The Ohio Sky Surveys
A Quick Review of the Data, 1965-1975
- the name given to the period of data collection,
processing and publication. There were seven surveys, and
a Supplement 2, each published in the Astrophysical Journal.
- the declination covered by the survey. Some surveys
did two sets of declinations.
- the range of right ascension. Not all surveys were able
to cover all 24 hours of right ascension.
- "beam @ RA", "beam @ dec"
- refer to beam size (the half-power beamwidth, which is the
width of the
main beam between the points at which the power has dropped to 1/2 of the
in minutes of arc), which varied slightly
with declination, and with an upgrade to the flat after Survey V.
- "start d/m/y", "end d/m/y"
- dates of data collection for each declination.
- "# scans avr"
- the number of scans averaged together to produce
preprocessed data at each surveyed declination. The telescope was
moved 20 minutes of declination at a time. Scans were at 0,
20 and 40 minutes of declination for each degree, at the then-current
- "integration time"
- period of time (in seconds) data was integrated or averaged
over to collect a data point.
- "RMS noise"
- the level in Kelvins of average noise. Sources
were considered "not detectable" when close to this level. (Don't
confuse Kelvins with Janskys!)
- the resolution level in Kelvins.
- "contour interval"
- the step value in Kelvins
- "2650 data", "612 data"
- the Ohio Survey also took data at 2650
MHz and 612 MHz for some surveys.
For All Surveys
- bandwidth = 8MHz
- scans 20' apart, except survey VI, decl +34 to +40 10' apart
- results from multiple scans except survey VI,
decl +20 to +30 single scans
For Some Surveys
- supplement 2
- taken from analog records in archives from 12/67-1/75 (?).
- "6th/3rd" drift removal
- each 2hr scan section fit with 6th order polynomial.
average scan (2 or more) fit by 3rd order polynomial
- "sd/10" drift removal
- running standard deviation to remove sources, then
integrate over 10 beamwidths (100'?) to obtain drift curve.
subtract drift curve, average all scans
compute and remove each point source response until
"arbitrarily close to zero"
then sum all point source responses
- (V) underestimation in flux density in surveys II,III,IV
- approx fix: increase fd of .16fu
- (VI and earlier) map corrections
- "this and previous surveys drawn on rectangular grid w/o correction
for precession, aberration, nutation. use Source list for accurate
position. each block was best fitted at corners for transformation
to epoch 1950.0 coordinates."
View Survey Data in Non-Table Format
The Ohio Survey Data
|decl max 1||38||37||20||0||63||41||0||1
|decl min 1||25||31||0||-16||40||0||-36||-11
|decl max 2|| || ||31|| ||-16||63||-25||
|decl min 2|| ||19|| ||-36||40||-31|| ||
|RA min (hr)||8||0||0||0||0||0||0||5;21
|beam @ RA||10||10||10||10||10||8||8||8
|beam @ dec||43||~40||~40||~40||42-50||~40||~40||
|start d/m/y|| || || ||1/70|| || || ||
|end d/m/y|| || || ||10/70|| || || ||
|# scans avr||2-5||2+||2+|| || ||1-2|| ||
|integ time sec||40|| ||9||9.3|
|rms noise K||.02|| ||.025||.023|| ||.023||.023||
|confusion K||.01|| || || || || || ||
|min source fu.||.37||.16||.16||.16||.18||.18||.18||.25
|contour int K||.025||.033||.033|| ||.033|| || ||
|contour int K|| || || || ||.041||.041||.041||
|2650 data|| || ||yes||yes|| ||yes||yes||
|612 data|| || ||yes?||yes?||yes?||yes?||yes?||
© 1996-7 Ohio State University Radio Observatory.
Originally designed by Point & Click Software, Inc.