DayStar Quark Magnesium I b2 Line Filter
 DayStar Quark Magnesium I b2 Line FilterDayStar Quark Magnesium I b2 Line Filter 

DayStar Quark Magnesium I b2 Line Filter

£1,439.00✓ 2 year warranty


1x in stock shipped 1-2 working days

About this product

Model:  ds_quark_ep_mag
Part Number:  DSZMG

Explore highly magnetised and powerful excitations in the bright Magnesium I (b2) line.

For use on refractors of F/4 - F/8 focal ratio refractors.

This latest and likely the last wavelength offered for Quark reveals a whole new area of highly magnetised high energy in the bright 5172.8Å wavelength. The eye is most sensitive at this wavelength so the image is significantly brighter than calcium. Views show both plage and dark mottling of chromospheric network.  

Important: To prevent damage, we recommend using an Energy Rejection Filter on telescopes of 80mm aperture or more, or when tracking the Sun for long periods. This can be a UV/IR cut filter mounted before the diagonal. For apertures over approximately 120mm requires consideration of multiple factors, please contact us for advice.


  • For use on F4 - F/8 focal ratio refractors, the user needn't worry about configurations. Just insert in your diagonal, add an eyepiece and view.
  • Exact filter bandpass will vary based on final telescope application. No specific FWHM bandpass is designated, but it will be around 0.4Å or lower. The fully optimised design eliminates the need for any adapters. It's all combined in one lightweight eyepiece sized device.
  • The new, compact design configuration eliminates unnecessary components, weight and associated costs. We even reduced power consumption, so the Quark can now operate all day off a small, palm-sized optional battery pack.
  • Red and Yellow glass ERF filters will not pass Magnesium. Daystar also recommends use with a UV/IR cut filter for safety. Users need to purchase an Energy Rejection Filter specific to their telescope for safe operation.
  • Baffles have been added to increase contrast and AR coatings are optimised for the 517nm wavelength. We even reduced power consumption, so the Quark can now operate all day off an optional small, palm-sized battery pack.

*The QUARK* assembly is a product of DayStar Instruments, using DayStar Filters' Fabry Perot etalon technology.

Why Magnesium I (b2)-line?

Magnesium is a highly magnetised chemical on the sun.  The temperatures for energetic activity emitting this line are calculated to be extremely high. Spectroscopically, a line "splitting" called the Zeeman effect can be observed, whereas the dark absorption "splits" and occurs slightly above and below the typical wavelength where light from non-magnetised activity is absorbed. Strong absorption can be seen spectroscopically at 5172Å.

Views in Magnesium reveal plage, large scale magnetic structure and dark absorptive mottling of the chromospheric structure. The line is brighter than Calcium, Hydrogen Alpha and even Sodium. So it's going to be very easy for observers to see and the exposures will be very short.

The MgI b2 lines are a triplet.  Our target is the middle, 5172.8Å line.

Magnesium I b2 line Quarks will all be 0.4 or narrower.


REFRACTORS: For brief observing sessions using refractors with less than 80mm of aperture when not using a tracking mount, no rejection is necessary. Be alert for any rise in temperature of your telescope, diagonal, or Quark.

For telescopes under approximately 120mm of aperture, a screw in UV/IR cut filter can be employed in front of the telescope diagonal. The UV/IR cut filter reflects UV and IR light back out the front of the telescope, reducing temperatures inside.

Do not use a UV/IR cut filter with a telescope with an integrated rear field flattener or Petzval lens. The UV/IR cut filter must be the first optical element to encounter concentrated light.

Note that Magnesium falls outside the passband of some UV/IR cut filter designs, so always verify that a prospective UV/IR filter passes 397nm before purchasing.

Observing with over 120mm of aperture requires consideration of multiple factors please contact us for advice.

Example Images

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