English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Pro

Presents the zaia usage as premium feature

ZAIA

Presents AI Discovery search usage as a premium feature

AI Discovery

Presents AI Discovery explain and summary usage as a premium feature

Content Analysis

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Presents the pdf analysis as premium feature

PDF Analysis

1500 Top-up

3000 Top-up

Zendy Basic

2500 Top-up

Zendy Unlimited

Presents the access of premium content as premium feature

Premium Content

When characterizing a high resolution echelle spectrograph, for instance forprecise Doppler work, it is useful to observe featureless sources such asquartz lamps or hot stars to determine the response of the instrument. Suchsources provide a way to determine the blaze function of the orders,pixel-to-pixel variations in the detector, fringing in the system, and otherimportant characteristics. In practice, however, many B or early A stars do notprovide a smooth continuum, whether because they are not rotating rapidlyenough or for some other reason. In fact, we have found that publishedrotational velocities and temperatures are not a specific and sensitive guideto whether a star's continuum will be smooth. A useful resource for observers,therefore, is a list of "good" hot stars: bright, blue stars known empiricallyto have no lines or other spectral features beyond the Balmer series withminima below 95% of the continuum.  We have compiled a list of such stars visible from Northern Hemispheretelescopes. This list includes all stars listed in the Yale Bright Star Catalog(Hoffleit & Jaschek 1991) as being single with V < 5.5, v sin i > 175 km/s, anddeclination > -30, and many other hot stars that we have found useful forcalibration purposes.  The list here of "bad" stars may also be of interest in studies of hot,slowly rotating stars.

Some Bright Stars with Smooth Continua for Calibrating the Response of High Resolution Spectrographs