Merlin66

I had very similar artifacts with an older s/h ED80. By checking the orientation/alignment of the notches with the three collimating screws on the outer edge of the objective cell I found a 100% match. Just "easing" the screws and leaving overnight to settle fixed the problem. Touch wood, it hasn't come back in the last five years or so........

Keep us posted on the status of your SHG. You have achieved a lot with this project. Look forward to seeing your future successes.

From your image the secondary doesn't look centred to the focuser tube.... Look at the large outer circle, this is the inside of the focuser. The outline of the secondary should be circular and concentric with the focuser. Your secondary looks too far to the left and too low. Can you see this?

Just a hint to new SHG users..... How do you know if your slit gap is at the focus of the telescope? Normal method is to check the top/ bottom edges of the solar spectrum being recorded. When in focus, they should appear tight and crisp. A quick way to get you close.... Use a finder to look through the objective and check that the slit gap appears in clean focus. Helps during initial set-up.

I'm sure with your dedication and rigour you'll find a solution.

Vlaiv, First approximation.... 1/300 the diam of the ball when using the sun. I use the Hubble artificial star torch. I also made an adaptor for the Hubble pinhole plate to fit the old Foucault tester. I can now "play" with various lamps -Neon, Flouro, etc to check the spectrum.

Vlaiv, Suiter gives details of the glitter spot sizing in his "Star Testing Astronomical Telescopes", Appendix F, p 337.

I think you are achieving spectacular results with your set-up. Unfortunately I’m a little concerned about the single array achieving your goal. As you know the Doppler shift due to solar rotation ( and any Doppler associated with filaments and proms) will always be an issue taking spectroheliograms and the spectral spread may be too much for the single array. Reducing the dispersion may help? I look forward to seeing your continued development of your SHG. You’re certainly at the cutting edge. The current CMOS cameras have good QE, fast frame rates and probably an easier solution. 😐

The SolarChatForum has many images taken with different combinations of filters. well worth checking out.

Yeah, would normally be fixed. It allows the declination axis to be set (or read) for a specific target. Should read zero when pointing to the Celestial equator and 90 deg when pointing at the Pole.

On the Daystar site they have a series of solar images showing the improvement in contrast as the bandwidth reduces. I have many single and double stack images but not of the same AR etc.

You can re-set the ASCOM driver ( I assume you use something like CdC?) to J2000, this would then match your APT coordinates.

Any other results from the 3D LowSpec builders?????

Currently around 9 mag. The ARAS forum has details, and spectra: http://www.spectro-aras.com/forum/viewtopic.php?f=36&t=2674&p=15109#p15109

I think all the available Herschel solar wedges work pretty well. My first was a 1.25" Intes version, OK but when I got seriously into solar observing I purchased a 2" Baader Herschel cool solar wedge. It has worked well for me (got a SPOD in July for a sunspot AR2767 image!) for many years. Buy once, enjoy forever.

Robert, I can't see an EQMod/ EQascom driver on the Skywatcher site - only the Ascom driver for the later Synscan hand controllers.... Connecting the EQDir cable from the laptop directly to the mount bypasses the Synscan controller.

Ade, Just to evaluate the set-up can you temporarily set the laptop closer to the mount, bypass the USB3 cable/hub and connect the EQMod cable. I had some "issues" with a USB2 camera when connected to a USB3 port......may be this is similar???? (Was there sufficient power to the mount when you tried??)

Buil's excellent page: http://www.astrosurf.com/buil/nebula/nebula.html Planetary nebula: http://astrosurf.com/aras/nebpl/nebpl.htm#spectre (Italian, but understandable) Extract:

NR are aggravated by longer effective focal lengths - definitely worse with barlows/ powermates. A T2 tilter is the way to go. Some cameras are worse than others. I get with them with the ASI 1600 and ASI 174, very noticeable above f15.

Neil, adding a green or Continuum eyepiece filter behind the Solar filter, will enhance the contrast.

The higher baud rate seems to be used when the new USB port on the mount is used (Not sure about your EQ6-R), otherwise it's the 9600 .

Read the full story: https://www.telescope-optics.net/chromatic.htm

Valerio, Looks like you're having fun with BASS Project!! Looks very good. The last profile (H alpha) shows a possible issue. Notwithstanding your calibrations (RELCO), the Telluric bands are not a perfect match. (You could even have used them to add to your calibration.) All in all, I think you should be pleased with your progress in such a short period of time. Keep it up.

Alan, You can’t bin CMOS sensors. The best would be to expose and then bin in software.

Nigella, A couple of things. Yes, using an extreme narrowband filter suppresses any residual chromatic aberration... But not all scope are well designed to work in the UV - spherical aberration can be a real issue. Luckily stopping down the aperture helps. I use an ED80 f7.5 stopped down to 60mm to give me the "minimum" recommended f ratio. Better still would be a larger aperture, longer focal length stopped to f15 (or greater) Resolution in the CaK is 1.66 better than that in H alpha - based on the shorter wavelength - this effectively means a 60mm in CaK works like a 100mm in H alpha. The CaK images (significantly reduced for upload) show some results with my DIY Cak filter (1A bandwidth). Hope that helps.