Doppler tuning unit for SM90 Telescope and Observatory: DurangoSkies.com

Doppler tuning unit for SM90	$345.00
[TMax 90]

Some events on the Sun, notably active flares and coronal mass ejections (CME), are extremely fast moving. If such features occur on the disc of the Sun, their high velocity towards the observer results in their wavelength being Doppler shifted shorter than Ha. If the velocity is high enough, this wavelength could be outside the passband of the filter and the feature would not be observable. The T-Max allows the user to de-tune the Solarmax slightly to bring such phenomena into better visibility.

All SolarMax series filters from 2002 to the present day, and most SolarMax 40's, have come with a T-max as standard equipment. Contrary to a widely held perception the T-Max does not act as a tuning device but actually de-tunes the filters towards the Blue end of the H-Alpha line. It accomplishes this by changing the angle at which the light passes though the Etalon. Situated directly behind the SolarMax unit it is comprised of two black plates, set screws, and a knurled knob that, when turned, causes the two plates to separate. One remains parallel to the telescopes objective cell while the other creates an angle between the etalon and the objective cell. This angle is less than .7 degree. Any more of an angle and the filter will be removed completely off band. Within the T-Max range of movement there will be the optimal view, further tilting, in either direction, than the T-Max allows will not result in a better view.

If your SolarMax or AS1 series filter was delivered before the T-Max was available you can easily add this accessory by calling Coronado with the serial number of your filter. Helios I, ASM, and SMN series filters will not accept the T-Max.

Other uses for the T-Max: When double stacking two filters to lower the bandpass you will also require a second T-Max. This T-max will be used to remove any ghosting caused by the interference between the two energy rejection filters (ERF) out of the FOV. The T-Max closest to the observer will still be used on for de-tuning the filter. When double stacking a PST with a SolarMax 40 you will also need to use the T-Max for the same reasons.

"I received my T-MAX TUNER on Monday. Of course it was raining all day. Today I set up my SolarMax mounted to a Megrez 80 and the T-MAX TUNER. What a great accessory. I am now able to tune the filter for astonishing detail of prominences as they fly off the sun. To me this is a must have item." - Bill Falcone