Gfamily

Many people will be aware of the Star Analyser diffraction grating, which fits into the optical path and allows capture of the spectral profile of stars, as an introduction to spectroscopy. However, the initial purchase price might put people off. So here's an affordable way of DIY-ing your own https://sites.google.com/view/star-analyser-alternative/home It doesn't provide spectra across the full field, but it'll do some... To be honest, I've not tried it out yet, waiting for some clear skies.

I understand it's the fuel and oxidant for the motors that's the issue, Hydrazine and N2O4 respectively. Yes, a A Nuclear power source could have been fitted, but in its orbit around the Earth/Sun L2 point it would be easy to get a comparable amount of energy from Solar Panels, but it's the propellant that's the issue. The key need is for something with enough momentum to provide adequate thrust, and although there are ion engines that don't need the same weight of propellant, I don't think we have ones yet that can provide the level of thrust needed to maintain station and control.

What's the issue with the 'ticking' I sometimes get when tracking? I'm not seeing any impact at the eyepiece, which tracks smoothly, but would this show up if I was trying to do any imaging? Is it a problem caused by balance, or are there any DIY maintenance issues that can be done to resolve the issue?

Episode 3 was good - and I read somewhere that Prof Cox thought it was particularly worthwhile. It relates the information that GAIA* has given us - https://www.bbc.co.uk/iplayer/episode/p09ybxpr/universe-series-1-3-the-milky-way-island-of-light * Over time, I suspect that this ESA mission will be give us more value than 99% of any of the others

Going back to an older post - Actually, we don't have access to the terrain, we only have what we can see, and from what we can see we draw a map. But we have the equivalent of aeroplanes that are crashing and burning because they've hit mountains we just can't see. So we know there must be something that we can't see. We can't we see it, so we call it dark. So then we try and work out what it is. However, if it was 'normal' matter it would have to behave as normal matter does - but it doesn't. So you either ignore the observations, or you come up with some other explanation for the observations. And that is the theory of Dark Matter

As a Podcast: Awesome Astronomy (closely associated with Astrocamp, the twice a year StarParty in S Wales) The Jodcast On Youtube Crash Course Astronomy (https://www.youtube.com/playlist?list=PL8dPuuaLjXtPAJr1ysd5yGIyiSFuh0mIL) ETA Everyday Astronaut

I've created a quick and dirty Google Sheet with the Herschel 400 targets (plus a few Solar System objects) to plot their size against their magnitude. This gives an idea of whether you'll want a large aperture or a wide/narrow field of view on your scope. Anyhow - feel free to play, but please don't mess with the data or control. Ta! https://docs.google.com/spreadsheets/d/10FPwh_zeAZPF3UfnL8Q_TDGnDGnQUn_2AQQ6KIMURpA/edit?usp=sharing

Another vote for IGAW - as has been said, it's the next step up from TLAO. An old 'classic' is the 3 book series "Burnham's Celestial Handbook"; though like many classics, it's not necessarily up to date. As with many of these books, they are available in preview mode on google books, so you can see how detail is presented https://www.google.co.uk/books/edition/Burnham_s_Celestial_Handbook_Volume_One/z3_CAgAAQBAJ?gbpv=1

It's often available from The Works. Alternatively, at somewhere like The Widescreen Centre https://www.widescreen-centre.co.uk/philips-planisphere-latitude-515-north.html Edit, just spotted they're out of stock there. Sorry

Here's a view of the Philips planisphere so you can see how it looks - I think I prefer the white on black appearance, but then, I've not used a blue on white version so who knows.

The important thing about a planisphere is to make sure you get one for the right latitude range. I'd expect most sold here to be correct for UK, but there are places that sell for other regions, and it'll be worth being specific. NB, the one that Louis D has is for a much lower latitude range (20-30 degrees) than us, so wouldn't be great, the one from FLO in Callisto's link is ideal. I bought one for our daughter when she was out in New Zealand that would be useless here. I like the Philips planisphere, as this gives the common names for the brighter stars, and that's a quick and easy way to learn them, as many charts just give the Bayer designations. Don't go for the 'glow in the dark' one though, that's just a gimmick you don't need (IMO, YMMV of course!)

When I bought my second scope, I went for the 102mm Mak, on a Synscan mount - and I found it quite a disappointment. Yes, good for planets and the Moon, but it really struggled with DSOs unless you could get out to really dark skies. The aperture didn't give enough light gathering for Galaxies and Nebulae to show up with enough contrast, and the long focal length gave a narrow field of view - which meant that Open Clusters didn't really show their best either. You could probably use it to survey double stars, but that's a fairly niche interest. Unfortunately, at the time, the budget didn't really allow us to go for the 127mm Mak, and it's only the last 4 or 5 years that I managed to get one second hand - now that is a much more capable scope.

Oh, and alternative to camping mats is Proplex / Correx sheeting. This is a twin-wall plastic sheeting used as floor protection by builders. It can be easily cut and will fold around the objective and can be held with sticky velcro pads. You can get a 2.4m x 1.2 m sheet for about £5 in Wickes. and that'll do multiple dewshields. Lighter and cheaper than foam mats, and folds flat for storage when not in use. https://www.wickes.co.uk/Proplex-Black-Surface-Protection-Sheet-2400-x-1200-x-2mm/p/118670

It is a good question - the consensus seems to be that the main cause of dew is the cooling of the objective. If this cools below the 'dew point', then water vapour in the atmosphere will condense onto the glass. Without a dew shield, the main cooling mechanism is by radiation to the much cooler sky, which can occur across the full 180 degrees open to the sky. With a dew shield, the exposure to the colder sky is reduced to a smaller angle, and this is said to reduce the rate of cooling of the objective I have a suspicion that there may also be an element that the dew shield creates a dead space for air close to the objective, and thus only a small amount of water vapour is available to be condensed out. You may be familiar with the way that condensation is worse at the beginning of a session, and that the air gets less humid as the evening progresses, I guess that if the condensation is reduced at the start of a session by the two factors mentioned above, then the overall problem is reduced as the air becomes generally less humid https://www.cloudynights.com/topic/57072-how-does-a-dew-shield-work/

My daughter bought a Manfrotto 222 head second hand for about £20 on eBay. To be honest I'd expected it to go for more.

Isn't it the other way around, "Svbony" ? Much easier to say.

Significantly de-focusing can do the same. It's how I first managed to get Jupiter centred on the webcam sensor - if it was the plan from the outset, I'd be thinking how clever I was; but in fact it was a case of 'I had <roughly> centred it in the eyepiece, and then swapped out the EP for the modded webcam' ; so, massively out of focus, which meant that light from Jupiter was bleeding onto the chip - enough for me to slew in the right direction.

Be aware though that some phones seem to limit the functions that other camera apps can access. Mrs G had a Nokia Android phone, and FV-5 couldn't go beyond 4 seconds, even though the built in camera could take longer images. But it was a pretty rubbish camera at night anyway

There are adapters that will take a 12v input and output 19v. With car cigarette lighter plugs.

Ahem, back to targets... The Coathanger is good fun, as it's so unexpected. Depending on your scope, the double double might be a test for your guests' eyes. If you're showing Jupiter and Saturn, you could also show them Uranus and Neptune - pointing out that neither was known about until relatively recently. You can then give them the challenge of seeing how soon they can 'bag' the remaining three planets.

I have to turn off Mobile Data, but apart from that it's as you'd expect: (Optional) Turn off WiFi on the phone Turn on the mount (Optional) Turn on WiFi on phone Select the 'SynScan' WiFi to connect to. Click through the warning that there's no Internet connection. Open Synscan app Hit the Connect button. It'll flash up the IP address and then should connect. (It's at this point where Mobile Data being on can bring up a message).

Hmmm, are your sure? I thought there was a detection of spectra from heavy elements in the visual wavelength observations made for the Neutron Star - Neutron Star merger that was correlated to a detection by LIGO, rather than it being anything that was detectable in the Gravitational Wave signal.

There are astigmatism correctors that can be fitted to eyepieces if you'd rather take your spectacles off. e.g. TeleVue Dioptrx - not cheap though.

I generally wear my spectacles for observing, so I can call Mrs G over and she won't need to adjust the focus* I use varifocals normally, but about 6 years ago got a pair of single vision spectacles for telescope use. Last evening I used them for the first time in a while, and discovered the downside - I now can't see the handset clearly as my 'near' vision has deteriorated so much. Getting old would be a real pain if it wasn't better than the alternative. * she always does, but that's fine.

This is pretty basic, but sometimes it's not clear whether you're seeing a target or not. You may all be doing this already, but last night I was out using Stellarium+ & Sky Safari+ 6 on my phone, and I realised that if I zoom in on a target I could then adjust the 'magnitude range' until the apps only showed the stars I could see in the eyepiece, which would let me know if I was really seeing the target or not. So, when I was looking to confirm that I was seeing the Saturn Nebula (C55), when SS+ 6 was showing all the stars down to 15 or less, it wasn't obvious, but if I reduced the magnitude so I could only see the background stars visible in the eyepiece ( <mag 11), it was clear that I was seeing the target in the expected place. Don't forget to set the eyepiece image flips before you start of course so that the app shows exactly what you're expecting to see in the eyepiece. I must remember to get out there again to see if I can see the RS Oph Nova tonight.