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The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| Three colour observations of southern red variable giant stars
UBV observations have been made of southern red variables of varioustypes over a period of two years. Accurate light curves of about 35variables have been obtained; in many cases the observations coveredmore than one cycle. It appears that the M-type SRb and Lb variablesdefine a curved strip in the (B-V)-(U-B) plane. The mean (U-B) of thevariable stars is about 0.5 mag bluer than the (U-B) of the nonvariableK-type giants. The red variables may be divided into different groups:the carbon stars and the M-type variables, of which the M-type stars areagain to be divided into three groups on the basis of their colorvariations and consequently their loops in the two-color plane.
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Observation and Astrometry data
| Constellation: | Δελφίνι |
| Right ascension: | 20h36m41.92s |
| Declination: | +18°16'33.9" |
| Apparent magnitude: | 8.631 |
| Distance: | 251.256 parsecs |
| Proper motion RA: | -16.8 |
| Proper motion Dec: | -12.9 |
| B-T magnitude: | 10.038 |
| V-T magnitude: | 8.748 |
Catalogs and designations:
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