Venus transit on 6.6.2012 – Hvar solar telescope observations

Written by Jaša Čalogović Wednesday, 06 June 2012 16:37

H-alpha, Venus transitDuring the morning hours of 6.6.2012, Hvar Observatory double solar telescope was able to observe and record the last Venus transit in this century. Photospheric and chromosperic telescope were used from the sunrise (3:44 UTC) till the end of transit (4:55 UTC). Unfortunately for those who missed it, the next Venus transit will not occur until December 2117. Observer was Nikša Novak and data were processed by Jaša Čalogović.

> Short movies generated from the telescope data can be accessed here


Online talk - Can solar activity and cosmic rays save us from global warming?

Latest news

Written by Jaša Čalogović Sunday, 01 April 2012 23:02

talk calogovic_IACAll those interested in solar influences on climate and especially in the contended topic about link between the cosmic rays and clouds can now online access the talk of Jaša Čalogović held on IAC, La Laguna on 15. March 2012.

> Click here for the abstract and video of the talk


Solar irradiance, cosmic rays and cloudiness over daily timescales

Latest publications

Written by Jaša Čalogović Tuesday, 20 December 2011 00:00

thumb cloudsAlthough over centennial and greater timescales solar variability may be one of the most influential climate forcing agents, the extent to which solar activity influences climate over shorter time periods is poorly understood. If a link exists between solar activity and climate, it is likely via a mechanism connected to one (or a combination) of the following parameters: total solar irradiance (TSI), ultraviolet (UV) spectral irradiance, or the galactic cosmic ray (GCR) flux. We present an analysis based around a superposed epoch (composite) approach focusing on the largest TSI increases and decreases (the latter occurring in both the presence and absence of appreciable GCR reductions) over daily timescales...

 GRL website


Cosmic ray modulation by different types of solar wind disturbances

Latest publications

Written by Mateja Dumbovic Tuesday, 20 December 2011 00:00

SWD-CR-dumbovic-2011The amount of the galactic cosmic rays (primarily protons) that hit the Earth is greatly influenced by the solar activity. On the short time scales it can be substantially reduced by the passing of solar wind disturbances, such as interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs). The resulting short-term cosmic ray depressions are generally denoted as Forbush decreases. We present a systematic statistical study of various aspects of Forbush decreases. The analysis is based on ground-based neutron monitor data and the in-situ solar wind data recorded by the Advanced Composition Explorer (ACE) satellite and provides empirical background for physical interpretations of short-term cosmic ray modulations.

 read publication (A&A website)

First announcement - XIth Hvar Astrophysical Colloquium

Latest news

Tuesday, 01 November 2011 03:12

binary starAt the occasion of the 40th anniversary of Hvar Observatory, XIth Hvar Astrophysical Colloquium: The Most Mysterious Binaries: Significance for Astrophysics will be organized from 2. to 6. July 2012  in Town Loggia, Hvar, Croatia. The scientific sessions will include topics:  Binaries as Tests of Stellar Evolution Models, Extreme and Unusual Binaries, Rapid Phases of Binary Evolution, Be Binaries and Highest to Lowest Mass Binaries. Deadline for a regular registration is 15. March 2012 (150 EUR) where after this deadline the late registration will be charged with 200 EUR.

 first announcement
 further details & registration 


First announcement - XIIth Hvar Astrophysical Colloquium

Latest news

Tuesday, 01 November 2011 03:12

thumb sun_heliosphereAt the occasion of the 40th anniversary of Hvar Observatory, XIIth Hvar Astrophysical Colloquium: The Sun and Heliosphere will be organized from 3. to 7. September 2012  in Town Loggia, Hvar, Croatia. The scientific sessions will include following topics: The Solar Photosphere - Theory and Observations, The Chromosphere - Link between the Photosphere and Corona, Eruptive Processes, CME's and Energetic Particles, Solar-terrestrial Connection and the Heliosphere, Observing Techniques, Data Analysis and Archives.
 pdffirst announcement
 further details & registration 

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  • Solar Activity Level: LOW
    Solar Activitly level is LOW.

    2-day Flare Index (entire sun): 6.7
    X-Class Flares: 0
    M-Class Flares: 0
    C-Class Flares: 5
  • Most Active Region: NOAA 12529
    The Most Active Region is NOAA 12529.

    2-day Flare Index: 3.9
    X-Class Flares: 0
    M-Class Flares: 0
    C-Class Flares: 3

    Region Statistics for Today
    Mount Wilson Class: b
    Area: 0850
    Nummber of Spots: 19
    Flares: C1.8 (07:40)

    Region Statistics for Yesterday
    Mount Wilson Class: b
    Area: 0820
    Nummber of Spots: 16
    Flares: C1.1 (01:36) C1.0 (18:28)


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