Contact information

Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki

Ursa Astronomical Association

Sun - 16.4.2016 at 13.14 Espoo Observation number 81406

Visibility III / V

Tommi Ropponen, Ursa (Etelä-Suomi)

First picture:

Sun in CaK light in the afternoon 16.4. In my opinion, a rather large comma 2529 is visible, which was somewhere also called a heart commotion unofficially because of its shape. This has been described using a 1.25 "CaK filter with a bandwidth of about 8 nm. Therefore, the resolution is not in the same range as in dedicated CaK devices.

Last three pictures:

I ended up compiling a composite from the 2016 and 2017 Sun Photographs. The latter three images are thus collages in the H-alpha and CaK wavelength ranges. The blue portion in the composite is part of the first image of this observation. The rest consists of other observations I reported to the Sky Guard and the observations are named in the last collage image. The photos were taken between April 16, 2016 and July 9, 2017 in seven different sessions. Yellow and red samples have been imaged at H-alpha wavelength, i.e., at about 656.28 nm. The real color would be "deep red," but artistic freedom would rumble, so yellow and red were used as colors. The images are partially inverted so that both the surface structures and the filaments & protuts can be displayed in the same image without separate exposures. The blue part of the image corresponds to that of the Calcium K-line wavelength (about 395 nm) and its actual color is somewhere on the purple side - here, however, the image is colored blue. "Artistic freedom" has been used in the composition and the images are not depicted from the "angle" of the Sun where they appear in the collage. The sub-pictures also show small equipment scythes, processing differences and, of course, the effect of different seeings. The first composite is a "mere image", the second marks the shooting times of the various parts and mentions the observation entered in the Sky Watch, and the last is an approximate scale of the Earth (the image comes from NASA's Apollo-era freely available images).

Links to H-alpha observations compiled here:

Additional information
  • Observation target
    • Sun
    • Keskitaso
  • Seeing
    • Good
Technical information

CaK image: OTA 80/480 mm FPL-53 APO, Baader CaK filter 1.25 ", Baader astro solar membrane, ZWO ASI 178MM. 5000 frames, 25% stacked. FireCapture, Autostakkert, Photoshop CC. H- the specifications of the alpha images are presented in separate observations.

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