Know-How

  • Tips for Choosing an Energy Rejection Filter for H-alpha-Observations

    The purpose of an Energy Rejection Filter is to prevent as much solar energy as possible from entering the telescope in the first place and thus avoid excessive heating of the etalon of an H-alpha filter. This is done most effectively by a filter in front of the telescope. At the same time, this prevents the air in the tube from heating up - the telescope remains close to the ambient temperature, and there are no air turbulences inside of the OTA due to temperature differences. If we look at the solar spectrum, it becomes clear that such a filter must primarily block visible light. Ideally, it reflects the solar energy energy instead of absorbing it and and does not heat itself up in the...
  • Important System Driver Update Information - For All QHYCCD Cameras

    Breaking news from QHYCCD: QHY - Important firmware driver upgrade 9/21 Based on an update notification of the USB chip, we added a new API in the firmware of all QHYCCD cameras between 2021.7.10 and 2021.9.4. According to the description, we were expecting that this modification would increase the stability of the USB link. Unfortunately, however, we have received feedback from our users that it can cause a random crash in single frame capture mode on some computers. These random events can occur after some minutes or some hours or even longer time frames. To test these reports, we changed back to the system driver release before 2021.7 and have confirmed that without this new API the random crashes disappear. In order to avoid this...
  • Comet Filters

    The two tails of the comets   The most impressive tail of a comet is caused by sunlight which is reflected and scattered by the dust trail of the comet - also called dust trail. In addition, there is often a gas tail, depending on the amount of gas emitted by the comet. This gas is ionized (excited to glow) by the energy of the solar wind. This ion tail shines preferably with the emission lines of OIII (501nm) and Cyan (511 and 514nm). If you want a better contrast for the comet in the sky, you must consider the following with the choice of suitable filters: There is no way to show only only the dominant light fractions of the dust tail (as with...

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