Merlin66

Louise, Re stars in slit gap.... You don't have an option to change target stars if your doing a specific observation. If there's a second star in the slit, as Lucas says you can just not select it for processing.

Louise, It's normally much easier to orientate the slit horizontal or vertically in the guide camera, this makes it easier to judge which way to nudge stars onto the slit and maintains the RA and Dec direction for acquisition. The slit gaps are 6mm long. The guide FOV will be constrained by the size of the visible slit plate and the focal length of the scope being used. You can roughly estimate your guide FOV by measuring the slit length on the guide image to get a scale mm/pixel. In my case due to the slit cover plate I have an opening/ FOV of 8mm x 6mm. Using CCDCalc (see image) this gives 9.8 x 7.4 arc min coverage. You want to achieve as good a focus as you can on the slit gap... then when positioning a target star it also should be in good focus (using the scope focuser).

Eric, I use the original Starlight Lodestar camera...

Louise, The FireCapture reticule can be adjusted in X-Y, to compensate for any misalignment. In my case the eFinder FOV is 105 x 79 arc min and the visible slit plate 9.8 x 7.4 arc min ( C11 @ f10) - See attached CdC screen The attached shows the typical PHD2 screen with slit overlay, slit positioned on target star and calibration/ guiding on target. Ken

Louise, Softy, softly.... The flip mirror in the book was used to replace the reflective slit option, which is now much more available.... Yes, for convenience and repeatability I have the length of the slit gap sitting along the Dec axis, so any PA issues would cause drift up/ down the slit - easy processed later. Think of the reflective slit plate as on on-axis guider... depending on your guide camera you should be able to view the whole of the available FOV around the slit. This allows you to use say PHD to nudge the target star onto the slit gap. Acquisition - I can use a 60mm finder with a ol' DMK41 as an electronic finder using FireCapture to accurately position a target star such that it's visible in the slit plate. (I also use EQMod to GOTO the target initially...) Doesn't have to be 100% aligned to the centre of the slit plate - you can set an off centre Cross wire to compensate.... Yes, I occasionally revert to plate solving - using the eFinder FOV, just to confirm the target. Plate solving a slit guider image doesn't work.....due to the secondary reflection images from the slit plate - you may be luckier than me, but never worked successfully for me. Summary: An eFinder with/ without plate solve to identify the target Align a cross wire overlay on the eFinder to drop the target onto the slit plate ( FireCapture has this ability) Nudge the target star into/onto the slit gap (I use the spectroscope feature of PHD) - try to get the target star close to the centre of the slit height to minimise aberrations. Start guiding......

The attached graph shows the impact of atmospheric dispersion.

Louise, Any updates?? Ken

Simon, Sounds good! All's well that ends well

Simon, I have the 1st edition, and that's pretty good. I like his style.

Simon, Maybe not.... The current SW Synscan manual still talks about serial connections.... http://www.skywatcheraustralia.com.au/wp-content/uploads/2016/12/HEQ5-EQ6-Hand-Control.pdf

The NEQ6PRO I bought had the dual SW saddle....the HEQ5 Pro was just the basic Vixen...maybe things have recently changed??

Hmmm, I disagree, being able to use either the Vixen or Losmandy dovetail gives opportunities to use various instruments with improved rigidity. Even without the belt drive mod, the HEQ5 Pro is quite capable.

Simon, Yes the saddle is part of the mount. According to FLO a dovetail is included... https://www.firstlightoptics.com/skywatcher-mounts/skywatcher-heq5-pro-synscan.html The ED80 is still available AFAIK, it's a doublet with an FL-53 element. I find it gives acceptable performance, but I only do solar imaging and spectroscopy. https://www.firstlightoptics.com/pro-series/skywatcher-evostar-80ed-ds-pro-ota.html

Simon, Can't answer all your questions.... my HEQ5pro is now almost ten years old. 1. Current Synscan is V4 2. Yes, Yes 3. Don't know, but I'd "assume" it's still the ol' D type where you need a Serial>USB adaptor (I use and recommend the KeySpan) 4. For visual, just! I use my HEQ5pro with an ED80 (roughly 5 Kg) and If I ever double up ie 2 x 5Kg it feels at it's limit - still functional - short OTA's should be OK. 5. I think the dovetails have always been extra. The standard saddle is a Vixen style. I replaced mine with an ADM dual (Vixen/ Losmandy). 6. I use a couple of Golf Buggy 20Ah SLA batteries (you'll need a 3 stage trickle charger - mine are now over ten years old and still going strong!) I also added a car computer converter (Maplins) 120W, 12V to 15V. Never had an issue, always enough power. 7. Yes, with short focus instruments (ie ED80 etc) 8. As I said mine is almost ten years old, been around the world twice and works well for me - no issues. Hope this helps. Ken

The laser and a centre spotted target on the objective will confirm the alignment of the focuser to the OTA. A Cheshire Eyepiece allows the objective elements to be confirmed as collimated with no tilt evident. Suiter in his "Star Testing Astronomical Telescopes", p122/123 shows the Cheshire reflection patterns for a 152mm f12 scope before and after collimation and states "Neither alignment gave noticeably different images at the eyepiece" Based on this the laser/ focuser alignment seems to be more critical.

There's a lengthy article on this subject in the usS&T, March 2020 issue.

Lucas/ Louise, The R value will always vary across the spectrum, even with perfect focus...always lower towards the blue.

Louise, The x10 in the X Axis.... I can only assume is due to an error in calibration settings - the wavelength entered and the display setting i.e. entered as angstrom but it thinks it's nm and then displays as x10 angstrom.......

Louise, Yes, SimSpec considers the CCD properties.... I'll look at that wavelength labelling issue and get back to you. The actual R value v's theory can vary due to numerous conditions. Also, remember, for a tilted slit plate the effective slit gap will be smaller than the physical - a 30 micron @15 deg tilt = 29 micron.

Louise, Under chart settings/ X axis "calibrated text" you need to set the units and description to Angstrom = "Wavelength ({0})

Joe, Which one? https://www.meade.com/solarmax-iii-solar-telescopes.html

Lucas, Congratulations on your successful build! Very promising results... What slit gap were you using? Have you measured a line FWHM and determined your R value? I used VSpec for many years but now use and recommend BASS Project. https://groups.io/g/BassSpectro There's a good solar spectrum resource http://bass2000.obspm.fr/solar_spect.php and a downloadable annotated solar spectrum http://bass2000.obspm.fr/download/solar_spect.pdf

https://pentax.com.au/products/70509/pentax-8-24mm-smc-zoom-eyepiece-for-spotting-scope but doesn't look like this "XL" version? https://www.rothervalleyoptics.co.uk/pentax-xl-8-24mm-smc-zoom-eyepiece-125.html

Current spectroscopic observations do not show a significant change across the visual spectrum...................

I use a Pentax XW 8- 24mm zoom for Ha observing. Great performance but it's BIG!! and heavy. Must try it out at night to see if it suffers the same performance issues as the current XF zoom.