Search results
Results From The WOW.Com Content Network
The filters are selected so that the mean wavelengths of response functions (at which magnitudes are measured to mean precision) are 364 nm for U, 442 nm for B, 540 nm for V. Zero-points were calibrated in the B−V (B minus V) and U−B (U minus B) color indices selecting such A0 main sequence stars which are not affected by interstellar ...
The amount of reddening is characterized by color excess, defined as the difference between the observed color index and the normal color index (or intrinsic color index), the hypothetical true color index of the star, unaffected by extinction. For example, in the UBV photometric system we can write it for the B−V color:
The typical axes for infrared color–color diagrams have (H–K) on the horizontal axis and (J–H) on the vertical axis (see infrared astronomy for information on band color designations). On a diagram with these axes, stars which fall to the right of the main sequence and the reddening bands drawn are significantly brighter in the K band ...
Using B and V filters in the UBV system produces the B–V colour index. [20] For 51 Pegasi, the B–V = 6.16 – 5.46 = +0.70, suggesting a yellow coloured star that agrees with its G2IV spectral type. [21] [19] Knowing the B–V results determines the star's surface temperature, [22] finding an effective surface temperature of 5768±8 K. [23]
A commonly adopted standardized photometric system is the Johnson-Morgan or UBV photometric system (1953). At present, there are more than 200 photometric systems. At present, there are more than 200 photometric systems.
UBV — Photoelectric Catalogue, magnitude and color of stars in UBV (Blanco et al. 1968) UBV M — UBV Photoelectric Photometry Catalogue (Mermilliod 1987) UCAC — USNO CCD Astrograph Catalog (UCAC1, UCAC2, UCAC3 & UCAC4) UGC — Uppsala General Catalogue (galaxies) UGCA — Uppsala Selected non-UGC Galaxies
The UBV catalog data format is in plain text. After uncompressing by unzip or gunzip it can be seen by any text viewers or by the online ADC viewer. Specifications for the catalog format are provided at the download sites. Original catalogue data, 1953-1985, 109293 objects (alternative reference is Mermilliod, 1987)
Apparent photographic magnitude is usually given as m pg or m p, or photovisual magnitudes m p or m pv. [3] [1] Absolute photographic magnitude is M pg. [3]These are different from the commonplace photometric systems (UBV, UBVRI or JHK) that are expressed with a capital letter. e.g. 'V" (m V), "B" (m B), etc.