noted in Paper I, the U-B color on this plate is estimated at only ~ -0.3. A spectrum taken by Margon and Downes (1981) is described as exhibiting strong Balmer absorption.
Blanco, V. M., Demers, S., Douglass, G. G., and FitzGerald, M. P. 1970, Pub. U.S. Naval Obs. 21, 1 (2nd series)
Bond, H. E. 1994, in Interacting Binary Stars, ASP Conf. Ser. 56, 179
Giclas, H. L., Burnham, R., Jr., and Thomas, N. G. 1971, ``Lowell Proper Motion Survey. Northern Hemisphere. The G Numbered Stars'', Lowell Observatory, Flagstaff, Arizona
Grauer, A. D., Bond H. E., Ciardullo R., and Fleming T. A., 1987, Bull. AAS, 19, 643
Greenstein, J. L. 1984, ApJ, 276, 602
Haro, G. and Herbig, G.H. 1955, Bol. Obs. Tonantzintla y Tacubaya, 12, 33
Hoag, A. A., Johnson, H. L., Iriate, B., Mitchell, R. I., Hallman, K. L., and Sharpless, S. 1961, Pub. U.S. Naval Obs. 17 (part 7), 345 (2nd series)
Heckathorn, J. N., Fesen, R. A., and Gull, T. R. 1982, A&AS, 114, 414
Lanning, H. H. 1973, PASP, 85, 70
Lanning, H. H., and Meakes, M. 1994, PASP, 106, 38
Margon, B. and Downes, R.A. 1981, AJ, 86, 747
McCook, G. P. and Sion, E. M. 1987 ApJS, 65, 603
Pounds, K. A., Allan, D. J., Barber, C., Barstow, M. A., Bertram, D., Branduardi-Raymont, G., Brebner, G.E.C., Buckley, D., Bromage, G.E., Cole, R.E., Courtier, M., Cruise, A.M., Culhane, J.L., Denby, M., Donoghue, D.O., Dunford, E., Georgantopoulos, I., Goodall, C.V., Gondhalekar, P.M., Gourlay, J.A., Harris, A.W., Hassall, B.J.M., Hellier, C., Hodgkin, S., Jeffries, R.D., Kellett, B.J., Kent, B.J., Lieu, R., Lloyd, C., McGale, P., Mason, K.O., Matthews, L., Mittaz, J.P.D., Page, C.G., Pankiewicz, G.S., Pike, C.D., Ponman, T.J., Puchnarewicz, E.M., Pye, J.P., Quenby, J.J., Ricketts, M.J., Rosen, S.R., Sansom, A.E., Sembay, S., Sidher, S., Sims, M.R., Stewart, B.C., Sumner, T.J., Vallance, R.J., Watson, M.G., Warwick, R.S., Wells, A.A., Willingale, R., Willmore, A.P., Willoughby, G.A. and Wonnacott, D. 1993, MNRAS, 260, 77
Stephenson, C. B., and Sanduleak, N. 1977 ApJS, 33, 459
Russell, J.L., Lasker, B.M., McLean, B.J., Sturch, C.R., and Jenkner, H. 1990, AJ, 99, 2059
APPENDIX
Information provided by Bidelman (private communication) resulted in the discovery that 15 positions for objects listed in Paper II were in error. Investigation indicated that an incorrect header was associated with the scan of the Guide Star plate originally archived onto optical disk. The incorrect astrometric solution, based on the use of an incorrect origin point, was subsequently applied in the positional determination when centroiding the object. The average offset for positions in right ascension is 14.17 seconds of time, with no detectable trend in the numbers. The offsets in declination range from +6.56 arcseconds through zero to -6.85 arcseconds as one progresses from west to east across the plate. This is consistent with a rotation being introduced into the bad plate solution. For 12 of the 15 objects affected, m(B) ranges from ~ 20 to m(B) ~ 21. Of the remaining three sources affected, better positions already exist. These include Lanning 111, which is the central star of PN G093.4+05.4, Lanning 116, the 8th magnitude star HD201033, and Lanning 122 = Lanning 51 = WD 2117+539. The complete list of objects with incorrect positions includes Lanning 96, 97, 98, 99, 100, 102, 104, 108, 111, 113, 114, 115, 116, 119, and 122. Corrected coordinates are listed in Table 2. All sources from this survey published to date, with updated coordinates determined from measurement of the HST Guide Star plate archive, are available in tables provided on-line in the World Wide Web pages devoted to the two-color survey. These may be accessed via the URL http://www.noao.edu/noao/staff/lanning/uvsurvey/index.html. All published works related to the two-color survey, including finding charts, are available on this link.
Table 2
Previously Identified Sources--Updated Positions
Source No. RA(J2000) DEC(J2000)
Lanning 96 20 40 36.9 +55 26 47.5
Lanning 97 20 40 45.1 +53 03 46.1
Lanning 98 20 42 20.0 +51 42 14.4
Lanning 99 20 43 48.1 +53 58 14.0
Lanning 100 20 43 51.7 +53 13 25.8
Lanning 102 20 46 00.1 +55 04 14.7
Lanning 104 20 46 56.5 +55 21 20.7
Lanning 108 20 54 12.3 +55 04 09.1
Lanning 111 21 00 32.8 +54 32 35.5
Lanning 113 21 02 46.4 +55 30 18.5
Lanning 114 21 01 54.5 +51 38 56.6
Lanning 115 21 04 35.3 +55 57 39.4
Lanning 116 21 04 48.8 +55 35 15.9
Lanning 119 21 12 23.0 +55 55 24.6
Lanning 122 21 18 56.4 +54 12 38.5
UV Survey Intro Page