IanL

Where stellarium control is lacking is that I can't initiate a slew/sync from the mouse but rather have to fumble around hitting ctrl key combinations.

+1 for that Chris; I found it a bit of a hassle doing the initial set-up between EQMOD/StellariumScope/Stellarium, but once I figured it out, it works reliably. Might be easier for beginners if there were fewer things in the installation and config process, but frankly when you're paying $0 for such good software it's not the end of the world. (Plenty of paid-for software has caused me far more issues down the years).

I concur that the only thing I would really like to change is the ability to either choose my own slew/sync keys in Stellarium. Trying to find ctrl-number key in the dark on a small laptop keyboard is not ideal. Either a key-remapping utility or even an on-screen set of controls that one could drive with a mouse would help on that front.

One thing I have been planning to to for over a year (but not got round to) is to try this:

http://www.autohotkey.com/

Apparently it allows macros to be created to switch applications and automate keystrokes, mouse input and joystick (and I would assume by extension gampad) control. I will see if I can find a way to link my X-box controller buttons to push the relevant ctrl-key combinations to Stellarium.

Actually, here is an interesting article about how a supernova could affect life on Earth:

http://www.space.com/4814-risk-earth-supernova-explosions.html

Basically the upshot is that if it was close enough, or one of the rare 'super luminous' types of supernovae at a greater distance, prolonged exposure to the additional blue light (for maybe six months) during periods when it should be dark could seriously disrupt the biological rhythms of mammals, and thus disrupt ecosystems in unexpected ways (at least in the short term).

Well, a few calculations on this...Type II supernova at 640 light years giving 10^46 Joules during a 10 second core collapse is 10^45 Watts. This is radiation at all wavelengths similar to that from a nuclear bomb. A negligible one per cent creates the neutrino driven Baryon expansion, the rest of the energy flashes out into free space and the intensity on a sphere at a given radius can be calculated.

The intensity at the Earth is 2.5*10^6 Watts per sq.m. for 10 seconds. Maybe as much as one half will be thermal radiation. An online figure quoted for the ignition of e.g. dry vegetation for the initiation of fires after a nuclear weapon explosion was 125 Joules per sq.cm. It looks like we may get ten times the dose needed to start fires across much of the land mass. Needless to say we would not want to be observing this event so the best place to avoid the thermal radiation is at the USA base on the south pole. I always wondered why they had so many people down there! They could well be wasting their time though. I have no information on the effects of the massive doses of gamma radiation which will pass through the Earth shield and there may be significant refraction of the thermal radiation over the polar horizon. Well, this is my brief analysis and I am not an expert on supernovae. I just wonder how much warning we may get?

Can you set out your calculations in a bit more detail? The assertion that the energy from a type II supernova at 640 light years distance would set fire to vegetation on the Earth's surface, insta-gamma-ray barbecue, etc. doesn't seem right to me. E.g. We've already calculated (and shown our workings) that the visible light component of Betelgeuse going supernova would be similar to that of the full Moon, albeit more dazzling due to being a point source rather than spread over half a degree.

Thus the amount of radiation at other wavelengths must follow the same rule in terms of intensity drop-off with distance. So light and any other forms of radiation would be far less intense than the noon-day sun at the equator, and vegetation there doesn't spontaneously combust as a result of being out in the Sun. I suspect that your maths is faulty but it would be good to understand why (or have you prove your point if you are right.)

From what I have read, a type II supernova at 100 light years distance would pose no threat to life on Earth, but one at a distance of about 50 light years would have some seriously bad effects (like destroying the ozone layer). So at 640 light years, we aren't going to be in any danger.

I think the problem with seeing it early after the collapse would be the inability to resolve detail through our atmosphere. Perhaps for a couple of months it would just appear as a bright point?

Well if we went for the three months before it fades scenario, then at the end of that the remnant it would be about 2.5 arcseconds so would probably look stellar unless you had fantastic seeing, but in the next three months it would grow to 5, so I reckon you'd be able to spot the evolution of the shape almost immediately it starts to fade and by the end of the first year it would be really obvious. Trouble is, it could be tonight or in a million years, nobody knows!

Just for comparison, within 2 years it would be the apparent size of Mars at a good opposition, and within 5 years it would be the apparent size of Jupiter. I'd imagine it would be fairly bright and easy to see/image due to it being close, especially early on since the hot material expelled would be dense (though it may be that other factors would obscure this for some time, ask Brian Cox tonight!)

Well, if we said that M1 has expanded by about one arcsecond per year, then perhaps our new remnant might expand by ten arcseconds year year, being ten times closer than M1. Perhaps it would take a while before you could see much.

Now I really do have some good news for you on this one:

We can use the small angle approximation to turn an object's distance in to it's actual size as follows:

D = X * d / 206,265

Where D is the actual size of the object, X is the angular size (in arcseconds) and d is the distance.

We know M1 is about 6,500 light years away and that it is expanding at a rate of 1 arcsecond per year. So

D = 1 * 6,500 / 206,265

D = 0.0315 light years

So M1 is expanding at just over 0.03 light years per year.

If we assume that Betelgeuse produces a similar remnant, we can re-arrange the small angle approximation formula to work out how much a Betelgeuse remnant would expand per year, as follows:

X = D * 206,265 / d

X = 0.0315 * 206,265 / 640

X = 10.16 arcseconds per year

So the answer is YES! With a pretty modest instrument (even a pair of binoculars) you would easily be able to see the expansion of the remnant, pretty much from the point where the main supernova had dimmed enough to allow it to show up.

I stand corrected, Wiki says -12 for two to three months, which is full moon like you said above. On the other hand, all that light will be originating from a single point rather than the disc of the Moon, so it will (I suspect) appear an awful lot brighter to look at directly in darkness, even though it doesn't provide much more illumination. (Still a full moon and a supernova out at the same time would make it really bright, if not exactly daylight).

I havnt seen stargazing live (ever) but people in my office have been quizing me about this, i honestly do not believe that it will bright enough to light up the sky.. Plus it may not happend for many many years...

And like said above i like it where it is

your guys might find this interesting, its the last naked eye supernova recording

http://en.wikipedia.org/wiki/SN_1604

SN1604 estimated to be about 20,000 light years away. Betelgeuse is about 640 light years away. The intensity of a star follow the inverse square law (since the area of the sphere illuminated by the light from the star squares with distance).

Assuming that both SN1604 and Betelgeuse put out a similar amount of light when they went/go supernova, then Betelgeuse will be 976 times brighter than SN1604 was. SN1604 was brighter than everything except Venus, and visible during the day for three weeks.

It is absolutely not an exaggeration to say that Betelgeuse going supernova will be like having a second sun, and if it happens during northern winter, there will be no darkness for the best part of a month.

Also liking that pier. Do you have a thread on here or a link to any details of how you built it?

Bear in mind the software relies on the g-sensors to work out the orientation of the phone, and may also rely on a magnetometer to act as a compass.

The g-sensors may or may not be that accurate for pointing depending on the quality. Mine were okay on my HTC Desire (old phone now) for about six months, it certainly showed the relevant part of the sky as you waved it over your head. After that they became rather erratic. I used Google skymap (free if it is still available) which does much the same as other planetaria. Sometimes it would work fine, others it would not have a clue where you were pointing. Occasionally waving the phone around you head randomly would sort it, but not always.

If the software relies on the compass/magnetometer function in any way, then it may well be sent off course if you bolt it right next to a big metal tube/tripod, don't know if this software does or not, but easy enough to test out.

I suspect that the simple attachment answer might be some sort of car/satnav cradle to hold the phone and bodge it to the side of the scope somehow. You could probably pick one up of eBay for peanuts to match your phone and bodge it. You might be able to lash that up to a spare finder bracket somehow.

I would just think about:

- Having some means to ensure the phone definitely stays in the cradle, e.g. a couple of cable ties around the whole thing at the start of each session and cut them off at the end.

- Ditto for the phone cradle to the scope, e.g. a short tie of some sort in case it becomes detached.

The last thing you want is for your phone to fall on the floor in the dark, especially on to a hard surface. It could end up at all sorts of angles over the course of a night so give it a good workout in the day (on a carpet) to test.