VI/25 POSS Plate Data (Palomar Obs. 1960)
National Geographic Society and Palomar Observatory Sky Survey Catalogue of
Plates
Palomar Observatory
<National Geographic Society (1960)>
ADC_Keywords: Surveys ; Plate data
Description:
This catalog contains plate-center and observational data for all
plates of the National Geographic Society and Palomar Observatory Sky
Survey (POSS) and its Whiteoak Extension. The POSS proper consists of
photographic reproductions of red-sensitive (Kodak 103a-E) and
blue-sensitive (Kodak 103a-O) plates taken of 937 different fields
with the 48-inch Palomar Schmidt telescope, covering the entire sky
above -33 degrees declination. This southern limit was extended to
about -45 degrees by J.B. Whiteoak using the same instrument for a
series of 100 photographs that have come to be known as the Whiteoak
Extension; thus, the survey as a whole includes 1037 fields. This
version of the catalogue consists of plate information reproduced from
the Catalogue of Plates and plate information on the Whiteoak
Extension derived from file headers of the SAOPSS II tape (Lund and
Dixon 1973). The fields of the catalog are POSS number, modified
Luyten-Palomar (MLP) number, equatorial coordinates of the plate
center (B1950), limits of the right ascension on the plate in radians,
galactic coordinate of the plate center, number of SAO stars on the
plate, observing dates and times, the hour angles for the
observations, length of exposure, and seeing rating. The following
basic quantities were taken directly from the Catalogue of Plates:
POSS number, exposure dates and times, hour angles, seeing ratings,
and coordinates in sexagesimal units. The following derived quantities
were calculated at the ADC: MLP number, equatorial coordinates in
radians, right ascension limits, galactic coordinates, and number of
SAO stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
nposs.dat 150 1037 List of plates of the POSS-I survey
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See also:
VI/30 : Plate Centers of the ESO Sky Survey (Holmberg+ 1974)
VI/114 : Plate Centers of POSS-II (Read, 2004)
Byte-by-byte Description of file: nposs.dat
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Bytes Format Units Label Explanations
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1-4 A4 --- POSS *Palomar Observatory Sky Survey (POSS) number
6-9 I4 --- MLP *[1/1037] Modified Luyten Palomar (MLP) number
10-20 F11.8 rad RArad Equatorial coordinates (1950) of plate center
21-31 F11.8 rad DErad Equatorial coordinates (1950) of plate center
33-43 F11.8 rad RAradmin *? Minimum right ascension, R.A.(min) (1950)
44-54 F11.8 rad RAradmax ? Maximum right ascension, R.A.(max) (1950)
56-61 F6.2 deg GLON Galactic longitude (lII) of plate center
62-67 F6.2 deg GLAT Galactic latitude (bII) of plate center
69-71 I3 --- SAO *Number of SAO stars on the plate
73-76 I4 yr Obs.Y *Year of the observing night
78-80 A3 "month" Obs.M Initial Month of observing night
82-83 I2 d Obs.D Day on which the observing night began
85-87 A3 "month" fObs.M Final Month (JAN - DEC) of observing night
89-90 I2 d fObs.D Day on which the observing night ended
92-93 I2 h ObsE.h *? Start time of the red plate, hours
95-96 I2 min ObsE.m ? Start time of the red plate, minutes
98-99 I2 h ObsO.h *? Start time. of the blue plate, hours
101-102 I2 min ObsO.m ? Start time of the blue plate, minutes
104-105 I2 h EHA.h *Starting hour angle of the red plate, hours
107-108 I2 min EHA.m Starting hour angle of the red plate, minutes
110 A1 --- EHAew [EW]Direction of the hour angle, East or West
112-113 I2 h OHA.h ? Starting hour angle of blue plate, hours
115-116 I2 min OHA.m ? Starting hour angle of blue plate, minutes
118 A1 --- OHAew [EW]Direction of the hour angle, East or West
120-121 I2 min Eexp Length of exposure for the red (E) plate
123-124 I2 min Oexp *? Length of exposure for the blue (O) plate
126-128 A3 --- Erate *? Seeing rating of the red (E) plate
130-132 A3 --- Orate *? Seeing rating of the blue (O) plate
134-135 I2 h RAh Hours of right ascension, 1950 plate center
137-138 I2 min RAm Minutes of right ascension
140-141 I2 s RAs Seconds of right ascension
142 A1 --- DE- Sign of declination, 1950 plate center
143-144 I2 deg DEd Degrees of declination
146-147 I2 arcmin DEm Minutes of declination
149-150 I2 arcsec DEs Seconds of declination
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Note on POSS: Palomar Observatory Sky Survey (POSS) number.
This is the plate number of the red (E) plate as listed in the
Catalogue of Plates. This machine-readable version is ordered by
declination zones decreasing by roughly 6-degree decrements from
+90 to -42 degrees. Within declination zones, the catalogue is
ordered by increasing right ascension.
The right ascension given for the two polar plates, POSS 570 and 567,
describes the orientation of the plates on the sky. When the plates
are oriented so that the plate label is in the top left corner, the
right ascension describes the line from the plate center to the middle
of the bottom edge.
The POSS numbers for the plates covering the declination zone of -30
degrees contain an `S' in byte 1; the `S' must be included because
some of the same plate numbers are used elsewhere in the catalogue.
Records 938 to 1037 of the catalogue contain the plate information for
the "Whiteoak extension." Only red-sensitive plates were taken in the
extension, so certain data fields concerning the blue (O) plates are
left blank. See also Section 4 below.
Note on MLP:
Modified Luyten Palomar (MLP) number. The MLP number is from 1 to 1037
when the catalogue is sorted by an integer quantity defined to
increase sequentially declination zone in the manner described above;
therefore, the MLP number can be used as a record number for the
sorted catalogue.
Note on RAradmin:
Limits of the right ascension on the plate, in radians. The limits
were computed by solving the corner equation for each plate (Nagy
1980, ADC Bull. 1, 28; Lund and Dixon 1973PASP...85..230L 1973PASP...85..230L). The right
ascension of the plate center, R.A.(center), the minimum right
ascension, R.A.(min) and the maximum right ascension, R.A.(max), are
such that R.A(min)<R.A.(center)<R.A.(max). This means that if
R.A.(center) is near 0.0 radians, R.A.(min) can be negative, and if
R.A.(center) is near 2 pi radians R.A.(max) can be greater than 2 pi.
Note on SAO:
Number of SAO (cat. I/131) stars on the plate. This number is taken
from the output multifile tape of the Palomar Plate Assignment (PPA)
program described by Nagy (1980).
Note on Obs.Y:
The observing date for the exposure, expressed as the two dates
spanned by the observing night; for example, January 31 - February 1
for overnight starting January 31. The actual calendar date of the
start of an exposure must be inferred from whether the start time
(bytes 101-111) is just before or just after midnight.
In all cases, the red and blue plates were taken in succession to
allow a comparison as free as possible from variations.
Note on ObsE.h, ObsO.h:
Exposure start times in Pacific Standard Time for both the red (E) and
blue (O) plates. For the Whiteoak extension (MLP numbers 938 through
1037) bytes 92-102 are left blank.
Note on EHA.h, OHA.h:
Hour angles at the start of exposure for both the red (E) and blue (O)
plates.
Each exposure in the Whiteoak extension (MLP numbers 938 through 1037)
was started on the meridian to maximize the quality of the plate at
such low declinations (see Lund and Dixon 1973 for further details
concerning the exposure techniques). Hence, the last 100 records of
the catalogue list give the starting hour angle of the red plate as
zero. The fields for the blue plate are blank in these fields, as only
red plates were taken in the Whiteoak extension.
Note on Oexp:
For the Whiteoak extension, MLP numbers 938 through 1037, this field
is blank.
Note on Erate:
Seeing rating of the red (E) plate on a scale of one to five. For the
Whiteoak extension, MLP numbers 938 through 1037, this field is blank.
Note on Orate:
Seeing rating of the blue (O) plate on a scale of one to five. For the
Whiteoak extension, MLP numbers 938 through 1037, this field is blank.
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References:
Lund J., and Dixon R. 1973PASP...85..230L 1973PASP...85..230L
Nagy T.A., 1980, ADC Bull., 1, 28
(End) Julie Anne Watko [SSDOO/ADC] 12-Dec-1995