Ags

Wrong thread - this is the one-scope thread 😀 Maybe I would go for a C5 and reducer.

Do I get to have a barlow or two as well? I guess it would be my Nirvana 16mm. I use it as a planet / lunar eyepiece in my Mak, and it is also the ideal exit pupil for DSOs in the Mak, and it works well as a finder eyepiece in the ST80. I found this one easier to answer than the one-scope thread.

I thought about a #23A or #25, but even though they are a bit brighter they are really only adding atmospheric dispersion back in. I am looking to go the other direction to a full Near IR filter instead. The other reason for the #29 is that I hope it will function as a low-tech H-alpha filter for DSOs. No it won't be perfect, but it will work better than the #25 for this. If I add an IR-block to the train, the #29 will be almost like a 70 nm H-alpha filter and as an added bonus will work at F2.0 when mounted behind my Nifty Fifty. In the old film photography days, the Wratten #29 was the filter used for H-alpha regions... I'm also hoping it will tighten up the stars in my ST80.

Go back to just one scope? The question doesn't make sense to me. It's like going back to just one eyepiece 😃

I found a mad new method to get the planet on the chip. After switching from eyepiece to camera I could not see the planet. I presumed it was simply out of focus so started dialing the focus knob. Eventually I was so far out of focus that the edge of a huge disk expanded into the field of view - the sensor was picking up Jupiter so defocused that the disk was probably 5 times bigger than the chip. The sensitivity of the ASI 178 is phenomenal! Anyway, once I saw the faint disk it was simple to improve the focus and move the scope incrementally to the center of the defocussed disk.

Jupiter 2019-07-30 21:15 UTC If you take a look at my previous Jupiter pics (taken with a Wratten #8 filter) a couple of things stand out: the equatorial bands are broadened and the moons are stretched into vertical smudges. I suspected this was atmospheric dispersion the Wratten #8 was not correcting sufficiently. Today I picked up a Wratten #29 (dark red) for the princely sum of EUR 15 that I thought would improve matters. Seeing was very bad tonight, and Jupiter is too close to a tall building, but I shot a 3 minute sequence. 2 minutes is the limit for Jupiter but I guess with just a low resolution 102mm scope I can get away with a bit more. As the Wratten #29 is very dark I increased the exposure from my usual 12ms to 33ms. Lookit the moons! For comparison, here is a Wratten #8 image on a night of better seeing:

A humble GSO Wratten #29 1.25" filter. But not delivered by the postman, I bought it in a real-life bricks-and-mortar astronomy shop!

I tried photographing the North America Nebula last night with my available equipment: ST80, ASI178MM, Wratten #8, AZ-GTi (in Alt-Az mode). This is a dress rehearsal for my upcoming attempt with my new (acquired today) Wratten #29 filter! I used DSS in mosaic mode to stitch several panels together in a kind of panorama. If you squint you can just about see Mexico 😃 Its 150 20 second subs in five panels. Gain was set to 99. Next time, now I know the stars in the area, I will just go straight for the Mexico region and not do a mosaic.

It always slews in completely the wrong direction when you are setting up goto.. After it has finished it's misguided slew, just loosen the clutches, point it at the moon and click the finish alignment option. Go-to operations after that are fine. Incidentally the Moon is the hardest object for a go-to system to find - it's precise absolute position varies from hour to hour. For the same reason the Moon is a bad choice as an alignment star. For the Moon and planets I just point the scope at the target and click point-and-track, I don't set up goto.

I have a new issue that my AZ-GTi points and tracks just fine, but after a few minutes of reliable tracking slews downward (in AZ) by about half a degree.

Set local latitude to 90 North and keep it in alt az mode?

Glad I found this thread as it confirms what I was seeing. I was out tonight with my teen grand-kids showing them Jupiter. How lucky the GRS was dead center and a shadow transit was in progress. I'm going to have to start using higher magnifications again - my eyes struggle with the 0.7mm exit pupil, but I bumped up the magnification from my usual 80x to 130x because I felt their eyes could manage it, and was surprised to see a tiny dark dot on the NEB. The first shadow transit I have seen in a while! Real enthusiasm around the scope, the two teens were pointing out different features to each other and taking their time to get the best view.

I saw them in green light visually today. No-one else could see them, but I picked them out on two occasions. Tried again after a couple of hours and could not see them at all, maybe seeing deteriorated... Hopefully they will grow!

@Philip R did you get a chance to weight the OTA?

Best thing to do is take a pair of binoculars to a dark sky site.

I found a good patch of seeing in a later sequence.

That's beautiful!

I discovered Sharpcap can do captures with a time limit rather than by a frame count, which is very useful to know! The best seeing was in the first minutes after I started shooting, after a few minutes thermals from an apartment block got too bad. There was thin cloud that made Jupiter disappear from the screen periodically. This might be my last Jupiter of the year - it is being lost in the twilight for me now (the south western sky is blocked for me). 30% of 6000 20ms frames stacked. Skymax 102 - ASI 178 MM - Wratten #8 Filter - Sharpcap and AS!

It's pretty good. You can go up to 200x on some targets, but this Jupiter season I have been using 80x as the larger exit pupil suits my eyes better (at 200x all I see is floaters - but the scope cannot be blamed for that). Your eyes may take higher magnification than mine can!

My initial idea was to use a "clean" nuke (like the Tsar Bomba, very big but relatively low fallout) to eject a large mass of debris into low Mars orbit which would then trickle into the atmosphere over decades. But that would make Low Mars Orbit a very hazardous environment (micrometeorites), so I felt something more controlled like a mass driver shooting pellets of compacted Phobos dust into a defined insertion orbit would be required. Phobos's escape velocity is only 40kmh and it's orbital speed is only 2.1 km per second. As a rough guess, a mass driver launching pellets at 1km per sec in the other direction (Mach 3) should be enough to put the pellet into an elliptical orbit that impacts Mars. The .220 Swift cartridge for example leaves the rifle barrel at 1250 meters per second, so Mach 3 for a mass driver doesn't sound crazy. Because we are shooting dust, possibly the mass driver could actually be like an ion drive accelerating electrically charged dust particles? Another reason to not nuke Phobos is if the atmosphere does not respond as expected to the additional dust, the mass driver can be switched off or modulated, but nuking is irreversible.

The 16mm will work well for all of those.

According to the following reference, a few tons of infalling space dust cause the Martian clouds: https://www.sciencedaily.com/releases/2019/06/190617125120.htm. These clouds can boost local surface temperatures by up to 20 Kelvin. Could we boost this effect by mass driving crushed dust from Phobos into the Mars atmosphere? 10 tons a day would already be a factor of 4 increase. All Mars terraforming strategies I know of first increase Mars temperature. That liberates the frozen CO2 deposits and leads to a positive feedback warming cycle as well as thickening the atmosphere. Regarding water, Mars has plenty, enough to cover one third of the planet in 100m of water. Atmospheric erosion is an issue - over geologic timescales. Needing to build an artificial magnetic field in the next 100,000 years doesn't sound like a big problem.

https://en.wikipedia.org/wiki/Moons_of_Mars#/media/File:PIA17352-MarsMoons-PhobosPassesDeimos-RealTime.gif

On my monitor the new version is more green, not less. But I like the pictures. There is a trick you can use to circularize the stars in your first pic. Load the picture into Gimp of Photoshop and duplicate the layer. Set the second layer to Darken Only, and then offset the second layer by a few pixels along the path of the trails. This will darken the start and end of the trails, making the stars rounder.

I use the Nirvana 16mm as a planetary and lunar eyepiece in a similar scope (Skymax 102) and it works very well indeed. But I have never used a Starguider so can't compare.